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Ground newsprint, yard trimmings, cotton gin trash and wood chips help conserve soil moisture, control weeds and improve cotton yields.
OILS in the Gulf and Atlantic Coastal Plain and Appalachian Plateau region tend to have loamy sand surface horizons, weak soil structure, low organic matter content, and acid subsoils. Even so, demands on these marginally productive soils have been escalating in response to increased population, loss of cropland to urbanization, and continued degradation through soil erosion. The increased use of conservation tillage has improved crop production, but in many cases, row crops, i.e, cotton and soybean, do not produce enough crop residue to increase soil organic matter content which is closely connected to a soil's fertility. Neither can they meet minimum residue cover requirements on soils that have been classified as highly erodible by the Natural Resource Conservation Service. To fulfill those requirements, most farmers must also plant winter cover crops.
Another way to meet the residue requirements is to use collected organic residuals such as newspaper and yard trimmings as residue cover during fallow periods. These two materials comprise about 65 percent of the solid waste stream coming from municipalities and can be a valuable source of organic carbon for marginally productive land.
Land application of organic by-products requires management of the carbon to nitrogen (C:N) ratio so that nutrients required by crops and soil microorganisms are available. Yard trimmings -- including leaves, shrub prunings, stumps, and grass clippings have a C:N ratio of < 40 to 60:1. Newspaper has a C:N ratio of > 500:1. If the C:N ratio of these materials is too high, most of the applied nitrogen can be immobilized by the soil microorganisms, making it unavailable to crops. The microorganisms that promote decomposition do require some N, which will come from either the soil nitrogen pool, or some added N source. The high nitrogen (2.5 to 3.0 percent) and phosphorus...