Erosion, especially on steep areas, is a common environmental issue seen throughout Polk County. One of the conservation practices that can help reduce the amount of soil leaving farm fields is contour buffer strips. These strips are usually placed along the contour of hills and planted to perennial vegetation. They alternate down the slope of the hill with wider cropped areas in between.
Historically, contour buffer strips are planted to a single species cool season grass. Iowa State University has taken this a step further with prairie STRIPS. Prairie STRIPS are designed the same way as the traditional contour buffer strip, but are planted to native Iowa prairie!
Prairie STRIPS have a multitude of benefits once established. One of their biggest benefits is reduced soil erosion. The Iowa State University STRIPS team determined that by converting 10% of a farm field to diverse, native prairie the amount of soil leaving the field can be reduced by 95%! The stiff native stems slow down the water running off the field and capture the sediment, holding it in place. This also improves water quality! Data showed that 85% of the nitrogen transported by surface water could be captured if 10% of the field is planted to prairie.
Increased biodiversity is another benefit seen from prairie STRIPS. The diverse plantings create habitat and food for bird species, insects, and other wildlife. Many of the species attracted to these areas prey upon crop pests and provide pollination services. Some game species also thrive in small prairie areas, increasing the recreation and hunting potential of your land!
The first step when establishing prairie STRIPS is to completely kill off existing weeds/weed seed banks. This is especially important if the area to be converted is pasture or an area that was not consistently managed by routine tillage or herbicides. You can kill off weeds by a few rounds of secondary tillage or use of herbicides. You want to make sure all weeds are suppressed before planting the prairie STRIPS.
Prairie seed can be planted using a drill or a broadcast seeder. Timing can play a role in which method you decide to use. For springtime or summer plantings, it may be best to use a drill, so the seed is not sitting on top of the soil. This reduces the risk of the seed being eating by wildlife or washing away during storm events. For last season or frost seedings broadcasting the seed may work best. The freeze thaw cycle over the winter will incorporate the seed into the soil. Some species of prairie even require a cold spell before they will grow!
During the first (and maybe second) growing season you will need to continue to suppress weeds. Prairie plants are very slow growing, so plantings can easily be taken over by weeds. In order to keep this from happening, allow the vegetation to grow to around a foot in height and then mow to 6 inches. If patches of thick weeds are present, spot application of herbicides may also be necessary. Once the prairie is established, usually in year 3, it will be able to out compete the weeds!
Once established, prairie STRIPS require very little maintenance. Usually a burning or mowing every 3 years is all that is needed to maintain a healthy, diverse planting. If mowing, the clippings could be used for livestock bedding or biomass feedstock. Some spot spraying of herbicides may be necessary if clusters of weeds begin to appear.
Grazing is another option for maintaining prairie. Careful consideration for nutritional content will be important, though. Towards the end of the season, prairie plants tend to lose much of their nutritional content because they are going dormant. Because of this, it may be best to hay or graze the vegetation in July or August.
If you would like to learn more about prairie STRIPS and how they may work on your farm look HERE or visit https://www.nrem.iastate.edu/research/STRIPS/.