Alum-treated poultry litter has dif

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-tomaximum
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.