Short-term Response of Soil Aggregate Stability and Labile Carbon to Contour Tillage, Diversion Terrace, Grassed Waterway, and Tile Drainage Implementation

Soil degradation has been of great concern for New Brunswick’s potato farmers, especially on sloped land and shallow soils. In this study we evaluated the initial response of labile soil carbon (C) fractions (permanganate oxidizable C – POXC; and particulate organic C – POC) and aggregate stability to two integrated best management practices (BMPIs) comprised of the following individual practices: diversion terraces (DT), grassed waterways (GW), and contour tillage (CT) [i.e., DTGW] and DT, GW, CT, and tile drains (TD) [i.e., DTGW+TD], relative to CT that served as a control. The more water was regulated in the field, the greater the increase in labile C; where DTGW and DTGW+TD gained 19.8% and 50.6% of POXC, respectively, while CT lost 11.2% of POXC. There was an increase in mineral associated organic matter (MAOM) C in the terraced BMPIs, despite the high amount of tillage events that took place during potato cultivation. Two BMPIs had no effect on aggregate stability, most likely due to the short duration of this initial monitoring study that spanned just over two growing seasons. Even though there were no improvements in soil structure, our findings showed that some stabilization of soil C is possible even during the initial two seasons following BMPI implementation.