By Ellen Albright and Laura Paletta el.at
Sometimes small areas on the landscape can have a big influence on downstream water quality. Certain areas of farm fields can be more susceptible to soil erosion, leading to greater sediment and nutrient losses to nearby lakes and rivers. Areas where the natural topography causes runoff water to come together in a temporary stream are particularly vulnerable. Grassed waterways are a classic conservation practice that can help protect these sensitive areas while safely moving water off the field. New research from Discovery Farms demonstrates that grassed waterways can significantly reduce soil and nutrient losses from crop fields.
Early Results Brought Surprises
Discovery Farms began monitoring two fields on different dairy farms in Kewaunee County in the fall of 2018. Runoff water was collected year-round at a monitoring station located at the edge of each field to determine the amount of water, soil, and nutrients leaving the field. The original goal of the study was to better understand how soil conservation practices affect soil and nutrient losses from dairy forage rotations in northeast Wisconsin. Cropping practices were similar between the two farms, and corn silage was the most common crop grown during the study (Table 1).
Both study fields had been managed in no-till for many years before monitoring began and overwintering cover crops were consistently used following the annual crops included in the rotation. Despite these soil conservation practices, substantial soil loss was measured at the sites in the spring and early summer of 2019. For one of the farms (hereafter “Farm 1”), field walkovers revealed sheet erosion in a small area where runoff water converged as it flowed off the field. At the other site (“Farm 2”), there was evidence of gully erosion within and near the existing waterway.
Source : wisc.edu