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  • Publication
    Turnover of Chicken Manure in Some Upland Soils of Asia: Agricultural and Environmental Perspectives
    Recycling of organic manure/waste is an important global issue to improve soil productivity for sustaining agricultural production as well as to preserve the environment. In Asia, rearing of poultry especially chicken is becoming one of the key industrial sectors and the wastes from clean-out operations may contribute largely to plant nutrients. Thus, some recent research works on the use of chicken manure (CM) in the uplands of tropical Asia are reviewed. Relative loss of the added CM-C was averaged 83% during a 90-day incubation and in-situ retention of labile organic-C was poor in 2 years, signifying long-term episodes to sequestrate its inherent low C. Ammonification of the added CM was rapid during 1-2 weeks followed by oxidation of NH4+. The high pH of CM remarkably influenced nitrification either after a lag phase or immediately after application, ensuing NO3- leaching to occur under favourable conditions. Net mineralization/ nitrification was greater with CM than with other wider C/N ratio organic residues. CM-N recovery was relatively low, indicating immobilization and other N loss processes. Likewise, a large N2O loss of added CM-N with or without other N sources under field (0.99%) and laboratory (6.66%) conditions was observed, along with presumable NH3 volatilization. Composted CM/litter could reduce the loss by limiting the transformation of organic N. Application of CM (fresh/composted) either alone or with inorganic fertilizers demonstrated crop yield benefits and reduced the use of the latter as well as a noticeable residual effect to the succeeding crops. Results suggest that strategic but agro-economically viable composting might have great advantages in synchronizing CM-N release with plant uptake and in reducing appreciable amounts of labile C and gaseous N loss under upland conditions and thus, in minimizing environmental risk.