Nitrogen transformation and ammonia volatilization from biosolids and compost applied to calcareous soil

One benefit of the use of composts and biosolids in agriculture is their nitrogen supplying capacity. Redeposition of ammonia volatilized from surface applied composts and biosolids may contaminate surface water and sandy soils. Laboratory incubation studies were conducted to quantify NH3 volatilization from a West Palm cocompost (WPCC) and biosolids (BSD) either surface applied or soil incorporated and to determine the relationship between NH3 volatilization and nitrogen mineralization. Such information is required to formulate guidelines for field application of composts or biosolids. Ammonia volatilization from the WPCC- or BSD amended soil was closely related to nitrogen mineralization and application method. More NH3 was volatilized from the BSD than the WPCC, which likely resulted from higher total N concentration and lower C/N ratio of the BSD. Nitrogen volatilization losses were greater with surface application than with soil incorporation. The amounts of NH3-N volatilized during an 180-d incubation period accounted for 18% and 23% of the total mineralized N for the surface applied BSD and WPCC, respectively. Soil incorporation increased nitrogen mineralization by more than 60% in the BSD and by 8-fold in the WPCC, but reduced NH3 volatilization by 5- and 150-fold, respectively for the BSD and WPCC.