ABSTRACT
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For decades, measures of soil chemical and physical properties have dominated our
views of what constitutes soil fertility. Soil biological fertility has been gaining attention
recently, and the soil biota are now better recognized as the key drivers of soil fertility
and productivity that they are. New methods employing advances made in microscopy,
molecular biology, and biochemistry have revealed a diversity of soil organisms previously
unimagined, indicating several orders of magnitude greater richness and abundance.
They have confirmed the regular occurrence of biogeochemical transformations, such
as dissimilatory nitrate reduction to ammonium, in environments previously thought
to be nonconducive for them. The past decade and a half have been particularly rich
in discoveries in soil ecology, as seen from preceding chapters. This chapter reviews some
of the major advances made in measuring soil biota and assessing their activity that are
significantly improving our understanding of soil ecology.
