Extension Communications
Extension 4-H Youth Building
Ames, Iowa 50011-3630
(515) 294-9915
|
|
Extension Communications |
5/18/04
Contacts:
Mahdi Al-Kaisi, Agronomy, (515) 294-1923, malkaisi@iastate.edu
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
Cultivation and Rotary Hoeing -- Important Decisions Ahead
AMES, Iowa --Iowa State University Extension researchers say choices made now about row-crop cultivation and rotary hoeing can have an impact on soil and wind erosion, soil productivity and overall profitability.
"Now that the seed is in the ground, it's time to think about cultivation," says Mark Hanna, ISU Extension ag and biosystem engineer. "First, the potential benefits include substantial weed control -- 70 to 80 percent of weeds can be removed from between rows with one cultivation pass. That can have a significant impact on productivity and profitability. Other benefits include breaking the soil crust, which aerates soil and crop roots and allows better initial water soak of rainfall. And, since weeds are controlled with steel, there's less overall use of chemicals."
"Most row crops respond positively to cultivation and rotary hoeing, but there are challenges as well. For conservation tillage producers who hit the target of having crop residues of more than 30 percent remaining on the surface at planting, that residue can make the process of cultivation and rotary hoeing difficult," says Mahdi Al-Kaisi, ISU Extension soil specialist. "And cultivation, like any tillage operation, turns over crop residue, leaving soil exposed to water and wind erosion. Moreover, seasonal rain may prevent timely cultivation, and if it does, the temptation to get the cultivator in the field as soon as possible could lead to significant soil compaction and yield reduction."
Al-Kaisi and Hanna say the key is to assess whether the benefits of cultivation outweigh the challenges and potential drawbacks. Al-Kaisi offers some things to consider. "The leading considerations are weed presence and soil sealing -- if they aren't a problem, cultivation isn't needed."
For those who want to use the rotary hoe, Hanna offers some tips. "Before hoeing, look at the crop to assess the stage. Don't knock the cotyledons off soybeans. Corn withstands hoeing better, but stop often to make certain the stand isn't damaged. Finally, in order to do a good job hoeing, follow this general rule: stir the soil's surface and get weeds at the white root hair stage -- any larger and it's probably too late. Sun and wind will dry and kill exposed weed roots. Wet soils (when the roots clump together) lower the effectiveness of hoeing or cultivation and may require a second pass in the opposite direction."
Producers also need to consider how soon the crop will establish a canopy cover. Canopies can reduce erosion by softening the impact of raindrops on the soil. Timing for establishing canopies depends on many factors, including those as simple as crop maturity and row width, but also factors like variety or hybrid and varying soil conditions.
Both Al-Kaisi and Hanna also say the nature of conservation tillage results in reduced evaporation. If conditions turn dry, soil moisture loss from opening up the soil can put cultivated crops at risk. In times of limited soil moisture, conservation tillage systems out-yield intensive tillage systems because tillage results in moisture loss.
In the end, farmers need a decision tree that calculates economic gain from weed reduction, long-term productivity loss from soil erosion, as well as the cost of poor water quality that results from soil erosion, and the impact of soil moisture status on the crop. For more information, refer to PM 1623 "Cultivation, an Effective Weed Management Tool," which can be ordered through ISU Extension county offices or at www.abe.iastate.edu/machinery.asp.
-30-
Funding support provided by USDA Natural Resource Conservation Service through Cooperative Agreement No. 74-6114-10-03.
ml: isufarm