Agriculture Reference
In-Depth Information
Table 1. Crop rotation, barley cultivar height, and barley seeding rate effects on wild oat biomass and
seed production in year three of a long-term rotation at Lacombe, Alberta, Canada. Herbicides were
applied at 25% of recommended rates (unpublished observations) a .
Crop rotation b
Barley cultivar
Barley
Wild oat
Wild oat
height
seeding rate
biomass
seeds
(# m -2 )
(kg ha -1 )
(# m -2 )
Barley
Short
200
2019 (811)
4318 (1756)
Barley
Short
400
521 (330)
1079 (754)
Barley
Tall
200
199 (90)
346 (160)
Barley
Tall
400
50 (21)
92 (39)
B-C-B-P
Short
200
660 (104)
1304 (240)
B-C-B-P
Short
400
259 (62)
485 (117)
B-C-B-P
Tall
200
40 (22)
82 (40)
B-C-B-P
Tall
400
21 (10)
32 (16)
a Values in parentheses represent standard error of the mean
b B-C-B-P = barley-canola-barley-pea
oat biomass and seed numbers approximately 40-fold. Growing barley in rota-
tion with canola and pea rather than continuously, and combining the rotation
effect with higher seeding rates and the taller barley cultivar decreased wild oat
biomass and seed numbers approximately 100-fold. The impact that crop rota-
tion provided is not well understood. In addition to reduced leaf and root dis-
eases, there may also be more subtle rotational responses that favour crop
health and enhanced crop competition with weeds. However, this study clear-
ly demonstrates that optimal factor combinations can have very significant
influences on weed management outcomes. Indeed, combining these factors at
optimal levels may be a more consistent and sustainable weed management
option than the repeated use of herbicides.
Summary
There are many agronomic variables and management strategies other than
herbicides that can be manipulated to discourage weed invasion. Combining
several management strategies rather than relying on one will increase the like-
lihood of successful weed management. Encouraging optimal crop canopy
health can guide decision-making and render agricultural land less susceptible
to weed invasion. Then, when necessary, herbicides can be judiciously used to
supplement cultural weed management techniques.
In this review we have attempted to address two of the three major habitat
characteristics that influence weed invasions - disturbances and, to a lesser
extent, high resource ability. The remaining habitat characteristic, low species
diversity, is difficult to address in modern agriculture, but can be an avenue of
defence against invading species [89]. However, even intercropping, which is
Search WWH ::




Custom Search