Extractability and bioavailability of phosphorus in soils amended with poultry manure co-composted with crop wastes

Abstract

Intensive livestock production and poor agricultural management have resulted to excessive loading of soil with phosphorus (P), thereby contributing to environmental pollution and impairment of water quality. A study was carried out to determine the extractability and bioavailability of P in soils treated with poultry litter (PL) co-composted with sugarcane and cabbage wastes. The manure was applied based on total P contents at 200 and 400 kg P ha-1, with maize (Zea mays L.) as the test crop. The co-composted PL increased maize growth relative to PL alone with the best growth occurring at the treatment rate of 400 kg P ha-1. Maize biomass and available P in soil varied in the order PL co-composted with sugarcane waste and cabbage waste (%) 50 > 33 > 25 > 0. Phosphorus contents in maize shoot were higher in sandy clay than silt loam soil and its recovery was higher in soil treated with PL co-composted sugarcane waste than co-composted with cabbage waste. An amendment with co-composted PL increased the extractable P fractions and P availability in the soils. The P fractions in the post-harvest soils varied in the order HCl-P > H2O-P > NaHCO3-P > NaOH-P and the fractions were significantly higher in the sandy clay than the silt loam soil. Also, the PL co-composted with sugarcane waste exhibited higher levels of P fractions in soils than co-composted with cabbage waste. Thus, co-composting poultry manure with crop wastes would better improve plant growth and P nutrition than sole-composted manure.