Tillage and residue management drive rapid changes in soil macrofauna communities and soil properties in a semiarid cropping system of Eastern Colorado

Tillage and stover harvest are common management practices in maize-based cropping systems around the globe. However, frequent soil disturbance and biomass export are likely to have negative long-term impacts on soil biological activity and a range of associated soil properties, and thus, there is great concern surrounding the sustainability of these practices. To address this issue, we examined soil macrofauna communities and a suite of soil chemical and physical properties in a recently established experiment (2.5 yrs. old) in Akron, Colorado. Notillage and residue retention practices were included in a full factorial randomized block design with the following treatments: no-fill + residue retention (NT/R); no-fill + residue harvest (NT/RH); conventional tillage + residue retention (CT/R); and conventional tillage + residue harvest (CT/RH). In year three of the experiment soil health parameters were assessed including: soil macrofauna diversity and abundance, aggregate stability, potential infiltration, and chemical fertility measures. The combined practice of residue retention with no-tillage (NT/R) resulted in greater macrofauna abundance, including a five-fold increase in earthworm abundance and biomass. Greater earthworm populations were associated with an increase in aggregate stability and a trend towards greater water infiltration under NT/R. While univariate tests did not reveal significant treatment differences in arthropod taxa, multivariate analyses indicated clear treatment effects on macrofauna communities, with tillage generally separating communities more than residue management. Soil chemical parameters indicated relatively less dramatic differences between treatments, but with some notable impacts of both residue retention and tillage on soil C and N dynamics. Findings from our study, among the first to examine whole soil macrofauna communities in the semi-arid Great Plains, suggest that no-fill and residue retention practices offer promise for improving soil biological activity and soil structural properties of soil, especially when these two practices are employed in combination.