Long-term conservation and conventional tillage systems impact physical and biochemical soil health indicators in a corn–soybean rotation

Agricultural management practices tend to influence soil structure stabilization, mediating many physical, chemical, and biological processes in soils. Therefore, understanding the long-term effects of management practices on various soil health indicators is crucial to develop sustainable agricultural practices. This study aimed to assess the long-term conventional and conservation tillage effects on soil physical (aggregates) and biochemical (soil organic carbon [SOC], enzymes, and microbial biomass) parameters under a range of tillage practices in a corn–soybean rotation in Nebraska. The experiment was conducted at two locations as follows: (1) Concord site (36 years) with the three treatments: no-till (NT), disk, and moldboard plow; and (2) Lincoln site (40 years) with four tillage treatments: NT, double disk, chisel, and moldboard plow. Results showed that NT at both sites significantly increased SOC concentration by 24%–66% compared to moldboard plow. Similarly, double disk tillage increased SOC by 54% compared to the moldboard plow at the Lincoln site. Arylsulfatase, β-glucosidase, hot- and cold-water extractable carbon, microbial biomass carbon, and nitrogen concentrations significantly decreased with the increased tillage intensity at both sites. This implies that the NT increased these parameters compared to the disk and moldboard plow. However, aggregate size fraction 0.053–0.25 mm was the only parameter higher under moldboard plow (20.8%) than NT. Overall, the results from these long-term studies indicate that NT, and to a lesser extent the reduced tillage practice of disk till, can improve soil health more than conventional tillage practices under a corn–soybean cropping system, suggesting the adoption of sustainable agricultural practices to improve soil health.