See more from this Session: Advances in Environmental Chemistry of Animal Manure
Monday, November 1, 2010: 10:00 AM
Long Beach Convention Center, Room 202B, Second Floor
Soil phosphorus (P) exists in numerous forms that differ in plant availability. Poultry manure (PM) and other organic fertilizers with a high proportion of stable P can alter the balance of P forms, thus affecting soil nutrient status. To investigate effects of PM on soil distribution and plant utilization of P, we conducted a greenhouse study with perennial ryegrass (Lolium perenne) in soil with PM at rates of 0, 22, and 112 mg P kg-1 of soil. Ryegrass biomass was harvested at 4, 8, and 16 weeks, and soil separated into rhizosphere and bulk fractions. Soil P was sequentially extracted by H2O, 0.5 M NaHCO3, 0.1 M NaOH, and 1 M HCl, followed by quantitation of inorganic P (Pi) and enzymatically hydrolysable organic P (Poe). Manure at 112 mg P kg-1 increased root P concentrations 1.4-fold and total P uptake 1.6-fold, but did not change plant biomass yield. PM had short-term effects on both Pi and Poe, with increased NaOH- and HCl-Pi, and decreased NaOH- and HCl-Poe at week 4. Labile-Pi (H2O and NaHCO3 fractions) was higher at week 16 with PM, suggesting replenishment of this fraction from stable P forms. Plant roots also affected P distribution, as labile-Pi in rhizosphere with PM was 16-20% higher than bulk soil at 8 weeks. These results demonstrate that a single PM application does not lead to accumulation of stable P, including HCl-P. Furthermore, PM may promote redistribution of specific soil P fractions, leading to plant utilization of stable P forms.