Effect of cattle faeces with different microbial biomass content on soil properties, gaseous emissions and plant growth
Daphne Isabel Jost, Rainer Georg Joergensen, Albert Sundrum
Department of Animal Nutrition and Animal Health, University of Kassel, Nordbahnhofstr. 1a, 37213, Witzenhausen, Germany.
A study was carried out to investigate the effects of different diets for heifers, low- and high-yielding cows on the microbial composition of their faeces and subsequently the impacts of these faeces on CO2 and N2O emissions, N mineralisation and plant N uptake. A diet low in N and high in acid detergent fibre offered to heifers resulted in faeces dominated by fungi. These faeces were characterised by a low content in microbial biomass C and N and a high ergosterol concentration in comparison to the faeces of high-yielding cows. Added to soil, faeces of heifers led to lower emission and stronger N immobilisation during a 14-day incubation in comparison to the faeces of high-yielding cows. Total N2O emission was significantly (P < 0.05) correlated with faecal microbial biomass N. Rye grass yield and N uptake were lowest in the soil supplemented with faeces from heifers in a 62-day pot experiment. Plant N uptake was influenced by the faecal microbial biomass C/N ratio and the fungal C to bacterial C ratio. In conclusion, the faecal microbial biomass was affected to a high degree by the feeding regime and faecal microbial characteristics revealed higher impacts on plant N uptake than soil microbial properties.