Simulation of rice yield under different irrigation and nitrogen application managements by CropSyst model

Abstract

The aim of this study was the calibration and validation of CropSyst model for rice in the city of Rasht. The necessary data were extracted from a field experiment which was carried out during 2005-2007 in a split-plot design. The main plots were irrigation regimes including continuous flooding irrigation and 5-day irrigation intervals. The subplots consisted of four nitrogen levels: zero N application, 45, 60 and 75 kg N ha -1 . Normalized Root Mean Squared Error (nRMSE) and Residual Mass Coefficient (Crm) in calibration years were 9.3% and 0.06, respectively. In validation year, nRMSE and Crm were 9.7% and 0.11, respectively. According to other indices to assess irrigation regimes and fertilizer levels, the most suitable treatments regarding environmental aspect were 5-day irrigation regime and 45 kg N ha -1 .

Evaluation of water productivity with three rice genotypes under different irrigation regimes and nitrogen fertilizer treatments in Rasht, northern Iran*

“…Therefore, the highest water productivity was achieved at a level of 100 kg N/ha 1 . Further, the results of the 7‐day irrigation interval were the most productive in terms of both physical and economic productivity, which is the reason why other studies usually consider 7‐ to 8‐day irrigation intervals as the most suitable (Ashouri et al ., 2009; Rezaei et al ., 2011; Zare et al ., 2014).…”

“…Although recent research has focused on the subject of calculating irrigation water requirements for rice and nitrogen fertilizer, which together play an important role in yield performance, most studies have focused on the role of a single producing factor, water or nitrogen fertilizer in a particular cultivar (Zare et al ., 2014; Liu et al ., 2019; Dong et al ., 2020). In addition, these studies did not calculate the physical and economic productivities of water through virtual water determination and, not surprisingly, did not compare these factors at different levels of water and nitrogen fertilizer and different rice genotypes.…”