Controlling stormwater runoff that limits water availability and dryland crop productivity

Authors: Baumhardt, Roland - Louis; DOCKAL, J - Former ARS Employee; Johnson, Grant; Brauer, David; Schwartz, Robert

Submitted to: Frontiers in Sustainable Food Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2020
Publication Date: 10/9/2020
Citation: Baumhardt, R.L., Dockal, J.R., Johnson, G.L., Brauer, D.K., Schwartz, R.C. 2020. Controlling stormwater runoff that limits water availability and dryland crop productivity. Frontiers in Sustainable Food Systems. 4. Article 533687. https://doi.org/10.3389/fsufs.2020.533687.
DOI: https://doi.org/10.3389/fsufs.2020.533687

Interpretive Summary: Precipitation is the only water source for the increasingly important dryland crops of the western Great Plains and runoff decreases both fallow and growing season available soil water for crop yields. ARS scientists from Bushland, TX, quantified storm water runoff and precipitation storage between 1984 and 2010 for variable precipitation and field conditions. Field management with stubble-mulch (SM) and no-tillage (NT) or with-slope and contour farming were compared. Yields for wheat and sorghum grown in a three-year wheat-sorghum-fallow (WSF) rotation were greater with NT compared with SM tillage due to less evaporation. NT had less soil loss than SM due to residue cover that prevented entrainment despite greater fallow runoff. Greater landscape slope increased fallow runoff, but soil water and dryland crop yields did not increase significantly with contour farming. These results will help farmers and crop consultants improve semiarid dryland cropping practices by decreasing evaporation and soil erosion with NT residues.

Technical Abstract: Continued pumping for irrigation from the non-recharging Ogallala aquifer in Kansas and Texas is unsustainable. Reducing risks for dryland wheat (Triticum aestivum (L.)) and sorghum [Sorghum bicolor (L.) Moench] production, which depends exclusively on precipitation to meet water demand is critical for future adoption. Stormwater runoff reduces the amount of precipitation available to crops, but management practices to minimize runoff concomitantly increase the opportunity time for infiltration and improve precipitation storage as soil water for crop use. Our objectives in this study were to evaluate tillage, slope and the effects of contour or with-slope farming on runoff, soil water at planting, and the growth and yield of wheat and sorghum grown in the three-year wheat-sorghum-fallow (WSF) rotation. Long-term, 1983 to present, runoff was measured from gauged terraced and contour farmed fields managed in the WSF rotation with no-tillage (NT) or stubble-mulch (SM) tillage. We found significantly greater mean cumulative runoff during fallow for NT than for SM but only for the 1.8% terrace slopes. The corresponding soil water with NT increased by a significant amount, approximately 27 mm, over SM due to reduced evaporation but generally did not differ due to slope. Wheat yield decreased significantly as slope decreased from 1.8% to 1.2% but exhibited no yield response due to tillage practice. In contrast, grain sorghum yields were greater with NT than SM tillage residue management. Farming along the contour or slope manifested no differences in soil water, crop grain yield, or water use; however, they did increase significantly with no tillage for sorghum but not wheat. We conclude that management of tillage was more effective than slope effects in increasing water availability to crops because of evaporation reduction with crop residue.