Location: Livestock Nutrient Management ResearchTitle: Legacy phosphorus in calcareous soils: effects of long-term poultry litter application on phosphorus distribution in Texas Blackland Vertisol Author
|Pagliari, Paulo - University Of Minnesota|
|Zhang, Mingchu - University Of Alaska|
Submitted to: Waste to Worth Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/10/2015
Publication Date: N/A
Technical Abstract: Sequential fractionation techniques, coupled with phosphatase hydrolysis, have allowed for greater understanding of manure/litter effects on soil phosphorus (P) distribution. We evaluated the effect of long-term (> 10 years) poultry litter (broiler and turkey litter) application at rates of 4.5, 6.7, 9.0, 11.2, and 13.4 Mg/ha on P in watershed-scale plots (cultivated and grazed/ungrazed pasture) near Riesel, Texas. Soil total extractable P (Pt), inorganic P (Pi) were quantified by sequential extraction with H2O, NaHCO3, NaOH, and HCl and a modified molybdate blue method. Hydrolyzable organic P (Pe) and non-hydrolyzable organic P (Pne) were determined in the extracted fractions following enymatic hydrolysis. Litter application increased Pt regardless of land-use type; compared to control. Compared to control, H2O-Pi from litter-amended plots increased by 9 to 34% (cultivated), and 7 to 30% (pasture), indicating substantial risk of soluble P runoff. Labile Po extracted with H2O and NaHCO3 decreased in the order: monoester > nucleic acid > phytate > Pne. Litter application did not affect NaOH-Pi or NaOH-Pe (P > 0.05), but increased NaOH-Pne. An average of 68% of Pt was extractable with HCl. The HCl-Pt composition was predominantly (95%) Po. Only trace levels of HCl-Pe were found; however, litter application increased HCl-Pne up to 217%. Thus, we concluded that repeated litter application increased levels of both soluble Pi and stable Pne, but specific response varied with application rate and land management. This study increased understanding of P distribution over time in soil with high clay and CaCO3 contents under differing land-use scenarios.