توسعه و کاربرد مدل رایانه‌ای مدیریت و برنامه‌ریزی آبیاری مزرعه گندم بر اساس بیلان آب در خاک و بارش مؤثر

Optimum management of water use in agriculture results in higher cultivated areas or enhances the share of water for municipal and industrial uses leading to economic development of a country. One of the effective methods in optimum water management is irrigation scheduling by using models which simulate water content in soils. In this study, a previously prepared model for irrigation water scheduling was modified to calculate daily effective rain, soil water content and deficiency. The model was applied for winter wheat field in Bajgah area using 13 years of local meteorological data. Furthermore, the effect of water storage in the soil profile on the amount and frequency of irrigation was examined. This model was written in Visual Basic.Net programming software. The model was run under two assumptions: 1) the effective rain compensates water deficiency of soil down to daily root depth and the excess water is assumed as deep percolation (case I) 2) the effective rain compensates water deficiency of soil down to maximum root depth and the excess water is assumed as deep percolation (case II). The results show that the amount and the frequency of irrigation in case 2 is less than case 1. Average amount and number of irrigation events decreased from 706.8 (mm) and 8 in case I to 569.2 and 6.4 in case II. The average relative percentage of effective rain increased from 45.2 % in case I to 76.9% in case II. The effective rain is 108.9 mm and the amount and number of irrigation events is 9 and 757.7 mm, respectively in case I (at probability level of 80%). The effective rain is 236.7 mm and the amount and number of irrigation events is 636.9 mm and 7.2, respectively in case II (at probability level of 50%). The effective rain is 165.6 mm and the amount and number of irrigation events is 712.6 mm 8, respectively in case I. The effective rain is 292.1 mm and the amount and number of irrigation events is 545.1 and 6, respectively in case II.