Soybean Irrigation Initiation in Mississippi: Yield, Soil Moisture, and Economic Response

Abstract

Abstract. Irrigated acreage is expanding and groundwater supplies are decreasing in the Mississippi Delta. Efficient irrigation scheduling of soybean [ (L.) Merr] will aid in conservation efforts to sustain groundwater resources. The objective of this study was to develop irrigation initiation recommendations for soybean grown on Mississippi Delta soils. Field studies were conducted on a deep silty clay (SiC) in 2012, 2013, 2014, and 2015 and on a deep silty clay loam (SiCL) and deep silt loam (SiL) or loam (L) soil in 2013, 2014, and 2015. Irrigation was initiated multiple times during the growing season and soybean yield and net return were determined to evaluate the effectiveness of each initiation timing. Growth stage, soil water potential (SWP), and soil water deficit (SWD) were compared at these initiation timings to determine which parameter or combination of parameters consistently predicted the resulting greatest yields and net returns. Stress conditions that reduce yield can occur at any time from late vegetative stages to full seed on these deep soils. The wide range of trigger values found for SWP and SWD to increase yields in different years emphasizes the complexity of irrigation scheduling. Monitoring soil moisture by itself or use of a single trigger value is not sufficient to optimize irrigation scheduling to maximize soybean yield with the least amount of water every year on these soils. Monitoring one or more parameters (e.g., leaf water potential, canopy temperature, air temperature, humidity, solar radiation, and wind) is needed in conjunction with soil moisture to directly or indirectly quantify the abiotic stresses on the plant to better define when a yield reducing stress is occurring. Keywords: Irrigation initiation, Irrigation scheduling, Soil water deficit, Soil water potential, Soybean, Water conservation.

Within-Field Variability in Granular Matrix Sensor Data and its Implications for Irrigation Scheduling

“…Second, how the method and nonuniformity of irrigation applications alter this variability (Saddiq et al, 1985;Clemmens, 1991) should be better understood. Third, any significant temporal changes in the critical water stress threshold as a result of weather and/or growth stage (Sadras and Milroy, 1996;Thompson et al, 2007;Pringle et al, 2019) should be modeled. Fourth, a profit response curve that includes irrigation costs and both underirrigation and overirrigation yield losses should be incorporated.…”

Current Research in Land, Water, and Agroecosystems: ASABE Journals 2017 Year in Review

“…Collections of irrigation research introduced by Dukes et al (2012) and Lamm et al (2016) presented 30 articles on a variety of these topics. In 2017, continuing research was presented on many of these issues, spanning subsurface drip (Lamm and Puig-Bargués, 2017;Lamm and Rogers, 2017), microirrigation (Ju et al, 2017), center pivot (Brar et al, 2017), lateral move (Nörenberg et al, 2017), and surface furrow (Pringle et al, 2017;Schlegel, 2017a, 2017b) irrigation systems.…”

“…Spatial variability of field capacity and root zone available water capacity in central Nebraska was adequately characterized by identifying a suitable predictor variable (Lo et al, 2017); for the study field, use of elevation, selected on the basis of site-specific knowledge and data, as the predictor variable provided better predictions than deep-soil apparent electrical conductivity. In the Mississippi Delta, furrow-irrigated corn yields and net returns were sensitive to drought stress during tasseling, silking, and pollination, on the basis of measured soil water potential and soil water deficit for multiple irrigation initiation timings on deep silty clay loam soils (Pringle et al, 2017). Bautista and Schlegel developed (2017a) and tested (2017b) software for estimating infiltration and hydraulic resistance parameters in surface furrow irrigation systems, with important benefits for modeling application uniformity.…”