A Survey Approach to Identify the Effect of Agricultural Management Practices on Labile Soil Carbon and Nitrogen in Wisconsin.

Amid ever-increasing enthusiasm for soil health there remains uncertainty about how best to measure it, to interpret the results, and to adapt agricultural management accordingly. This research takes a survey-based approach to identify how labile carbon (C) and nitrogen (N) – as permanganate oxidizable carbon (POxC), potentially mineralizable carbon (PMC) and potentially mineralizable nitrogen (PMN) – respond to variations in management across six watersheds in Wisconsin. Soil samples were taken from over 250 fields and 40 farms in spring of 2015, 2016 and 2017, before corn planting. Data were analyzed to identify the effect of no-till, cover crops, manure applications and more diverse crop rotations on soils’ labile C and N pools via linear regression, multivariate analysis and regression tree analysis. Preliminary results suggest that no-till and manure applications did not affect median POxC and PMN values. This reflects the importance of site specific co-variates in understanding the relationship between management and soil health. Findings from this study will highlight the degree at which these best management practices can improve biological nutrient cycling and thereby reduce fertilizer input requirements across varied landscapes in Wisconsin.