Soil health indicators and crop yield in a long-term cropping system experiment

Soil health indicators that link to ecosystem services, such as water and nutrient cycling, crop yield, environmental quality, and biodiversity, are needed. We measured 65 soil physical, chemical, and biological properties as potential soil health indicators from a 36-yr-old tillage and cropping system experiment and related these properties to crop yield in eastern Montana. Tillage and cropping systems were fall and spring-till continuous spring wheat (Triticum aestivum L.) (FSTCW), no-till continuous spring wheat (NTCW), no-till spring wheat-barley (Hordeum vulgare L., 1984-1999) replaced by spring wheat-pea (Pisum sativum L., 2000-2019) (NTWP), and spring till spring wheat-fallow (STWF, traditional system). Soil aggregation and stability, Al, Cd, Fe, Mn, P, and Pb concentrations, soil organic matter, water-extractable C and N, CO2 flush, beta-glucosidase, and autoclaved citrate-extractable protein (ACEP) were lower, but bulk density was greater with STWF than other treatments. Mean crop yield across years was also lower with STWF than other treatments. Multivariate analysis indicated that most promising soil health indicators that related to crop yield were CO2 flush, KMnO4-extractable C, and Ca, Al, and Fe concentrations. Absence of crops during the fallow period reduced soil health indicators and crop yield with STWF compared to NTCW and NTWP. Because of significant response to management practices and relationship to crop yield, soil biological properties may be used in a routine test to measure soil health in addition to physical and chemical properties.