Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
5/10/02
Contacts:
Mahdi Al-Kaisi, Agronomy Extension, (515) 294-1923, malkaisi@iastate.edu
Mark Hanna, Ag and Biosystems Engineering Extension, (515) 294-0468, hmhanna@iastate.edu
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,
jmcguire@iastate.edu
FOR IMMEDIATE RELEASE
Post-Planting Tillage Options
Ames, IA (May 9, 2002) -- Now that most of the crop is in, it's time to plan for post-planting tillage. There are sound management reasons to consider rotary hoeing and cultivation -- even in a conservation tillage program -- including weed control and crust busting.
Mahdi Al-Kaisi, agronomist, and Mark Hanna, agricultural engineer, with Iowa State University Extension say producers must weigh the benefits of post-planting tillage against the disadvantages. Among them -- the potential for increased soil erosion, soil compaction (when soils are wet), soil moisture loss when soils are dry, higher fuel bills, more time spent in the fields, and the risk of increased weed problems by pulling buried weed seed to the surface where it can germinate. Also, post-planting tillage reduces crop residues, which are essential in combating soil erosion and maintaining soil moisture.
"Weed control is a challenge that even the best managers find interfering with their conservation tillage program," says Al-Kaisi. "So, while producers should minimize tillage and soil disturbance, they also cannot be expected to endure serious yield and income losses due to weed pressure. When weeds become a problem, post-planting tillage is an alternative to applying another round of herbicide."
Al-Kaisi says that soil crusting is another significant problem, particularly with limited residue cover. "High intensity rains break down soil aggregates, causing the bare soil's surface to seal. Significant runoff can result, and when rapid drying occurs, hard crust layers can form on the top two inches of the soil causing a significant challenge for emerging plants."
Hanna says that the rotary hoe offers good weed control when the crop is small, poses little risk of compaction, and causes very little disturbance of crop residue. "Rotary hoeing is the best way to abate soil crusting and enhance crop emergence. The best way to do it is to keep tractor speeds between eight and ten mph, run with the rows, and work just deep enough to flip the weeds out. Look for weeds at the white root hair stage -- any larger and it's probably too late for the hoe."
Then your best option becomes the cultivator, according to Hanna. He advises operating it at a depth of one-and-a-half to two inches to destroy and invert weed roots. "Focus on scraping the weeds up and out of the soil without disturbing the soil too deeply or turning residues under. For the best soil management, try to maintain your residue cover until the crop canopy closes the rows."
Funding support provided by USDA Natural Resource Conservation Service through Cooperative Agreement No. 74-6114-0-2.
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