Re-vegetating closed landfills with native plants definitely has its own set of challenges. Nonetheless, it is a rewarding process once complete.
by Nicholas Demel
When a landfill has reached the end of its lifecycle, the process of closing the location can be challenging and tedious. Once proper procedures have been followed to ensure the landfill is closed according to the appropriate codes, the re-vegetation process can begin.
Soil Needs
A successful site re-vegetation requires proper planning, application, and management. The re-vegetation process for each site will vary depending on the site’s location and climate; however, the overall goal of establishing native plants remains constant.
In an ideal situation, the original topsoil from the landfill will have been separated from the subsoil when the landfill was first developed. Depending on the geographical location, the topsoil is usually the first 8 to 18 inches of soil. Sufficient amounts of topsoil are crucial when establishing native plants. Topsoil contains the nutrients and minerals that plants require to survive. Microorganisms, nutrients and organic matter are not found in subsoil; and the pH is not ideal in subsoil either.
Addressing Common Mistakes
Below are the most common mistakes that result in unsuccessful re-vegetation, and what can be done to prevent these mistakes.
- Problem: Inadequate soil preparation.
Solution: Implementing proper soil tests, and adding correct amounts of soil amendments should be a priority. Adding too much fertilizer can easily burn young seedlings, or even prevent them from germinating. Amendments might also be required to adjust the soil pH. The ideal pH for most native species is between 5.5 and 6.5.
- Problem: Not using a nurse crop if erosion issues are a concern.
Solution: A nurse, or cover crop, offers quick establishment, erosion control and ground stabilization. They also provide new seedling with protection, and help prevent runoff. There are numerous options when selecting a nurse crop. The most common species used are oats, wheat, barley, annual ryegrass or triticale.
- Problem: Planting the wrong type of seed for the region.
Solution: The native plants that are to be seeded should consist of a blend of species that are local to the geographical area. Introducing plants from other areas could result in poor plant establishment.
- Problem: Planting at the wrong time of the year.
Solution: For the best results, warm season native plants should be seeded in the early spring, when the ground temperature is warm enough for seed germination. On the other hand, cool season native plants should be seeded in the early fall. All sites are different, so be certain when the optimal planting time is before seeding the site.
- Problem: Not planting enough seed.
Solution: Higher seeding rates will ultimately result in a quicker site establishment. If too little seed is planted, the site might take several years to establish, if at all. Planting adequate amounts of seed from the beginning assures the best possible site re-vegetation.
- Problem: Not planting live seed.
Solution: Always plant seed on a Pure Live Seed (PLS) basis. PLS is figured by multiplying the purity of the seed by the total germination. Planting seed on a PLS basis, ensures that the proper amount of live seed is being used for the project. Planting seed on a bulk basis could easily result in poor site establishment.
- Problem: Inadequate planting methods.
Solution: Native seed can either be drilled, broadcasted or hydroseeded. Depending on the site, drilling the seed with a native grass seed drill will typically result in the best outcome. If the seed is broadcasted, the site should be rolled or cultipacked after the seed is spread. Rolling or cultipacking will ensure good seed to soil contact. It is recommended that the seeding rate be increased by 50 to 100 percent when sites are being broadcasted or hydroseeded. Drill seeding prior to hydroseeding (assuming slope is not an issue) is best, as this will ensure good seed to soil contact.
- Problem: Planting seed too deep.
Solution: When using a native grass seed drill, ensure that depth bands are used to prevent the seed from being planted deeper than 1/4 inch. Seeds that are planted deeper will most likely germinate, but will not have enough energy to emerge as seedlings.
- Problem: Not addressing run-off if slopes are an issue.
Solution: During heavy rain events, run-off can be a major issue. Newly established plants as well as any seeds are susceptible to being washed away by heavy rain. On sites with slopes, steps should be taken to prevent run-off. Erosion blankets, berms and hay bales are only a few examples of products designed to reduce erosion during heavy rainfall events.
- Problem: Not controlling weed pressure.
Solution: If weeds become an issue during the establishment period, the best option is to mow them. This will allow the native plants to grow without having to compete with weeds for water and nutrients. Once the site is established, weed management may be accomplished by chemical means.
Being aware of these common mistakes; working to avoid them will allow for greater success when re-vegetating landfills with native plants.
Several steps can also be taken to help enhance the success of any landfill re-vegetation. If the landfill site is located in an area that will not receive adequate rainfall to establish the native plants, supplemental irrigation should be used if possible. Portable irrigation systems will be able to keep the soil moist, allowing the seeds to germinate and the plants to establish.
Site Management
It is also important to develop and stick to a site management plan. Regular maintenance is required for the closed landfill, and the newly established plants can benefit from upkeep as well. The site might require mowing. If the area is mowed, leave mower clippings on the ground. They act as mulch to help aid in the prevention of run-off. Soil amendments such as lime and fertilizer may also be applied to help the plants flourish.
Consider planting a diverse blend of grasses, forbs and flowers. A diverse blend will not only offer erosion control, but it is also a great way to attract pollinators and wildlife while also beautifying the landscape.
Re-vegetating closed landfills with native plants definitely has its own set of challenges, nonetheless it is a rewarding process once complete. Turning an eyesore into a beautiful landscape by simply using native plants is an amazing feat.
Nicholas Demel is a Reclamation Specialist with Bamert Seed Company (Muleshoe, TX), a leader in the native grass seed industry for more than 66 years. He specializes in site reclamation, pasture re-vegetation, and wildlife habitat management. He can be reached at (800) 262-9892, via e-mail at [email protected] or visit bamertseed.com.