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We examined various forms of nitrogen (TKN, NH3-N, Org-N, and NOx-N) in a laboratory experiment, along with other parameters, in laying hen manure as it was dried from 75% (fresh manure) to 60, 50, 40, and 30% moisture content (MC), respectively. Ammonia nitrogen (NH3-N) emissions from the manure samples during drying were quantified. The results showed that N losses were a very small portion (less than 1 mg NH3-N emitted based on one kg of the manure on a drymatter basis) in each sample. The higher the MC of the manure, the higher NH3-N to TKN ratio retained in the manure and the faster the manure dried, the less NH3-N was emitted from the manure. The nitric N (nitrate and nitrite N) was present in the manure in very low concentrations. The concentration was reduced when the samples were dried. The C/N ratios were in the range of 5.57 to 6.79 with the ratio for the fresh manure being in the middle. Anaerobic and aerobic plate counts in the manure samples varied and could not be used as any indication regarding N losses.

We concluded that drying manure quickly would minimize NH3 emission and, therefore, retain N in the layer manure.