|MODALA, N - Texas A&M University|
|ALE, S - Texas A&M Agrilife|
|RAJAN, N - Texas A&M Agrilife|
|MUNSTER, C - Texas A&M University|
|DELAUNE, P - Texas A&M Agrilife|
|NAIR, S - Texas A&M Agrilife|
|BARNES, E - Cotton, Inc|
Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2015
Publication Date: 6/1/2015
Citation: Modala, N.R., Ale, S., Rajan, N., Munster, C., Delaune, P., Thorp, K.R., Nair, S., Barnes, E. 2015. Evaluation of the CSM-CROPGRO-Cotton model for the Texas rolling plains region and simulation of deficit irrigation strategies for increasing water use efficiency. Transactions of the ASABE. 58(3):685-696.
Interpretive Summary: Crop simulation models are increasingly being used as research tools to address a variety of agricultural issues, such as crop water use and irrigation water management. In the United States, development of crop simulation models began in the late 1960's and focused on cotton. Several cotton simulation models have been developed since then, one of which is the CSM-CROPGRO-Cotton model. Past evaluations and applications of CSM-CROPGRO-Cotton have focused mainly in the humid southeastern United States, and there has been a need to test the model for the arid and semi-arid cotton production regions of the western United States. The objective of this study was to perform a comprehensive evaluation of CSM-CROPGRO-Cotton for irrigated cotton systems in the semi-arid conditions of the Texas Rolling Plains. Cotton growth and water use data from four field experiments conducted at Chillicothe, Texas were used in the evaluation. Simulations of cotton growth in response to water deficit were comparable to field measurements. The simulations showed that deficit irrigation practices with normal weather conditions could conserve water without affecting cotton yield. With this research effort, an important cotton simulation tool has been evaluated and improved, which will provide benefit to a growing number of cotton scientists and researchers who use simulation models to solve important cotton production problems.
Technical Abstract: Cotton is one of the major crops cultivated in the Texas Rolling Plains region and it is a major contributor to the regional economy. Cotton cultivation in this region is facing severe challenges due to the increase in the frequency of droughts and projected decrease in rainfall in the future. Development and evaluation of deficit irrigation strategies for this region could potentially conserve water while maintaining cotton yields. In this study, the Decision Support System for Agrotechnology Transfer (DSSAT) Cropping System Model (CSM), CROPGRO-Cotton was extensively tested and then used for evaluating various deficit irrigation strategies for this region. The model inputs were obtained from the field experiments conducted at Chillicothe, TX, during four growing seasons: 2008-2010 and 2012. The model was first calibrated using the data from a 100% evapotranspiration (ET) replacement irrigation scheduling experimentconducted in 2012 and then validated on three other irrigation scheduling treatments (75% ET replacement, soil moisture based, and tensiometer based) conducted in the same year. The model was further evaluated using the data from cotton tillage and irrigation experiments conducted in an adjacent field during 2008-2010. The model calibration, validation and evaluation results were satisfactory except under dry conditions (0% ET replacement and 33% ET replacement). Simulated maximum seed cotton yields under normal and dry weather conditions were achieved at 100% and 120% ET replacement scenarios, respectively. Percentage increases in seed cotton yield were marginal (1.6 to 6.5%) when theamount of irrigation water applied was increased from 66% to 100% ET replacement under normal rainfall conditions. However, under less than normal rainfall (drier) conditions, percent increase in seed cotton yield was substantial (about 33.5%) when irrigation strategy was switched from 70% to 100% ET replacement. The simulations demonstrate that adopting deficit irrigation practices under normal weather conditions can conserve water without adversely affecting seed cotton yields. However, under dry conditions, there is a risk of increased yield loss and therefore producers should consider that risk when adopting deficit irrigation strategies.