Ground covers help fight weeds

Organic farmers who need to periodically amend their soils with compost after planting can still control weeds—and hold down costs—by using fabric ground covers, according to U.S. Department of Agriculture scientists. USDA said findings from its studies would be welcome news to organic farmers who till composted manure into their crop fields after planting.

USDA Agricultural Research Service soil scientist Larry Zibilske, who works at the agency's Integrated Farming and Natural Resources Research Unit in Weslaco, Texas, studied how these ground covers limit water penetration and affect carbon and nutrient levels in soils.

Zibilske conducted a soil chamber study using two types of commercial ground covers: a needle-punched, double-layer fabric and a tightly woven material made of flat polypropylene strands. He used two types of compost in the research: poultry litter pellets or a compost mix of cattle manure and other organic materials.

Zibilske monitored the movement of nutrients from the two types of composted materials through the two types of ground covers for 30 days. Water was able to pass freely through the fabric cover, but the polypropylene cover limited the movement of water for the first two weeks. However, water was able to pass through the polypropylene cover much more easily by the end of the study, perhaps because the cover was becoming coated with organic molecules from the compost.

Zibilske found that soil microbial activity indicators were essentially the same in soils protected by fabric covers, soils protected by polypropylene covers and control soil samples where the movement of nutrients had not been impeded by a ground cover. He said this similarity suggests that these ground covers did not significantly alter or limit biological activities in the soil.

The results from this study were published in the International Journal of Fruit Science.