Agriculture Reference
In-Depth Information
Land Uses
(Lee 1985); the third edition of
Biology and Ecology of Earthworms
(Edwards and Bohlen
1996);
Earthworms in Waste and Environmental Management
(Edwards and Neuhauser 1988);
Earth-
worm Ecology in Forest, Rangeland and Crop Ecosystems
(Hendrix 1995); the first edition of
Earthworm Ecology
(Edwards 1998); and
Earthworm Management in Tropical Agroecosystems
(Lavelle et al. 1999). These extensive literature sources provide excellent pointers to the needs for
future research, promising directions for investigations and problems needing attention. Based on
these works, we can summarize the needs for earthworm research on agricultural topics.
RECENT TRENDS
Implications for the roles of earthworms in agriculture can be found in nearly the entire range of
topics covered in the various International Symposia on Earthworm Ecology. This is partly because
many researchers are interested in the potential beneficial influences of earthworms on soil fertility
and agricultural production, soil conservation, environmental quality, and the like. However, from
a broader perspective, agricultural systems often tend to be much more easily studied than more
complex natural ecosystems, and effects of earthworms on soil processes, fertility, and plant growth
are more obvious in managed agroecosystems than in natural ecosystems. Thus, agricultural eco-
systems provide a ready crucible in which to test ideas about earthworms, sometimes beyond their
role in agriculture.
Research topics relevant to agriculture in the International Symposia on Earthworm Ecology
include earthworm systematics, biogeography, ecology, and behavior; effects on soil processes
(nutrient and organic matter dynamics, soil structure, and hydrology); uses in waste management
and land management; ecotoxicology; and interactions with other soil organisms. For example, a
listing of such topics was compiled from the programs of symposia and is summarized in Table
15.1. This compilation also includes the number of presentations (both oral and posters) within
each topic category. Although it is not intended that firm conclusions be drawn from such a relatively
small sampling of the earthworm literature, a few new interesting trends can be seen.
First, there has been a steady increase in the number of agriculturally related contributions
(Table 15.1). These were 57% at ISEE4, 77% at ISEE5, 86% at ISEE6, and 86% at ISEE7. Whether
these numbers represent a worldwide increase in research interest in earthworms in agroecosystems
is not clear, but it seems to be a strong indicator of such a trend. There seems to be little change
in research into biogeography and biodiversity in managed systems over the four symposia. There
TABLE 15.1
Number of Contributions within Various Topics Relevant to Agroecosystems Presented at
the International Symposia on Earthworm Ecology (ISEE)
Number of Contributions
ISEE4
(Avignon)
ISEE5
(Columbus)
ISEE6
(Vigo)
ISEE7
(Cardiff)
Biogeography and biodiversity in managed systems
11
12
7
11
Management effects on abundance/distribution (tillage, cropping systems)
20
15
3
9
Managed introductions and land use
7
5
11
8
Nutrient cycling processes (decomposition, mineralization, microbiology)
13
19
5
8
Soil physical properties (aggregation, porosity, infiltration, leaching)
12
16
3
14
Effects on plant growth (rhizosphere effects, disease suppression)
3
9
6
14
Waste processing and vermicomposting
14
21
10
38
Ecotoxicology (effects of pesticides and heavy metals)
11
14
12
37
91
111
57
132
