State & Federal Practices
Cropland Erosion
Sheet & rill erosion occurs when water begins to flow off the land. Sheet erosion is difficult to see because the soil is lost in a way similar to a few sheets of paper being peeled from a tablet. Rill erosion leaves definite marks where the soil has been washed away. Ephemeral erosion is runoff water flowing from uneven landscapes tends to concentrate in natural, depressional channels. These channels can be reshaped and farmed across, but continued, concentrated flow takes away the soil. Eventually, a gully will form. Gully erosion over time, heavy rains with gushing, concentrated runoff can seriously erode soil and create very large ditches or gullies on the land.
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To slow the erosion a combination of ground cover and terraces offer excellent erosion control. Covering the ground prevents raindrops from bombarding the soil. Covering the ground is also a very effective way to control erosion by wind. It is the most commonly used method. Another way to reduce erosion by wind is the wind barriers.
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The following are erosion control practices:
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Terraces
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Grass waterways
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Contour Farming
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No-Till
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Strip-Till
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Cover Crops
Windbreaks
Windbreaks reduce wind speeds, control snow drifting and accumulation in farmsteads, provide wildlife habitat, enhance farmstead value, and provide a more pleasant environment. Reduced wind speeds in the winter months provide monetary benefits. Homes or confinement buildings require 7 to 25 percent less fuel for heating. Livestock protected by the windbreak are 3-7 percent more efficient in conversion of feed to weight gain. Other benefits of windbreaks are measured in quality of life improvement.
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Windbreaks should be properly designed and located for maximum benefits. The standard L-shaped, square corner windbreak can be modified. Trees can be planted in groups instead of rows. Corners can be rounded or merged together. The key for the optimum protection is providing wind protection on the Northwest quadrant.
No-Till & Strip-Till
In a no-tillage system, crops are sown into undisturbed soil with plant residue on the surface. No-Till is recommended for planting soybean following corn, for planting corn following soybean on well-drained soils, and for any rotation on moderately-sloped fields.
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Strip-tillage system, more than two-thirds of the row width is left undisturbed, and the remaining strip is tilled to create a seedbed for spring planting. Strip-tillage is recommended for corn production on poorly drained soils and low-sloped fields.
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Plant rye or wheat as winter cover crops. This is good option when you are growing low-residue crops such as soybeans. Stop using the moldboard plow. Drive slower on tillage operations. Driving faster throws more soil and covers more residue. No-till drill soybeans instead of planting them conventionally. No-till drilling keeps more residue on the soil surface, and generally produces a quicker canopy.
Cover Crop
Cover crops planted in the fall between harvest and planting of spring crops, this will reduce soil erosion, limit nitrogen leaching, suppress weeds, increase soil organic matter and improve overall soil quality. Small grain cover crops increase surface cover, anchor corn and soybean residues, increase water infiltration and reduce erosion. Common cover crops used in Iowa include winter hardy plants like rye and wheat. Other less common, but also effective cover crops include oats, turnips, radish, and camelina.
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In addition to the environmental and soil quality benefits, several cover crops are suitable for grazing by livestock. Using cover crops may reduce the total energy demands of the farm, by capturing nutrients that would be lost to leaching thus reducing the farm's requirement for high energy inputs. Producers must plant early enough in the fall to allow for good establishment before winter, but also must kill winter hard cover crops soon enough to prevent yield losses in the following crop.
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Edge-of-Field
In addition to incorporating conservation practices in the field, many Iowa farmers are adopting edge-of-field practices that help to significantly improve water quality in the state by managing the loss of nitrogen from cropland.
Approximately 50% of Iowa cropland has subsurface drainage, based on United States Department of Agriculture Census of Agriculture date from 2012 and 2017. While this subsurface drainage makes it possible to farm previously wet soils, the drainage system also carries dissolved nitrogen from farm fields to the streams, rivers, lakes, wetlands, and other surface waters of the state.
Excess nitrogen in surface water leads to local, regional, and national-level alterations to aquatic ecosystems resulting in decreased water clarity, increased algal growth, and oxygen deficiencies that cause fish kills and reduce biotic diversity. Excess nitrogen also harms potable water supplies. Nitrate-nitrogen concentrations above the 10 mg/L NO3-N drinking water standard established by the United States Environmental Protection Agency are not uncommon in Iowa in surface waters and groundwater.
Filter Strip
A strip of dense herbaceous vegetation such as grass, trees, or shrubs that filters runoff and removes contaminants before they reach water bodies or water sources such as wells. Filter strips are most effective when used in combination with other agronomic or structural conservation practices.
The vegetation slows water flow and allow contaminants like sediment, chemicals and nutrients to collect in grass, trees, and shrubs. Filter strips improve water quality for fish and other aquatic life. Grass, trees and shrubs provide cover for small birds, animals and pollinators. Ground cover reduces soil erosion. The vegetative strips move row crop operations further from a stream.
Filter strips are most effective on slopes of 5% or less. Filter strips for cropland must be at least 15 feet wide. Steeper slopes require wider strips. A minimum of 50 feet width is required for filter strips on forestland. You should not use a filter strip as a roadway and/or driveway.
Grass Waterways
Grassed waterways are shaped constructed channels that are seeded to grass or other suitable vegetation to convey water to a stable outlet at a non-erosive velocity. A structure is often installed at the base of the waterway to stabilize the waterway and prevent a new gully from forming.
Grass cover protects the waterway from gully erosion and traps sediment in runoff water. Vegetation can filter and absorb some of the chemicals and nutrients in runoff water. Vegetation provides cover for small birds and animals.
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Pasture & Hayland Planting
Planting grass and legumes-suitable for pasture, hay, or biomass production- to reduce soil erosion and improve production. This practice does not apply to the establishment of annually planted and harvested food, fiber or oilseed crops.
Pasture & Hayland Planting improves or maintains livestock nutrition and health. Provides forage supplies during periods of low forage production. Pasture and Hayland reduces soil erosion, and it improves soil health and water quality. Lush pastures give cover and habitat for wildlife. As plants recycle and roots die, organic matter in the soil is improved.
Prescribed Grazing
Managing the harvest of vegetation with grazing and/or browsing animals. This is often attained through a rotational or mob grazing system where pastures are divided into four or more pastures or paddocks with fencing. Cattle are moved from paddock to paddock on a prearranged schedule based on forage availability and livestock nutrition needs.
Prescribed grazing improves and/or maintains species composition and vigor of plant communities. Quantity and quality of forage for grazing and browsing animal health and productivity.
If you adopt prescribed grazing, you may also qualify for cost-share for these other supporting conservation practices in fencing and watering facility.
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Terraces
A terrace is an earthen embankment constructed across a field slope. They break long slopes into shorter ones- usually following the contour. There are two basic types of terraces-storage terraces and gradient terraces. Storage terraces collect water and store it until it can infiltrate into the ground or release through a stable outlet. Gradient terraces are designed as a channel to slow runoff water and carry it to a stable outlet.
Terraces will help reduce erosion by reducing slop length, retain runoff for moisture conservation. Terraces also provide nesting habitats.
State Cost Share Application & Maintenance Agreement
NRCS-Federal Application
NRCS Direct Deposit Form