Final draft2

Climate-Smart Agriculture _ Training Manual Subtropical fruit production Figure 4 Different types of fruit flies occurring in South Africa. Source: Photo R de Jager. Monitoring is the first and most important must be considered. These are summed up as step in implementing effective integrated pest follows: control. It should be implemented systematically on an ongoing basis, down to the same number • Rainfall of representative plant samples within specified • Land use and vegetation cover blocks, so that data collected for generations of • Topography and terrain profile crops can be compared to determine whether • Soil type and depth an integrated pest management strategy is • Hydrology and water resources effective or needs to be improved. • Socio-economic and infrastructure conditions 3.5 WATER HARVESTING Rainwater harvesting is the gathering and storage of rainwater from roofs, land surface catchments, or rock catchments utilizing basic techniques as well as more complicated ones such as contemporary storage tanks. It employs a variety of ways to concentrate, collect, and store rainfall and surface runoff for various applications by connecting a runoff generating region with a distinct runoff receiving area. Because it allows for local food production, particularly at the family level, this approach is highly successful in increasing food security. Water harvesting is classified into three types: Water harvesting may be categorised into rainfall harvesting, floodwater harvesting, and two types: in-field harvesting and ex-field groundwater harvesting. When deciding on the harvesting. In-field harvesting, which includes best water collecting technology, a lot of things rooftop harvesting, water collection, and micro- catchments, is the most relevant as a solution to homesteads' lack of access to water in rural communities. 250

Climate-Smart Agriculture _ Training Manual Subtropical fruit production Rooftop harvesting – is often used as a method Another notable example of a mitigation of getting reasonably clean water that may be adaptation synergy is agroforestry, which is used for drinking and other domestic purposes. one of Africa's most visible land-use systems The 'catchment' area is the homestead's roof, across landscapes and agro-ecological zones. and it uses gutters and pipelines to direct water The significance of agroforestry stems from into tanks. the fact that it increases land productivity Water collection – effectively prevents net by providing a favourable microclimate, runoff from a given area by storing rainwater permanent cover, improved soil structure and and extending the period for infiltration. This organic carbon content, greater infiltration, method of water retention employs a variety of and higher fertility, therefore decreasing the strategies, including ridges, terraces, borders, demand for mineral fertilisers. Agroforestry is and mist harvesting. advantageous because it affects all three pillars Micro-catchment – there are numerous of CSA: adaptation, mitigation, and productivity. benefits to utilizing this system, including the Planting trees provides assets and revenue from fact that it is easy and affordable to build, has carbon, as well as wood energy and increased a high runoff efficiency, frequently avoids or soil fertility, while ecosystem services and tree lowers erosion by decreasing runoff, and can products may give livelihood advantages to be used on virtually any slope as well as flat people, particularly during drought years. The surfaces (Rutherford, 2003). majority of these advantages have immediate implications for local adaptation while also 3.6 INDIGENOUS TREE SPECIES / contributing to global efforts to reduce AGROFORESTRY atmospheric greenhouse gas concentrations. Many indigenous fruits are well recognized and highly valued throughout Southern Africa, especially by rural people that rely on these trees for food security. Indigenous crops can improve food security, boost global competitiveness, and diversify the agricultural sector. Indigenous plant species have the benefit of being better suited to local conditions and so have a greater chance of combating land degradation, promoting a sustainable agro-system, and maintaining natural plant heritage. Identifying and promoting alternative crops and cropping systems, such as agroforestry or the domestication of indigenous fruit trees, is therefore an essential approach for adapting to climate change, particularly for resource-poor rural households and emerging farmers. Native fruit tree crops offer numerous benefits over alien varieties. They are better adapted to the marginal and degraded soils that are frequent in communal areas, have higher drought tolerance, 251

Climate-Smart Agriculture _ Training Manual Subtropical fruit production reduced input and maintenance requirements, Indigenous trees can also be planted as living the fruit is extremely nutritious, and they are fences, creating a natural barrier as they resistant to several pests and diseases that are develop. Certain indigenous fruit trees are well widespread in foreign crops. Domestication of adapted to this and yield fruit that may be used indigenous fruit trees in South Africa, on the to make a variety of goods. These indigenous other hand, has been rather sluggish, possibly trees are well suited to local circumstances and due to a lack of suitable knowledge on tree grow well, if slowly, in dryland settings. Planting species best suited to certain areas. these trees beside an existing fence can give Indigenous fruits provide great prospects for extra protection, and as the fencing ages and alternative and specialised products to augment deteriorates, the trees will provide enough or replace traditional agricultural products and protection. Windbreaks can also be provided by crops. Indigenous fruits may be used to make these trees. a variety of value-added products such as jam, juice, and dried goods. Figure 5 Dovyalis caffra (kei-apple/ umQokolo) planted as a living fence. Practical Activity 3 1. What if any of the mitigating factors are being implemented by farmers in your area? 2. Do you believe that crops grown in your area will provide new problems to farmers, and if so, what do you believe these issues will be? 3. Is there a possibility of developing new crops in your region as a result of climate change - what crops and why? 4. What suggestions would you give to your farmers to help them adapt to climate change? 252

Climate-Smart Agriculture _ Training Manual Subtropical fruit production 4 CONCLUSION If the appropriate technological, institutional, socioeconomic, and regulatory infrastructure CSA is founded on three concepts: flexibility of is in place, crop management methods and agricultural practices, support for agricultural approaches have great potential to adapt to systems that maintain the integrity of the land and contribute to climate change mitigation. while boosting output for food security, and While agriculture contributes considerably to reduction of greenhouse gas emissions. climate change, it also presents options for Because of climate change, crops that have adaptation and mitigation. CSA is not a single been traditionally planted in one area may agricultural method or technique that can be no longer be able to grow there, but crops used globally. It is a procedure that includes that were previously impossible to grow site-specific assessments to determine the could now be viable due to changes in the best agricultural production technology and climate. Furthermore, ecological services that methods. support crop development (e.g., pollination, soil biodiversity) may be impacted. For these reasons, crop production must be addressed at the agricultural system level. 253

Climate-Smart Agriculture _ Training Manual Subtropical fruit production 5 REFERENCES AND RESOURCES Davis CL & Vincent K (2017). Climate Risk and Vulnerability: A Handbook for Southern Africa. Second edition. CSIR, Pretoria, South Africa. Food and Agriculture Organisation (2013). Climate-Smart Agriculture Sourcebook. Rome: Food and Agriculture Organization of the United Nations E-ISBN 978-92-5-107721-4 (PDF). www. climatesmartagriculture.org/72611/en. Gregory PJ, Johnson SN, Newton AC & Ingram JSI. (2009). Integrating pests and pathogens into the climate change/food security debate. Journal of Experimental Botany. 60 (10): 2827-2838. https://doi. org/10.1093/jxb/erp080 Heeb L, Jenner E & Cock MJW (2019). Climate-smart pest management: building resilience of farms and landscapes to changing pest threats. J Pest Sci. 92: 951-969. https://doi.org/10.1007/s10340-019- 01083-y. Mafongoya P, Gubba A, Moodley V, Chapoto D, Kisten L & Phophi M (2019). Climate change and rapidly evolving pests and diseases in Southern Africa. In: Ayuk E., Unuigbe N. (eds) New Frontiers in Natural Resources Management in Africa. Natural Resource Management and Policy. Vol 53. Springer, Cham. https://doi.org/10.1007/978-3-030-11857-0_4. Padgham J (2009).Agricultural development under a changing climate: opportunities and challenges for adaptation (English). Joint departmental discussion paper; issue no. 1. Washington, DC: World Bank. http://documents.worldbank.org/curated/en/293891468154156734/Agricultural-development-under- a-changing-climate-opportunities-and-challenges-for-adaptation Republic of South Africa (2019). National Climate Change Adaptation Strategy, Version UE10, Dept. Environment, Forestry and Fisheries. https://www.environment.gov.za/sites/default/files/docs/ nationalclimatechange_adaptationstrategy_ue10november2019.pdf. Schulze RE (2017). Sustainability of Climate. Fertasa 57th Annual Congress 2017. http://www.fertasa. co.za/publications/archives/2011-current Schulze RE (2010). Atlas of Climate Change and the South African Agricultural Sector: a 2010 Perspective. Pretoria, RSA: Department of Agriculture, Forestry and Fisheries. https://www.nda.agric.za/doaDev/ sideMenu/forestry/docs/Booklet%201%20Agric%20Setting%20Scene.pdf 254

Climate-Smart Agriculture _ Training Manual Subtropical fruit production LIST OF FIGURES Figure 1 Maximum and minimum temperatures in South Africa 224 with projected changes due to climate change effect. 228 Figure 2 Horticultural Zones in South Africa. 244 Figure 3 Citrus trees planted under shade netting. 250 Figure 4 Different types of fruit flies occurring in South Africa. 252 Figure 5 Dovyalis caffra (kei-apple/ umQokolo) planted as a living fence. 229 242 LIST OF TABLES Table 1 Description of Horticultural Zones. Table 2 Comparing current agricultural practices and Climate-Smart Agriculture. 255

MODULE 7 Vegetable Production Compiled by Erika van den Heever, Dr Nadia Araya, Dr Hintsa Araya, Sidwell Tjale, Musa Mtileni, Manaka Makgato, Khomotso Maboka, Dr Salmina Mokgehle, Andy Sithole, Lulama Vitshima, Dr Christian du Ploo and Dr Sonja Venter Agricultural Research Council – Vegetable and Ornamental plants

Climate-Smart Agriculture _ Training Manual Vegetable production Table of Contents 1 INTRODUCTION 261 2 CROP SELECTION 263 2.1 CLIMATE 264 2.2 QUALITY OF THE SOIL 266 2.3 WATER 268 2.3.1 Water availability 268 2.3.2 Water quality 268 2.3.3 Watering methods 269 2.4 CROPS AND CULTIVARS 270 2.5 SIZE, SUPPLIES AND COST ANALYSIS 270 2.6 BIOLOGY OF PLANT PESTS AND DISEASES 271 2.6.1 Diseases 272 2.6.2 Pests 275 2.6.3 Common vegetable pests 275 2.7 WEEDS 279 2.8 CONVENTIONAL VEGETABLES VERSUS INDIGENOUS OR TRADITIONAL VEGETABLES 280 2.9 OTHER IMPORTANT ASPECTS OF VEGETABLES TO DROUGHT TOLERANCE 282 2.10 SEED PRODUCTION SYSTEMS – ACCESS TO CLIMATE-RESILIENT PLANTING MATERIAL THAT IS DROUGHT RESISTANT (FARMER PRODUCTION SYSTEMS) 283 3 SOIL MANAGEMENT 284 3.1 ORGANIC MATTER OF SOILS 284 3.2 HOW TO MAKE COMPOST 284 3.3 MULCHES (DROUGHT-RESISTANT SOIL) 288 3.4 ROTATION OF CROPS 292 3.5 BAG SYSTEM 292 3.6 COVER CROPS 294 3.7 GREEN MANURE 296 3.7.1 Sunn hemp (Crotalaria juncea L.) 296 4 SOIL IMPROVEMENT AND IRRIGATION 297 4.1 RAINWATER HARVESTING 297 4.2 INTERCROPPING STUDY AT ARC 300 4.3 VERMICULTURE 301 4.4 IRRIGATION SYSTEMS 301 4.4.1 Influence of environmental factors in the selection of the irrigation system 301 4.4.2 Types of irrigation systems and a comparison of the different systems 302 4.5 SOIL MOISTURE 306 4.6 WATERING TECHNIQUES 308 4.7 WATER REQUIREMENTS OF VEGETABLE CROPS 308 257

Climate-Smart Agriculture _ Training Manual 309 Vegetable production 309 4.8 WATER-SAVING TECHNIQUES 309 4.8.1 Use of greywater 312 4.8.2 Rooftop water harvesting 312 4.8.3 In-field rainwater harvesting 313 4.9 INSTRUMENTS MAKING IRRIGATED SYSTEMS MORE EFFICIENT 313 5 SELECTED DROUGHT TOLERANT VEGETABLES 313 5.1 PEARL MILLET 313 5.2 TARO (COLOCASIA ESCULENTA (L.) OR AMADUMBE 313 5.3 WILD MUSTARD (BRASSICA JUNCEA L.) 314 5.4 WILD MELON (CITRULLUS IANATUS L.) 314 5.5 SWEET POTATO 314 5.6 SPINACH (SWISS CHARD) 315 315 5.6.1 Introduction 315 5.6.2 Soil requirements 315 5.6.3 Climatic requirements 315 5.6.4 Cultivars 316 5.6.5 Crop rotation 316 5.6.6 Soil preparation 316 5.6.7 Planting method and spacing 316 5.6.8 Fertilisation 316 5.6.9 Water requirements 316 5.6.10 Harvesting 317 5.6.11 Storage 317 5.6.12 Disease control measures 317 5.6.13 Pests 317 5.7 AMARANTH (AMARANTHUS SPP) 318 5.7.1 Origin and distribution 318 5.7.2 Production level: South Africa 318 5.7.3 Major production areas 318 5.7.4 Cultivars 319 5.7.5 Description of the mature plant 319 5.7.6 Climatic requirements 319 5.7.7 Soil requirements 319 5.7.8 Propagation 320 5.7.9 Soil preparation 320 5.7.10 Field layout and design 320 5.7.11 Planting 321 5.7.12 Fertilisation 321 5.7.13 Irrigation 321 5.7.14 Weed control 5.7.15 Pest and disease control 5.7.16 Other cultivation practices 258

Climate-Smart Agriculture _ Training Manual 321 Vegetable production 322 322 5.7.17 Harvesting maturity 322 5.7.18 Seed harvesting 322 5.7.19 Post-harvest handling 322 5.7.20 Screening 322 5.7.21 Grading 322 5.7.22 Packing 323 5.7.23 Storage 323 5.7.24 Preserving methods 323 5.7.25 Transport 324 5.7.26 Marketing 324 5.7.27 Utilization 325 5.8 COWPEAS 325 5.8.1 Introduction 325 5.8.2 Soil requirements 325 5.8.3 Climatic requirements 325 5.8.4 Cultivars 325 5.8.5 Crop rotation 325 5.8.6 Soil preparation 326 5.8.7 Planting time 326 5.8.8 Growth period 326 5.8.9 Seed 326 5.8.10 Spacing 326 5.8.11 Fertilisation 327 5.8.12 Water requirements 327 5.8.13 Planting process 327 5.8.14 Cultivation after planting 327 5.8.15 Weed control 328 5.8.16 Diseases 328 5.8.17 Harvesting 328 5.9 PIGEON PEAS 328 5.9.1 Background 328 5.9.2 Production areas 328 5.9.3 Climatic requirements 328 5.9.4 Soil requirements 328 5.9.5 Rainfall 328 5.9.6 Propagation material 329 5.9.7 Soil preparation 329 5.9.8 Planting 329 5.9.9 Fertilisation 5.9.10 Irrigation 5.9.11 Weed control 259

Climate-Smart Agriculture _ Training Manual 329 Vegetable production 329 329 5.9.12 Pest and disease control 330 5.9.13 Harvesting methods 330 5.9.14 Uses 330 5.10 BAMBARA GROUND NUTS (VIGNA SUBTERRANEA) 330 5.10.1 Origin and distribution 331 5.10.2 Production levels in South Africa 331 5.10.3 Major production areas in South Africa 332 5.10.4 Varieties and cultivars 332 5.10.5 Mature plant 332 5.10.6 Climatic and environmental requirements 332 5.10.7 Soil requirements 332 5.10.8 Cultivation practices 333 5.10.9 Weed control 333 5.10.10 Pest and disease control 334 5.10.11 Other cultivation practices 334 5.10.12 Harvesting 334 5.10.13 Post-harvest handling 337 5.10.14 Marketing 338 5.10.15 Utilization LIST OF FIGURES LIST OF TABLES 260

Climate-Smart Agriculture _ Training Manual Vegetable production 1 INTRODUCTION industrial needs (Mjoli, 2010). Improvements in water use efficiency (WUE) in agriculture are Vegetables are the fresh edible parts of some necessary due to a lack of freshwater, growing herbaceous plants such as roots, stems, leaves, input prices, and population growth. Increased flowers, fruit, or seeds. These plant components water-use restrictions and severe droughts are consumed raw or prepared in a variety of continue to have a negative impact on rural ways, most often as a savory rather than sweet people in South Africa. meal. For millennia, the term \"vegetable\" South Africa is an arid country that ranks in the referred to any edible plant materials, including world's top 30 driest. South Africans use 237 flowers, fruits, stalks, leaves, roots, and seeds. litres of water each day, which is more than the Another rather arbitrary concept is utilised in world average of 173 litres. culinary and cultural traditions. Savoury fruits Food and nutrition security is a major concern and vegetables like tomatoes and courgettes in South Africa. Moreover, extreme weather are included, as are blossoms like broccoli and occurrences such as El Nino and El Nina, as well seeds like pulses (Harri & Bianchini, Franca, as increasing temperatures, poor soil fertility, 2003; Melissa Petruzzello, 2018). and unpredictable rainfall, will worsen food Vegetables are produced throughout the and nutrition security, negatively impacting whole world, with various degrees of success resource-poor households. depending on the global climate. As a result of Another issue that contributes to the need global agricultural trade, it is now feasible to is water quality. Water quality is the ability buy vegetables grown hundreds of kilometers of a body of water to be safe, drinkable, and abroad, from subsistence farmers supporting appealing to all forms of life on the planet. their families' food needs to agribusinesses The already scarce fresh water in South Africa with huge acreages of single-product crops. is deteriorating in quality due to increased After harvesting a crop, common procedures pollution and the devastation of river catchments include grading, storage, processing, and caused by urbanization, deforestation, river selling. Because they are abundant in vitamins, damming, wetlands destruction, industry, minerals, and dietary fiber while being low in mining, agriculture, energy consumption, and fat and carbs, raw vegetables are an essential accidental water contamination. Pollution and element of human nutrition. Many nutritionists watershed degradation are becoming more recommend that people should consume five prevalent as the human population rises. or more servings of fruits and vegetables each The amount of water on the earth is constant day. and cannot be raised or decreased, although it South Africa is one of the nations most likely is distributed unevenly. to suffer severe water scarcity due to a lack of effective water management systems (Mjoli, 2010). This will almost probably lead to water tensions between residential, agricultural, and 261

Climate-Smart Agriculture _ Training Manual Vegetable production South Africa receives only 300-400 mm of rain production systems, as will innovative practices each year. This is nearly half the global average. like better weather forecasting, more resilient As a result, South Africa is classified as a water- food crops, and risk insurance. These strategies stressed country. will need to adapt to local, regional, and global This guide does not provide a step-by-step situations, and they may differ significantly from action plan. There is no one-size-fits-all solution farmer to farmer. that can be applied to every scenario. Mulching, As a consequence, this manual will offer intercropping, conservation agriculture, solutions that may be customized to different crop rotation, integrated crop-livestock crop systems. It takes a technical approach to management, agroforestry, improved grazing, the issue, such as research findings. In certain and better water management will all play a situations, definitions for technical terminology role in the transition to climate-smart vegetable are supplied. 262

Climate-Smart Agriculture _ Training Manual Vegetable production 2 CROP SELECTION • Mustard greens • Okra Crop selection is very important to crop farming • Summer squashes success. It is a criterion that must be satisfied • Most herbs before starting a farming business. Even in Drought-tolerant crops have deeper root the absence of a predetermined location and systems to cope with both heat and low water site for a farm, the crop to be grown can be levels. Many of them grow fast, reducing chosen primarily based on its marketability their long-term water requirements. Drought- and profitability, as well as the current farm tolerant strains exist for several vegetables conditions (biotic factors refer to living that demand a lot of water, such as the Black organisms and topographic features, various Diamond watermelon and the Heatwave II climatic factors such as water availability, tomatoes. When looking for drought-resistant temperature, and so on). Before planting, seeds and plants for gardening, look for labels farmers should consider drought-tolerant that state the plant can thrive in higher temps vegetables that have been specifically chosen and needs little to moderate water (Figure 1). for drought tolerance, as well as those that thrive in hot, dry environments. Among the most popular options are: • Cowpeas, black-eyed peas and field peas • Edible amaranth • Quinoa Figure 1 Grouping vegetables according to their water needs. Source: Linda, 2019. 263

Climate-Smart Agriculture _ Training Manual Vegetable production If you anticipate a dry year, instead of sowing 2.1 CLIMATE seeds, buy seedlings to develop your garden. A nearby nursery will have a big selection of The climate of a given region is defined as the drought-tolerant vegetable seedlings. temperature, humidity, daylight, and wind If you select a fast-maturing item, such as conditions of that location. Climate has a zucchini (which grows in approximately 60 days substantial impact on all stages and processes from seed to fruit), you will have a bountiful of vegetable development. Water is an harvest within a month of putting it into your important consideration, and South Africa has garden. If you must start from seeds, choose been classified as one of the world's 30th driest vegetables that develop quickly from seed to countries (Figure 2), with an annual average harvest, such as spring radishes, which may be rainfall of less than 500 mm, significantly less harvested in less than 30 days. than the global annual average rainfall of 860 Different plants require different amounts of mm (FAO, 2016), and which is expected to water for optimal growth. If you don't design decrease as a result of climate change due to your garden with the water demands of global warming. particular plant species in mind, you may end Rainfall in South Africa is also unevenly up over- and under-irrigating. Instead, focus on distributed. The eastern half of the country is giving the right quantity of moisture to plants significantly wetter than the western half due to while conserving water by grouping vegetables the nature of the weather. Droughts and floods in your garden based on their drought tolerance occur regularly in South Africa, impacting the and watering requirements. quantity of water available across the country. Figure 2 Annual rainfall distribution in South Africa. Source: Rand water, 2021. 264

Climate-Smart Agriculture _ Training Manual Vegetable production Table 1 Water use in South Africa. Usage Source: Ashwell & Hoffman, 2001. (%) Water user 60 18 Agricultural use (including irrigation) 11.5 Environmental use 10.5 Urban and domestic use Mining and industrial use It is described as the time when the conditions develop from seed to maturity. Depending on required for plants to mature and produce are where you live, you may never experience frost; present in your region for them to grow and instead, your dry season will act as \"winter\". produce. The number of days elapsed between You have no control over the length of your the last frost in the spring and the first frost in growing season because it is completely the fall determines the duration of the growing governed by your region's environment (Table season, which is measured in days. On a wide 2). Vegetable farmers should consider the scale, these two dates mark the beginning and following climatic parameters when growing end of the period of time during which plants vegetables. Table 2 Climatic conditions to be considered in the production area. Temperature • Hottest month: Maximum & minimum temperature • Coldest month: Maximum & minimum temperature Rainfall • Average annual rainfall • When is the dry season? Position • Latitude and longitude • Height above sea level • Slope of the land Soil • Soil type (sandy, silty, clay, mixture) • pH • Is the soil saline (salty)? • Soil depth 265

Climate-Smart Agriculture _ Training Manual Vegetable production • Temperature • Radiation What are the lowest and highest temperatures A minimum of six hours of direct sunshine each in the area? The temperature of an area day should be received by the plot. However, determines which crops may be grown and in the early stages of growth, some shade from when they can be planted. natural or man-made sources may be useful to protect young plants from withering due to • Relative humidity excessive sunlight. This can cause problems with irrigation scheduling. At sea level, the relative humidity 2.2 QUALITY OF THE SOIL is greater than on the Highveld. Infestation of diseases, such as mildew on pumpkins, can be The capacity of a soil to execute certain tasks for worsened by hot and humid conditions. specific land uses or within specific biological limitations is referred to as soil quality. Despite • Frost the fact that this capacity is innate in soils, it The latest date of frost determines when frost- differs from one to the next. Organic-matter sensitive crops may be sown. Frost may have content, salinity, tilth, compaction, accessible an influence on the growing season of a crop. nutrients, and rooting depth are just a few of Planting a certain crop poses a risk if it takes the indicators that may be used to measure the a long growing season to develop and there is health or condition of the soil in any given area, frost in the area. as well as its quality. • Wind • Slope The wind direction influences planting The slope of a field must be addressed when arrangement since it affects irrigation and crop preparing and farming the soil. Erosion development. Windbreaks may be necessary may easily occur if the slope is steep and for high-wind areas. The continuous breeze inappropriate farming methods are utilised. affects water evaporation. • Soil conditions • Rainfall The site should have enough drainage. The most To plan your irrigation, you'll need to know essential component of a farm is the soil, and it how much rain has fallen. It is critical to deduct must be well-managed. The percentage clay, pH, the quantity of water that must be applied at kind of soil, soil texture, and planting depth are a specific period (monthly and/or seasonally) all important factors to consider. Each location from the overall amount of water that must be has its own type of soil, and understanding the applied. Watering must be timed according to soil's history and keeping track of agricultural the plant's developmental cycle. operations is essential for crop rotation. • Hail Quality loam to clay loam soils are suitable for The history of hail falls should be kept since it vegetable cultivation as depicted in Table 3. is essential to plan around the risk of hail in a given location, as it can be a substantial risk that can result in crop loss, either partial or whole. 266

Climate-Smart Agriculture _ Training Manual Vegetable production Sandy soils may be troublesome due to excessive The greatest physical quality of the soil is water and nutrient drainage, as well as the contributed by fresh organic matter that presence of nematodes. All of these variables decomposes fast. The presence of moisture, will result in crop stress and lower yields. nitrogen, and warm temperatures accelerates Good soil is required for a high yield. All of decomposition. Organic matter slows the loss the nutrients necessary for healthy plant of minerals through soil leaching until they are growth must be present in the soil, as well as liberated by microorganisms. Organic waste a structure that permits plants to stand erect. breakdown increases soil structure, allowing The soil structure must be capable of retaining roots to penetrate deeper into the soil. Organic sufficient air and water for plant roots while matter incorporation can enhance the water- allowing excess water to drain. The bulk of holding capacity of sands and sandy soils, nutrients are recycled from the soil naturally whereas aggregation in heavy soils can aid in by plant roots and returned to the soil by drainage. Crop rotation is required to maintain falling leaves and other organic debris. Organic high soil productivity. Although some soil is waste is consumed by earthworms and other naturally fertile, the majority of soil is infertile creatures and converted to humus, which or has lost nutrients as a result of bad farming darkens and strengthens the topsoil. Humus is methods. readily removed or washed away if the soil is left exposed. In most instances, the subsurface yields less. Table 3 Depicts some of the characteristics of typical soil types. Soil type Features Methods of improvement Sand Less than 10% clay, won’t aggregate or Regularly add organic matter and Sandy loam will slightly aggregate fertiliser, use green manure crops Sandy clay loam 15-20% clay, forms a stable ball without Add organic matter, fertiliser and use to clay loam difficulty green manure Clay 20-40% clay, can be rolled into a stable Organic matter is less important. The Silt sausage amount of fertiliser required will be determined by soil analysis. More than 40% clay, good water holding Add organic materials, compost, and capacity, very hard when it dries gypsum Poor structure, good fertility Add loose organic matter, use green manure 267

Climate-Smart Agriculture _ Training Manual Vegetable production A soil laboratory should examine the nutritional 2.3 WATER quality of the soil on a regular basis. The optimum rate of fertiliser application is determined by the Water is vital in the process of transporting nutritional state of the soil. It is usually a good nutrients and carbohydrates from the soil to idea to have your soil tested. Enquire with your the plants. At some point in their existence, local extension service or a fertiliser company all plants will be harmed by water scarcity or for assistance. drought. This can be lethal to plants or lead The soil analysis is broken down into two sections: them to grow at a much slower rate in some soil characterization and fertility status, and soil situations. Plants that have been exposed to fertilisation recommendations. The study covers extended drought may be more susceptible to a variety of topics, including soil characteristics secondary infection by pests and diseases than (pH, texture, percent exchangeable sodium, they would be otherwise. The following are percent organic matter, and salinity expressed some examples of water parameters that can as electrical conductivity). The plant's fertility affect plant growth: condition is described in terms of nutrients 2.3.1 Water availability available to it. The second section, named The amount of water required to grow \"fertility recommendation,\" lists the amounts vegetables at maximum yield might be rather of fertiliser that should be used. These amounts large. On a 1 000 m2 (very small scale) of are determined by the crop requirements, crop vegetable growing, 15000-20000 litres of water management strategies that affect the crop (as are required per week. described in the information sheet), existing Vegetable production will be limited to 100-200 soil fertility levels, and the producer's desired m2 if a borehole is the sole accessible water yield target. A special notification is given if the source and does not supply water at a rate of at results of the tests suggest that a salt or sodium least a litre/sec. hazard exists, or if the information provided If municipal water is used, the cost should be reveals any other unique problems. carefully calculated. The pH of the soil, for example, determines Select irrigation systems that are appropriate whether it is acidic or alkaline in nature. The pH for the land and crops being grown. The system of acidic soil is 7, while the pH of alkaline soil is must be easy to use and maintain. 7. A pH of less than 7 indicates that the soil is 2.3.2 Water quality acidic, whereas a pH of greater than 7 indicates Another significant factor to consider is the that the soil is neutral. A plant that grows well water quality. If the water quality is inadequate, in acidic soil will suffer in alkaline soil, while a it will have a negative impact on the soil quality, plant that grows well in alkaline soil will struggle which will have a negative impact on the crop in acidic soil. Without a soil testing kit, it's quality. Wastewater (greywater) is, for example, impossible to detect the pH content of the soil but local farmers and extension officials should be able to tell you whether it's neutral, acidic, or alkaline. 268

Climate-Smart Agriculture _ Training Manual Vegetable production the water that comes from sinks, bathtubs, Transplants showers, and washing machines, among other Watering is necessary before and after places. Water for the garden usually does not transplanting, especially in hot weather when need to be treated with chemicals or biological immature plants can't replace water lost via agents before use. It is vital to consider the their leaves. following while using wastewater for your Leafy crops garden: wastewater that contains an excessive Leafy crops (such as cabbage and spinach) amount of dirt should be removed. The water require roughly 25 litres per square meter from a washing machine's final rinse, on per week of water and should be actively the other hand, can only be used in modest developing from the time they are seeded amounts. The safest sort of wastewater is bath or transplanted. Any interruption in the or shower water. There is a scarcity of clear water supply might have an impact on yield scientific information on the long-term impacts and quality. In the summer, splitting the of bath/shower water on soils after extensive water supply into two applications may be use. When this product has been used in the preferable. As the crops mature, more water past, no detrimental impacts on the soil or plants should be applied. In cooler months (winter), have been observed. According to estimations, however, single weekly irrigation is sufficient. excellent soil with a high organic matter content Root crops can hold about 25 of wastewater per square The typical weekly water requirement for metre of the surface area every week. Using potatoes, carrots, and sweet potatoes is wastewater in a cycle with freshwater to purify between 10 and 15 litres per square meter. the soil of possibly dangerous chemicals is In the absence of rain, regular watering is an effective method. To aid in the natural required, with the goal of ensuring that water decomposition of waste leftovers, thick mulches permeates deeply into the soil. Poor root should be spread to areas that are maintained development is hampered by insufficient by wastewater. irrigation. When tubers begin to form, 2.3.3 Watering methods potatoes require more water. For all vegetable crops, good yields are Other crops impossible without enough water during the The average water need for crops including entire growing season. Some crops require more green beans, green peas, pumpkin, tomato, water than others, and the water requirements and cowpea is 25 litres per square meter, of various cultivars of the same crop might but this varies depending on the stage vary. The following are merely suggestions that of development. Excessive leaf growth is should be tweaked depending on the season encouraged by too much water up to this and conditions on your plot or garden: point. Water-efficient vegetables Seedlings Cowpeas, amaranth, pigeon peas, and The critical time is between sowing and the Bambara, for example, are drought-tolerant emergence of the seedlings. At all times the crops that may be cultivated in rain-fed soil in contact with the seed must be moist. environments if the rain is evenly distributed. 269

Climate-Smart Agriculture _ Training Manual Vegetable production 2.4 CROPS AND CULTIVARS production in your area and for selling in your market. The seed firm wants to know what the When determining which crops to grow in summer and winter temperatures will be when a given year, it is vital to make an informed the first frost will occur, and how long each decision. The first condition is that your crop has season will persist in each site. a market that is appropriate for it. Determine the market's size, the distance between the 2.5 SIZE, SUPPLIES AND COST market and its location, as well as the quality ANALYSIS and quantity of products that the market requires. Make sure you understand the crop's Producing vegetables is an expensive endeavor. climatic requirements and compare them to the High input and labor expenses are required climate in your area to see if the crop will grow to produce vegetables commercially, and as a in your area of production. result, the best possible yield and quality are Crop selection is also influenced by the types required. Almost all of the aforementioned of nutrients that the crops under consideration aspects have an impact on costs and financial may provide. Vitamin A is one of the nutrients resources. You should abandon the concept if in our diets that is badly lacking, so dark-green you don't have enough money to purchase all of leafy vegetables and orange vegetables should the necessary inputs for vegetable cultivation. be ingested on a regular basis. Carrots, butternut The materials that will be required, such as squashes, and orange-fleshed sweet potatoes, fertiliser, seeds/seedlings, and chemicals, will as well as leafy vegetables like Amaranthus and be determined as part of the planning phase. spinach, are among the most significant crops The size of the garden or field will dictate the to plant in your vegetable garden. type of cultivation procedures and equipment It's crucial to choose the right cultivars. A that will be used. If the fields are small, the task tomato, for example, is more than just a tomato; can be accomplished by hand, requiring the use there are numerous varieties, including short of tools such as garden forks, rakes, hand hoes, growers, long growers, processing cultivars, and a wheelbarrow. In all other circumstances, and fresh market cultivars. To guarantee that a tractor with the necessary implements is the appropriate cultivar is selected for all required. Because vegetable seeds are often vegetable crops, it's a good idea to first figure very small, successful planting necessitates a out who the crop's target market will be. The fine seedbed. most successful technique is to talk to several The size of the plots that will be created will be seed firms and figure out which cultivars are determined by the volume of products that will best for production in your area and for selling be sold. Plant in accordance with an anticipated in your market. The seed firm wants to know marketing date as well. what the summer and winter temperatures will When deciding on the arrangement of the be when the first frost will occur, and how long vegetable plots, keep in mind the crop rotation each season will persist in each site. The most strategy that will be utilised. successful method is to talk to several seed firms and figure out which cultivars are best for 270

Climate-Smart Agriculture _ Training Manual Vegetable production 2.6 BIOLOGY OF PLANT PESTS Pest and disease control can be exceedingly AND DISEASES costly, even prohibitively so in some cases. If a farmer chooses to apply pesticides, he or she is Vegetable growers are constantly confronted liable for the expense of the chemicals, spraying with insect pests and diseases that wreak equipment, and protective clothes. Pesticides havoc on their crops (Figure 3). Typically, are sometimes applied haphazardly, causing they'd seen these in past seasons, and the environmental damage. Disease control may symptoms appear to be the same. There are need extra effort on the farmer's or gardener's times, however, when an atypical pest (not part. It's possible that this is one of his or her native to South Africa) may appear. Exotic creations. He or she could also be forced to pay pests are a source of concern for farmers, for the services of others in order to carry out as they have the potential to disrupt the disease control initiatives. Small-scale farmers agricultural and horticulture industries, as who cannot afford these management methods well as raise production costs and consumer may experience a different form of loss than prices (Hoffmann, Learmonth & Wood, 2014). their larger counterparts. Figure 3 General plant pests and diseases. Source: ARC. 271

Climate-Smart Agriculture _ Training Manual Vegetable production They may need to sell their product as quickly to causing severe damage. Plant diseases can as possible due to its limited shelf life. For the cause mouldy coatings, wilting, scabs, blotches, development of a disease, the presence of rusts, and decay, to name a few symptoms the three components listed below (Scholthof, (Bost, 2021). 2006) (Figure 4) is required. 2.6.1.1 Disease transmission Windblown, rain, or dust are common ways for • Pathogen invasive species to travel from plant to plant • Host in vegetable crops (Table 4). Humans spread • Favorable environmental conditions germs through a variety of techniques, including 2.6.1 Diseases plant cultivation, grafting, pruning, and moving The plants that they infect and reproduce on infected plant material. Animals such as insects provide the energy for vegetable diseases. and mites, in addition to humans, are common They are typically encouraged by wet weather, disease vectors (lvarez-Hernández, 2019). poor drainage, and limited airflow, in addition Figure 4 The disease triangle. Source: Scholthof, 2006. 272

Climate-Smart Agriculture _ Training Manual Vegetable production Table 4 The method by which plant diseases transmitted. Host Components of epidemics Resistance refers to the ability of a plant to exclude or overcome the effect of a Pathogen pathogen or any other damaging factor. Levels of resistance vary. Susceptibility refers to the inability of a plant to resist the effect of a pathogen or Environment any other damaging factor. Time Human • Type of crop. activities • Age of host plant: Some hosts become more susceptible to a particular disease as they get older. Some pathogens only attack hosts in the seedling stage. • Presence or absence of virulent races, i.e. races of the pathogen that can attack the crop. • Amount of inoculum near the host, e.g. the amount of plant debris in the field infected with fungi, bacteria or viruses, or the number of virus-infected weeds growing in or near the crop. • How does the pathogen spread? • Moisture. Increasing levels of moisture will increase the incidences of most fungal and bacterial diseases. • Temperature: Too high or too low temperatures can “break” resistance in the host, destroy the pathogen, or affect the rate at which the pathogen infects or multiplies. • How long do particular events last, e.g. how long does the environment remain favorable for disease to attack the plant? How many cycles can the pathogen go through in the life span of the crop? • Choice of site, e.g. is the soil well-drained drained or poorly drained? • Choice of planting material e.g. does the grower use clean seed. • Disease control. Does the grower use chemical sprays, resistant varieties, sanitation, etc.? • Wind • Runoff and flood irrigation The wind has been shown to play a significant Runoff and flood irrigation play an important impact in the spread of some fungus. Spread role in the transmission of soil-borne illnesses, can occur over long distances. particularly fungus and bacteria. • Rain and overhead irrigation • Insects and other vectors The spread of germs and fungi in the environment Many viruses, including aphids, that are is aided by splashing water. Spreading is often transmitted through insects and other vectors, done over a short distance. rely on this mechanism of transmission. 273

Climate-Smart Agriculture _ Training Manual Vegetable production • Seeds ̶ DISEASES People can spread diseases across extraordinarily Because disease organisms are microscopic, long distances, even between countries, by they cannot be seen and therefore their using sick seeds as planting material. Vaccines: arrival and accumulation in the crop cannot Vaccines are effective at stopping the disease be monitored as easily as the arrival and from spreading. accumulation of insect pests in the crop. To protect the crop from possible infection, it is • Diseased nursery seedlings possible that regular preventative sprays will be This is how some fungi, bacteria, and viruses required in some cases. spread from one plant to another in a nursery. ̶ SYMPTOMS • Boots and shoes Since disease organisms are small, they can't This method allows people to spread many be seen, thus their arrival and buildup in the pathogens, mostly soil-borne pathogens. crop can't be tracked as easily as insect pests. In rare circumstances, regular prophylactic sprays • Field equipment (e.g., tractors) may be necessary to protect the crop against People use this method to spread both soil- infection. borne and foliar diseases. In other circumstances, the farmer's • Why is accurate diagnosis important? observations and careful sampling can make Disease control requires a significant investment the difference between a correct diagnosis and of time, effort, and money. A faulty diagnosis can none at all. result in control errors that are both damaging and expensive. As a precautionary measure, one It is helpful for farmers to know what types of should strive to become as proficient at making symptoms to look for, even if they do not do the diagnoses based on symptoms as possible in final diagnosis. case expert assistance is unavailable and the situation demands it. • Expand awareness of what is going on around • Identification of pests and diseases Due to a lack of knowledge, it might be difficult You must be aware of what is going on in for a farmer or gardener to effectively diagnose your immediate surroundings. You must know pests and illnesses in the field. He or she will need whether summers are typically hot and dry or to call a plant pathologist or an entomologist whether they are typically mild and wet; in other who works in a laboratory in these cases (for words, you must know the climate. You must example, the Agricultural Research Council, know whether it was warm and rainy during the Vegetable, Industrial and Medicinal Plants). previous week or the previous month. ̶ INSECTS You also need to know what kinds of crops It is vital to inspect the crop at least once a week people are growing in your area and the way in to see if any pests are present. Chemicals are that they are commonly produced in the area. only used to counteract them if they are present Certain disease patterns in your area become and in harmful amounts. more apparent if you pay attention to growers as they describe what they do and what problems they encounter. 274

Climate-Smart Agriculture _ Training Manual Vegetable production • Ask yourself: How soon does the farmer/ • In some form or another, pests attack gardener need an answer? all vegetable crops to varying degrees of If you think a farmer or gardener is suffering severity. To effectively control an insect from a significant disease outbreak, you must infestation, it is critical to first identify the intervene within two to three days in order type of insect that is attacking your crop as to save the crop. Even if the situation appears accurately as possible. bleak, you should take the appropriate steps if • Keep track of pest and disease problems you need more time to make a diagnosis since throughout the season so that you can you are diagnosing a problem you are unfamiliar plan and prepare better for the following with. It can help you learn from the experience, season. The success of vegetable gardening in addition to supporting the farmer in planning is greatly enhanced by the implementation for the future season. of a pest and disease management programme. The equipment that advisors will need to bring • When it comes to reducing the need with them when conducting field assessments. for chemical control, good agricultural Apart from your mental equipment, you may practices and maintaining high fertility find it useful to have the following items with and vigorous growth are two of the most you: effective methods. • A pocket knife • Pesticides should be used with caution. The • A spade or trowel first rule of safety is to carefully read the • A notebook instructions on the container's label and to • Plastic bags to collect samples follow them exactly as they are written • Labels • Before purchasing a pesticide, check to • Questionnaire see if it contains a list of the pests that will be controlled. Use the proper products in accordance with the manufacturer's 2.6.2 Pests instructions, and avoid using higher The presence of insect pests in any vegetable concentrations or larger dosages than what garden can cause significant problems. Insects is recommended. feeding on the plant may prevent the plant • Store pesticides out of reach of children and from growing properly, resulting in a poor crop animals, behind locked doors, and away or even a complete crop loss. The use of natural from food. Always store pesticides in their and biological methods to reduce the damage original, clearly labelled containers, and caused by insect pests is becoming increasingly properly dispose of any empty containers popular in the long run. There are cultivars of after they have been used. various vegetables, for example, that have been specifically bred to be pest-resistant (Masabni, Dainello & Cotner, 2009). 2.6.3 Common vegetable pests Pests that attack leafy vegetables include flies, Developing an integrated pest management bugs, mites, worms, and molluscs, to name a (IPM) strategy that incorporates insect-resistant few. Flies, bugs, mites, worms, and molluscs cultivars as well as environmentally friendly are the most common pests that attack leafy pest control methods can help to reduce insect vegetables. Here is a list of the most common damage. When growing vegetables, keep the pests of leaf vegetables and information on how following considerations in mind: to prevent, control, and manage them if you grow greens or plan to grow them. 275

Climate-Smart Agriculture _ Training Manual Vegetable production 2.6.3.1 American bollworm 2.6.3.2 Aphids Beans, brassicas, peas, potatoes, and tomatoes With soft, pear-shaped bodies that are are among the crops that are attacked by the predominantly green or black, these insects bolworm, (shown in Figure 5). Black, brown, (see Figure 6) are typically found in colonies green, or pink larvae with an off-white stripe sucking sap from the new tender growth parts running along the sides and abdomen are of most vegetables. common colours for this species. It can cause damage to the leaves, flowers, pods, and fruit of a plant. Figure 5 American bollworm. Source: BASF, 2017. Figure 6 American Aphids. Source: Levy & Sideman, 2016. 276

Climate-Smart Agriculture _ Training Manual Vegetable production 2.6.3.3 Bagrada bug and flower petals at night. Vegetables that are With an orange cross on its back and spots and young and in bloom are particularly vulnerable bands of colour across its abdomen (see Figure to attack. 7), this shield bug looks like a small dragonfly. 2.6.3.5 Cutworm It is capable of attacking a wide variety of Usually grey, waxy worm-like grubs as in Figure vegetables, but it prefers cabbage. 8. It is possible that colour variations will occur. 2.6.3.4 Spring/Chafer beetle They can be found in the upper soil surface and A medium-sized beetle that is yellow-brown chew on seedlings that are at or just below soil in colour and feeds primarily on young leaves level, according to the USDA. Mostly active at night, they prey on all types of crops. Figure 7 Bagrada bug. Source: ARC, 2016. Figure 8 Cutworm Source: Plant Care Today, 2021. 277

Climate-Smart Agriculture _ Training Manual Vegetable production 2.6.3.6 Diamond-back moth motion. Bean pods and developing tomatoes A light-green caterpillar (see Figure 9), which are the primary targets of this pest. usually feeds on the undersides of leaves 2.6.3.10 Thrips making holes in the leaves. The main target are Minute/very small insects that can be found brassicas (cabbages). hiding between the folded leaves of a variety 2.6.3.7 Fruit (pumpkin) fly of plants (see Figure 10). As they damage Brown flies with yellow bands or spots on their the foliage, they leave silvery blotches on the wings. Young fruit is stung, and the stinger leaves. It primarily targets beans, pumpkins, lays eggs under the skin. Maggots are most onions, and tomatoes, but it also targets a wide commonly found on small, immature fruits. range of other crops. Attack all different kinds of pumpkins. 2.6.3.11 Red spider mites 2.6.3.8 Greater cabbage moth Microscopic, spider-like insects that range in Caterpillars are green when young, but older colour from red to brown. Although difficult caterpillars may have a white line and black to detect with the naked eye, this pest spins a spots on their backs as they mature. Frequently web on the underside of foliage, causing it to encountered in groups where a web is being brown and yellow. All vegetables are vulnerable spun. Specifically, cabbages are targeted. to attack, especially in extremely hot and dry 2.6.3.9 Plusia looper conditions (see Figure 11). A green caterpillar that feeds on the outside of 2.6.3.12 Other beans and tomatoes, as well as on the inside of Many other lesser important insect pests can beans. When they move, they create a looping sometimes become more important depending on several factors. Figure 9 Diamond-back moth. Source: Maulana et al., 2016. 278

Climate-Smart Agriculture _ Training Manual Vegetable production Figure 10 Thrips. Source: Varela, Seif, & Lohr, 2003. Figure 11 Red spider mite. Source: Finkle, 2021. 2.7 WEEDS is constantly evolving, and the term itself is a relative one (Chandrasena, 2019). Weed is a general term used to describe any plant that grows in an area where it is not • Weeds compete with plants for resources wanted. Since the beginning of human attempts such as light, nutrients, water, and soil. to cultivate plants, humans have had to contend with the invasion of weeds into areas designated • Can serve as a breeding ground for pests for crop production. Some undesirable plants and diseases. were later discovered to have virtues that were not initially suspected, and as a result, they • Endanger the health of both animals and were removed from the category of weeds and humans. placed under cultivation. When other cultivated plants were transplanted to new climates, they • It interferes with the operation of the farm. escaped cultivation and became weeds or Because of this, weeds must be eliminated. In invasive species, resulting in the extinction of a vegetable garden, weeds are typically pulled the cultivar. As a result, the category of weeds out by hand or with a hand hoe, which is a tool specifically designed for weeding. 279

Climate-Smart Agriculture _ Training Manual Vegetable production 2.8 CONVENTIONAL VEGETABLES as a result of their status as a threatened VERSUS INDIGENOUS OR and endangered species. Slowly but steadily, TRADITIONAL VEGETABLES universities, research centres, and development organisations are beginning to pay attention to The dietary diversity, food security, and African vegetables (Figure 12). livelihoods of populations across Sub- The ARC has been researching these crops, Saharan Africa are enhanced by the presence focusing on cultivation practices, resource of approximately 1000 different species of use efficiency, nutritional value, drought indigenous and naturalised vegetables. These tolerance, and their similarities and difference foods are also important components of to commercial or conventional vegetables in alimentary traditions and cultural identity, but terms of yield and quantity. they have been neglected and underutilised Amaranth Spider Corchoru Leafy Nightshad plant s Mustard e Cowpea Amadumb Okra Bambara e Groundnut Figure 12 Examples of indigenous and naturalised vegetables. Source: ARC. 280

Climate-Smart Agriculture _ Training Manual Vegetable production To measure the nutritional value of water-sown handle adverse climatic conditions. Increasing crops, an investigation was conducted at the the amount of water and fertiliser applied to ARC. This research studied orange-fleshed sweet the crop will increase the water productivity of potatoes, among other crops, like amaranth, traditional vegetable crops. The study disproves swiss chard, and spider flower. the notion that traditional vegetable crops do Food and nutrition security is only possible in not require fertiliser or water, as claimed by resource-poor households if they make efficient the researchers. Agricultural production was use of agricultural resources and incorporate conducted with low inputs reduced all of these traditional vegetable crops into their food outcomes (i.e., without water and fertiliser). This systems. Swiss chard produced the highest raw indicates that water and soil fertility stresses edible biomass, both underwater stress and significantly impact traditional vegetable crop with no water, and traditional vegetable crops productivity. produced stems that were unusable for human According to the findings of the study, Swiss consumption. chard has significantly higher levels of Fe, In addition, when there is no water stress, crop Zn, and -carotene than traditional vegetable evapotranspiration is ordered in the following crops. The average content of micro nutrients order: under normal operating conditions with no water stress is 5.3 mg 100 g-1 for iron, 0.5 mg I. Orange-fleshed sweet potato leaves, 100 g-1 for zinc, 1.6 mg 100 g-1 for zinc, and 3 for example. mg 100 g-1 for -carotene. Under severe water stress conditions, Fe and Zn demonstrated II. Amaranth, also known as sarsaparilla consistency, whereas -carotene decreased III. Spider flowers, as well as significantly, which is consistent with previous IV. Swiss chard is a type of cabbage. findings. Low input agricultural practices The crops, on the other hand, can be ranked (with low water and fertiliser inputs) did not from most water-intensive to least water- necessarily lead to nutrient-depleted crops, intensive when faced with severe water scarcity: according to the study. They raised the nutrient I. Orange-fleshed sweet potato leaves, levels in some cases. for example, Fe content of Amaranth increased from 8.2 mg 100 g-1 to for example. 28.1 mg 100 g-1, whereas Fe content of Spider II. Spider flower, also known as flower increased from 7.5 mg 100 g-1 to 34.4 III. Swiss chard, as well as mg 100 g-1 The nutrient content of crops cannot IV. Amaranth. be evaluated in isolation as regards yield or raw Previous research suggests that Amaranth edible biomass, as they are interdependent. is more tolerant of water stress than other The nutritional yield is a critical crop vegetables. Because water is a limited resource, management parameter in agriculture. It increasing crop water productivity must be indicates the amount of nutrients that can considered. be harvested over the course of the entire The findings support the idea that traditional growing season. In water-stressed conditions, vegetable crops are drought-tolerant and can the highest average nutritional yield of Fe was 1444 g ha-1 from Spider flower, 213 g ha-1 from 281

Climate-Smart Agriculture _ Training Manual Vegetable production Swiss chard, and the highest average nutritional sweet potato leaves were ranked first, second, yield of -carotene was discovered in Amaranth third, and fourth for -carotene. The following (1933 g ha-1). Traditional vegetables are capable are the key findings: I traditional vegetable crops of yielding higher levels of Fe and -carotene, as (Amaranth and Spider flower) have exceptional opposed to Swiss chard. Aside from that, the productivity when compared to Swiss chard, nutritional yield of traditional vegetable crops and nutrition water production can be achieved declined when grown with low input agricultural with minimal input (supplemental irrigation and practises, where the nutritional yield of -carotene no fertiliser application). saw a significant decrease. With supplemental irrigation (water stress), no fertiliser application, 2.9 OTHER IMPORTANT ASPECTS and leaf harvesting treatment combinations, OF VEGETABLES TO DROUGHT the nutritional yield of Fe, Zn, and -carotene TOLERANCE in orange-fleshed sweet potato storage roots dropped by approximately 50%. Despite the To combat both heat and low water levels, low nutritional yield of orange-fleshed sweet drought-tolerant vegetables develop deep root potato storage roots, it is recommended that systems. Because many of them grow quickly, RPHs use orange-fleshed sweet potato storage they have lower water requirements in the as a dual crop to increase their nutritional yield. long run as well. Difficult-to-grow vegetables, In unfavourable production conditions, using such as the Black Diamond watermelon and the dual crop option offers more benefits. The the Heatwave II tomatoes, are now available nutritional yield of orange-fleshed sweet potato in drought-tolerant varieties. In your search for storage leaves increased from 518 to 574 g ha-1 seeds and plants suitable for drought-resistant for Fe, from 35 to 37 g ha-1 for Zn, and from 281 gardening, look for labels that state the plant to 300 g ha-1 for -carotene. prefers hot temperatures and has low to The average nutritional water productivity for moderate water requirements (Linda, 2019). selected micro-nutrients ranged from 740 mg m-3 (orange flesh sweet potato leaves) to 1392 • Seed color as an important mg m-3 (Spider flower) mg 100 m-3 for Fe, (ii) 35 morphological characteristic mg m-3 (orange flesh sweet potato leaves) to 177 mg 100 mg m-3 (Spider flower) for Zn, and The morphological characteristics of landraces (iii) 617 mg 100 mg m-3 (Swiss chard) to 2748 and indigenous crops are identified based on mg Fe, Zn, and -carotene. The highest water the hypothesis that they are associated with productivity for Fe (1981 mg m-3) and Zn (230 performance, such as the hypothesis that seed mg m-3) was found in Spider flower, whereas the colour is associated with drought tolerance. A highest water productivity for -carotene (3119 study confirmed that the colour of the seeds mg m-3) was found in Amaranth. In the most has an impact on early crop establishment. severe water-stressed conditions, spider flower, Compared to light coloured seeds, dark-coloured amaranth, Swiss chard, and orange-fleshed seeds had a better chance of emergence. sweet potato leaves are the four highest- Under field conditions, this trend was able to ranked crops for Fe. Spider flower, Swiss chard, be extrapolated successfully (e.g. groundnuts, Amaranth, and orange-fleshed sweet potato wild melon, maize landraces, cowpeas and wild leaves were the top-ranked for their Zn content. mustard). Amaranth, Swiss chard, and orange-fleshed 282

Climate-Smart Agriculture _ Training Manual Vegetable production • Cultivar selection ability to sustain one's livelihood. Seed systems Seed companies invest a great deal of time and are critical in ensuring that farmers have access money in research so that the best cultivar for to adaptable crops and varieties, as well as the each region can be identified and the necessary flexibility to obtain seed when they need it data can be collected to aid in the decision- (Kansiime & Mastenbroekvan, 2016). Farmer making process. It is also necessary to include seed systems, which include the following, information from local comparative strip trials provide this seed security: that have been conducted by study groups and individual farmers. • The right seeds Smallholders can only gain access to crops that The risky option is to rely solely on the advice are not prioritised by the private sector, but of a neighbour because the current season which are locally adapted, drought-resistant, will be different from the previous one. As a and important for household food and nutrition result of combining all of the information, the by way of seed production systems, which are identity of three to five cultivars that can be primarily focused on smallholders. These are used will be quickly determined. It is critical to typically grown by women for women. choose cultivars with a short growing season, i.e., those that mature early, to achieve better • The right time performance under drought conditions. Farmers can access what they need quickly if they have access to locally available farmer • Market-driven horticultural characteristics seed, which is critical in the current context • Maturity required to coincide with cropping of shortages in the formal seed sector and if farmers are forced to plant early or replant as a season, supply the market and reduce the result of unpredictable weather. risk of weather-related crop failure • Resistance to diseases, insects, stress, • The right price and physiological disorders that can be Farmer seed systems offer low-cost seed to depended on is essential (For example, smallholder farmers who cannot afford to make blossom-end rot) annual purchases of hybrid maize seed, let alone the even more expensive package of chemical 2.10 SEED PRODUCTION inputs required to unlock their yield potential. SYSTEMS – ACCESS TO As the economy continues to deteriorate, they CLIMATE-RESILIENT PLANTING provide an important safety net for vulnerable MATERIAL THAT IS DROUGHT communities, as well as a lifeline for smallholder RESISTANT (FARMER farmers with limited financial and technical PRODUCTION SYSTEMS) resources. Furthermore, farmer seed systems provide reservoirs of plant genetic resources Given the complexity that African agriculture is that farmers will need to continue to adapt to facing as a result of climate-induced stresses, climate change in the future. Farmers surveyed increasing agricultural resilience should be a top by the farmer field schools look for certain traits priority. Seed systems are critical for enhancing that they need to adapt to local conditions, such resilience because seed security is directly primarily high-yielding, drought-tolerant, and linked to food security and, in general, to the early maturing varieties. 283

Climate-Smart Agriculture _ Training Manual Vegetable production 3 SOIL MANAGEMENT are one of the world's largest carbon sinks, and their contribution to the global carbon 3.1 ORGANIC MATTER OF SOILS cycle is significant. As a result, the dynamics of SOM/SOC and the ability of soils to provide Soil organic matter (SOM) is the organic matter the ecosystem service of carbon sequestration component of soil, consisting of plant and animal through SOM management have recently detritus at various stages of decomposition, cells received a great deal of attention. and tissues of soil microbes, and substances When it comes to most upland soils, the synthesised by soil microbes. SOM has a variety concentration of SOM in the soil generally of beneficial effects on the physical and chemical ranges from 1 percent to 6 percent of the properties of soil, as well as on the soil's ability total mass of topsoil. Soils with less than 1% to provide regulatory ecosystem services. SOM organic matter in their upper horizons are most is particularly important for the functions and common in deserts, whereas soils in low-lying, quality of the soil. wet areas can have up to 90% SOM in their Soil organic matter (SOM) benefits soil function upper horizons. Organic soils are those that through a variety of complex, interactive have 12 to 18 percent soil organic carbon (SOC) edaphic factors. A partial list of these benefits in their composition. to soil function includes improvements in soil The living biomass of microbes can be divided structure and aggregation, water retention and into three categories: fresh and partially biodiversity, pollutant absorption and retention, decomposed detritus, and humus (composted buffering capacity, as well as the cycling and organic matter). Surface plant litter, also known storage of plant nutrients. SOM increases soil as fresh vegetal detritus, is typically excluded fertility by providing cation exchange sites from the composition of SOM. and acting as a reservoir of plant nutrients, particularly nitrogen (N), phosphorus (P), and 3.2 HOW TO MAKE COMPOST sulphur (S), as well as micronutrients, which are slowly released as a result of the mineralization • Where to make a compost heap? of SOM over time. As a result, the amount of Build the compost pile on soil or grass rather SOM present in the soil and soil fertility are than concrete or asphalt to take advantage of highly correlated. the earthworms and soil microorganisms that SOM also serves as a major sink and source of will migrate from the soil into the compost pile soil carbon, according to the USDA (C). In spite as they break down organic matter. Building of the fact that the carbon (C) content of soil a pile in a warm, partly shady spot that is organic matter (SOM) varies considerably, SOM protected from too much wind and sunlight is typically estimated to contain 58 percent will prevent the pile from drying out too quickly C, and the term \"soil organic carbon\" (SOC) is in warm, dry climates (it must have at least 6 frequently used as a synonym for SOM, with hours of full sunlight per day). Build the pile in measured soil organic carbon content often serving as a proxy for SOM. Solvents in soil 284

Climate-Smart Agriculture _ Training Manual Vegetable production a sunny location if you live in a cool climate. Do • Building a compost heap not place the pile in an area where water may »» A good size for the compost heap is 2 collect. Excessive moisture at the bottom of the spades by 2 spades (2m x 2m). pile may halt the composting process or cause »» The heap should be about twice as big odor issues. at the bottom as at the top. »» Start by levelling the spot for compost • What can be used in making compost? making. Composting is a viable option for approximately »» Have all the material to be used for the half of the waste we generate each day. Almost compost ready. anything that was once alive or was once a part of something alive can be used in a compost pile, and it does not have to be organic. Look at the activators in Table 5 for more information. Table 5 Compost making. Activators Other materials you can add Very slow to rot • Comfrey leaves • Autumn leaves • Young weeds • Wood ash • Egg boxes • Tough hedge without seed • Cardboard • Fruit and clippings • Grass cuttings • Paper towels and • Woody prunings • Chicken manure vegetable remains • Sawdust • Pigeon manure bags • Tea bags • Wood shavings • Cardboard tube, • Coffee grounds • Manures mixed • Old flowers • Bedding plants with straw • Old straw, hay, • Young hedge • Gerbil, hamster clippings and rabbit bedding • Soft prunings • Perennial weeds Do NOT add the following ingredients to compost • Meat • Cooked food • Coal and ash from • Manure from • Fish • Very soapy water coal dogs, cats and pigs • Diseased plants may carry disease • Disposable organisms and nappies parasites that can be transmitted to • Glossy magazines humans 285

Climate-Smart Agriculture _ Training Manual Vegetable production All large pieces should be cut into smaller • Place a 15-20 cm layer of dry brown material pieces before being assembled. Do not use on the ground to begin the pile building more than one type of material in a layer. It process. is critical to maintaining the proper balance between carbon-rich (brown) and nitrogen- • The base must be constructed in such a rich (green) materials. The rate of composting way that sufficient air can pass through and the quality of the finished compost can be it. If possible, it is preferable to add water affected by the way certain types of material to each layer of dry material rather than are mixed or the proportions of the materials attempting to wet the entire pile after it has are changed. Ideally, 3 parts brown to 2 parts been constructed. green and 1 part manure should be used in this ratio. A large number of browns will decompose • The entire pile should be as wet as a sponge too slowly, whereas a large number of greens that has been thoroughly wrung. After the will produce an odour. Assemble enough of the dry material layer has been constructed, it following materials to form a pile that is at least should be moistened but not soaked. 2 metres long, 2 metres wide, and 1 metre high: Carbon-rich brown (dry) material: First layer • To establish the first layer, spread a 10-15 • Wood shavings, sawdust, hay, wheat straw cm layer of fresh green material on the and corn stalks, shredded cardboard and ground. A pitchfork can be used to quickly newspaper mix the layers together for better results. • o Green (fresh) material: Nitrogen-rich Second layer materials such as grass clippings, fresh • Use kraal or chicken manure, mature leaves and twigs from harvested plants, compost, or bone meal to cover the top thinned seedlings, fruit and vegetable layer of the first layer with a layer about waste (such as peelings), tea bags, and egg 10 cm deep. The manure, old compost, shells can all be used bone-meal, and blood-meal speed up the decomposition of the compost heap. • Animal manure that is high in nitrogen: fresh chicken, cattle, or horse manure are Third layer examples • Lastly, apply a thin layer of soil and ash approximately 3 cm deep. Compost piles develop most effectively when • You should repeat the process (base layer, they are constructed in layers. A good way to first layer, second layer, third layer) three or ensure that the material is added in the proper four more times or until you have used up proportion is to layer it on top of each other as all of the material. follows: • As you build the compost heap, moisten Base layer each layer with water as you go. • The organisms in the soil, in particular • Loosen the soil in the area where you will earthworms, will aid in the rotting process be constructing the compost heap. This by mixing the material and increasing will aid in the growth of bacteria and fungi. airflow. Microorganisms in the heap require air to break down and decompose the organic material they are consuming. 286

Climate-Smart Agriculture _ Training Manual Vegetable production • A top layer of soil, dry grass, leaves, or • After approximately three weeks, the sawdust is required to keep odours in compost must be turned over, covered, and to deter flies from entering. When and allowed to re-heat to its original the construction of the compost heap is temperature. When the compost is free of completed, take two sticks of about 2m in offensive odours and is a dark brown color, length and push them into the heap, shake it is ready to be utilised these from side to side and pull them out, so that the pile can be aerated When it comes to vegetables, compost should not be used on the following: Cover • Straw, soil, old sacks, or plastic can be used • Carrots and beetroot because it has a to cover the heap. Moisture and heat are tendency to cause split and malformed kept in by this method roots Heat • Beans because it attracts harmful insects • Contribute to the decomposition of plant • Onions, because it causes early bolting and and animal matter as well as the destruction of weeds and weed seeds thick-necked onions, which are undesirable characteristics Figure 13 How to make a compost heap. Source: ARC. 287

Climate-Smart Agriculture _ Training Manual Vegetable production 3.3 MULCHES (DROUGHT- Aside from providing soil cover, mulching RESISTANT SOIL) also serves several other purposes, including preventing soil water loss through evaporation, Garden soil can behave in two ways: as a sieve, delaying weed growth and promoting the more allowing water to filter down quickly, or as a efficient use of nutrients, maintaining good sponge, allowing water to soak in slowly. Soil soil structure, and protecting harvested crops that is porous and drought-resistant holds water, from contamination by soil. It also serves to allowing the plant to have a constant supply protect the soil from erosion caused by water of moisture. To improve drought resistance, and wind, as well as hail damage. It is true that incorporate high-quality organic material (such herbicide application is effective at suppressing as compost) into drought-resistant soil at the the growth of weeds, but it can have negative start of each growing season. consequences for soil ecosystems and the environment, such as decreasing soil microbial If one wants to reduce evaporation or limit the activity and increasing water contamination. amount of water that evaporates before it can It is possible for smallholder and commercial be absorbed into the soil, one should plant farmers, depending on the type of material used, more water-wise plants. The use of a thick to increase yield while simultaneously lowering layer of organic mulch in a garden or field saves the costs associated with vegetable cultivation water more quickly, easily, and economically by mulching their fields. Mulch application has than any other method available. Mulch aids in been shown to improve water use efficiency the conservation of moisture, the prevention (WUE), crop growth, and yield, according to the of water runoff, and the improvement of soil research. In the root zone, mulch directs excess health, all of which contribute to stronger, rainwater away from the plant's roots, allowing deeper root growth and improved plant health. the moisture regime to remain more consistent. Mulches are defined as a thick layer (50-150 Organic mulch should be applied around mm) of organic material that is spread over bare drought-tolerant vegetables at a depth of soil to protect it from the elements. Mulches 5-7cm. Straw mulch is an excellent choice for have a number of advantages that come with vegetable gardens. It decomposes over time, their use, including the following: releasing organic material and nutrients into the soil as a result. Mulches are divided into • Regulates soil moisture and temperature two categories: organic mulches and inorganic • Enhances water infiltration mulches. Molasses derived from animal or • Prevents soil erosion plant materials are known as organic mulches; • Suppresses weeds on the other hand, inorganic mulches include • Prevents crop damage gravel, crushed rock, and synthetic plastic in a Wet, low-lying soil should not be mulched. Also variety of colours. When compared to plastic keep in mind that mulch can attract termites and mulch, organic mulches such as dry grass, has other drawbacks, such as being less long- sawdust, and paper would have the advantage lasting and potentially creating a fire hazard. of decomposing in the soil at the end of the Organic mulches can be made from a variety of growing season, gradually increasing soil organic sources, including the following: matter and contributing to waste reduction. 288

Climate-Smart Agriculture _ Training Manual Vegetable production Lawn mowing moisture-holding capacity. When sawdust is It is high in nitrogen and can be used as a used, it should be thoroughly decomposed mulching material. The mowings from most before being used. lawns contain more than 1% nitrogen and 2% Newspaper potash, respectively. The mowing of lawns can Unlike most other materials, newspapers have also be used as green manure, which can be excellent moisture-retaining properties. A layer worked into the soil and used to make compost. of hay, straw, or wood shavings placed over the paper will improve its appearance while also Straw preventing the paper from being blown away This is clean, contains few weed seeds when by the wind. Paper is extremely effective at purchased directly from farms, is inexpensive inhibiting the growth of weeds. Because it is when purchased in bulk, and is quick and dense enough to prevent sunlight from readily simple to lay down. Dig it into the soil during passing through to the soil, it is most effective the autumn, and by the spring, it will have when applied after irrigation or precipitation. assimilated and become indistinguishable from Paper eventually decomposes and contributes the rest of the soil. humus to the soil, albeit at a slow rate. Plastic mulches Plastic covers are inorganic and extremely Wood shavings/sawdust effective, but they are only partially compatible It is generally agreed that sawdust and wood with drip irrigation systems in most cases. When shavings are safe and effective soil improvers planting early in the spring, plastic can also be that do not acidify the soils when used in used to raise the temperature of the soil. appropriate quantities. Additionally, it aids in soil aeration while also increasing the soil's Figure 14 Examples of mulching spinach beds. Source: ARC. 289

Climate-Smart Agriculture _ Training Manual Vegetable production In order to demonstrate the benefits of mulches, such as newspaper and grass, were mulching, a research study was conducted at used in this study to provide an alternative ARC. The researchers used a variety of mulching weed control technique. These organic mulches materials in their research, including newspaper, may be beneficial when degrading into the black plastic, and grass/hay mulches, all of soil to increase soil organic matter. Weeds which were found to effectively stop or reduce frequently emerge from planting holes, no weed growth, possibly as a result of the matter how small and insignificant they were incoming radiation being absorbed. Newspaper in terms of number and size, and black plastic mulch and grass mulch were found to be just as and newspaper mulches are ineffective at effective at suppressing weeds as black plastic completely eliminating them. mulch at suppressing weeds. When it comes to According to this study, mulching (grass/hay newspaper mulch, the results are consistent, and white plastic) improved water use efficiency with the application of newspaper mulch on (WUE) while also increasing yield in Swiss chard sweet potato plants suppressing weeds in the production. If you live in a country with limited field. water resources, like South Africa, water savings of up to 65% can make a significant difference It is recommended to avoid using maize-meal in the success of a crop's production. For both sacks as mulch because they degrade over commercial and small-scale farmers, grass/hay time and can pollute the environment. In both mulch could be a viable strategy for increasing cases, weeds were allowed to grow beneath water use efficiency (WUE) and weed control. the mulch and pressure was applied against the More research on different colours of plastic mulch as it rose upwards, resulting in the maize- mulches and organic mulches is needed to meal bag mulch being torn to pieces. Despite increase yield and water use efficiency (WUE). the fact that herbicide treatment is effective in Both organic and inorganic mulches conserved weed management, there are concerns about water while also lowering electrical consumption its limitations, such as the cost of the chemicals in proportion to irrigation water consumption, and the manner in which they are used. resulting in a net water conservation benefit. A negative impact of herbicides on soil Comparing white plastic and grass/hay mulches ecosystems and the environment will include to other mulching treatments, white plastic and lowering microbial activity in soils and grass/hay mulches significantly increased water contaminating the water. Natural organic savings. 290

Climate-Smart Agriculture _ Training Manual Vegetable production Figure 15 How to apply mulch. Source: ARC. 291

Climate-Smart Agriculture _ Training Manual Vegetable production 3.4 ROTATION OF CROPS The crops included in the plots shown above are as follows: It is essential to follow crop rotation practices when growing vegetables, and it should be • Legumes: beans, peas, cowpeas, pigeon done on a consistent basis. When it comes to peas, Bambara crop rotation, the best definition is that it is a crop production strategy that involves planting • Brassicas: cabbage, chinese cabbage, kale, different crops in a specific order so that no radish, cauliflower crop is planted on the same piece of land more than once every three to four years, preferably • Root crops: carrots, onions, beet, sweet four to six years (Table 6). potato, amadumbi Crop rotation is recommended for improving soils and conserving resources, but it may have • Solanaceae: tomato, potato, peppers the greatest impact on disease levels in the soil • Leafy crops: swiss chard, amaranthus, when used in conjunction with other practices. Many infections can survive after a crop has cleome been removed from the soil, according to It is possible to include cucurbits (such as experts (e.g. black-rot of cabbage). pumpkins, squashes, melons, and cucumbers) Without the practice of rotational cropping, and green mealies at any point in the rotation. the incidence of infestation will undoubtedly Another general rule is to avoid planting an increase, and the cost of control measures will underground-bearing crop in the same soil for rise in lockstep with it. It also has the potential two consecutive seasons if possible. to reduce insect populations and perennial weed infestations, which are both detrimental 3.5 BAG SYSTEM to crop production. Perennial weeds, which are expected to become a serious problem with In order to maximise yield per unit area for continued cultivation, are also a concern. household production, this method of growing vegetables is an alternative to traditional methods. Plants grown in a bag system grow vertically upwards, resulting in more plants and yield per unit area than plants grown in a traditional system (Figure 16). Table 6 An example of a rotational cropping system with four plots over five years. Year 1 Plot 1 Plot 2 Plot 3 Plot 4 Plot 5 Year 2 Leafy crops Legumes Brassicas Root crops Solanaceae Year 3 Solanaceae Leafy crops Legumes Brassicas Root crops Year 4 Root crops Solanaceae Leafy crops Legumes Brassicas Year 5 Brassicas Root crops Solanaceae Leafy crops Legumes Legumes Brassicas Root crops Solanaceae Leafy crops 292

Climate-Smart Agriculture _ Training Manual Vegetable production Figure 16 Bag system just after transplanting. soil, less effort is required to clean the leaves Source: ARC. prior to consumption or marketing. It is possible This system is recommended for small-scale to produce organically. household gardens with a limited supply of good-quality soil available. The availability The Swiss chard/spinach in this small bag of good soil and land/space for household system, when fully planted, can provide a family vegetable production is increasingly becoming of four with a bunch of spinach once a week for a major source of concern. However, there is an a month (Figure 16). alternative method of growing vegetables and optimising yield per unit area for household Inputs required to plant vegetables in a bag production that is worth mentioning. Plants system grown in a bag system grow vertically upward, allowing for more efficient use of available • Empty maize-meal bag (80, 50 or 25, 12.5 space/land because of the vertical growth. The kg bag bag system can be used in places that were previously thought to be unsuitable for food • Water-soluble fertiliser (multi-feed and gardens, such as paved land and balconies, and calcium nitrate) has the potential to save money. The bag has the ability to hold water for a longer period • Growing medium (compost, sawdust or soil of time, preventing water and nutrients from with very good drainage) being washed away into the soil. Because the leaves of the plant are not in contact with the • Watering can • Seedlings 293

Climate-Smart Agriculture _ Training Manual Vegetable production Figure 17 Bag system (pictured, Ms Hellen Mokitlane). Source: ARC. Advantages of the bag system of regular crop production, with the goal of • It conserves water since there is a minimum improving soil health and moisture retention, amount of water draining out of the bag. preventing soil erosion, and adding nitrogen or • It suppresses weeds, no weed control is organic matter to the soil (USDA, 2021). needed. A cover crop is a fundamental and long-lasting • Plant leaves are free from soil particles tool that can be used to manage a variety of since plant leaves face upwards. soil health functions. It is defined as any type of • There is a high yield per unit area, compared plant that is grown for the purpose of improving to growing on a flat area. any number of conditions associated with long- • Requires less area to produce food (56 plants m-2). term agricultural production. a cover crop is a crop that is planted to manage soil fertility, soil Disadvantages of the bag system quality, water, weeds, pests and diseases, as well • Poor drainage medium can have a negative as biodiversity and wildlife in an agroecosystem, effect on moisture distribution and root which is an ecological system managed and aeration. largely shaped by humans to produce food • Bags need to be supported and kept upright across a range of intensities. Agroecosystems for uniform distribution of water. are ecological systems that are managed and • Maize-meal bag cannot be re-used, with largely shaped by humans to produce food time it can tear apart and disintegrate, (Sarah, 2013). depending on the durability of the bag. Why consider a cover crop? • Cover crops can be used to suppress the 3.6 COVER CROPS growth of weeds. In reality, they are capable As defined by the USDA, a cover crop is any plant of much more. Some popular cover crops, population that is grown between the rows of such as oats, rye, and sorghum, produce another crop, or that is planted between periods biochemical exudates that are toxic to weed seeds and prevent them from germinating. 294

Climate-Smart Agriculture _ Training Manual Vegetable production • Cover crops can provide protection against • Cover crops have a significant impact on root knot nematodes, which are the most erosion reduction. However, at our current costly pest in the world. Brassicas produce rate of topsoil loss, we will have no food- isothiocyanates in their root exudates, producing soil in just 60 years, making it a which are toxic to this invading organism. precious and life-sustaining medium (in all Furthermore, isothiocyanates have been contexts). Soil erosion is caused by only shown to provide protection against some 0.1% of all rainfall events, which accounts of the most destructive fungal diseases. for 75% of all soil erosion. It was anticipated that the residues from no-till farming would • Cover crops containing brassicas can also aid in the prevention of losses due to produce an allelopathic response, which extreme weather, but this has not proven can be used to discourage the growth of to be the case. If you compare living mulch weeds. Several unidentified compounds, from a cover crop with crop residues from as well as isothiocyanates, appear to be no-till farming, there is no comparison. involved in this process. It has long been known that the decaying residues of • Cover crops provide a habitat for beneficial crucifers inhibit the germination of weeds insects, as well as providing them with and the growth of some crops (particularly nectar and pollen. They are becoming small-seeded crops). Due to the fact that an increasingly important component of weed seeds are typically smaller in size than the Integrated Pest Management (IPM) crop seeds, they are at a disadvantage in this strategy. While velvet beans are not suitable situation. Growers must be cautious when for human consumption, when used as planting small-seeded crops such as lettuce a cover crop, they help to increase the after a cover crop dominated by brassicas number of beneficial free-living predatory because the seeds will germinate quickly. nematodes in the soil, which is beneficial to The breakdown compounds produced the environment. by mustard as the leaves decompose are particularly effective against grasses that Recommended cover crops include oats, velvet are a source of concern. Additionally, rye, beans, cowpeas, forage sorghum, dry beans, wheat, and hairy vetch produce compounds soya beans, clover, chickpeas, buckwheat, that discourage the growth of weeds. barley, wheat, lupines, lucerne, teff, ryegrass, and vetch. • In addition, cover crops provide a constant Elements affecting the choice of a cover crop supply of glucose to the soil's microbial workforce through the roots of the plants. • Know what the desired outcome should be However, this is not the end of the story. • What the farm’s environment is When these crops are harvested, they • What the farm’s existing soil fertility levels provide a tremendous humus-building opportunity, as well as all of the benefits are that accrue as a result of increasing humus • What are the growth patterns and nutrient levels in the soil. Cover cropping has been shown to improve soil structure, particularly requirements of the farm’s commercial when a cocktail of cover crops is used, crops according to extensive research. • Need sufficient financial resources to implement a cover-cropping program 295

Climate-Smart Agriculture _ Training Manual Vegetable production Also, consider the following before a crop is 3.7 GREEN MANURE chosen They are called \"green manure\" because they • Climate provide nutrients to the soil much as manure • Soil type, soil depth, and composition, pH does. Growing specific plant or crop varieties and turning them into the soil to improve the level overall quality of the soil is referred to as green • Fertility manure. The crop can be harvested and then • Existing soil surface covering ploughed into the soil, or it can be simply left • Frost patterns and severity in the ground for an extended period of time • Crop pests and diseases before being tilled into garden areas (Tilley, 2020). Examples of a few crops know for green Advantages of cover crops manuring are included below. • Contribute to soil nutrients which are then 3.7.1 Sunn hemp (Crotalaria juncea L.) made available to growing crops Do you want a cover crop that will increase • Increase soil fertility organic matter, provide nitrogen, grow in low • Improve soil structure fertility sandy soils, and is free of nematodes? • Reduce soil erosion Do you want a cover crop that will increase • Reduce weed pressure organic matter, provide nitrogen, grow in low • Contribute to breaking pest and disease fertility sandy soils, and is free of nematodes? cycles Because of its rapid growth and requirement for • Trap nutrients a relatively short growing season, sunn hemp • Increase the organic matter in the soil can be an excellent alternative. It thrives in • Reduce effects of compaction and plough well-drained soils with pH levels ranging from pans 5-7.5. Sunn hemp has been used extensively • Improved macro- and micro-organism as a soil improvement or green manure crop activity in the soil in the tropics due to its ability to produce large • Lower soil temperatures amounts of biomass in as little as 60-90 days, • Reduction in quantities of pesticides and making it an excellent choice for this application. herbicides used on regular crops As a result, it has the potential to increase organic matter levels in the environment Potential disadvantages while also sequestering carbon. Furthermore, • Higher direct input costs and management because it is a legume, it has the ability to fix requirements large amounts of nitrogen. A cover crop such • More competition for soil nutrients and as sunn hemp can improve soil properties moisture between the cover crops and the by reducing erosion and conserving water regular crops while also recycling nutrients from the plants • A potential rise in weed pressure if cover that grow in it. Suitable for use in hot, humid crops are not managed correctly summer rainfall areas (or irrigation). The best • Increased risk of fire due to the large time to plant is as soon as soil temperatures quantities of dry material left on the land reach 16oC (October - November). Sow at a rate • Increase need for specialized machinery to of 40-50 kg ha-1. manage cover crops 296

Climate-Smart Agriculture _ Training Manual Vegetable production 4 SOIL IMPROVEMENT AND IRRIGATION 4.1 RAINWATER HARVESTING season or climates with average annual rainfall greater than 600 mm, can be sufficient to Rainwater harvesting is the process of collecting maximise the productivity of Amaranth and rainwater after it has fallen. Storage of water is Swiss chard. When grown under the in-field required in order to make it available for use rainwater harvesting technique during a wet later on. Surface runoff of rainwater is being rainfall season, both amaranth and Swiss chard generated, collected, stored, and conserved yielded significantly less than when grown in order to mitigate the effects of rainwater under normal conditions (see Figure 19). In shortages that occur on a temporary basis. contrast to Swiss chard, this reduction in yield Trapping and holding rain where it falls can help was more pronounced in Amaranth, indicating to increase the amount of water stored in the that Amaranth is better adapted to high rainfall soil profile over time (see Figure 18). events, in which soil available water exceeds crop water requirements. Testing rainwater harvesting and conservation As a result, during drier rainfall seasons, or techniques for vegetable crops: Case study in arid and semi-arid climatic regions where using Swiss chard and Amaranth at ARC annual rainfall is typically less than 600 mm, the yield of both Amaranth and Swiss chard is lower Results of this study indicate that the use of in comparison to the yield during wetter rainfall simpler tillage techniques such as conventional seasons. tillage, in conjunction with a wet rainfall Figure 18 Preparing rainwater-harvesting plot and plastic covered catchment area. Source: ARC. 297

Climate-Smart Agriculture _ Training Manual Vegetable production Furthermore, the infield rainwater harvesting water-logging conditions than Swiss chard and technique (IRWH) outperformed the tied ridges that it is, therefore, likely to require a lower and conventional tillage techniques for both water supply in order to produce its maximum crops in terms of yield and quality. According yield. Agro-processing benefits from Amaranth to the results, the response of Swiss chard to cultivation in dry-land conditions during a the implementation of the IRWH technique wet season have been demonstrated for was more pronounced than that of Amaranth, postharvest agro-processing applications. The indicating that Swiss chard has a greater crop's response to severe drought conditions (as demand for water than Amaranth. In addition, measured by seasonal rainfall received during when comparing Swiss chard and Amaranth, the growing season, as well as the length and the reduction in canopy growth and yield frequency of dry spells during a dry season) still caused by water stress was more severe in the needs to be assessed in order to provide a more former crop. detailed assessment of the crop's performance The results obtained thus far in this study when grown on dry land. indicate that Amaranth is more tolerant of Figure 19 Rainwater harvesting and mulching trial of Swiss chard and Amaranth planted in November 2015. Source: ARC. 298

Climate-Smart Agriculture _ Training Manual Vegetable production Investigating the interactive effects of water equation, there are no statistically significant and nitrogen on yield, nutritional water differences in water use between 33% FC and productivity and metabolomics of nightshade 66% FC. This is due to the fact that the trial was (Solanum retroflexum) at ARC conducted in open field conditions and rain had to be factored into the soil water balance The results revealed that nightshade responded equation. in a variety of ways to different irrigation and The highest average Zn content was obtained nitrogen (N) treatment regimes (Figure 20). In under rain-fed irrigation treatments, and the comparison to the well-irrigated treatments highest average N content was obtained at a (66% and 100% FC), the 33% FC (field capacity) rate of 100 kg ha-1, with an average yield of 75 kg treatment produced lower fresh biomass yield ha-1. This study found that the lowest Zn content but had higher water productivity, indicating was found in the 100% FC and 200 kg ha-1 N that increasing water application up to an treatments. This suggests that maintaining 100% optimum level could result in increased biomass FC soil moisture content while increasing your N yield. Given that nitrogen is a highly mobile application rate from 150 kg ha-1 will result in a nutrient in the soil and that irrigation water is decrease in Zn content in the leaves. Fe content applied on a frequent basis, the reduction in of nightshade under rain-fed and irrigated fresh biomass yield observed with the 100% conditions was identical when fertilised with 0 FC treatment could be attributed to leaching kg N ha-1 of nitrogen. When fertilised with 150 out of N beyond the root zone. Fresh biomass kg ha-1 of nitrogen, the lowest iron (Fe) content yield was significantly higher with the moderate was obtained and the values decreased sharply; irrigation treatment (66% FC), and crop water however, when fertilised with 150 kg ha-1 of productivity was highest with the rain-fed nitrogen, the lowest Fe content was obtained irrigation treatment (66% FC). Because the trial and the values decreased sharply. was conducted in open field conditions and rain had to be factored into the soil water balance Figure 20 Improving water and nitrogen efficiency of nightshade. Source: ARC. 299