Manure phosphorus extractability as affected by aluminum- and iron by-products and aerobic composting.
Shifts in manure phosphorus (P) chemical forms and pool sizes induced by water treatment residuals and industrial mineral by-products are largely undefined. We conducted a manure P fractionation study to determine mechanisms of reduction of dissolved reactive phosphorus (DRP) in poultry manure upon mineral by-product additions. The effects of composting on the P immobilization efficacy of the by-products were determined using laboratory self-heating composting simulators. The mineral by-products included an aluminum-water treatment residual (Al-WTR) and an iron-rich titanium-processing by-product. The noncomposted manure averaged 0.11 g g(-1) of total P as DRP forms. The by-products significantly reduced manure DRP, by an average of 39 and 48% in the Al- and the Fe-treated manure, respectively. The by-products also reduced the 0.5 M NH4F-extractable phosphorus (FEP) fraction. Shifts in P forms between FEP and 0.1 M NaOH-extractable phosphorus (SHEP) depended upon the Al and Fe contents of the by-products while the combined FEP + SHEP pool remained constant. Phosphate sorption measurements supported the observations that the Fe-rich by-product was more effective at reducing manure DRP and enhancing the formation of SHEP forms at the expense of FEP than the Al-WTR. Composting had no effect on the efficacy of either by-product to reduce DRP. Potential mechanisms of enhanced P stabilization in treated manure upon composting included chemical shifts from the DRP and FEP fractions to the citrate-bicarbonate-dithionite extractable P fraction. Thus, the choice of P immobilization agents affected the stability of immobilized P forms and should be taken into consideration in developing manure processing and nutrient stabilization methods.
Dao
T H
TH
USDA-ARS, Animal Manure and By-Products Lab., BARC-East, Beltsville, MD 20705, USA. thdao@anri.barc.usda.gov
Sikora
L J
LJ
Hamasaki
A
A
Chaney
R L
RL
D000818:Animals; D001420:Bacteria, Aerobic / Q000502:physiology*; D001682:Biological Availability; D003247:Conservation of Natural Resources; D004787:Environmental Pollution / Q000517:prevention & control; D008372:Manure; D010758:Phosphorus / Q000737:chemistry* / Q000378:metabolism*; D011200:Poultry; D012037:Refuse Disposal; D012989:Soil Pollutants / Q000032:analysis*; D012995:Solubility
D008372:Manure; D012989:Soil Pollutants; D010758:Phosphorus