Vegetative mulch retains rain

ST. PAUL, Minn. – As a mulch in vegetable production, the cover crop hairy vetch greatly reduces pesticide runoff and soil erosion, making it an excellent alternative to plastic mulch often used by vegetable growers.

Agricultural Research Service scientist Pamela Rice spoke on her research at a meeting of the American Chemical Society in San Diego, Calif.

Rice is with the ARS Soil and Water Management Research Unit, based at the University of Minnesota at St. Paul.

Vegetable growers now often use polyethylene mulch to maintain soil moisture and control weeds. When it rains, however, the plastic increases surface runoff because 50 percent to 75 percent of the field is covered with plastic. Rain cannot penetrate into the soil.

The runoff contains eroded soil and agricultural chemicals that may have potential harmful effects on organisms in nearby streams and rivers.

In a three-year collaborative study, Rice and co-workers at the Environmental Quality Lab and the Sustainable Agricultural Systems Lab at the Henry A. Wallace Beltsville Agricultural Research Center, Beltsville, Md., have developed a more sustainable vegetable production system that uses hairy vetch, a vegetative mulch.

ARS has demonstrated that hairy vetch is economical and can effectively control weeds.

The study compared runoff and soil erosion from field plots using vegetative and plastic mulch. Fields with plastic mulch lost two to four times more water and up to 10 times more sediment than the plots using hairy vetch mulch.