Abstract Soil health indicators (SHIs) are used to detect changes in soil conditions in response to management. However, management effects must be disentangled from other factors influencing SHI variability. Specifically, how annual weather affects SHI remains poorly understood. To address this gap, we analyzed soil annually for 5 years at 64 sampling points in two silt loam fields, in Minnesota. One field had annual crops (maize, Zea mays L.; winter camelina, Camelina sativa L. Crantz.; soybean, Glycine max L. Merr.; wheat, Triticum aestivum L.; and winter barley, Hordeum vulgare L.) while the other had perennial crops (alfalfa, Medicago sativa L. and Kernza, Thinopyrum intermedium (Host) Barkworth & D.R. Dewey). We measured mineralizable carbon (MinC), extracellular enzymes, microbial biomass, soil organic carbon, mineral‐associated organic matter, and particulate organic matter (POM) at 0‐ to 15‐cm and 15‐ to 30‐cm depth. We present two key findings. First, growing season weather was correlated with annual changes in several indicators. The most striking relationships were between growing season mean air temperature (MAT) and 1‐, 4‐, and 12‐day MinC ( p < 0.001). MAT was not correlated with 21‐day MinC. MAT–MinC correlations were depth‐dependent: positive at 0–15 cm ( r = 0.65–0.68) and negative at 15–30 cm ( r = −0.39 to −0.60). Second, soil health improved in the perennial field. Most illustrative of this finding were gains in arbuscular mycorrhizal fungi ( p = 0.013), subsurface MinC, and POM ( p < 0.001). In summary, we recommend that soil health assessment account for annual weather, and suggest that perennial crops lead to improved soil health.
Kundert et al. (Sun,) studied this question.