Soil health and ecological resilience of no-till, organic, and mixed-crop livestock systems in eastern Washington State

Combining concepts of soil health and ecological resilience provides a useful framework for assessing and identifying sustainable soil management strategies. Major soil health concerns globally and in the Palouse region of eastern Washington State include erosion, organic matter (SOM) loss, and acidification. Alternative cropping systems have the potential to improve these areas of soil health through practices such as no-tillage, diversified rotations, and reduced chemical inputs. Here, we report on a 9-year study (2012–2020) examining four alternative farming systems in the Palouse and their impacts on soil health and ecological resilience, accounting for soil erosion, SOM depletion, acidification, and financial performance. The four systems included (i) a no-till system (NT) using a typical 3-year spring pea-winter wheat-spring wheat rotation with conventional herbicide and fertilizer use; (ii) a mixed crop-livestock system (MIX) using a 3-year pea-winter wheat-spring wheat rotation with livestock integration and reduced herbicide and fertilizer use; (iii) an organic system that integrates sheep and intercropping with three years of alfalfa/grass hay and six years of grain cereals and legumes (ORG_crop); and (iv) an organic system that integrates sheep into an eight-year rotation with six years of alfalfa/grass hay and two years of grain cereals and legumes (ORG_hay). All four farming systems were above the maximum ecological resilience threshold for soil erosion, below the minimum threshold for soil organic carbon (SOC) content, above the minimum threshold for acidification, and above the minimum threshold for economic performance. In terms of erosion control, NT performed the best, followed by ORG_hay, MIX, and then ORG_crop. In terms of carbon stock, ORG_hay performed the best as it was the only system to not decrease in surface (0–15 cm) SOC. With acidification, ORG_crop and ORG_hay performed better than NT and MIX at the surface (0–7.5 cm), but all farming systems were similar when considering 0–30 cm. With economics, ORG_hay had the highest average net returns across the nine growing seasons, followed by ORG_crop, MIX, and then NT, with all four systems hypothetically outperforming a typical conventional tillage farm in the area. ORG_hay had no major tradeoffs and overall performed best, having similar or improved ecological resilience in all areas measured compared to the other cropping systems. The data from this study suggests that Palouse farmers may benefit in converting a small percentage of their fields to organic alfalfa/hay mixtures. However, farmers may need to be incentivized to implement this due to the risk involved.