Agriculture Reference
In-Depth Information
for only 8 to 10 weeks. This often made additional weed control necessary with either
row cultivation or more herbicides.
The discovery of glyphosate, the active ingredient in Roundup, furthered the adop-
tion of no-till practices around the world. Glyphosate is a very effective nonselective
herbicide. It kills most plants that it touches but is readily deactivated in the soil.
The development of transgenic crops that are tolerant to glyphosate promoted the adop-
tion of no-till agriculture as improved weed control became easier to achieve. Now
farmers could plant and produce a crop without tillage. Preplant tillage was replaced
with an application of glyphosate combined with a residual herbicide, such as atrazine,
to kill existing weeds and prevent early-season weed competition. After emergence the
crop can then be sprayed with glyphosate to control weeds emerging later in the season.
The development of these two technologies has worked to greatly increase adoption of
herbicide-tolerant maize in Argentina,
13
shown in Figure 12.12. The use of atrazine
continues to be an important tool for weed control and is applied at reduced rates.
Glyphosate has replaced atrazine in most no-till fields in Argentina. Clearly, the use
of herbicide-tolerant maize has facilitated the use of no-tillage practices that have
lowered costs for the individual farmer.
Even greater advantages have helped push the adoption of insect-tolerant cotton in
China.
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A government program recommended adoption of insect-resistant (Bt) cotton
starting in 1999. Some large farms adopted this new variety, but most of the seed was
purchased by very small farmers. In 2001 nearly 30 percent of the total area planted to
cotton was transgenic Bt cotton. Average yields were increased using the Bt cotton
Figure
12.12.
Adoption of no-till and Roundup in Argentina. (Used by permission of
AgBioForum, cited in Ref. 23.)
