Impacts of Silage Tarps on Soil Arthropods, Soil Properties and Crop Yields

SARE Participatory Action Research study examines the pros and cons of silage tarping on yield and the biodiversity of below-ground organisms.

Soil Diversity is Often Overlooked as an Area of Conservation

Tilling and herbicides are two of many tools that farmers can use to manage weeds, but use of either one can degrade soil health and life. As a result, many farmers are exploring the use of silage tarps as a way to suppress weeds while limiting the need to use tillage. Unfortunately, little is known about the impact of tarping on crop production or on the biodiversity of below-ground soil organisms.

In response, Eva Kinnebrew explored the impacts that using silage tarps may have on weed control, soil arthropod species, physical soil properties and crop yields. Funded by a Northeast SARE Graduate Student Grant, the project offers farmers a clearer understanding of the impacts of this increasingly popular weed management technique.

Sustainability Impacts of Tarping

Environmental sustainability was a cornerstone of Kinnebrew’s SARE project. Many farmers and researchers are currently exploring alternatives to herbicides and tilling, which have negative impacts on soil and biodiversity. Tarping is being heralded as a viable alternative to these damaging practices, but, before this research, its impacts on soil biodiversity were not well tested.

Farmers are in general much less familiar with soil biodiversity in comparison to other biological groups, like pollinators. Therefore, Dr. Kinnebrew saw this research as an opportunity to not only assess tarps’ sustainability, but also raise awareness around soil organisms, which play a key role in controlling pests and improving soil health. 

“Being a farmer is a very complex job; you have the economic side of things and also many ecological considerations.’ says Kinnebrew. “I believe a lot of farmers are interested in conservation but may not be aware of ecological groups like soil arthropods. Yes, some of them are pests, but most of them are beneficial and not everybody realizes that.”

Collaborative Efforts Lead to Optimal Outcomes

Kinnebrew, then a PhD student at the University of Vermont, collaborated with farmers to ensure that her research aligned with their needs. The findings? Tarps dramatically reduced weed cover (around 30% weed cover in tarped plots versus 90% in control plots) and doubled crop yields.

The tarps’ negative impacts on soil life were less than anticipated too, resulting in an immediate decline in surface-active species, like ants and beetles, but these communities quickly recovered after tarps were removed.

Impacts on soil-dwelling species like springtails and millipedes were more subtle, indicating some evidence of a slow progressive decline in their biodiversity in the weeks after tarps were removed. Overall, the negative impacts were not as significant as Kinnebrew had anticipated, and these results may show promise in the sustainability of this practice.

Kinnebrew’s research provides farmers with an opportunity to improve the environmental, economic and production efficiency of their operations by providing new insights on a cost-effective, chemical-free method to control weeds and improve crop productivity without compromising soil quality or health.

A recent post-project evaluation of SARE projects awarded between 2016–2019 found that Kinnebrew’s participatory approach was key to the project’s success. “My project was really inspired by what the farmers were interested in,” says Kinnebrew. “A lot of knowledge points in my project were co-created with the farmers.”

Visit https://www.sare.org/sare-impacts-GNE19-205 for more information on this project’s impact.

Impacts of Silage Tarps on Soil Arthropods, Soil Properties and Crop Yields is part of a series produced by Insight for Action as part of a post-project evaluation of SARE’s regional grant programs. For more information visit https://www.sare.org/sare-impacts.

For information on grants and resources available from SARE, visit www.sare.org.