Cattle Urine as a Fertiliser: Micro-biochemical Changes in Fermenting Cattle Urine and Implications on Plant Nutrient Conservation

Aim: The aim of this study was to evaluate the microbial and biochemical changes in fermenting urine, a practice used by farmers in Sub-Saharan Africa before its application as a soil fertility input.

Methodology: Two 5-litre sterile plastic containers, with a closable ends were each filled with fresh urine to capacity. One container was closed and the other left open. The set-up was replicated three times. Twenty millitres of fresh urine was taken from the bulk collection for microbial and chemical analysis. Urine samples were also taken and analysed at 4-day fermentation intervals till 24 days.

Results: Fresh urine had pH=8.2 and contained Aspergillus spp. and Escherichia coli, with the latter being dominant. After 12 days of fermentation, Penicillium spp. and Pseudomonas spp. emerged and progressively increased, especially under the closed system. Whereas Aspergillus spp. counts increased in both systems, E. coli counts dropped dramatically and eventually disappeared at 16 days. The pH in the open system surged to 9.7, while that of the closed containers remained nearly stable (8.2). Organic N was not significantly (p>0.05) affected by closure of the containers. In the open system, Organic N concentration dropped up to 72%. However, NH4-N concentration increased steadily in the closed system until day 24; but dropped dramatically in the open system. Nitrate concentration increased slightly up to day 8, and thereafter, declined sharply by 97% in the open system. Similarly, in the closed system, this N species dwindled progressively but not to extinction.

Conclusion: There is a shift in microbial communities in urine from Aspergillus spp. and Escherichia coli in fresh urine to Penicillium spp. and Pseudomonas spp. 12 days after the onset of fermentation. Nitrate-N is favoured by the open system, while the ammonium-N increased more in the closed system.