Analysis and Prediction of Water Deficit for Soybean, Corn and Cotton in the State of Mississippi

Author(s): Feng, G.

Supplemental irrigation are becoming common practice in Mississippi to stabilize and increase crop productivity and quality after crop late vegetative growing season. Agriculture consumes 90% of consumptive water use, 80% is from groundwater, only 20% is from surface water in the US second largest annual rainfall state of Mississippi. In western Mississippi, groundwater levels are declining due to increasing groundwater withdrawal for irrigation. Mississippi Delta will face a serious shortage of water for agriculture. In eastern Mississippi, the groundwater is so deep and expensive to pump for irrigation, majority of growers choose using surface pond water for irrigation. Sustainable conjunctive use of surface and ground water resources for irrigation requires knowledge of crop water requirements and deficit (difference in precipitation and evapotranspiration). Therefore, water deficit of dominant irrigated crops, soybean, corn and cotton in Mississippi western Delta and eastern Blackland Prairie regions was estimated. Historical weather data in the two regions dating back to 1800 were analyzed using time series statistical models. The patterns of changes in air temperature and precipitation in the past and future were determined. The obtained trends and other results will help understand climate change and provide agroecosystem models with information to assess agriculture sustainability and competitiveness as affected by such climate change in the future. Water requirements of the three major crops in the two regions were calculated using Hargreaves method. Spatial and temporal probability distribution and frequency of water deficit in both Delta and Blackland Prairie were analyzed. As a result, we are able to forecast water deficit of each individual crop during every growing stage in the state of Mississippi for irrigation scheduling, drainage design, rainfall harvest planning, and agronomic management practice development to make most use of both ground and surface water resources.

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