Phosphorus in alum amended poultry litter systems: distribution, speciation, and interactions with aluminum oxides
Date
2005
Authors
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Publisher
University of Delaware
Abstract
Phosphorus (P) enrichment of aquatic environments has altered their ecological functioning and diminished their commercial, recreational, and aesthetic values. As the limiting nutrient factor for algal growth in natural waters, P must be controlled in order to mitigate and/or prevent these negative impacts. Therefore, recent investigations have focused on understanding the role of agronomic point-source nutrient pollution, such as confined animal feeding operations (CAFOs) (i.e. poultry production facilities), in the decreased water quality in the Mid-Atlantic Region (PA, MD, DE, VA, WV, and Washington D.C.) of the United States. Because of intensive poultry production on the Delmarva (Delaware, Maryland and Virginia) Peninsula, manure management policies have recently been implemented, of which the benefits remain to be quantified. These laws require comprehensive nutrient budgets for farms which land apply animal waste. As best management practices (BMPs) are becoming incorporated into environmental legislation, an understanding of their chemical basis, on a molecular-scale, will ensure their potential to preserve and improve environmental quality. ☐ Initially, a fundamental understanding of the components in PL which react with P is needed. Therefore, the first objective of this study is to differentiate the forms of phosphate in PL, based on the order of their removal during a routine sequential extraction. Fast and inexpensive, this fractionation procedure may prove useful for manure analyses required in nutrient management plans. However, a chemical understanding of the extraction process will determine its accuracy for assessing the chemical composition of animal wastes. Chapter 2 provides a critical evaluation of an extraction method commonly used to determine P speciation in animal wastes. By implementing a P-specific analytical tool, x-ray absorption near edge structure spectroscopy (XANES), new interpretations of this traditional soil science technique is possible. This will allow for more accurate risk assessment when evaluating the nutrient content of PL which is to be land applied. ☐ The second objective is to understand the adsorption of phosphate onto aluminum surfaces, similar to those found in alum amended poultry litter. These reactions are extremely complex due to the presence of organic compounds in the waste in addition to varying pH conditions as the birds develop. Overall, the aim is to provide a molecular-scale understanding of P retention at the aluminum oxide-water interface, because of the importance of this reaction in the alum amendment BMP. In Chapter 3, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy is used to investigate the sorption of phosphate and an organic acid (oxalate) onto a model surface, amorphous aluminum oxide. In conjunction with batch aqueous sorption experiments, this technique shows how these two anions, present simultaneously and in large quantities in PL, react with a mineral surface in the presence of each other. The results and interpretation from this study can then be extrapolated to the more complex PL system, to improve and optimize the alum amendment practices. By integrating novel spectroscopic techniques with traditional soil science methods, more in-depth solutions to nutrient management concerns can be developed and current management practices can be fully understood so that improvements, if needed, are possible.