Forest Application Vs. Agricultural Application Essay -- Nature Sludge

Forest Application Vs. Agricultural Application There is increasing interest in using forest systems for the treatment of wastewater sludge. Forest application offers several advantages over agricultural application. There is usually a long period of time between the application and removal of the crop. This gives an opportunity for organic compounds to decompose. Another advantage is that there is less of a chance that organic or inorganic compounds will enter the food chain after harvest. Trees benefit from sewage sludge through increased growth rates. In an oak forest in northern Michigan, sludge was applied at a rate of 8 Mg dry solids/ha to provide 400 kg/ha of nitrogen. Tree diameter growth was increased by 63% over areas that had no application (Nguyen et al. 1986). In loblolly pine stands in South Carolina, basal area growth was increased by 46% and tree volume by 33% by the application of sludge (McKee et al. 1986). Sludge increases the productivity of understory vegetation on poor-quality sites. Herbivorous animals benefit for the increased quantity and quality of vegetation(increased phosphorous and protein levels)(Haufler and West 1986). Sludge may be applied to all ages of forest, from clearcuts to mature forest. However, each growth stage has advantages and disadvantages. Clearcuts offer economical application, since temporary spray irrigation or solid spreaders may be used. The disadvantage is that applying high nutrient levels will increase weed growth and subsequent small mammal populations, making establishment of trees difficult. Application to young forests eliminates tree survival problems. However, overhead application is required due to small tree heights. This dictates that application be d... ...es. In Cole, D. W, C. L. Henry, and W. L. Nutter, eds. The Forest Alternative for Treatment and Utilization of Municipal and Industrial Wastes. University of Washington Press. Seattle, Washington. Nguyen, P. V., J. B. Hart,Jr., and D. M . Merkel. 1986. Municipal sludge fertilization on oak forests in Michigan: Short-term nutrient changes and growth responses. In Cole, D. W, C. L. Henry, and W. L. Nutter, eds. The Forest Alternative for Treatment and Utilization of Municipal and Industrial Wastes. University of Washington Press. Seattle, Washington. Red, J. T., and W. L. Nutter. 1986. Municipal wastewater renovation on a coastal plain, slash pine land treatment system. In Cole, D. W, C. L. Henry, and W. L. Nutter, eds. The Forest Alternative for Treatment and Utilization of Municipal and Industrial Wastes. University of Washington Press. Seattle, Washington.