RZWQM2 simulated irrigation strategies to mitigate climate change impacts on cotton production in hyper–arid areas

Authors: CHEN, XIAOPING - Yangzhou University; DONG, HALBO - Yangzhou University; FENG, SHAOYUAN - Yangzhou University; GUL, DONGWEL - Chinese Academy Of Sciences; Ma, Liwang; Thorp, Kelly; WU, HAO - Yangzhou University; LIU, BO - Yangzhou University; QI, ZHIMING - McGill University - Canada

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2023
Publication Date: 9/29/2023
Citation: Chen, X., Dong, H., Feng, S., Gul, D., Ma, L., Thorp, K.R., Wu, H., Liu, B., Qi, Z. 2023. RZWQM2 simulated irrigation strategies to mitigate climate change impacts on cotton production in hyper–arid areas. Irrigation Science. 13(10). Article 2529. https://doi.org/10.3390/agronomy13102529.
DOI: https://doi.org/10.3390/agronomy13102529

Interpretive Summary: Improving cotton water use efficiency (WUE) under future climate scenarios by optimizing irrigation management is crucial in very dry areas. Assuming a current baseline atmospheric carbon dioxide concentration (CO2) of 380 parts per million (ppm), the Root Zone Water Quality Model 2 (RZWQM2) was used to evaluate the effects of four climate change scenarios: 1) 2.7 degrees F increase in temperature and current CO2 concentration, 2) 3.6 degrees F increase in temperature and current CO2 concentration, 3) 2.7 degrees F increase in temperature and an increase to 490 ppm CO2 concentration, and 4) 3.6 degrees F increase in temperature and an increase to 650 ppm CO2 concentration on soil water content, soil temperature, aboveground biomass, cotton yield and WUE under full irrigation. Cotton yield and irrigation water use efficiency (IWUE) under ten different irrigation management strategies were also analyzed for economic benefits. Under scenario 3 cotton yield increased by 9.0% and under scenario 4, a 30% yield increase occurred relative to current conditions. Because of greater cotton yield and less transpiration, a 9.0% and 24.2% increase in cotton WUE occurred under scenarios 3 and 4, respectively. The highest net income ($1515 per acre) occurred when irrigated at 25.6 inches and net water yield ($0.032 per cubic foot) was highest at 19.7 inches per growing season These results suggested that deficit irrigation can be adopted in irrigated cotton fields to address the agricultural water crisis expected under climate change.

Technical Abstract: Improving cotton (Gossypium hirsutum L.) yield and water use efficiency (WUE) under future climate scenarios by optimizing irrigation regimes is crucial in hyper–arid areas. Assuming a current baseline atmospheric carbon dioxide concentration (CO2) of 380 ppm (baseline, BL0/380), the Root Zone Water Quality Model 2 (RZWQM2) was used to evaluate the effects of four climate change scenarios based on air temperature increase (1.5 and 2.0 oC) and CO2 concentration (380, 490, and 650 ppm); S1.5/380, S2.0/380, S1.5/490 and S2.0/650; on soil water content, soil temperature, aboveground biomass, cotton yield and WUE under full irrigation. Cotton yield and irrigation water use efficiency (IWUE) under ten different irrigation management strategies were analyzed for economic benefits. Under current CO2 concentration (S1.5/380 and S2.0/380), the average simulated aboveground biomass of cotton (vs. BL0/380) declined by 11% and 16%, respectively, whereas under elevated CO2 (S1.5/490 and S2.0/650) it increased by 12% and 30%, respectively. The simulated average seed cotton yield (vs. BL0/380) increased by 9.0% and 20.3% under the S1.5/490 and S2.0/650 scenarios, but decreased by 10.5% and 15.3% under the S1.5/380 and S2.0/380 scenarios, respectively. Owing to greater cotton yield and lesser transpiration, a 9.0% and 24.2% increase (vs. BL0/380) in cotton WUE occurred under the S1.5/490 and S2.0/650 scenarios, respectively. The highest net income ($3741 per ha) and net water yield ($1.14 per cubic meter) of cotton under climate change occurred when irrigated at 650 mm and 500 mm per growing season, respectively. These results suggested that deficit irrigation can be adopted in irrigated cotton fields to address the agricultural water crisis expected under climate change.