Newly established prairie strips intermittently increase soil carbon beneath the strip, but not in surrounding cropland

Abstract

Prairie strips, zones of agricultural land converted to perennial vegetation, have the potential to sequester soil carbon and improve soil health. In this study, we introduced prairie strips to two cropping systems that had been maintained with cover crops and reduced chemical inputs for the previous 30 years. We evaluated soil carbon within newly established prairie strips and in adjacent cropland, measuring microbial biomass carbon (MBC), permanganate oxidizable carbon (POXC), and mineralizable carbon (MinC) in each of the first 3 years of prairie strip establishment. We also measured C stocks in particulate organic matter (POM) and mineral-associated organic matter (MAOM) fractions 3 years after prairie strip planting. We found prairie strip effects on soil C depended on the form of C measured, and the year (which included different crops and management activities). Prairie strips showed higher soil MBC and MinC than cropland during corn and wheat years, but not during a soybean year, and did not alter C in POM or MAOM fractions after 3 years. We also found no evidence that prairie strips increased soil C in adjacent cropland soils. Within each year, soil MBC and MinC responded to management practices that occurred shortly before sampling in prairie strips and cropland, suggesting that these measurements may be most appropriate for tracking short-term (weeks) responses of soil C. Overall, we find that prairie strips generally have a positive impact on fast-cycling soil C during early establishment in multiple cropping systems, but effects are highly dependent on annual and intraannual management and the specific form of C being measured.