Protect and Enhance the Nation's Resource Base and Environment
Reducing Air Pollution: Conservation Tillage in Arizona Cotton
Impact Nugget
Where a no-till grain drill was used to plant wheat, barley or oats
on existing cotton beds (as a cotton to small grain transition), PM-10
dust emissions from tillage operations were reduced about 80 percent
in the fall (November/December). During the transition from the cotton
harvest to the planting of a small grain crop, the number of tractor
passes across the field went from 5 for conventional tillage to1 pass
for conservation tillage, with concomitant savings in fuel, labor and
equipment costs.
Issue
Cotton growers typically prepare and maintain fields by performing tillage
(soil disturbing) operations that include landplaning; leveling; several
disking operations; chisel plowing; and cultivation for weed control
and maintenance of irrigation furrows. Historically cotton growers had
to follow Arizona statutes related to pink bollworm (Pectinophora gossipiella,
Sanders) control which required tillage following cotton harvest. Recent
regulatory changes have allowed for a reduction in tillage when a small
grain crop is planted following cotton and irrigated in December. Researchers
at the University of Arizona are looking at ways to reduce the number
of times a farmer has to pass through his fields with a tractor and
tillage implement, thereby saving money on fuel and labor without reducing
economic returns to growers.
What has been done?
Conservation tillage is defined as a production system that eliminates
or reduces tillage operations to the minimum required to produce a crop,
and in which 30 percent of the previous crop residue remains on the
surface after planting. Advantages in other parts of the country have
included an increase in the overall productivity of the soil by increasing
the soil’s organic material and moisture-holding capacity, and
reducing erosion. The Arizona research is looking at whether these advantages
will hold true in desert soils. While it has been adopted in other parts
of the United States, conservation tillage didn’t catch on with
Arizona growers until recently when the cost of diesel fuel increased.
Field experiments were conducted at two CALS agricultural centers (3
years at Marana and 2 years at Maricopa with the third year underway)
and also with commercial farmers in central Arizona. These trials compared
conventionally tilled cotton and reduced tillage double cropping of
cotton and small grains where oats or barley were planted without tillage,
following cotton harvest and shredding of the cotton stalks. About 236,000
acres of cotton were grown in Arizona during the last season.
Impact
Reduced tillage operations cut back on the amount of dust raised as
tractors pass over the field. The conventional cotton tillage regime
includes five operations at the end of the season: shred, disk, rip,
disk again, and list. In a conservation tillage system there is only
the shredding operation at the end of the cotton season. Where a no-till
grain drill was used to plant wheat, barley or oats on existing cotton
beds (as a cotton to small grain transition), PM-10 dust emissions from
tillage operations were reduced about 80 percent in the fall (November/December).
During the transition from the cotton harvest to the planting of a small
grain crop, the number of tractor passes across the field went from
five for conventional tillage to one pass for conservation tillage,
with concomitant savings in fuel, labor and equipment costs.
Overall, conservation tillage practices and the cotton-small grain
double-crop system increases economic returns to the growers, reduces
their labor costs and the number of tractors they need to farm, and
saves money in controlling pink bollworm.
Funding
Hatch Act
USDA Western Region Sustainable Agriculture Research and Education grant
Arizona Grain Research and Promotion Council
Contact
William B. McCloskey, associate specialist
Department of Plant Sciences
The University of Arizona
PO Box 210036
Tucson, AZ 85721-0036
(520) 621-7613 office
(520) 621-7186
Email: wmcclosk@ag.arizona.edu
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