Agriculture Reference
In-Depth Information
250
OTHER
MCSE System
*
Conventional
No-till
Reduced Input
Biologically Based
150
*
GRASS
*
CHEAL
50
*
AMARE
-50
0
100
200
DCA Axis 1 (λ
2
= 0.39)
Figure 7.2
. Detrended correspondence analysis (DCA) of weed seedbank species compo-
sition in four annual row-crop systems on the MCSE. Data are scores for replicate plots
(n=6) of each system for the 5 years sampled (every three years, 1990-2002). Asterisks
indicate scores for the four dominant weeds used in the ordination. AMARE =
Amaranthus
retroflexus;
CHEAL =
Chenopodium album;
Other = Other dicots; Grass = all grass spe-
cies. Ovals group data points (majority) of Conventional and No-till and of Reduced Input
and Biologically Based systems to highlight divergence in weed seed banks. Modified from
Davis et al. (2005).
upper U.S. Midwest (Nurse et al. 2009). This species dominates in the both the
fertilized and unfertilized tilled plots (48% and 60% of total biomass, respectively;
Table 7.4). And while precipitation does not predict plot biomass production (fertil-
ized and not), the abundance of
S. faberi
across years is correlated with early spring
rainfall and temperature (Robinson 2011). Interestingly,
S. faberi
was not a domi-
nant weed in either the emergent or seed bank communities of the adjacent annual
row-crop systems (Davis et al. 2005), even though the abundance of grass weed
species, in general, differed among crops and cropping systems (Figs. 7.1 and 7.2),
suggesting that the presence of a crop—or management of these systems—inhibits
or reduces the abundance of this species.
