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ARS Home » Southeast Area » Jonesboro, Arkansas » Delta Water Management Research » Research » Publications at this Location » Publication #338401
Title: Irrigation initiation timing in soybean grown on sandy soils in Northeast Arkansas

Author
item CHLAPECKA, J. - University Of Arkansas
item MANN, A. - University Of Arkansas
item BENSON, N. - University Of Arkansas
item Reba, Michele
item TEAGUE, TINA - University Of Arkansas

Submitted to: Arkansas Agricultural Experiment Station Research Series
Publication Type: Experiment Station
Publication Acceptance Date: 3/1/2017
Publication Date: 3/15/2017
Citation: Chlapecka, J.L., Mann, A.M., Benson, N.R., Reba, M.L., Teague, T.G. 2017. Irrigation initiation timing in soybean grown on sandy soils in Northeast Arkansas . Arkansas Agricultural Experiment Station Research Series. 637:165-169.

Interpretive Summary: The decision of when to irrigation a soybean crop depends on many things including soil type and weather and impacts yield and net profit. A study was completed to evaluate a furrow-irrigated soybean field with sandy soils in Mississippi County, AR. A major objective of this 2015 study was to validate and expand University of Arkansas Extension Service irrigation timing recommendations. The study used plant growth measures with local weather station data and sensors to estimate evapotranspiration (ET) and soil moisture. Four initiation treatments were evaluated with irrigation starting when ET deficits reached 1 inch (early), 2 inches (standard), and 3 inches (late); there also was a rainfed check. Plots extended the length of the 35 acre field. Treatments were arranged strip-plot, randomized complete block design with three replications. Yield monitor measured yield response to irrigation timing depended on soil texture in the spatially variable field. There were two soil textures – coarse sand and sandy loam - classified using measures of soil electroconductivity (EC). Soil water deficits in both the rainfed and late initiation treatments reduced yield of plants in coarse sand. In sandy loam portions of the field, the non-irrigated rainfed plants produced the lowest yields, but plants receiving early irrigation also produced lower yields compared to standard and late initiation timing. There was increased lodging with the early irrigation initiation, and this likely contributed to the yield reduction. Current Arkansas guidelines suggest a conservative irrigation regime, and results from this trial validate those recommendations.

Technical Abstract: Irrigation initiation timing was evaluated in furrow-irrigated soybean field with sandy soils in Mississippi County, AR. A major objective of this 2015 study was to validate and expand irrigation timing recommendations that pair plant growth measures with weather cues including use of local weather station data and atmometers to estimate evapotranspiration (ET) and use of Watermark sensors to measure soil moisture. Four initiation treatments were evaluated with irrigation starting when ET deficits reached 1 inch (early), 2 inches (standard), and 3 inches (late); there also was a rainfed check. Plots extended the length of the 35 acre field. Treatments were arranged strip-plot, randomized complete block design with three replications. Despite above average rainfall amounts in 2015, there were periods during crop reproductive development when measured ET and soil moisture values exceeded deficit thresholds. Yield monitor measured yield response to irrigation timing depended on soil texture in the spatially variable field. There were two soil textures – coarse sand and sandy loam - classified using measures of soil electroconductivity (EC). Soil water deficits in both the rainfed and late initiation treatments reduced yield of plants in coarse sand, which encompassed ca. 12% of the field. In sandy loam portions of the field, the non-irrigated rainfed plants produced lowest yields, but plants receiving early irrigation also produced lower yields compared to standard and late initiation timing. There was increased lodging with the early irrigation initiation, and this likely contributed to the yield penalty. Current Arkansas guidelines suggest a conservative irrigation regime, and results from this trial validate those recommendations.