Irrigation scheduling in Pakistan

Abstract

Water, being the "life blood" of both plants and animals is a limiting factor in the agricultural economy of most of the late developing countries. Pakistan is no exception. Where water is plentiful, it is often wasted. This wastage often results in waterlogging. Where there is a limited supply of water, wastage leads to decreased yields and salinity problems. Efficient use of limited irrigation water supplies in Pakistan has become more important since the demand for irrigation water has increased and new sources of supply are becoming harder to develop. To get the most out of each unit of water one must know how much water to apply, when to apply, where to apply and how to apply water to crops. Present on-farm water management practices are the major constraint on food production in Pakistan. In spite of limited irrigation water supplies, over-irrigation is a common practice in Pakistan due to unleveled fields and lack of knowledge of plants' water requirements. Tremendous delivery losses have been measured by others in badly managed earthen watercourses. Extensive measurements on farmers' fields indicated substantial field irrigation application losses. To determine the proper amount and timing of irrigation, different methods of determining crops peak water use were compared. Water use as estimated from pan evaporation was more closely correlated to actual water use under the conditions of the study than were estimates using the empirical equations. Consequently, estimates of water use based on pan evaporation are recommended for use in this area. The need for an irrigation extension advisory service to provide scientific irrigation scheduling services to Pakistani farmers has been recognized. Accordingly, scientific irrigation schedules were prepared for a maize crop. Recommendations were made regarding reorganizing the existing institutional infrastructure both in public and private sectors to implement on-farm water management in Pakistan with irrigation scheduling as its basic component.