Evaluating DSSAT program for simulating wheat yield production with different irrigation and nitrogen applications under Upper Egypt conditions

The overall objective of this work was to study the irrigation scheduling effects on the productivity of irrigated wheat in relation to mineral organic nitrogen fertilization, including initial testing of the DSSAT v4.7.0.0 model. In order that, a field experiment was conducted under Upper Egypt conditions in El-Mattana Agricultural Research Station, Luxor governorate, Egypt. The data of irrigation scheduling ((I1) 1.2, (I2) 1.0 and (I3) 0.8 pan evaporation coefficient) and mineral organic nitrogen fertilization program ((F1) 75 kg N fed-1 as compost, (F2) 75%N as compost + 25% N as mineral, (F3) 50% N as compost + 50% N as mineral (F4) 25%N as compost + 75% N as mineral and (F5) 75 kg N feddan-1 as urea) (feddan = 4200 m² = 0.420 hectares = 1.037 acres) during the two studied seasons 2016/17 and 2017/18, were used for model calibration and validation. Model evaluation results showed a closer relationship between CERES-DSSAT and observed wheat grain yield at both seasons. The values of relative root mean square error (RRMSE), coefficient of residual mass (CRM) and index of agreement (d-stat) were 6.6, 9.6 and 0.90 in the 1st and 3.9, 1.7 and 0.92 in the 2nd season, respectively. So, it could be concluded that the model works well under Upper Egypt condition, thus, studying the impacts of different management and climate change can be applied.