Soil health indicators for water-limited regions: Evaluating relative sensitivity to compost and cropping intensification

In the water-limited agroecosystems of the US Great Plains, management strategies such as compost application and cropping system intensification have been promoted to improve soil health and help adapt to increasing climatic variability. However, accurately assessing the ability of these strategies to support soil health in arid and semiarid regions hinges upon selecting indicators sensitive to management and linked to essential soil functions, especially those related to soil water dynamics. Using a suite of soil physical and biological parameters, this study assessed the effects of common management interventions to support soil health and evaluated the extent to which these key soil health metrics were related to soil water dynamics within two long-term studies in Akron, Colorado, and Clovis, New Mexico. Soil physical indicators included aggregate stability (mean weight diameter [MWD]), bulk density, and saturated hydraulic conductivity, while biological indicators included measures of soil macrofauna and microbial communities. Compost application was the primary driver of increased aggregate stability and abundance of soil biota at both sites, though effects of cropping system intensification were observed for some indicators. Measures of soil microbial abundance were correlated with MWD, but saturated hydraulic conductivity was generally not correlated with other measured variables. Our findings indicate that MWD and microbial abundance are linked and sensitive to management, and further research to connect measures of soil biological and physical health to soil water dynamics in semiarid systems is necessary to develop regionally relevant frameworks for soil health assessment.