During the digestion process, gaseous nitrogen (N) is converted to ammonia (NH3). In this water-soluble form the nitrogen is available to the plants as a nutrient [5]. A particularly nutrient-rich fertilizer is obtained if dung and urine is digested.
Compared with solid sludge from fermented straw and grass, the liquid slurry is rich in nitrogen and potassium.
The solid fermentation sludge, on the other hand, is relatively richer in phosphorus.
A mixture of solid and liquid fermented material gives the best yields. The nutrient ratio is then approximately
N:P2O5:K2O = 1:0.5:1 [6].
A fermented slurry with a lower C/N ratio has better fertilizing characteristics.
Compared with fresh manure, increases in yield of 5% - 15% are possible [6].