Comparing Measurable Indicators of Soil Health under Two Different Forage Harvesting Methods Four times During the Growing Season

View the project final report

• 2014 annual report

Commodities

• Agronomic: general hay and forage crops

Practices

• Animal Production: grazing management
• Natural Resources/Environment: indicators
• Soil Management: soil microbiology, soil quality/health

This two year long soil health and grazing project has confirmed that in the Midwest region on diversified pastures of cool season grasses and forbs the act of grazing by sheep or cattle will stimulate an increase in microbial life in the soil as indicated by CO2 levels measured with the basal Solvita test. This increase of microbial life occurs within 12 to 48 hours of the grazing event and the production of CO2 returns to neutral or even slightly negative by 7 days post grazing.

Introduction:

Our 2014 trial was focused on comparing the impacts on soil health of grazing immature (before flowering) vs late maturity (after seed head formation) forages. In addition, we repeated our soil health impact on a mid- summer grazing of 2nd growth pastures and a fall/ September grazing. We had three plots in each experiments; control, (nothing done), a mechanically clipped plot, and our grazed plot and did 3 replications, all soil sampling done on day 7 post grazing. We did both Haney and PLFA soil testing on all soil samples. The only consistent finding was that on the average, the grazed plot showed lower scores on the various test results indicating soil health, Haney soil health score, Solvita CO3 levels, and PLFA total biomass.
The results were not expected and further literature reviews suggests that the soil life will respond to grazing simulated event in 12 to 72 hours. We only tested at 7 days post grazing and may have missed changes that occurred sooner.

While most of our SARE funds were used in the 2014 activities, we did have about $700 left over from unused labor funds and decided to do a trial that looked at the impacts of soil heath post grazing over time. While we had hoped to look at impacts on soil health of various grazing practices, it appears that we first need to validate a positive impact of grazing on soil health indicators.