Microbial activity in pig slurry-amended soils under aerobic incubation

A 120-day aerobic incubation experiment was conducted to study the effects of pig slurry application on soil microbial activity. Pig slurry was added to soil at rates of 0 (control treatment), 150 and 300 m(3) ha(-1). Soil samples were taken after 0, 7, 14, 30, 45, 60, and 120 days of incubation and analyzed for total organic C and microbial biomass C contents, and basal respiration. Most of the organic C applied to soil with pig slurry was readily decomposed within 30 days. During the first phase (0 to 14-30 days), the addition of pig slurry to the soil, especially at the larger rate, increased microbial biomass C content, microbial biomass C/total organic C ratio, basal respiration, and metabolic quotient. The microbial growth and the increase of their activity that these results reflected were not persistent, since the initially measured values in pig slurry-amended soils decreased and reached those of the control soil in a relatively short time.