Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
5/23/03
FOR IMMEDIATE RELEASE
Contacts:
Mark Hanna, Ag and Biosystems Engineering, (515) 294-0468, hmhanna@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,
jmcguire@iastate.edu
Using Post-Planting Cultivation in a Conservation Plan
Ames, IA -- Much of the 2003 crop has been planted and the thoughts of many Iowa farmers are now turning to the cultivator. Recent rains have many farmers concerned about weed control and soil crusting.
Mark Hanna, agricultural engineer, Iowa State University Extension, says that even farmers who use conservation tillage may have valid reasons to cultivate. “The keys are to be certain that cultivation is needed for weed control or crust busting, and to minimize burying crop residue."
If weeds or crusting are not a problem, Hanna says producers should leave the cultivator in the shed. “The potential for soil erosion increases with cultivation because it buries residue and loosens the soil. There are other drawbacks, including possible root pruning, increased topsoil compaction, higher fuel use and more time spent in the fields, and the risk of ineffectiveness. Moreover, cultivating too deeply can increase weed problems by pulling buried weed seed to the surface where it can germinate. Cultivating without a good reason is just asking for trouble."
For weed management in soybeans, especially narrow-row soybeans, Hanna says the rotary hoe can be an effective tool. “Hoes offer good weed control in small crops, cause little compaction, and limit the amount crop residue loss. Hoeing must be done just after weeds germinate -- at the white root stage -- to be effective. Tractor speeds should be in the range of 8 to 10 mph. Work at a shallow depth -- just enough to flip the weeds out."
When the weeds or crop outgrow the rotary hoe, the best option becomes the cultivator. Hanna advises operating at a depth of 1.5 to 2 inches -- just enough to invert and destroy weed roots. “Focus on scraping the weeds up and out of the soil without disturbing the soil too deeply or turning residues under. Set the sweeps as close to the row as practical (guidance systems can help limit operator fatigue)."
“When the crop is small, use shields and keep the tractor's speed
just slow enough to avoid covering or injuring the crop, but as the crop
grows, cultivation speeds can be increased to 7 mph. Spend time setting
up and checking the cultivator. See how deep the sweeps are going and
check to see if it is uprooting small weeds."
Variables can interfere with even the best management, but no matter what
the problem is, use the cultivator only for weed pressure or crusting,
and once the crop shades the soil and weed germination stops, put the
cultivator away.
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Funding support provided by USDA Natural Resource Conservation Service through Cooperative Agreement No. 74-6114-10-03.
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