The Indus Basin irrigated agriculture is backbone of national economy and is the largest single user of water (> 93%) in Pakistan. The level of agricultural production is directly related to the availability and efficient use of water. With increased water demand for domestic and industrial uses, water availability for agriculture is decreasing, necessitating its efficient use for sustaining crop production. Thus, the consumptive use of water (CUW; evapotranspiration) information is essential for estimating irrigation water requirements in arid and semi-arid regions of the country. Such information is crucial for planning, development and management of water resources. The CUW information is also crucial while negotiating contracts and treaties for water distribution of major river systems.
The Water Resources scientists at NARC carried out this research during 1975-1986 in collaboration with six provincial institutes in different agro-ecological zones of the country: (i) Arid Zone Research Institute, D.I. Khan; (ii) Agricultural Research Institute (ARI), Tarnab, Peshawar; (iii) Sindh Agri. University, Tandojam; (iv) MRE Project, Bhalwal; (v) LRD, Lahore; and (vi) ARI, Sariab, Quetta. The crops studied were wheat, maize, soybean, cotton, sugarcane berseem, sorghum, barley, rapeseed, mash-bean, gram, pea, potato, onion, tobacco, citrus and guava. Factors affecting water use efficiency (fertilization, soil moisture stress, irrigation level, etc) and crop water use were studied. Measured values of crop water use/CUW were correlated to potential evapotranspiration (computed crop evapotranspiration using climatic data) and crop coefficients were developed. These coefficients can be used for estimating water requirement of crops for areas where actual measurements are not available or are costly and time-consuming. This information is used by planners, policy makers, researchers, university students and teachers while dealing with the subject of water.
The findings were compiled in two widely circulated reports. These reports summarize crop growing seasons, actual crop evapotranspirations, moisture stress yield functions and crop coefficients for 17 selected crops grown in major agro-ecological regions of Pakistan.
Ahmad, M., S. Mehmood, S. Ahmad and R. Amin. (1989). Consumptive use of water for wheat in southern NWFP. Journal of Engineering and Applied Sciences, 8:81-84.
Ahmad, S. (1989). Irrigation scheduling as affected by planting dates for three major crops. Pakistan Journal of Water Resources, 2:12-18.