Decreases of NM between March and July coincided with plant N uptake. The increase of MC and decreases of MN during the 3 yr of the study were related to increased plant production. Burning tended to reduce MC during dry years and increase it in normal to wet years. Mowing and raking decreased MC and MN, probably because of reduced root biomass and removal of standing vegetation. Nitrogen addition resulted in higher MN and tended to reduce MC, possibly by modifying the composition of the microbial population.
Microbial biomass seems to play a critical role in conserving N in the tallgrass prairie ecosystem.