6. Nature of research needed
There are a number of requirements that need
to be met if soil macrofauna are to be used as
indicators of soil health (Linden et al., 1994).
These are summarised below.
• The identification of cause-effect mechanisms.
It is very difficult to directly link soil biological
activity with plant production, but relationships
could be formed with other vital components
of soil health--soil structure and
nutrient cycling;
• The need to identify easily visible soil macrofauna
that respond quickly to changes in food
resources, habitat or microclimate conditions;
• The need to identify soil quality indices which
can be sampled, sorted and identified easily;
• The need for a baseline or reference points to
compare changes in indicator parameters
which must be monitored through time, probably
for at least seven years (Douglas, 1987);
• The need to differentiate between long- and
short-term management effects on soil biota;
and
• The need for a universal protocol for measuring
soil biota which would standardise results
and make comparisons possible between experiments.
There is also a need for a greater recognition by
funding organisations of the importance of soil
biota in categorising soil health, which has already
been acknowledged by farmers. An analysis
of the top 50 responses of farmer-identified soil
health properties in the United States of America
indicated that organic matter (1) and earthworms
(3) rated more highly than yield (10) and cost of
production and profit (30) (Romig et al., 1995) as
indicators of soil health.