Preliminary crop coefficients for late planted short-season soybean: Texas High Plains

Authors: Marek, Gary; Evett, Steven - Steve; Colaizzi, Paul; Brauer, David

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2021
Publication Date: 6/7/2021
Publication URL: https://handle.nal.usda.gov/10113/7709470
Citation: Marek, G.W., Evett, S.R., Colaizzi, P.D., Brauer, D.K. 2021. Preliminary crop coefficients for late planted short-season soybean: Texas High Plains. Agrosystems, Geosciences & Environment. 4(2). Article e20177. https://doi.org/10.1002/agg2.20177.
DOI: https://doi.org/10.1002/agg2.20177

Interpretive Summary: Declining well capacities in the Texas High Plains has led to cotton becoming a popular alternative to water-intensive crops like corn. Cotton’s relatively short planting window coupled with unfavorable soil water conditions may prevent planting prior to dates that result in adequate heat unit accumulation. Hail or other severe weather events may also destroy or damage cotton crops early in the season, leaving producers with limited options for late planting of other crops. One option includes the planting of short-season soybean. However, limited crop water use (ET) and crop coefficient (Kc) data exist for such crops in the region. Researchers from USDA-ARS Bushland presented daily crop coefficients (Kc) for late-planted soybean grown on large weighing lysimeter fields. Results showed that although maximum daily Kc values were not different than published values, season length was 24 to 29 days shorter than for soybean planted in mid-May. Late planted short-season soybean may be a profitable option for producers following failure of cotton or other summer crops in the Texas High Plains and surrounding region.

Technical Abstract: Having similar profit potential but roughly half of the water requirements of corn, cotton has become an attractive crop in the Texas High Plains where groundwater levels and well capacities continue to decline. However, unpredictable and erratic precipitation often results in conditions either too wet or too dry for ideal germination. Coupled with a relatively short planting window for adequate heat units and the threat of severe weather events, cotton crops can fail, leaving limited options for producers wanting to plant a second summer crop. One option is short-season soybean. However, limited data on crop water use (evapotranspiration, ET), crop coefficient (Kc), and yield exist for late-planted soybean in the semiarid region. Following unseasonably wet conditions in May of 2019, a short-season soybean variety was planted on 13-June in weighing lysimeter fields at the USDA-ARS Conservation and Production Laboratory at Bushland, TX. The irrigated fields were serviced by a lateral move sprinkler system and subsurface drip irrigation. Preliminary results showed that although maximum daily Kc values were not different than published values, season length was 24 to 29 days shorter than for soybean planted in mid-May. Seasonal water use was less than that of archived data using earlier planting dates in two of three years, although those studies used different varieties. Late planted short-season soybean may be an option for producers following failure of cotton or other summer crops in the Texas High Plains. However, additional data are needed to support this conclusion and to better characterize interannual variations in weather.