Nutrient value of alum-treated poultry litter for land application

Abstract

Alum-treated poultry litter has different chemical composition and biological properties than conventional poultry litter. To develop agronomic application rates for this particular organic fertilizer to cropland, the nutrient value (nutrient plant availability) of alum-treated poultry litter needs to be determined. Typical alum-treated poultry litter was collected from a broiler farm and examined for nutrient content, nutrient release kinetics, and nutrient value by leaching the material for 190 d under simulated weathering conditions. Nutrients recovered in the leachate were characterized and treated as the potentially plant-available portion. The artificial leaching revealed that alum-treated poultry litter released 21.4 g of dissolved organic C, 13.8 g of total dissolved N, 0.6 g of total dissolved P, and 34.6 g of K per kilogram into leachate during the 190-d weathering. The predominant nutrient release occurred in the first 5 wk and fit first-order exponential rise-to-maximum models (for dissolved organic C, total dissolved P, total dissolved N, NH4-N, K+, Na+, Cl-, and SO4(2-)) and logarithmic equations (for Ca2+ and Mg2+). The nutrient value of alum-treated poultry litter is estimated at N, 13.8 g.kg(-1); P, 0.75 g.kg(-1); K, 34.6 g.kg(-1); and S, 24.2 g.kg(-1). The concentration of Al in litter leachate remained below 0.2 mM and thus no Al toxicity should be concerned. Based on these results, it is recommended to apply alum-treated poultry litter at 7.3 t.ha(-1) for achieving an N supply of 100 kg.ha(-1) to common field crops while preventing excessive P runoff losses from high test P soils.

Effect of aluminum sulfate on litter composition and ammonia emission in a single flock of broilers up to 42 days of age

“…These lower litter WS P concentrations are consistent with the findings of several reports (Smith et al, 2004;Do et al, 2005) even when different measuring methods were used (Sims and Luka-McCafferty, 2002), although the action mechanism of alum with regard to reducing P solubility is unclear (Moore et al, 2000). This reduction could be caused by the precipitation of soluble compounds of Al-P or the sorption of WS P by amorphous Al hydroxides that are formed when Al 31 is dissolved from the alum hydrolyzed in the alkaline litters (Guo and Song, 2009).…”

“…The time course of pH reduction is related to the rate of alum applied. As the litter was renewed at the beginning of the study, our application rate of alum was lower than that reported in the United States by Guo and Song (2009). As expected, alum resulted in a more acidic litter as it provided a source of hydrogen ions (H 1 ), with 6 moles of protons per mole of alum.…”

“…At 42 days of age, the ratio of WS P to total P was about 40% lower in the alum-treated litter with respect to the control. Both runoff and leaching losses of P following land application of poultry litter are largely determined by the WS content of P in the waste (Guo and Song, 2009), this being one of the biggest problems facing the poultry industry. This reduction of the WS P content of the alum-treated litter has been described previously in multi-flock broiler litter in laboratory (Moore and Miller, 1994) and commercial conditions (Sims and Luka-McCafferty, 2002; -N, and total and water-soluble (WS)P content for the control and alum-treated litters.…”

Bentonite can decrease ammonia volatilisation losses from poultry litter: laboratory studies

“…Alum addition to spent litter is an established practice to decrease ammonia volatilisation and P losses due to runoff or leaching after land application. However, these additions may be detrimental to the agronomic P value of the spent litter (Warren et al 2008a;Guo and Song 2009). Conventional alum additions are not, therefore, a tool to return maximum fertiliser value from spent litter, and the cost of application must be justified on another basis.…”

“…However, because these additives tend to retain P in forms that may not be plant available they may decrease the fertiliser value of the spent litter (Guo and Song 2009).…”