Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
7/26/01
For Immediate Release
Contacts:
Mahdi Al-Kaisi, Department of Agronomy, (515) 294-1923,
malkaisi@iastate.edu
Mark Hanna, Ag and Biosystems Engineering, (515) 294-0468,
hmhanna@iastate.edu
Del Marks, Continuing Education and Communication Services,
(515) 294-9807, delmarks@iastate.edu
Steep Farm Slopes Need Permanent Vegetation
AMES, Iowa -- Row crops planted in Iowa fields that have slopes of more than 18 percent will lose soil to erosion faster than it can be replaced through natural soil building processes, according to two Iowa State University Extension scientists.
This soil loss will happen regardless of soil type and tillage type. Farmers should consider removing row crops from these areas and establishing permanent vegetation say ISU Extension agronomist Mahdi Al-Kaisi and agricultural engineer Mark Hanna.
Determining slope can be done in a couple of ways. "Your best option is checking the county soil survey, but you can also estimate the slope by looking at the landscape," says Al-Kaisi. "An average-sized person can look up slope while keeping a level gaze. If your line-of-sight intercepts the soil within 30 feet or less, the slope is 18 percent or greater. Keep a level gaze by sighting across the top of a level."
Determining how large sloping areas should be before they are deemed a problem can be a judgment call, says Hanna. "The key is to identify areas that are large enough to manage. For example, if the sloping area is less than the width of your average tillage pass, it may be too small to manage. On the other hand, just because a sloping area of land seems small doesn't mean it shouldn't be managed in the way that best suits it."
Hanna and Al-Kaisi say there are many possible solutions for removing sloping land from row crop production. "Options include strip cropping, pasture, putting land in the Conservation Reserve Program, or establishing simple strips of permanent vegetation within a field as waterways," says Al-Kaisi. "Strip cropping systems (growing crops in a systematic arrangement of strips on the contour to reduce erosion) can include cover crops like small grains or hay. The size and location of the strips depend on the size of the field and the length of the slope. Strip crops can be used as cash crops for farmers who do not own livestock. Local offices of the Natural Resource Conservation Service (NRCS) or Iowa State University Extension can provide information about strip cropping."
Using steep slopes as pasture may be as simple as erecting temporary electric fence, or setting a permanent fence if the area is large enough to justify the expense and effort. Farmers who don't have livestock in their operations can try developing working relationships with neighboring livestock farmers.
"But, more important," Hanna says, "If the area is large enough to consider pasture, it says that some long-term thinking may be in order. In other words, is row cropping the best use for this land at all? If there are a lot of areas in a field with steep slopes, perhaps the land in question is more valuable to someone with livestock."
Enrolling in CRP, or using permanent vegetation as waterways may be the best use for small areas of steeply sloping land, and farmers can check for assistance from federal, state and local conservation programs.
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