Agriculture Reference
In-Depth Information
EFFECTS OF EARTHWORMS ON SOIL PROPERTIES AND PLANT
PRODUCTIVITY IN AUSTRALIA
There is a great variety of ways in which earthworms can influence soil properties and plant
productivity (Lee 1985; Lavelle 1988; Curry 1994; Edwards and Bohlen 1996). Several studies
have been made of the influences of the most common earthworm species in agricultural soils
in southern Australia: on soil structure (e.g., Barley 1959c; Doube et al. 1994b,e; Hindell et
al. 1994a,b,c, 1997; Hirth et al. 1994, 1996; Friend and Chan 1995; Chan et al. 1997; Curry
and Baker 1998), nutrient availability (Barley and Jennings 1959; Baker et al. 2004a), burial
of surface organic matter and lime (Barley 1959b; Baker et al. 1993e, 1998b, 1999a), distribution
of beneficial microorganisms (Stephens et al. 1993b, 1994a,b; Doube et al. 1994c,d; Stephens
and Davoren 1994), reduction of incidence of root diseases (Stephens et al. 1993a, 1995;
Stephens and Davoren 1997), and plant yield and quality (Abbott and Parker 1981; Temple-
Smith et al. 1993; Garnsey 1994a; Stephens et al. 1994a; Baker et al. 1997b, 1999b). Two of
these topics are addressed in more detail in this chapter: the influence of earthworms on pasture
production and the burial of surface-applied lime and organic matter.
Laboratory and field experiments have shown that some exotic earthworm species (mostly
Lumbricidae) can substantially improve the availability of soil nutrients and the quality and quantity
of pasture and crop productivity in Australia. For example, Baker (1998a) demonstrated that the
anecic earthworm
could increase pasture yields by as much as 60% within field cages at
one site in the Mt. Lofty Ranges, S.A., 5 months after introduction. Similar trials throughout S.A.,
Victoria, and southern N.S.W. also demonstrated that the endogeic species
A. longa
A. caliginosa
and
A.
trapezoides
, can increase pasture production substantially (Baker et al. 1996,
1999b, 2002b; Chan and Baker unpublished data) (Figure 14.2). The degree of increase varies
, as well as
A. longa
70
A. caliginosa
A. trapezoides
A. longa
60
50
40
30
20
10
0
8 15 30 45
Initial Numbers of Worms/Cage
FIGURE 14.2
Percentage increases in pasture production when varying numbers of earthworms were added
to field cages in South Australia and Victoria. Comparisons were with controls (no earthworms added). Data
are for approximately 5 months of exposure to the earthworms and are averages for seven sites. (Data redrawn
from Baker et al. 1999b.)
