Enhancing long-term no-till wheat systems with cover crops and flash grazing

Abstract

Monoculture practices under conventional tillage (CT) are detrimental to sustainable soil ecosystem functions and services under intensive agriculture practices, ultimately diminishing net benefits. Conservation practices, such as no-till (NT) and cover crops (CC) can nurture sustainable soil ecosystem functions and services. The impact of introducing CC, grazing, intercropping, and reverting to tillage in a long-term NT continuous wheat system on soil properties was evaluated in three years of implementation. Treatments were CT and combinations of NT, CC, grazing, and intercropping wheat with radishes and turnips. Tillage significantly decreased large macroaggregates (33–39%), mean weight diameter (21–26%), and POX-C (21–29%) within large macroaggregates and increased small macroaggregates (40–65%) compared to all CC treatments (including grazed and intercropped) within a 3-year period. Reverting to tillage after 12 years of NT significantly increased bulk density by 19%, reduced total porosity by 21% and soil water content by 28% compared to all CC treatments. In addition, Cover crops (including grazed and intercropped) enhanced NT as evident in significant improvements in POX-C (19–32%), large macroaggregates (37–51%), mean weight diameter (22–31%), bulk density (8–13%), total porosity (10–18%), and measured soil water content (11–14%). Flash grazing CC did not result in any adverse effects compared to all other treatments for measured parameters. Ultimately, reverting to tillage in a long-term NT system significantly degraded soil physicochemical properties. In contrast, implementing CC to long-term continuous wheat systems resulted in rapid soil improvements within the 3-year study period which were reflected in enhanced stored soil moisture storage of up to 39% higher under CC compared to CT. Flash grazing CC can be successfully implemented in NT systems without adversely affecting soil physicochemical properties. Intercrops did not show pronounced effects possibly due to winterkill.