Keep soil in your field, where it benefits you most

Keep soil in your field where it benefits you most

When exploring changes to reduce the impact your cropland practices have on surface water quality, UW Discovery Farms recommends to control soil loss first.

Consider results from our UW Discovery Farms seven-year study of two western Wisconsin watersheds.  The two watersheds studied are approximately 160 miles apart.  Both have silt loam soils, yet they have completely different landscapes and farming practices.

The Dry Run Watershed, located near Baldwin, WI, is mostly devoted to corn and soybeans, and farmers conduct tillage to mediate cooler soils.  These farms sit on long slopes that are gentle to moderately steep.

The Jersey Valley Watershed, located near Cashton, WI, has farming practices associated with dairy crop rotations and manure management.  By necessity of steep slopes that drop quickly to riparian streams, most farmers have adopted no-till crop establishment and have contour field strips. 

Table 1 shows soil loss on three edge-of-field monitoring sites from the seven-year watershed studies. Each year showed unique weather patterns based on rainfall intensity, timings and air temperature which all play a roll in runoff.  The crop species present (corn, soybeans, alfalfa) influenced soil loss because of field management, canopy cover and surface residue.
Note the difference in soil loss on the DR1 field between 2014 and 2017.  Both years this field was planted as soybeans.  After seeing soil loss results in early project years, this farm began limiting tillage passes, especially before soybeans.  In 2017, no-till soybeans were planted after corn grain, compared to vertical tilled soybeans in 2014.

No-till crop establishment is one tool that can be used to reduce soil loss, as shown at site JV4. Here, a combination of year-round soil cover, little soil disturbance and landscape conservation practices kept soil in place even during extreme rainfall.  Throughout the seven-year study, the crop rotation at JV4 included corn grain, corn silage and alfalfa rotation. Not a single year broke above 250 lbs / ac of soil loss. 

JV5 is on a dairy that utilizes drag-line manure incorporation, vertical tillage prior to planting and most corn harvested as silage. We saw high soil loss values in 2014 and 2016 as seen in Table 1.  Most of 2014 soil loss on this basin was in June before a corn crop canopy was formed, and most 2016 soil loss was in September after corn silage harvest, when there was minimal ground cover.  Here, we learn that minimal ground cover + traditional disturbance manure injection can result in significant soil loss on either end of the growing season.
More and more Wisconsin dairies are planting winter rye immediately after corn silage to establish green cover and cycle nutrients.  We see farmers and custom manure applicators beginning to use low disturbance toolbar configurations to inject manure.  And, with such minimal soil disturbance through the manure application, many farmers can plant the next crop without tillage.

So keep in mind some of these management tools that can keep soil in your field 1) No-till crop establishment; 2) Tool bar manure injectors designed for low soil disturbance; 3) Establishing a resilient cover crop after corn silage harvest; and 4) Contour field lay out with grassed waterways. §