Relationships between denitrification, microbial biomass and indigenous soil properties

Drury, C.F.; McKenney, D.J.; Findlay, W.I.

Relationships between denitrification, microbial biomass and indigenous soil properties

1991

Drury, C.F. | McKenney, D.J. | Findlay, W.I.

The relationships between denitrification, soil microbial biomass and selected soil properties were investigated in 13 soils which varied in physical and chemical properties. It was hypothesized that estimates of biomass C may be directly related to the background (unamended) denitrification rates. Denitrification potential (with C and NO3(-) amendments) was also compared to biomass C and the indigenous soil properties. The background and potential denitrification rates were measured in these soils during 75 h of anaerobiosis. Background denitrification was highly correlated with biomass C, organic C content and moisture content at field capacity (-33 kPa). Soil organic C was also highly correlated with microbial biomass C. Nitrate was not limiting for most soils as in all but two soils the residual NO3(-) content following incubation exceeded 10 mg N kg-1. Hence, NO3(-) concentration was not strongly correlated with the background denitrification rate. The denitrification potential was 5 times greater than background denitrification. In our study, C was the factor limiting denitrification. Further, microbial biomass appeared to be a sensitive indicator of both soil C content and background denitrification. There was no significant relationship between any of the other soil chemical and physical properties measured and the denitrification potential.

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