Assessment of Multiple Management Systems in the Upper Midwest

Abstract

Independently, reduced tillage, multicrop rotations, and organic fertilization are expected to enhance soil biological properties; outcomes are less understood when these management strategies are integrated with conventional or organic system management. Over 9 yr, soil biological properties of microbial biomass C (MBC) and N (MBN) and soluble organic C (SolC) and total soluble N (SolN) were measured to evaluate these practices. A full factorial arrangement within each management system of the following strategies were used: 2‐yr vs. 4‐yr rotation; conventional tillage (CT) vs. strip tillage (ST); and unfertilized vs. fertilized with inorganic fertilizer or manure in the conventional and organic systems, respectively. Parsing out independent effects from integrated strategies demonstrated that across all years, MBC and MBN were not influenced by system management but were higher in 4‐yr than 2‐yr rotations, ST than CT, and fertilized than unfertilized treatments; SolC and SolN were greater in fertilized treatments and SolN greater in CT treatments. Independent strategies, however, reacted differently when integrated under the two management systems. Under conventional system management, MBC increased with time only when ST was combined with a 4‐yr rotation, regardless of fertilization strategy; whereas, under organic system management, MBC increased with time in all ST treatments regardless of rotation or fertilization strategy. Results confirmed expectations that reduced tillage and increased rotation diversity positively impacted measured soil parameters, but inorganic vs. organic fertilizer resulted in few differences. Selecting and using individual strategies to achieve positive soil changes will depend on system‐level management and how strategies are integrated.