Phosphorus Fate and Transport in Biosolids Amended Soils II: Phosphorus Losses in Runoff from Soils Used for Corn Production
Abstract:Phosphorus (P) plays a crucial role in the health of freshwater and estuarine ecosystems, behaving as the principal limiting nutrient in freshwater eutrophication (Correll, 1981). There is mounting evidence that soils with very high concentrations of P are significant sources of nonpoint P pollution of surface and shallow ground waters (Sharpley et al., 1994; Sims et. al., 1998).
High concentrations of soil P can be caused by repeated application of organic residuals, such as animal manures, biosolids, and composts. The relatively low N:P ratio of these materials frequently results in a significant over-application of P when applied to cropland at nitrogen (N)- based rates. For example, application of biosolids containing 15 g N kg-1 and 10 g P kg-1 to meet the plant available N (PAN) requirements of corn (150 kg ha-1) adds 110 kg P ha-1 to the soil; in comparison, P removal in corn grain is about 25 kg P ha-1 (Maguire et al., 2000b, Pierzynski, 1994). In the Mid-Atlantic region, long-term application of biosolids at N-based rates has been demonstrated to increase soil P to excessive levels (Maguire et al., 2000a). At the same time, the rapid growth of urban and suburban populations within the Chesapeake Bay watershed has led to increased volumes of municipal biosolids. This creates a dilemma for wastewater treatment plants and for nutrient managers who must balance disposal needs with the potential for environmental degradation. Clearly, an understanding of the forms and quantity of P in surface runoff from biosolids-amended soils is critical to the development of effective P-based management strategies.
As a source of P, biosolids can differ from other organic residuals because they are often amended with lime, iron salts (e.g., FeCl3) or aluminum salts (e.g., (Al2(SO4)3 – alum) during the wastewater treatment plant (WWTP) process. The effect of WWTP process on runoff P losses has only recently been examined and little research has been published on the effects of biosolids application on runoff P. The objectives of this study were to: (i) quantify and compare P runoff losses from soil following biosolids or PL applications; and (ii) to assess the relationship between soil and runoff P.
Document Type: Research Article
Publication date: 2003-01-01
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