Irrigation Water Use Efficiencies of Twin-Row Vs. Single Row Soybean and Cotton Plantings in the Humid Mississippi Delta.

In the humid climate of the Mississippi (MS) Delta, high intraseasonal variability in the rainfall received during the critical periods of crop growth often makes irrigation necessary to maximize crop yields. Farmers in this region, generally, meet their crop irrigation water demands by pumping water from the shallow MS valley alluvial aquifer underlying this region. However, water withdrawal beyond the aquifer’s natural recharge levels is resulting in significant groundwater-level declines there by threatening future water-availability. A field study was initiated to compare the water use efficiencies between twin-row and single row planted cotton (Gossypium hirsutum L.) and soybean (Glycine max L.) cropping systems under varying irrigation levels in a Dundee silt loam soil in the humid climate of MS Delta. Both cotton and soybean were planted with 102 cm row spacing and were furrow irrigated. In the twin-row plantings, two rows were centrally placed within the row spacing of 20 cm. Irrigation levels were full irrigation, half irrigation, and no-irrigation (rainfed), scheduled based on soil water levels. The water use efficiency between single-row and twin-row under the three irrigation levels will be presented.