Watershed development as a growth engine for sustainable development of rainfed areas

Globally humankind is facing a great challenge of achieving food security for the ever growing population and growing per capita incomes particularly in the emerging giant economies like Brazil, Russia, India, China, and South Africa. The urgent need to decrease poverty and undernourishment while protecting the environment means delicately balancing development and sustainability resulting in increased additional pressure on the global food production system. In the foreseeable future agriculture will continue to be the backbone of economies in Africa and South Asia in spite of growing incomes and urbanization, globalization, and the declining contribution.......

New Paradigm to Unlock the Potential of Rainfed Agriculture in the Semiarid Tropics

The twenty-first century has presented complex and multiple challenges for humankind and the main challenge is to achieve food security for all with scarce water resources and increasing land degradation. The world is facing a severe water scarcity that is already complicating national and global efforts to achieve food security in several parts of the world. Agriculture is the world's second largest consumer of water after forestry. The second important factor controlling world food production is soil health, which is severely affected due to land degradation. The growing human population is reducing the per capita avaiiability of land as well as water differently in different parts of the world. Growing...........

On farm evaluation of the effect of low cost drip irrigation on water and crop productivity compared to conventional surface irrigation system

This on-farm research study was carried out at Zholube irrigation scheme in a semi-arid agro tropical climate of Zimbabwe to determine how low cost drip irrigation technologies compare with conventional surface irrigation systems in terms of water and crop productivity. A total of nine farmers who were practicing surface irrigation were chosen to participate in the study. The vegetable English giant rape (Brassica napus) was grown under the two irrigation systems with three fertilizer treatments in each system: ordinary granular fertilizer, liquid fertilizer (fertigation) and the last treatment with no fertilizer. These trials were replicated three times in a randomized block design. Biometric parameters of leaf area index (LAI) and fresh weight of the produce, water use efficiency (WUE) were used to compare the performance of the two irrigation systems. A water balance of the inflows and outflows was kept for analysis of WUE. The economic profitability and the operation, maintenance and management requirements of the different systems were also evaluated. There was no significant difference in vegetable yield between the irrigation systems at 8.5 ton/ha for drip compared to 7.8 ton/ha in surface irrigation. There were significant increases in yields due to use of fertilizers. Drip irrigation used about 35% of the water used by the surface irrigation systems thus giving much higher water use efficiencies. The leaf area indices were comparable in both systems with the same fertilizer treatment ranging between 0.05 for surface without fertilizer to 6.8 for low cost drip with fertigation. Low cost drip systems did not reflect any labour saving especially when manually lifting the water into the drum compared to the use of siphons in surface irrigation systems. The gross margin level for surface irrigation was lower than for low cost drip irrigation but the gross margin to total variable cost ratio was higher in surface irrigation systems, which meant that surface irrigation systems gave higher returns per variable costs incurred. It was concluded that low cost drip systems achieved water saving of more than 50% compared to surface irrigation systems and that it was not the type of irrigation system that influenced the yield of vegetables significantly but instead it is the type of fertilizer application method that contribute to the increase in the yield of vegetables. It was recommended that low cost technologies should be used in conjunction with good water and nutrient management if higher water and crop productivity are to be realized than surface irrigation system

Rainwater harvesting to enhance water productivity of rainfed agriculture in the semi-arid Zimbabwe

Zimbabwe’s poor are predominantly located in the semi-arid regions and rely on rainfed agriculture for their subsistence. Decline in productivity, scarcity of arable land, irrigation expansion limitations, erratic rainfall and frequent dry spells, among others cause food scarcity. The challenge faced by small-scale farmers is to enhance water productivity of rainfed agriculture by mitigating intra-seasonal dry spells (ISDS) through the adoption of new technologies such as rainwater harvesting (RWH). The paper analyses the agro-hydrological functions of RWH and assesses its impacts (at field scale) on the crop yield gap as well as the Transpirational Water Productivity (WPT). The survey in six districts of the semi-arid Zimbabwe suggests that three parameters (water source, primary use and storage capacity) can help differentiate storage-type-RWH systems from “conventional dams”. The Agricultural Production Simulator Model (APSIM) was used to simulate seven different treatments (Control, RWH, Manure, Manure + RWH, Inorganic Nitrogen and Inorganic Nitrogen + RWH) for 30 years on alfisol deep sand, assuming no fertiliser carry over effect from season to season. The combined use of inorganic fertiliser and RWH is the only treatment that closes the yield gap. Supplemental irrigation alone not only reduces the risks of complete crop failure (from 20% down to 7% on average) for all the treatments but also enhances WPT (from 1.75 kg m−3 up to 2.3 kg m−3 on average) by mitigating ISD

Assessing impacts of agricultural water interventions in the Kothapally watershed, Southern India

The paper describes a hydrological model for agricultural water intervention in a community watershed at Kothapally in India, developed through integrated management and a consortium approach. The impacts of various soil and water management interventions in the watershed are compared to no-intervention during a 30-year simulation period by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Kothapally receives, on average, 800 mm rainfall in the monsoon period. 72% of total rainfall is converted as evaporation and transpiration (ET), 20% is stored by groundwater aquifer, and 8% exported as outflow from the watershed boundary in current water interventions. ET, groundwater recharge and outflow under no-intervention conditions are found to be 64, 9, and 19%, respectively. Check dams helped in storing water for groundwater recharge, which can be used for irrigation, as well minimising soil loss. In situ water management practices improved the infiltration capacity and water holding capacity of the soil, which resulted in increased water availability by 10–30% and better crop yields compared to no-intervention. Water outflows from the developed watershed were more than halved compared to no-intervention, indicating potentially large negative downstream impacts if these systems were to be implemented on a larger scale. On the other hand, in the watershed development program, sediment loads to the streams were less than one-tenth. It can be concluded that the hydrological impacts of large-scale implementation of agricultural water interventions are significant. They result in improved rain-fed agriculture and improved productivity and livelihood of farmers in upland areas while also addressing the issues of poverty, equity, and gender in watersheds. There is a need for case-specific studies of such hydrological impacts along with other impacts in terms of equity, gender, sustainability, and development at the mesoscale

Rainfed Agriculture – Past Trends and Future Prospects

This chapter discusses the past and present trends and future direction of rainfed agriculture. Topics covered include: the relationship between rainfed agriculture and water stress; crop yields in rainfed areas; constraints in rainfed agriculture areas; the potential of rainfed agriculture; and the new paradigm in rainfed agriculture

Opportunities to Increase Water Productivity in Agriculture with Special Reference to Africa and South Asia. Stockholm Environment Institute, Project Report - 2009

Our primary goal in this paper is to describe how improvements in water and land management can increase the productivity of water in agriculture, which, broadly defined, means getting more value or benefit from the volume of water used to produce crops, fish, forests and livestock (Kijne et al., 2003). We begin by reviewing water scarcity and water productivity at the global level. We then describe ten Key Messages regarding efforts to improve water productivity in agriculture, with emphasis on Africa and South Asia

Managing water in rainfed agriculture—The need for a paradigm shift

Rainfed agriculture plays and will continue to play a dominant role in providing food and livelihoods for an increasing world population. We describe the world’s semi-arid and dry sub-humid savannah and steppe regions as global hotspots, in terms of water related constraints to food production, high prevalence of malnourishment and poverty, and rapidly increasing food demands. We argue that major water investments in agriculture are required. In these regions yield gaps are large, not due to lack of water per se, but rather due to inefficient management of water, soils, and crops. An assessment of management options indicates that knowledge exists regarding technologies,management systems, and planning methods. A key strategy is to minimise risk for dry spell induced crop failures, which requires an emphasis on water harvesting systems for supplemental irrigation. Large-scale adoption of water harvesting systems will require a paradigm shift in Integrated Water Resource Management (IWRM), in which rainfall is regarded as the entry point for the governance of freshwater, thus incorporating green water resources (sustaining rainfed agriculture and terrestrial ecosystems) and blue water resources (local runoff). The divide between rainfed and irrigated agriculture needs to be reconsidered in favor of a governance, investment, and management paradigm, which considers all water options in agricultural systems. A new focus is needed on the meso-catchment scale, as opposed to the current focus of IWRM on the basin level and the primary focus of agricultural improvements on the farmer’s field. We argue that the catchment scale offers the best opportunities for water investments to build resilience in smallscale agricultural systems and to address trade-offs between water for food and other ecosystem functions and services

Improved livelihoods and food security through unlocking the potential of rainfed agriculture

Eighty per cent of the world's agricultural land area is rainfed and generates 58% of the world's staple foods (SIWI, 2001). The importance of rainfed agriculture varies regionally, but produces most food for poor communities in developing countries. In sub-Saharan Africa (SSA) more than 95% of the farmed land is rainfed, while the corresponding fIgure for Latin America is almost 90%, for South Asia about 60%, for East Asia 65% and for Near East and North Africa 75%. Farming systems in sub-Saharan..........................