NITROGEN AND ORGANIC-MATTER LOSSES DURING STORAGE OF CATTLE AND PIG MANURE

Solid pig manure (240 g kg(-1) DM) and solid cattle manure (150-180 g kg(-1) DM) were stored in an open storage facility during spring-summe r and autumn conditions for periods of 9-14 weeks during 1994 and 1995 . Concentrations of C, N, P and K were determined prior to and after s torage, corrected for dry matter losses and distance from the surface. Temperature and, in experiments with pig manure, gas phase compositio n inside the manure heap were monitored during storage. Nitrogen losse s as ammonia volatilization, nitrous oxide emission and leaching were measured, while total denitrification was estimated from mass balance calculations. For both cattle and pig manure there was little differen ce between seasons with respect to the pattern of decomposition, as re flected in temperature dynamics and C/N turnover. In contrast, there w as a distinct difference between manure types. Pig manure was characte rized by maximum temperatures of 60-70 degrees C, although the concent rations of oxygen and methane clearly demonstrated that anaerobic cond itions dominated the interior parts of the heap for several weeks. Los ses of C and N from pig manure both amounted to c. 50%. In contrast, t he temperature of cattle manure remained close to the air temperature throughout the storage period and cattle manure had lower, not signifi cant losses of C and N. Leaching losses of N constituted 1-4% with bot h manure types. Ammonia volatilization from cattle manure constituted 4-5% of total N, and from pig manure 23-24%. In pig manure a similar a mount of N (23-33%) could not be accounted for after storage, a loss t hat was attributed to denitrification. Nitrous oxide emissions amounte d to <2% of estimated denitrification losses.