Improving Soil Health at Tree Nurseries

At nurseries, trees are grown in rows for several years until they reach a desired size for sale. The ground between rows is typically left bare, which provides an opportunity for weeds to take hold. Nurseries typically control weeds with tillage, herbicides, or mowing. Tillage can be especially problematic for waterways, as loose soil is prone to washing into streams after rain events.

Excess sediment, or dirt, that washes into the river can smother aquatic organisms. Dirt also tends to pick up pollutants as it travels into streams. In rural areas such as Warren County, sedimentation typically occurs because of construction or agricultural activities.

Partnerships for Success

With support from the National Fish & Wildlife Foundation, the Compact conducted several studies at two tree nurseries (Eller Trees and Hidden Valley Nursery) looking at cover crop seed blends to determine which mix and application method would improve soil health and reduce erosion.

The Compact tested four different seed blends in collaboration with the Warren County Soil & Water Conservation District and the Tennessee State University Nursery Research Center. The team measured soil moisture content and water infiltration, soil temperature, soil coverage, and weed control.

Study Results Support Cover Crop Adoption

Results showed that cover crops, regardless of seed blend or planting method, are a viable way to reduce tillage and improve soil health in nursery settings. A drop seeder was found to be the most efficient planting method. At the conclusion of the trials, the Cumberland River Compact indefinitely loaned the drop seeder used for this research to the Warren County Soil & Water Conservation District for nurseries in the McMinnville area to borrow.

The study also found that increasing seeding rates above recommended averages may be necessary in nursery settings. This is because the soil at tree nurseries often has established perennial grasses that reduce cover crop seed germination and viability. Although tillage prior to seeding improves germination rates, the Compact does not recommend tilling the soil prior to seeding due to the potential for soil erosion.

Cover crops are a best management practice proven to reduce erosion and pollutants in waterways. This research conducted by the Compact and partners demonstrates that tree nurseries, like those found in McMinnville, can use cover crops to improve soil health and protect streams and rivers in the Cumberland River basin.