Author
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Shogren, Randal |
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Submitted to: Journal of Sustainable Agriculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/24/1999 Publication Date: N/A Citation: N/A Interpretive Summary: A biodegradable alternative to polyethylene (PE) mulches is needed so farmers can avoid the nuisance and cost of disposal of PE films at the end of the growing season. Kraft paper has been considered in the past as a replacement for PE film, but paper loses nearly all of its strength when wet and biodegrades too rapidly. Recent work has shown that paper coated with resins made from polymerized vegetable oils can resist degradation an weed growth long enough for most crops (>8 weeks). It has now been found that such resins also give paper much improved wet strength, an important factor in avoiding tears during rain and wind. Also, as little as 25-50% of the resin based on paper weight is enough to give a significant improvement in wet strength as well as slow degradation. The economics of such a resin coated paper compare favorably with PE mulch. This work could benefit farmers by offering a low cost, biodegradable, totally natural alternative to PE mulch films and also by creating new markets for plant fibers and vegetable oils. Scientists in industry and academia developing and testing degradable mulch films would also benefit. Technical Abstract: Kraft paper was impregnated with vegetable oil-based resins and then tested for wet strength, rate of biodegradation in soil, and ability to inhibit weed growth. Resins included oxidatively polymerized soybean and linseed oils and a polyester formed by the reaction of epoxidized soybean oil and citric acid. Wet strengths were significantly higher for resin coated papers (4-10 MPa) than uncoated paper (0.5 MPa). Rates of weight loss during soil burial for resin coated papers (40-90% oil added) were about 1/2 to 1/5 of those for uncoated papers or paper coated with unpolymerized oils. When tested as mulches on the top of soil, resin coated papers maintained their integrity for 8-12 weeks while uncoated paper largely disintegrated by 8 weeks. Coating with unpolymerized oils also inhibited disintegration and weed growth although not as much as coating with polymerized oils. |
