Paper Mulch Coated with Vegetable Oil Offers Biodegradable Alternative to Plastic

Paper is gaining over plastic in mulches used to grow commercial fruits and vegetables as well as the home-grown varieties, according to Agricultural Research Service (ARS) studies in Peoria, Ill. A main reason for this trend is that vegetable-oil-coated paper mulch may be a less costly alternative to plastic mulches, which are expensive to remove.

Brown paper coated with vegetable oils like soybean and linseed oil can protect the crop from weeds and insects and is completely biodegradable, according to ARS chemist Randal L. Shogren at the National Center for Agricultural Utilization Research (NCAUR) in Peoria, Ill. That gives paper a big advantage over plastic mulches that cost about $240 an acre. Soy oil costs around 15 cents a pound, so growers and home gardeners can expect a reasonable cost for paper mulches made with vegetable oil.

Shogren coated plain brown kraft paper--used to make grocery store bags--with several types of vegetable oils, including soybean, linseed and a chemically-modified soybean oil plus a catalyst. The vegetable-oil-coated paper withstood wind and rain long enough for the crop to grow, but then began degrading in the soil.

In trials, Shogren found that kraft paper treated with a combination of epoxidized soybean oil and citric acid held up for 13 weeks compared to untreated kraft paper, which was 50 percent degraded in 2-1/2 weeks. A U.S. patent on the technology has been approved. Field trials in Live Oak, Fla., in cooperation with the University of Florida (Gainesville) are in progress. Currently, field trials are being planned with an industry partner.

Shogren presented information on the paper mulches at the 6th International Conference on Frontiers of Polymers and Advanced Materials in Recife, Brazil, March 5-9.

ARS is the chief scientific research agency of the U.S. Department of Agriculture.

Scientific contact: Randal L. Shogren, ARS National Center for Agricultural Utilization Research, Peoria, Ill., phone (309) 681-6354, fax (309) 681-6691, shogrerl@ncaur.usda.gov.