Abstract :
Sustainable food production will depend on the judicious use of water resources as fresh water for human consumption and agriculture is becoming increasingly scarce. To meet future food demands and growing competition for clean water, a more effective use of water in both irrigated and rainfed agriculture will be essential. Options to increase water use efficiency include the conservation of rainfall, the reduction of irrigation water losses and the adoption of cultural practices that will increase production per unit of water.
Water use for crop production is depending on the interaction of climatic parameters that determine crop evapotranspiration and water supply from rain. The compilation, processing and analysis of meteorological information for crop water use and crop production will therefore constitute a key element in developing strategies to optimize the use of water for crop production and to introduce effective water management practices.
In the 1970s, FAO developed practical procedures to estimate crop water requirements and yield response to water stress which have become widely accepted standards in the planning and management of irrigated and rainfed agriculture. As a follow-up to recommendations of a panel of high-level experts convened in 1990, further studies have been carried out which have led to the development of revised procedures for reference evapotranspiration and crop evapotranspiration. The new procedures and guidelines have been recently published in the FAO Irrigation and Drainage series and include the adoption of the Penman–Monteith approach as the new standard for determining reference crop evapotranspiration (ETo) calculations. Procedures have been developed to use the method also in conditions when no or limited data on humidity, radiation and wind speed are available.
Procedures for estimating crop evapotranspiration are revised with an update of the crop coefficients that allow more accurate estimates for a wide range of crops and for various crop, soil and water management practices. Daily ETo calculations are included by separating soil evaporation and crop transpiration estimates through the dual crop coefficient.
The use of climatic data for the development of practical criteria in planning and management of irrigated and rainfed crop production is demonstrated at the hand of some examples using the FAO computer programmes and climatic database.
Agrometeorology needs to play a key role in the looming global water crisis. Appropriate strategies and policies need to be defined, including strengthening of national capacities in the use of climatic data for planning and management of sustainable agriculture and drought mitigation. Cooperation between FAO and WMO in this field may serve as an example of such efforts.
