Cover Crops Improve Soil Health and Water Quality in the Shatto Ditch Watershed, Kosciusko Co, in.

In the Midwestern US, tile drainage is a necessary management tool supporting agricultural production. However, this practice facilitates the transfer of excess fertilizer nutrients from agricultural soils to adjacent ditches, especially when fields are bare. These non-point sources also contribute to elevated nutrients in Lake Erie and the Gulf of Mexico, which have been linked to algal blooms and subsequent widespread hypoxia causing ecological and economic problems. The planting of winter cover crops (CC) offers a potential management strategy to reduce nutrient leaching from fields to tile drains. We are quantifying the influence of CC on soil and water quality at the watershed scale in the Shatto Ditch Watershed (SDW), Indiana. During Fall 2013 and beyond, we increased CC coverage from ~12% (321 acres) during the pre-treatment year to ~67% (1610 acres) and are measuring the effect of CC planting on soil nutrients. We are also investigating whether there are predictable relationships between soil quality and tile drain nutrient leaching. In Fall 2013, Spring and Fall 2014, and Spring 2015, when increased CC plantings were growing on fields, soil NO₃^--N and water extractable phosphorus were lower in CC fields compared to those without (ANOVA, p=<0.0001) suggesting that nitrogen and phosphorus may be tied up in CC tissue during Fall and Spring. There was also a positive relationship between soil and tile drain NO₃^--N suggesting that cover crops could reduce NO₃^--N loss from tile drains. We did not observe a significant increase in SOC in fields with CC versus those without CC in any season yet microbial community health and function improved in fields that contain CC, suggesting organic matter quality was improving with CC. Given these results, year-round study of soil and tile drain chemistry is warranted in order to definitively link soil and water quality benefits of CC.