The impact of alum addition on organic P transformations in poultry litter and litter-amended soil.
Poultry litter treatment with alum (Al(2)(SO(4))(3) . 18H(2)O) lowers litter phosphorus (P) solubility and therefore can lower litter P release to runoff after land application. Lower P solubility in litter is generally attributed to aluminum-phosphate complex formation. However, recent studies suggest that alum additions to poultry litter may influence organic P mineralization. Therefore, alum-treated and untreated litters were incubated for 93 d to assess organic P transformations during simulated storage. A 62-d soil incubation was also conducted to determine the fate of incorporated litter organic P, which included alum-treated litter, untreated litter, KH(2)PO(4) applied at 60 mg P kg(-1) of soil, and an unamended control. Liquid-state (31)P nuclear magnetic resonance indicated that phytic acid was the only organic P compound present, accounting for 50 and 45% of the total P in untreated and alum-treated litters, respectively, before incubation and declined to 9 and 37% after 93 d of storage-simulating incubation. Sequential fractionation of litters showed that alum addition to litter transformed 30% of the organic P from the 1.0 mol L(-1) HCl to the 0.1 mol L(-1) NaOH extractable fraction and that both organic P fractions were more persistent in alum-treated litter compared with untreated litter. The soil incubation revealed that 0.1 mol L(-1) NaOH-extractable organic P was more recalcitrant after mixing than was the 1.0 mol L(-1) HCl-extractable organic P. Thus, adding alum to litter inhibits organic P mineralization during storage and promotes the formation of alkaline extractable organic P that sustains lower P solubility in the soil environment.
Warren
Jason G
JG
Animal Waste Management Research Unit, USDA-ARS, Bowling Green, KY 42104, USA. Jason.warren@ars.usda.gov
Penn
Chad J
CJ
McGrath
Joshua M
JM
Sistani
Karamat
K
D000534:Alum Compounds / Q000737:chemistry*; D000818:Animals; D005591:Chemical Fractionation; D006851:Hydrochloric Acid / Q000737:chemistry; D006868:Hydrolysis; D008372:Manure; D010710:Phosphates / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry*; D010833:Phytic Acid / Q000737:chemistry*; D011200:Poultry; D017693:Sodium Bicarbonate / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry; D012987:Soil
D000534:Alum Compounds; D008372:Manure; D010710:Phosphates; D012987:Soil; D010758:Phosphorus; C041524:aluminum sulfate; D012972:Sodium Hydroxide; D010833:Phytic Acid; D017693:Sodium Bicarbonate; D006851:Hydrochloric Acid