In order to study the effect of the rate of addition (9, 18, 27t/ha) on a dry weight basis of raw cattle manure and an anaerobically diggested manure on soil microbial activity, an incubation experiment have been conducted, at the Federal University of Santa Maria, using a Red-Yellow Podzolic, (São Pedro Unit), from november 1983 to february 1984. The evolution of CO2 was proportional to the rates of the residues added. Total CO2 evolued, after 70 days of incubation, for raw manure treatments was, in average, 29% greather than the anaerobically diggested manure, althought both of then have presented the same relation C/N. Aproximatelly 14 and 21% of organic carbon of anaerobically diggested manure and raw manure, respectivelly, volatilized as CO2 independentelly of the rates of both residues.
cattle manure; biodigestor effluent; microbial activity
