Water use in agriculture is at the core of any discussion of water and food security. Agriculture accounts for, on average, 70 percent of all water withdrawals globally, and an even higher share of “consumptive water use” due to the evapotranspiration requirements of crops. Worldwide, over 330 million hectares are equipped for irrigation. Irrigated agriculture represents 20 percent of the total cultivated land, but contributes 40 percent of the total food produced worldwide.
Competition for water resources is expected to increase in the future, with particular pressure on agriculture. Significant shifts of inter-sectoral water allocations will be required to support continued economic growth. Due to population growth, urbanization, industrialization, and climate change, improved water use efficiency will need to be matched by reallocation of as much as 25 to 40% of water in water stressed regions, from lower to higher productivity and employment activities. In most cases, this reallocation is expected to come from agriculture, due to its high share of water use. The movement of water will need to be both physical and virtual. Physical movement of water can occur through changes in initial allocations of surface and groundwater resources as well as conveyance of water ‘sales’, mainly from agricultural to urban, environmental, and industrial users. Water can also move virtually as the production of water intensive food, goods, and services is concentrated in water abundant localities and is traded to water scarce localities.
At the same time, water in agriculture will continue to play a critical role in global food security. Population is expected to increase to over 10 billion by 2050, and whether urban or rural, this population will need food and fiber for its basic needs. Combined with the increased consumption of calories and more complex foods, which accompanies income growth in much of the developing world, it is estimated that agricultural production will need to expand 70% by 2050. If this expansion is not to come at the expense of massive land conversions and the consequent impact on carbon emissions, agriculture will have to intensify. Given that irrigated agriculture is, on average, at least twice as productive per unit of land, provides an important buffer against increasing climate variability, and allows for more secure crop diversification, it is certain that irrigation will continue to play a key role in ensuring global food and nutrition security.
The above projections for both water and food security appear, at first look, to be contradictory, On one hand, there is a need to use less water in agriculture, but on the other hand, more intensive use of water in agriculture is a key element of sustainable intensification of food production. Resolving this apparent quandary requires a thorough reconsideration of how water is managed in the agricultural sector, and how it can be repositioned in the broader context of overall water resources management and water security.
Practical Challenges for Water in Agriculture
The ability to improve water management in agriculture is constrained by perverse policies, major institutional performance, and financing limitations. The critical public and private institutions – including agricultural and water ministries, basin authorities, irrigation managers, water user and farmer organizations – generally lack the authorizing environment and capacities to carry out their functions effectively. For example, basin authorities often have limited ability to enforce allocations, and hence, to convene stakeholders. The institutions charged with developing irrigation often limit themselves to capital intensive, larger scale schemes, and tend to rely on public sector approaches rather than develop opportunities for private financing and management. Farmers and their organizations are often responding to highly distorted incentive frameworks in terms of water pricing and agricultural support policies.
Most governments and water users fail to invest adequately in the maintenance of irrigation and drainage (I&D) systems. While inadequate management and operation may play a part in the poor performance of I&D systems, it is especially the failure to adequately maintain systems that results in their declining performance and the subsequent need for rehabilitation. This failure to provide adequate funds for maintenance of the I&D system has resulted in the all too familiar “build-neglect-rehabilitate-neglect” cycle.
Improving the efficiency of water use in agriculture will also depend on matching off-farm improvements with incentives and technology transfer for on-farm investments in improved soil and water management and improved seeds. Options such as enhanced seeds, low-till, alternate wetting and drying, sustainable rice intensification, and others exist, but require matching improvements in water delivery systems to provide on-demand service, with the use of information technology like soil moisture sensors and satellite evapotranspiration measurement to improve efficiency and productivity of water in agriculture.
Last Updated: Apr 04, 2017