Rainfed agriculture produces much of the food consumed globally and by poor communities in developing countries. It accounts for more than 95% of farmed land in sub-Saharan Africa; 90% in Latin America; 75% in the Near East and North Africa; 65% in East Asia; and 60% in South Asia. Water productivity, ‘the amount of crop produced per drop’, tends to be low in rainfed farming systems, while losses from evaporation are high. Land is often degraded, crops frequently die because of drought or floods and few methods are in place for managing water more effectively. In parts of sub-Saharan Africa and South Asia, productivity is particularly low, which results in food insecurity and poverty for rural communities.
Most countries in the world depend primarily on rainfed agriculture for their grain food. Despite large strides made in improving productivity and environmental conditions in many developing countries, a great number of poor families in Africa and Asia still face poverty, hunger, food insecurity and malnutrition where rainfed agriculture is the main agricultural activity.
Though many farmers in rainfed areas capture and store water for use as supplemental irrigation, millions more are entirely dependent on rainfall. The inherent uncertainty and extensive poverty that characterize rainfed systems generate research questions that are quite different from those pertaining to irrigated agriculture. We need to better understand the risks and trade-offs that households face in rainfed settings. We must explore the reasons why many methods for enhancing soil and water management are not adopted by looking more closely at institutions, livelihood strategies, and social, economic and political constraints. We must also deepen our understanding of how livestock production in water scarce environments can be improved.
In many areas, increasing populations have placed substantial pressure on rainfed cropland and on the land and water resources used by livestock. Soils often have inadequate amounts of essential nutrients and organic matter, and ecosystems have lost a portion of their inherent biodiversity.
Managing rainwater and soil moisture more effectively and using supplemental and small-scale irrigation in combination with increased use of organic and inorganic fertilizer, better access to markets, and increased security over land and water resources will be essential to improving the livelihoods of farmers in rainfed areas. . More effective utilization of water and moisture on farms can cut losses from dry spells, which claim one in five harvests in sub-Saharan Africa. A more assured harvest gives farmers the security they need to risk investing in other productivity-boosting technologies, such as fertilizers and improved seed . Irrigation allows farmers to grow a second, often higher-value, crop, such as fruits and vegetables that are more sensitive to water-stress. Once farmers are able to grow more lucrative crops, they are on the road to livelihood and food security.
In several regions of the world rainfed agriculture generates among the world’s highest yields. These areas are predominantly temperate regions, with relatively reliable rainfall and inherently productive soils. However, even in tropical regions, particularly in the subhumid and humid zones, agricultural yields in commercial rainfed agriculture can exceed 5–6 tonnes per hectare. At the same time, the dry subhumid and semiarid regions have experienced the lowest yields and the weakest yield improvements per unit of land. Here, yields can be as low as one tenth of more productive regions.
The knowledge already exists to at least double yields in rainfed agriculture, even where water poses a particular challenge: the key is promoting an institutional and economic environment that facilitates adaptation and adoption strategies. Needed for success are human capacity building and stronger institutions. Investments are needed in institutional and human capacities to plan and manage water for rainfed agriculture at the catchment scale, where local runoff water resources can be diverted, stored, and managed.
A way forward?
There is an urgent need to develop a new paradigm for soil and water management in rainfed systems. We need to have a holistic approach that includes proper management of natural resources so that the system’s productivity can be enhanced and poverty can be reduced without causing further degradation of the natural resource base.
Supplemental irrigation can play a very important role in reducing the risk of crop failures and in optimizing productivity. There is potential for delivering excess rainwater to storage structures or groundwater, because even under improved systems there is loss of 12–30% of the rainfall as run-off.
Many researchers are increasingly beginning to regard the divide between rainfed and irrigated systems as both artificial and unhelpful.
Key issues in rainfed agriculture include:
- Yields can be increased by improved management of rainwater in rainfed systems which presently generates excessive runoff and causes soil erosion Investments to maximize rainfall infiltration and the water-holding capacity of soils minimize land degradation while increasing the water available in the soil for crop growth. This infiltration will result in improvements in the quality of natural ecosystems and of water in aquatic ecosystems.
- Policy on water resources management for agriculture remains focused on irrigation, while the framework for integrated water resources management at watershed and basin scales concentrates primarily on allocation and management of blue water in rivers, groundwater, and lakes. What is needed is effective integration that focuses on investment options for water management across the continuum from rainfed to irrigated agriculture and which incorporates a multisectoral approach.
- There is generally enough rainfall to double and often even quadruple yields in rainfed farming systems, even in water-constrained regions. But it is available at the wrong time, causing dry spells, and much of it is lost. Apart from water, upgrading rainfed agriculture requires investments in soil, crop, and farm management and improved infrastructure, markets, and better and more equitable access to and security over land and water resources. To improve production and thus rural livelihoods in rainfed areas, rainfall-related risks need to be reduced, which means that investments in water management are a entry point to unlock the potential in rainfed agriculture.
Comprehensive assessment of Agriculture/IWMI http://www.iwmi.cgiar.org/assessment/Water%20for%20Food%20Water%20for%20Life/Chapters/Chapter%208%20Rainfed.pdf
Water issue brief: http://www.iwmi.cgiar.org/Publications/Water_Issue_Briefs/PDF/Water_Issue_Brief_10.pdf