Impacts of pellet pH on nitrous oxide emission rates from cattle manure compost pellets

ABSTRACTPrevious reports indicated that the emission of nitrous oxide (N2O) when manure compost pellets (MCP) were applied to soil was greater than when ordinary manure compost or inorganic fertilizer was applied, but that applying pellets of nitrogen-enriched manure compost, a by-product of deodorizing manure during composting, resulted in N2O emission rates less than those from MCPs. To investigate the mechanism by which N2O emission rates and cumulative emissions were reduced in nitrogen-enriched manure composts pellets (N+MCP), we studied the impact of pellet pH on N2O emission, because pH is different between MCP (pH 8.6) and N+MCP (pH 5.3). In an incubation experiment, the pH of pellets was adjusted to five levels (5.3, 6.0, 7.0, 8.0 and 8.6) with acid or alkaline solutions, and the pellets were incubated without soil in a beaker at 30°C for 90 d (MCP) or 42 d (N+MCP). A large peak in N2O emission rate was observed soon after beginning the incubation (within 1–3 d) in the neutral and alkaline treatm...