Effects of strip tillage and production inputs on soil biology across a spatial gradient

Strip tillage results in soil disturbance levels similar to those of conventional tillage systems in the row locations (strip) and properties of no-till in the interrow (between-row) locations. In this Study, biological and physical soil properties in the region spanning the row to interrow were investigated and results were compared among strip-tillage systems utilizing different inputs (conventional fertilizer and pesticides vs. USDA-approved organic inputs) and rotation regimes (Continuous tomato (Lycopersicon esculentum Mill.) vs. a 3-yr vegetable rotation). Bulk density was significantly greater in the interrow locations. Soil respiration potential was greatest in the interrow and least in the row locations, and greater in treatments receiving organic inputs relative to synthetic inputs. No differences in soil N mineralization potential were determined. Microbial biomass C and N were greatest in interrow and least ill row locations. Total soil C and N Values did not vary from row to interrow locations or as a result of synthetic vs. organic inputs. The data suggest that organically managed production systems are less biologically stratified than conventional input systems under strip-tillage management. Although net C mineralization was similar between chemical and organically managed systems, greater microbial biomass values in the organic treatment systems may have been the result of continuous additions of weed biomass during the Summer. The hypothesis of a gradient effect for biological activity in strip-tillage systems from row to interrow appears to be true in systems managed with synthetic fertilizers and pesticides, but nor true of organically managed systems.