N Mineralization and Microbial Dynamics in Manured and Non-manured Fields.

On-farm comparison of microbial and mineralization dynamics in two conventionally managed fields were conducted to compare the impact of manure application. In-situ mineralization chambers at two depths (0-10 cm and 0-20 cm) were used to measure cumulative net mineralization and microbial biomass changes over time. Net cumulative mineralization was not significantly different, yet tended to be greater in the non-manured field at the 0-10 cm depth. Mineralization of N was lowest in the 0-20 cm depth incubations in the manured field. Fall microbial biomass was consistently greater in the manured field over three years. Microbial biomass was typically greater in the bulk and incubated soil of the manured field during the growing season, as well as the surface 0-10 cm, than in the 10-20 cm depth. Although manure was injected at the 15 cm depth, the expectation of greater microbial and nutrient dynamics at this depth was not encountered.