OL 333 Assignment Five Discussion
Climate Smart Agriculture
Assignment Five. Survey of techniques for buffering against dry spells, the late arrival of rain, an early end to the rainy season, and from strong tropical rains.
This week’s discussion can be downloaded here.
Worldwide, challenges for smallholder farmers have increased. Harvest production may be down leading to reduced incomes and reduced crops for family consumption. These challenges can be due to changes in the beginning and end of the rainy season, unpredictable rain during the rainy season, and increased soil erosion and crop damage during extreme weather events. There are simple, low-cost/no-cost activities that subsistence farmers can adopt that can increase harvest production by buffering the effects of unpredictable rainfall, drought and extreme weather events, thereby increasing family nutrition and agricultural income.
CHANGING CROPPING CYCLES AND CROP MIXES. Here are a selection of techniques for adjusting growing cycles and crop mixtures for farmers to use in adapting to climate change. Many of the techniques have overlaps and include similar activities. However, some of the techniques may be more culturally appropriate for your communities or more appropriate for your agricultural context.
-Multiple and mixed cropping.
-Early maturing crop varieties.
-Drought resistant crop varieties.
ROTATIONAL CROPPING. Different crops use different amounts of nutrients to grow. If you grow the same type of crop over and over again on the same plot of land, some nutrients will become depleted causing the soil and its nutrients to become imbalanced. Some examples of plants and the nutrients they use to grow:
-pumpkins and melons like as many nutrients as they can get
-corn and tomatoes use a lot of nitrogen
-vegetables use less nutrients
-beans and peas fix nitrogen in the soil
Because of this, it is good to rotate plants from plot to plot each season—or even better—to grow different types of crops together. Crop rotation will also help reduce pest and disease problems.
Rotations with legumes reduce the requirements for artificial fertilizers. Pigeon peas and other legumes also have strong roots that break through pans and aerate the soil. Pigeon peas also recycle phosphorus from deeper layers of the soil and make it available to shallower rooted crops in the following rotation.
Rotations have great advantages over mono cropping systems including:
-providing for protein and vitamins in family diets
-fixing of nitrogen by legumes, which result in cost savings and yield improvements
-breaking disease and pest cycles
-improving soil structure
-spreading of financial risk
Rotational crops should preferably include legumes such as beans, soybeans, pigeon peas, cowpeas, sugar beans or ground nuts but can also include sunflower, sweet potato and vegetables. Rotating crops helps to control weeds, diseases and pests by breaking their life cycles through the introduction of a new crop.
There is a very good “how to” of crop rotations in the “Conservation Farming Handbook for Hoe Farmers” on pages 33 through 37 in the list below.
RELAY CROPPING. Relay cropping means that a new crop is planted or sown before the previous one is harvested. This can provide advantages for both crops as one of them may provide nitrogen, shade, support or may discourage pests. Care is needed to ensure that appropriate combinations are selected—for example some crops are sensitive to shade in the early growth stages.
MULTIPLE CROPPING/INTERCROPPING/MIXED CROPPING. This is the planting of food crops, fruit trees and timber tree species in a single farm field. These crops may have different characteristics which make them attractive to cultivate together. For example, one crop may provide high yields, while the other gives lower yields, but has better resistance to drought (or to certain diseases and pests). The latter may provide a harvest if rains are poor, the first maximizes crop yields if there are good rains.
Arable crops may also be inter-planted with perennials like trees (agroforestry), shrubs and grasses. Inter-cropping has several advantages especially to small farmers:
-It allows for a midseason change of plan according to the amount of rain in the early parts of the season.
-A combination of legumes and cereals may increase the nitrogen status of the soil.
-Plants with different rooting patterns need not compete for nutrients and water. Deeper rooting species may pump up nutrients and make them available to shallower rooting species when their leaves fall or if their prunings are used as mulch.
-It spreads labor requirements for planting and harvesting.
-Higher yields per unit area are obtained as result of higher growth rates, fewer losses due to diseases, insects, and weeds, and more efficient use of water, light and nutrients.
-Lower farming risks. The failure of one crop may be compensated for by other crops.
-Soil is less prone to soil erosion, because it is almost continually covered especially when perennials are used.
Other benefits of intercropping include:
-shade and windbreaks
-leaves and prunings are incorporated into the soil and improve soil structure, water retention and fertility
-the roots and canopy of the plants help reduce soil and wind erosion
-the tree canopy’s can reduce direct negative impact of raindrops, sunlight and wind erosion
-the variety of plants can provide additional income to the farmer
-they can help regulate the soil’s moisture content
-leguminous plants and trees increase soil nitrogen
-sequential plantings of different crops can replenish soil fertility
Mixing different crops in one field echoes processes found in nature and can maximize plant nutrient use by synergy between different crops. Intercropping with nitrogen fixing legumes adds “top dressing fertilizer” to the soil. Intercropping different crops with different feeding zones which do not compete for nutrients maximizes soil nutrient use.
In planning a field layout for mixed cropping think of a typical selection of about 10 to 15 crops grown on small farms in your area. Consider staple crops, fruit, vegetables, legumes and crops with high market value. Be sure to also include trees and underutilized crops. The plants will have different relationships of complementarity, synergy, multipurpose functions and recycling. Multiple crops can be grown together simultaneously or sequentially over time.
Reflecting on the selection of crops you have made, consider their characteristics and the different kinds of relationships between them. Example characteristics could include:
-Nutrients: are there any legumes or crops that need more nutrients?
-Timing: which crops are fast growing and which are slow-growing?
-Roots: which crops have shallower root systems and which are deep-rooted?
-Natural repellents: are there crops (e. g. onion family) that can naturally repel insects?
-Length and light: how tall do the crops get? Which crops can and cannot tolerate shade?
Draw a map of the typical farm in the area and note where there is and isn’t water, where there is and isn’t sun, where there are steeply sloping fields and where there is level land. Indicate on the map where the different crop combinations might grow better, and where rows of trees (for example) might create valuable shade, a windbreak, or valuable nitrogen fixing, mulch and fodder. Indicate where you can grow crops mixed together such as beans and corn—or where you could sequentially grow crops such as nitrogen fixing crops after corn.
AGROFORESTRY. Agroforestry is the integration of trees and shrubs into the farming system so that they are managed, protected and harvested for the benefit of people and livestock. Agroforestry brings benefits which include:
-food for people in the form of fruit, leaves or seeds
-food for livestock in the form of leaves or pods
-firewood for fuel
-poles for fencing
-stabilization of soil on steep slopes
-trees increase water infiltration and build the water table
-recycle nutrients that cannot be reached by short rooted plants such as vegetables
-trees can also be used as windbreaks
Trees are multifunctional. They can provide increased economic gains for farmers—both in improving soil and protecting crops—but also in providing fodder for animals and wood. They can be used in alley cropping, contour hedgerows, and as living mulches. Trees can help farmers spread risk—for example—if a crop fails and they need cash they might be able to sell wood.
ALLEY CROPPING. Alley cropping is an agroforestry practice in which perennial, preferably leguminous trees or shrubs, such as pigeon peas and moringa olifera, are grown simultaneously with crops. The trees, managed as hedgerows, are grown in widely spaced rows and crops are planted in the interspaces or “alley” between the tree rows. During the cropping cycle the trees can be pruned and the prunings used as mulch. Alley cropping has many benefits:
-improved crop performance due to the addition of nutrients and organic matter to the soil/plant system
-a reduction of the use of chemical fertilizers
-improved soil structure resulting in better infiltration
-soil erosion control
-the provision of additional products such as forage, firewood or stakes when a multipurpose tree legume is used as the hedgerow
-an improvement in weed control
Trees and shrubs can diminish the effects of extreme weather events, such as heavy rains, droughts and windstorms. They prevent erosion, stabilize soils, raise infiltration rates and halt land degradation. They can enrich biodiversity in the landscape and increase ecosystem stability. Agroforestry systems in Africa have shown to increase maize yields by 1.3 and 1.6 tons per hectare per year. Increasing wood production on farms can also take pressure off forests which would otherwise result in their degradation. Agroforestry systems tend to sequester much greater quantities of carbon than agricultural systems without trees. Agroforestry is therefore important both for climate change mitigation as well as for adaptation through reducing vulnerability, diversifying income sources, improving livelihoods and building the capacity of smallholders to adapt to climate change.
See pages 64 through 75 in Garden Africa’s “Growing Health” for a list of useful trees for agroforestry in the resource list below.
CROP DIVERSIFICATION. Realistically all of these techniques are incorporating crop diversification. Field crops can be important sources of nutrients during the rainy season, but it is important to encourage families not to neglect the vegetable garden at the expense of annual (staple) crops. It is also important to include perennial crops in the fields such as cassava, pigeon pea and moringa. A variety of grains (including millet and sorghum) should be grown for improved nutrition as well as crop security. If the rains are poor and then at least some crops will serve.
EARLY MATURING CROP VARIETIES. If the rainy season starts two weeks late and ends two weeks early there may not be enough time for the farmers’ crops to reach fruition. Early maturing crop varieties can help solve this problem. Organizations such as International Crops Research Institute (ICRISAT) have been working for over 20 years developing early maturing varieties of nutritious crops such as pigeon pea. This also means that if they have a short duration rainy season— farmers can still get one harvest. Early maturing varieties of cowpea and gram can provide a high protein source when food is generally scarce during the hunger season before crop harvest.
In planning mixed cropping for your farming community, you can easily work with an agricultural extension agent familiar with your context to determine if there are improved varieties, drought resistant varieties, and early maturing varieties of crops that would be useful to your farmers in buffering against drought and unpredictable rain.
DROUGHT RESISTANT CROP VARIETIES. If there is a four week dry period in the middle of the rainy season, farmers may lose their crops. Drought resistant crops can help solve this problem.
-Many indigenous vegetables
-Many indigenous trees
Traditional Seed. In the IFPRI study below on soil and water conservation technologies in Ethiopia, they discovered the traditional seed is risk reducing in both low and high rainfall areas, where as improved seed is only significantly risk reducing high rainfall areas.
Conclusion. Interestingly, many of these systems have similarities—it’s more the lens that you are viewing the cropping system through that gives it its name. For example mixed cropping systems can include trees—agroforestry can include mixed crops. The different systems also look at a rotation of plants that allow for nitrogen fixing plants to replenish soil nutrients. They also all look at reducing farmer risk. The diversity of plants and crops protect farmers from the failure of a mono crop; if one of the species in the mixed crops fails there will be other species that can be sold or eaten. These systems also allow farmers to experiment by planting early maturing and or drought resistant crops as a safety mechanism in case of a drought or an early end to the season—a safety mechanism that allows them to take the risk of planting potentially more valuable plants that are not as drought tolerant nor as early maturing.
This Week’s Resources can be linked to on the resource page “Links to Climate Smart Ag 333.”
IFPRI: Are Soil and Water Conservation Technologies a Buffer against Production Risk in the Face of Climate Change? Insights from Ethiopia’s Nile Basin
This is the best general overview available for this section on LEISA and soil and water. I have used this book extensively:
ILEIA: Learning AgriCultures. Module Two. Soil and Water Systems
Permaculture Resource Book Module No. 4. Healthy Soil
FAO: “Climate-” Smart Agriculture. Policies, Practices and Financing for Food Security, Adaptation and Mitigation.
Agrodok: Water harvesting and soil moisture retention
CFU: Conservation Farming & Conservation Agriculture Handbook for Zambia Hoe Farmers
Garden Africa – Growing Health: A very thorough training manual by a great NGO with offices in London and projects in Southern Africa.
Healthy Harvest: A training manual for community workers in good nutrition, and the growing, preparing and processing of healthy food.
Farming for the Future – A Guide to Conservation Agriculture in Zimbabwe
Good luck—I look forward to hearing about your project —please move on to Assignment Five.