See more from this Session: Symposium--Do -Omics Hold Promise for Greater Understanding of Soil Microbial Ecology
Results from a California annual grassland soil show both heterotrophic activity and nitrification turn on within 3 hours of the rainfall event. Soil respiration and changes in dissolved organic carbon and nitrogen are greatest within the first three hours following wet-up. Trends in nitrification and gene expression for nitrification follow those of nitrous oxide emissions, all peaking at nine hours after the rain pulse. Denitrifier gene expression of nitrite reductase was never detected, while that of nitrous oxide reductase was detected consistently at a very low level in keeping with the amounts reported previously in studies of inactive denitrifiers in pure culture. Together, these data suggest that nitrification is the primary source of nitrous oxide in this soil at this time of year.