Farmers and scientists have identified a wide range of land and water management practices that can address land degradation and increase long-term agricultural productivity. The benefits of these improved land and water management practices to farmers and rural economies include higher crop yields, increased supplies of other goods such as firewood and fodder, and increased resilience to climate change. These benefits occur because these improved land and water management practices:
• Increase soil organic matter
• Improve soil structure
• Reduce soil erosion
• Increase water filtration
• Increase efficiency of water use
• Replenish soil nutrients
• Increase the efficiency of nutrient uptake.
Four of the most promising improved land and water management practices that are particularly relevant to locations which contain plenty of drylands such as the Sub - Saharan Africa are:
1. Agroforestry—the deliberate integration of woody perennial plants (trees and shrubs) with crops or livestock on the same tract of land. It can be used to solve the scarcity of food as for example in Malawi, maize yields increased by about 50 percent when nitrogen-fixing Faidherbia albida trees were planted in farms. In Senegal, the presence of Piliostigma reticulatum and Guiera senegalensis shrubs in fields has increased nutrient use efficiency over sole crop systems, and has helped to create “islands of fertility” that have greater soil organic matter, nitrogen, and phosphorus concentrations under their canopies than in open areas.
2. Conservation agriculture is a combination of reduced tillage, retention of crop residues or maintenance of cover crops, and crop rotation or diversification. It can be used to solve the scarcity of food as for example in Zambia, maize yields in conservation agriculture systems with crop rotation can be more than 50 percent higher than yields under conventionally tilled maize. conversation agriculture is a combination of reduced tillage retention of crop residues or maintenance of cover
Benefits
• Time saving and thus reduction in labour requirement.
• Reduction of costs, e.g. fuel, machinery operating costs and maintenance, as well as a reduced labour cost.
• Higher efficiency in the sense of more output for a lower input
• Organic matter increase.
• In-soil water conservation.
• Improvement of soil structure, and thus rooting zone.
• Reduction in soil erosion, and thus of road, dam and hydroelectric power plant maintenance costs.
• Improvement of water quality.
• Improvement of air quality.
• Biodiversity increase.
• Carbon sequestration.
Limitations
The most important limitation in all areas where conservation agriculture is practised is the initial lack of knowledge. There is no blueprint available for conservation agriculture, as all agro-ecosystems are different. A particularly important gap is the frequent dearth of information on locally adapted cover crops that produce high amounts of biomass under the prevailing conditions. The success or failure of conservation agriculture depends greatly on the flexibility and creativity of the practitioners and extension and research services of a region. Trial and error, both by official institutes and the farmers themselves, is often the only reliable source of information.
3. Rainwater harvesting involves low-cost practices such as planting pits, stone bunds, and earthen trenches along slopes that capture and collect rainfall before it runs off farm fields. It can be used to solve the scarcity of food as for example farmers in Burkina Faso have doubled grain yields using multiple water harvesting techniques, including stone bunds and planting pits.
Benefits
• There is easy maintenance
• Farmers have to pay less for water bills and there is reduced demand for ground water
• Suitable for irrigation as there is little requirement for building new infrastructure to harvest rainwater
• Reduces flood and soil erosions in low lying lands
Limitations
• Unpredicted rainfall so farmers can’t be too reliant on it
• There could be high start up costs
• Regular maintenance will be needed to prevent it from becoming breeding grounds for pests such as mosquitos
• There is storage limits
4. Integrated soil fertility management is the combined use of judicious amounts of mineral fertilizers and soil amendments such as manure, crop residues, compost, leaf litter, lime, or phosphate rock. It can be used to solve the scarcity of food as for example on West
Africa, adoption of integrated soil fertility management across more than 200,000 hectares resulted in yield increases of 33–58 percent over a four-year period.
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