Simulating Nitrogen and Irrigation Effects on Wheat Production in Bangladesh under Changing Climate

Abstract

Climate change impacts are visible in Bangladesh which requires adoption of judicious crop management practices for sustainable agriculture. Crop simulation models are effective in this regard and can be used for optimizing water and nitrogen inputs for maximization of wheat yields. Two field studies were conducted at Bangladesh Agricultural Research Institute (BARI) for evaluating the effect of increased temperature on wheat production under variable water and N rates, through the use of DSSAT v4.6 model. Thirty years historic weather data and BARI Gom-26 wheat-cultivar coefficients, as generated through use of GLUE of DSSAT model, were used for evaluating the impact of temperature rise with variable rates of irrigation water and nitrogen. The effects of four levels of nitrogen (0, 40, 80 and 120 kg ha-1) and four irrigation levels [0 (no irrigation), 1, 2 and 3] on wheat yield were evaluated under 0°C, 1°C, 2°C and 3°C rise in temperature. Simulation results indicated that wheat yield increased with increase in nitrogen application rate, but decreased with the temperature rise. Crop growing duration was reduced by about five days for each degree rise in temperature, irrespective of levels of irrigation water and nitrogen-rates. In general, there was yield reduction of 8.13, 16.77 and 24.97 % with increased temperature of 1°C, 2°C and 3°C, respectively, when compared with no temperature rise treatment. For interaction of temperature rise-N dose, the magnitude of yield decline under temperature rise was higher with increased dose of N. Agronomic N use efficiency at different N rates and temperature rise level were calculated. N use efficiency decreases with the increase in temperature rise and the highest (29.95 kg grain kg-1 N) was obtained from 40 kg N ha-1 treated plot with 0°C temperature rise i.e. existing atmospheric temperature. Simulation results indicated increase in wheat yield with higher levels of irrigation water, and interaction of irrigation level with temperature rise was significant. Irrigation use efficiency decreases with the increase in temperature rise. From the present study, it was seen that the interaction of temperature rise with varying levels of N and irrigation water was significant, and there is a need to design the appropriate inputs’ management, as the adaptation strategy, to sustain the wheat yield under climate change situation.