Optimization of cotton irrigation management for different climatic conditions using the CROPGRO-Cotton model

To study the feasibility of CROPGRO_cotton model in the optimization of cotton irrigation management under different climatic conditions, the empirical values corresponding to 25%, 50% and 75% of the empirical frequencies of precipitation were obtained by ranking the frequency fitness line of precipitation data during 20 years of cotton fertility at the experimental site, and then the years corresponding to three empirical frequencies were selected as typical years: 2015 (abundant water year), 2001 (flat water year), and 2006 (dry water year). By combining cotton fertility stages, irrigation frequency and irrigation amount, 21 irrigation regimes (T1~T21) were identified and simulated using the calibrated DSSAT model for cotton irrigation regimes under the three precipitation year types, and the results showed that under the best combination of irrigation usage, yield and water utilization, 2015 (abundant water year), 2001 (flat water year), and T20 irrigation management should be selected in 2006 (dry water year).Under the three typical years, the effect of temperature change on cotton yield and water utilization was investigated, and it was found that the increase of temperature would reduce cotton yield and water utilization, but a reasonable irrigation management would reduce the negative effect of climate change on cotton yield and water utilization,According to the simulation results under different situations, T20 irrigation management can minimize the yield variation range under temperature change, and has a high water utilization rate, which has good applicability. Keywords: Cotton; DSSAT model; Irrigation management; Typical years; Applicability