Author
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Zibilske, Larry |
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Submitted to: International Journal of Fruit Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/20/2010 Publication Date: 6/8/2010 Citation: Zibilske, L.M. 2010. Permeability of fabric ground covers to organically-derived nutrients. International Journal of Fruit Science. 10(2):109-122. Interpretive Summary: Plastic ground covers are used to improve crop production. They can greatly reduce the expenses of growing crops. Many plastic ground covers are made of impervious materials, but newer types are made to be more porous. Impervious ground covers can prevent growers from using organic fertilizers, which must be tilled into the soil before the ground cover is put in place. During the growing season, adding more fertilizer is a problem with impervious ground covers. We evaluated fabric-type ground covers to determine whether they would allow organic fertilizer nutrients to pass through to the soil, adding the nutrients the plants need. We tested compost and poultry litter and measured how much carbon, nitrogen, and phosphorus were able to get through the ground covers. We also measured a soil enzyme that told us if soil biology was affected by the ground covers. One cover tested was a porous, water-compatible material and the other a tightly woven cover with water repellency. Both materials allowed passage of nutrients into the soil. The porous cover allowed slightly more carbon than the tightly woven material. However, both were not as good as bare soil. After two weeks, both covers passed nutrients similarly. The covers reduced nitrogen passage compared to the bare soil. They also reduced passage of phosphorus, but the woven material passed more phosphorus than the porous. The soil enzyme tested was increased in all treatments, indicating that the biological environment was not changed during the incubation. Initially, the water repellency of the woven material greatly slowed movement of water into the soil. However, by two weeks, some of the repellency was overcome, perhaps by coating the plastic cover material with organic molecules from the organic amendment. Placement of the ground covers could change the way water moves through the covers, or could cause it to run off without entering the soil. This would change the results and must be remembered when using ground covers. These results say that applying solid fertilizers to fabric ground covers has promise for fertilizer supplementation after it has been placed on the ground. Technical Abstract: Synthetic ground covers are used to improve crop production. These can reduce input costs and have been shown to be economical production tools. Many plastic ground covers are impervious, but newer types are woven or engineered to be more porous. Ground covers can pose an obstacle for growers using solid, organic fertilizers, which must be tilled into the soil before application of the ground cover. In-season fertilization becomes a problem because many covers are impervious. In this study, fabric-type ground covers were tested to determine whether they would allow passage of organic fertilizer nutrients, either from compost or poultry litter applied to the cover material. Soluble carbon, nitrogen, phosphorus, and ß-glucosidase activity were monitored over a month-long incubation of soil columns with two covers. One was porous and hydrophilic and the other was tightly woven hydrophobic cover. Both allowed migration of nutrients into soil columns. The porous cover was slightly more (105%) conductive to added carbon than the woven material. Both were less conductive than bare soil (84% for the porous cover and 80% for the woven cover). After two weeks, both covers passed nutrients similarly. Covers reduced the nitrogen passage to 62% to 71% of the bare soil rate. Phosphorus passage was also reduced. Data for the porous, woven, and bare soil were 6.5%, 7.4%, and 7.9% of added phosphorus. The woven material passed more phosphorus than the porous. ß-glucosidase activity was similar for all treatments, indicating that the biological environment was not altered during the incubation. Initially, the hydrophobic character of the woven material greatly slowed infiltration. However, by two weeks of incubation, some of the hydrophobicity was overcome, presumably by organic coating of the cover from the decomposition of the organic amendment. Local conditions and configurations of the ground covers with respect to water drainage may affect the amounts passing through the cover. Experimental results indicate that applying solid fertilizers to fabric ground covers has promise for in-season fertilizer supplementation. |
