Ultraviolet absorbance (280 nm) of compounds released from soil during chloroform fumigation as an estimate of the microbial biomass

A rapid, inexpensive adaptation of the fumigation-extraction method for estimating the soil microbial biomass based on the fact that certain molecules absorb in the near ultraviolet (UV) region of the electromagnetic spectrum is described. A highly significant, positive linear relationship (r=0.94***) between biomass C as measured by fumigation-extraction, and estimates of the microbial biomass organic matter as measured by UV absorbance at 280 nm was obtained. Similarly, highly significant relationships were obtained between UV estimates of the microbial biomass and biomass total N and biomass ninhydrin-reactive N (r =0.91*** and r=0.92*** respectively).