NURSE CROPS

Extra care needs to be taken when planting prairie into bare soil, because wind and water erosion can severely reduce prairie plant establishment. Prairie seeds need to be planted shallow in the soil (1/8” – 1/4” deep) to maximize germination and emergence. Because native seeds require shallow sowing depths, they are exposed to wind and water in bare soil sites and are much more susceptible to being moved off site and/or being clustered into a portions of the site resulting in uneven coverage. In addition, loose soil often moves around on the site, potentially burying seeds too deep reducing their ability to emerge.

Delayed germination of natives can also be problematic in bare soil. Each prairie species has a unique suite of conditions needed for germination. A diverse prairie seed mix of 40 – 60 species will include some species that require 4 weeks or more to germinate and others that germinate in a week or two. This creates a situation of staggered germination after sowing; a few plants emerge one week and a few more the next week and so on. This random emergence of prairie seedlings does not stabilize bare soil quickly leaving the planting site exposed to soil erosion/deposition that can result in further seed loss over time.

Finally, it is a known fact that prairie plants grow slowly and remain small aboveground in the first growing season, leaving a lot of bare soil exposed to erosion. We often see in first year prairie plantings annual weeds such as foxtail (Setaria spp.) stabilizing bare soil rather than the prairie plants.

Nurse crops are commonly used to reduce soil erosion when prairie is planted into bare soil. These are annual cereal crops that are included with the prairie seed at the time of planting. Nurse crop seeds are chosen in part because they readily germinate and quickly develop into mature plants, providing competition against weeds and effectively holding the soil in place while native seedlings are getting established. Due to their life history characteristics, nurse crops tend to diminish by the third year and will not interfere with prairie plant establishment and growth if establishment mowing is used. We recommend oats for spring plantings and winter wheat for fall plantings. The seed calculator will automatically recommend the appropriate nurse crop and seeding rate that is needed to reduce soil erosion on the planting site.