Over the last half-century, significant productivity gains in agriculture have protected the world from devastating food shortages and the threat of mass starvation. Water management, in both rain-fed and irrigated agriculture, was instrumental in achieving those gains. A key component in Green Revolution technologies based on fertilizer application and the use of high yield varieties, improved water management helped boost productivity - or output of "crops per drop" - by an estimated 100% since 1960.
The next 30 years will throw up new challenges. As world population grows - to an estimated 8,300 million in 2030 - agriculture must respond to changing patterns of demand for food, combat food insecurity and poverty in rural areas, and compete for scarce water with other users. To meet those multiple demands, says FAO, agriculture policies will need to unlock the potential of water management practices to raise productivity, promote equitable access to water and conserve the resource base. It proposes a strategy to "re-invent" water management in the agriculture sector, based on modernization of irrigation infrastructure and institutions, the full participation of water users in the distribution of costs and benefits, and the revival of flagging investment in key areas of the agricultural production chain.
Water for crops. The water needs of humans and animals are relatively small - the average human drinks about four litres a day. But producing the same person's daily food can take up to 5,000 litres of water. That is why the production of food and fibre crops claims the biggest share of freshwater withdrawn from natural sources for human use, or some 70% of global withdrawals.
FAO's recent report World agriculture: towards 2015/30 projects that global food production will need to increase by 60% to close nutrition gaps, cope with the population growth and accommodate changes in diets over the next three decades. Water withdrawals for agriculture are expected increase by some 14% in that period, representing an annual growth rate of 0.6%, down from 1.9% in the period 1963-1999. Much of the increase will take place on arable irrigated land, forecast to expand globally from some 2 million sq. km to 2.42 million sq. km. In a group of 93 developing countries, water use efficiency in irrigation - i.e. the ratio between water consumption by crops and the total amount of water withdrawn - is expected to grow from an average 38% to 42%.
Progress will also depend on a shift from what FAO calls "a culture of supply management" to one of "demand management". The supply-driven model underpinned most water development during the past half-century, as large national or state agencies placed extensive farming areas under irrigation. However, they proved less successful in managing those systems after construction. Decision-making was typically top-down and bureaucratic, leaving little flexibility to downstream users in choosing cropping patterns, calendars, and water delivery schedules. Often, unreliable water deliveries forced users to overexploit groundwater. It became evident in the 1980s that many irrigation schemes had become a burden on national budgets and a source of environmental degradation.
FAO views positively the far-reaching irrigation reforms, beginning in the 1990s, that led to massive transfer of responsibility to local water user associations and a shift to demand-driven management strategies. Today, farmers are increasingly involved in decisionmaking and in bearing the cost of operation and maintenance of irrigation systems. "One of the first priorities of modernization is to assess the physical conditions of the irrigation system and identify the practical options for moving towards more reliable and flexible water delivery service and accommodate a variable demand for water services," FAO says. Ultimately, it is the users who must decide on the level of service they require and are willing to pay for.
"Negative externalities". But water management in the new century is not simply about crop production. "While the specific objective is to provide a more reliable and adequate water supply for crops," FAO says, "management will always have significant impacts on economic activities, environmental processes and people's health." Like industry, agriculture is under pressure to reduce the impact of its "negative externalities", particularly those associated with the application of fertilizers and pesticides.
But there also needs to be wider recognition that sound water management produces positive results, including the socio-economic viability of entire rural areas, through development of the social capital required to manage irrigation systems and the expansion of transport and marketing infrastructure to sell agricultural produce. Positive environmental effects of irrigation include the creation of artificial wetland systems, micro-climates and associated biodiversity. Land management for rain-fed agriculture helps control soil erosion and protect downstream areas from floods. "Recognizing the diversity and the amplitude of these externalities is fundamental to sustainable development," FAO says. Conversely, management focused solely on crops will become unsustainable in economic and environmental terms.
Policy interventions. FAO sees broad scope for policy intervention to help "re-invent" agricultural water management. It recommends a strategic approach to development of available land and water resources in order to meet demand for food products and agriculture commodities, and a broader awareness of the productivity gains that can be achieved through wise water use.
Individual farmers and households need to be assured "stable engagement" with land and water resources, meaning land tenure and water use rights that are flexible enough to promote comparative advantage in food staples and cash crops. Those rights must to be matched by access to rural credit and finance and dissemination of technology and good practices in water use. There also needs to be a re-adjustment in management strategies away from formal irrigation systems and towards pro-poor, affordable technologies, such as small-scale water harvesting.
At irrigation scheme level, modernization programmes will help extract the full value out of sunk costs and reduce pressure on public funds. Modernization strategies should transform rigid command-and-control systems into much more flexible service-delivery systems. Agriculture should - and can - shoulder its environmental responsibilities much more effectively by minimizing the negative environmental impacts of irrigated production and seeking to restore the productivity of natural ecosystems.
Finally, government policy and investment must help local markets for agricultural produce to become more effective in meeting local demands. This means investment in key public goods, such as roads and storage, as well as institutional capacity, but will also demand a more progressive role for large-scale private investment.
Modernization. "Where irrigation has a comparative advantage, irrigation institutions need to adopt a service orientation and improve their economic and environmental performance - for example, by adopting new technologies, modernizing infrastructure, applying sound administrative principles and promoting user participation. The central task of providing irrigation services must be linked more closely to agricultural production, and the needs of other users at basin level."
Investment. "Incentives for individuals and user groups to invest in water control requires a clear comparative advantage, both in servicing local and export markets. Needed is a mix of micro-credit for small holders, well regulated commercial credit for emergent and large-scale farmers and concessional finance for large scale public infrastructure."