In a collaborative work between the Agricultural Research Service Soil and Water Management Research, the University of Castilla-La Mancha in Spain, West Texas A&M University, and Texas A&M AgriLife, researchers adapted a crop model for use in the Texas High Plains to simulate crop water use and corn yield to help producers adjust center-pivot irrigation strategies and maximize profitability with limited water.
Crop producers in this semi-arid region of the Texas High Plains largely depend on groundwater irrigation. Each season, crop producers in the region evaluate how much land area could be irrigated under the pivot with limited water. Addressing this is not straightforward because producers must consider reducing irrigated areas, which influences grain yield, input costs, and the timing of the irrigation applications.
To help producers with these decisions, researchers completed a study that uses 25 years of climatic data to simulate corn production using a range of irrigation capacities, the maximum amount of water that can be delivered to an irrigated acre in a day, to evaluate water allocation strategies that could increase profitability and improve the efficient use of water.
Many crop producers in the Texas High Plains irrigate crops using a center-pivot, equipment that often needs five or more days to complete a single revolution around the field. When evaluating strategies to maximize profit under limited irrigation capacities, the study considers the time factor of moving the center-pivot because this influences how much water can be applied and the end-of-season yield.
The model showed that for irrigation capacities representative of the region and a growing season with average rainfall, maximum profitability was achieved by irrigating about 75% of entire pivot area with the remaining area in fallow (unplanted field) or dryland cotton. Concentrating water generated greater net returns because of lower seed and fertilizer costs and greater corn yields that compensated for lack of production in fallow areas. In years with seasonal drought, the irrigated area would need to be further constrained to avoid crop failure and maximize profits.
"Results from this adapted model allow producers to evaluate how best to allocate the limited water that is available to a fraction of the land area under the pivot that, over the long term, maximizes profitability and utilizes water resources more efficiently," said Soil Scientist Robert Schwartz with Soil and Water Management Research. "Some scenarios in the study even demonstrated that profitability could be maximized by irrigating a fraction of the area but using less water compared to irrigating the full pivot circle, thereby conserving groundwater for future use."
"This study has demonstrated that the crop water use model MOPECO can be adapted to many different scenarios and is a useful tool for improving the environmental and economic sustainability of agricultural systems where water is limiting," said Alfonso Domínguez researcher of the Centro Regional de Estudios del Agua of UCLM. "A simplified version of this model is being tested in many semiarid areas of the Mediterranean basin and the Americas with the objective of making it available to the farm sector through an online platform."
This research was supported in part by the Ogallala Aquifer Program.
The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $17 of economic impact.
