Distribution of Plant Nutrient Elements and Carbon in Particle Size Fractions of Broiler Litter Ash

Abstract

An estimated 10.8 million tons of broiler litter and 3.0 million tons of turkey litter were produced in the United States in 2009. Poultry litter is a mixture of manure, bedding material (e.g. wood chips, sawdust, or straw), feathers, and spilled feed. Poultry litter contains high levels of Ca, N, P, and K, and is often applied as a fertilizer on fields in close proximity to poultry houses. Repeated poultry litter application to these fields can increase soil P to levels in excess of plant requirements, resulting in potential environmental risk. An alternative to land application of poultry litter is its use as a fuel in electricity generation. Ash from this process has been used as a fertilizer after sieving to < 1.27 cm, with the larger fraction being discarded in landfills. The objective of this study was to determine the elemental composition of size fractions of broiler litter ash samples produced using a variety of burn durations and temperatures. Ten 2-kg broiler litter ash samples were collected from a biomass gasification test plant and sieved into five size fractions. Nutrients in the ash were extracted using Mehlich-1 solution. In most cases, nutrient concentrations were higher in the finer two fractions while C concentration was higher in the coarser (> 0.5 mm) fractions. Nevertheless, the amount of P in the coarsest fraction ranged from 15 to 25 percent of the total extractable phosphorus in the ash. With such high P content in the coarse fraction, there is a potential of P leaching when this fraction is disposed of in landfills. We recommend that the coarse fraction should be crushed and mixed with the fine fractions before the ash is used as a fertilizer and soil amendment.