Since 1996, U.S. farmers have responded to a number of industry-altering
changes, including lower crop prices, the availability of genetically
engineered seed, and environmental incentives embodied in farm legislation.
How have these shocks affected farming and conservation practices
used by farmers? USDA's Agricultural
Resource Management Survey (ARMS) provides a new source of information
about production
and conservation practices on sample fields in major field crop
producing States. Data from 1996 to 2000 show significant trends
beginning to emerge, which may have implications for environmental
quality.
Genetically
Modified Soybeans
HT
seed and glyphosate herbicide use soared...
Use of herbicide-tolerant (HT) soybean seed has enabled
farmers to use glyphosate herbicides that are effective
in controlling weeds during crop growth.
…while overall herbicide use decreased on
soybeans...
With soybean producers relying more on glyphosate herbicides,
the number of herbicide treatments has declined. The
annual per-acre average of all herbicide active ingredients
also declined. Adopting HT soybean varieties has allowed
producers to switch to herbicides that are more effective
at lower rates of use per acre.
…and cultivation for soybean weed control
dropped.
The use of glyphosate herbicides during soybean growth
allowed farmers to reduce cultivation for weed control,
especially on intensively tilled soybeans (i.e., soybeans
planted on land plowed or tilled so as to leave little
or no crop residue, one-fourth of planted acreage in
2000).
Tillage
Intensive
tillage increased on highly erodible land
More highly erodible land under intensive tillage reverses
a previous trend toward soil-conserving tillage. Intensive
tillage requires less management and may be perceived
by farmers as less risky.
Crop
Rotation
More corn/soybean rotation in the Northern Plains
and Lake States
Rotating corn with soybeans increased in regions where
continuous corn production had been the norm. Adding
soybeans to the rotation may reduce use of nitrogen
fertilizers and insecticides.
Nutrient
Management
Broadcasting nitrogen fertilizer without incorporation
has declined
Where nitrogen is applied to soybeans (about one-sixth
of soybean area in 2000), broadcasting without incorporation
is down from 49 to 28 percent of treated acres. This
trend substantially reduces the risk of nitrogen runoff
to surface waters.
