Proceedings of the 2019 Mississippi Water Resources Conference

Year: 2019 Authors: Hodges B.C., Tagert M.L., Paz J.O., Reginelli D.

There have been numerous studies on soil moisture as it pertains to irrigation in Mississippi, but more work is needed in the agricultural region known as the Blackland Prairie, located in the northeastern part of Mississippi. Here, an increasing number of producers are showing an interest in irrigation. It is not economical to access groundwater over most of the region due to the depth of the aquifer, so many producers use surface water for irrigation. Sprinkler irrigation is the primary application method, to accommodate the changing topography across the landscape. Soil moisture sensors have been shown to conserve water usage while maintaining yields on irrigated fields, helping to better time irrigation applications with crop water needs. However, more work is needed to determine the ideal number of sensor sets needed over a given area and the best placement of sensors within a field. There are many variables that can affect soil moisture including topography, soil type, and the variability of vegetation. This study is being executed on a 15-ha soybean field under sprinkler irrigation near Brooksville, MS, in the Blackland Prairie region. A 55-m grid was placed over the field, resulting in 44 sample locations; Watermark Granular Matrix soil moisture sensors were installed at 12- and 24-inch depths at each sampling point. The sensors were wired to data loggers, which recorded soil tension measurements hourly. Plant height and leaf area index (LAI) were measured weekly from June 29 through August 17, 2018. Soil texture was measured for each grid point, showing a relatively homogenous field with a silty clay loam as the dominant soil type. Results show spatial differences in soil moisture over time, with more variability when the soil profile is drier.