Assessing the impacts of future climate on cotton production in the Arizona low desert

Authors: AYANKOJO, IBUKUN - UNIVERSITY OF FLORIDA; Thorp, Kelly; MORGAN, KELLY - UNIVERSITY OF FLORIDA; KOTHARI, KRITIKA - UNIVERSITY OF KENTUCKY; ALE, SRINIVASULU - TEXAS A&M UNIVERSITY

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/23/2020
Publication Date: 8/24/2020
Citation: Ayankojo, I.T., Thorp, K.R., Morgan, K.T., Kothari, K., Ale, S. 2020. Assessing the impacts of future climate on cotton production in the Arizona low desert. Transactions of the ASABE. 63(4):1087-1098. https://doi.org/10.13031/trans.13731.
DOI: https://doi.org/10.13031/trans.13731

Interpretive Summary: Possible changes in climate could alter agricultural productivity in some regions. Global predictions of future climate are available from various climate modeling groups around the country. Data from these models can be combined with crop growth models to predict future impacts on agricultural productivity. In this study, we used data from nine future climate models to drive simulations with a cotton growth model for central Arizona conditions. Results demonstrated that, without adaptation efforts, cotton yield is expected to decline by 50% in central Arizona by the end of the century. Reductions were driven by projected increases in air temperature. Water requirements for cotton production are also expected to increase by 10-15%. The findings are important for stakeholders in the U.S. cotton industry, such as Cotton Incorporated and Arizona cotton growers.

Technical Abstract: Cotton is an important crop in Arizona with a total cash value of approximately $32 million in 2018. In recent years, heat stress from increasing air temperature has reduced cotton productivity in the Arizona low desert (ALD); however, the effects of future climate on ALD cotton production have not been studied. In this study, the DSSAT-CSM CROPGRO-Cotton model was used to simulate the effects of future climate on cotton growth, yield and water use in the ALD area. The projected climate forcings for the ALD were obtained from 9 global climate models under two representative concentration pathways (RCP 4.5 and 8.5). Cotton growth, yield, and water use were simulated for mid-century (2036 to 2065) and late-century (2066 to 2095) and compared to the baseline (1980 to 2005). Results indicated that seed cotton yield was reduced by at least 40% and 51% by mid-century and late century, respectively, compared to the baseline. Of all the weather variables, the seasonal average maximum (r2 = 0.72) and minimum (r2 = 0.80) temperatures were most correlated with yield reductions. Under the future climatic condition of the ALD, cotton growth or biomass accumulation slightly increased compared to the baseline. Irrigation requirements in the ALD increased by at least 10% and 14% by mid-century and late-century, respectively. Increases in irrigation requirement were due to an increase in crop water use; hence, higher pressure on freshwater withdrawal for agricultural purposes is anticipated in the future. Therefore, cotton cultivars that are tolerant to long periods of high temperature and improved management practices that promote efficient crop water use are critical for future sustainability of cotton production in the ALD.