ABSTRACT
Soil microbial biomass measurements have been used in studies of soil organic matter
dynamics and nutrient cycling in a variety of terrestrial ecosystems. They provide a measure
of the quantity of living microbial biomass present in the soil, and in arable soils account for
~1%–5% of the total soil organic matter (Jenkinson 1988; Smith and Paul 1990). Measure-
ments of the carbon (C), nitrogen (N), phosphorus (P), and sulfur (S) contained in the soil
microbial biomass provide a basis for studies of the formation and turnover of soil organic
matter, as the microbial biomass is one of the key definable fractions (Brookes et al. 1990).
The data can be used for assessing changes in soil organic matter caused by soil manage-
ment (Powlson et al. 1987) and tillage practices (Spedding et al. 2004), for assessing the
impact of management on soil strength and porosity, soil structure and aggregate stability
(Herna´ndez-Herna´ndez and Lo´pez-Herna´ndez 2002), and for assessing soil N fertility status
(Elliot et al. 1996).
