Minimum tillage and no-tillage winter wheat-summer fallow for low precipitation regions

Authors: Wuest, Stewart; Williams, John

Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2020
Publication Date: 4/17/2021
Citation: Wuest, S.B., Williams, J.D. 2021. No-tillage and minimum tillage winter wheat-summer fallow for low precipitation regions. Journal of Soil and Water Conservation. 76(3):246-255. https://doi.org/10.2489/jswc.2021.00062.
DOI: https://doi.org/10.2489/jswc.2021.00062

Interpretive Summary: Dryland wheat (Triticum aestivum L.) is the principle crop grown on 3.35 million hectare of the semi-arid Inland Pacific Northwest (PNW) of the United States. Much of this region receives no more than 12 inches annual precipitation in weather patterns typical for a Mediterranean climate. Successful crop production in this region depends on adequate precipitation capture and storage and weed control, which has proven problematic under no-tillage -the most effective soil and water conservation practice. Sweep-tillage (ST) has been proposed as an equally effective conservation system, with local, conventional wisdom certain that it can produce higher yields than no-tillage systems. A comparison study established in 2006 and concluded in 2018 was used to evaluate the performance of no-tillage and ST winter wheat–summer fallow production systems. The working hypothesis for this research was there would be no statistically significant differences in any of the soil and plant characteristics measured. Sixteen 0.04 ha plots were established in a randomized complete block design, with two rotation entry points for a total of 4 treatment plots per year replicated in four blocks. Data were analyzed using a generalized linear mixed model. The no-tillage system produced significantly higher crop yields (50±2 bushels per acre) at higher precipitation use efficiencies than the ST system (42±2 bushels per acre). Water infiltrated more readily, and soil temperatures were lower in the no-tillage system. The higher yields and lower soil temperatures in the no-tillage system were unexpected and contrary to previous research conducted in this region.

Technical Abstract: Dryland wheat (Triticum aestivum L.) is the principle crop grown on 3.35 million hectare of the semi-arid Inland Pacific Northwest (PNW) of the United States. Much of this region receives no more than 266 mm annual precipitation in weather patterns typical for a Mediterranean climate. Successful crop production in this region depends on adequate precipitation capture and storage and weed control, which has proven problematic under no-tillage (NT) -the most effective soil and water conservation practice. Sweep-tillage (ST) has been proposed as an equally effective conservation system, with local, conventional wisdom certain that it can produce higher yields than NT systems. A comparison study established in 2006 and concluded in 2018 was used to evaluate the performance of NT and ST winter wheat–summer fallow production systems. The working hypothesis for this research was there would be no statistically significant differences in any of the soil and plant characteristics measured. Sixteen 0.04 ha plots were established in a randomized complete block design, with two rotation entry points for a total of 4 treatment plots per year replicated in four blocks. Data were analyzed using a generalized linear mixed model. The NT system produced significantly higher crop yields at higher precipitation use efficiencies than the ST system (NT 3.38±0.33, ST 2.66±0.27 Mg ha-1). Infiltration rates were higher and soil temperatures were lower in the NT system. The higher yields and lower soil temperatures in the NT system were unexpected and contrary to previous research conducted in this region.