I have received many questions recently about the use of compost on native soil sports fields, either as an amendment or topdressing.
Compost has been used on native soil fields for many years. Its benefits include improving soil structure and adding nutrients. A high-quality compost with a bulking agent such as wood chip enhances soil porosity and, in turn, improves drainage capabilities. Enhancing soil quality leads to better turf quality, as deeper roots help turf withstand drought and heat stress. Composted materials also contain essential minerals like nitrogen and phosphorus, which support seed germination, establishment and overall turf health. When applied as a topdressing, compost helps retain moisture and keep seed in place during establishment. These benefits are well-documented, with informative resources available, such as Penn State’s “Using Composts to Improve Turf Performance.”
Compost is derived from various materials such as biosolids (sewage), manure, yard waste, spent mushroom compost, coffee grounds, plant and food waste. The quality and safety of compost are regulated by the EPA (Part 503), which sets standards for the presence of heavy metals such as zinc, copper, cadmium and lead; pathogens such as E. coli and Salmonella; salts, and odors. Biosolids and sewage-based materials are closely monitored for their application on food crops, and cannot be used in organic food production. For use on sports fields, compost should include a bulking agent, be free of weed seeds, and not have an excessive odor. Biosolids and manure-based composts may have an odor for a couple of weeks after application.
Forever chemicals (per- and polyfluoroalkyl substances, or PFAS) are synthetic compounds that persist in the environment and the human body, where they are known to cause adverse health effects. These chemicals are used to make products resistant to grease, water and heat, and they are found in a range of items from carpets and bakeware to pizza boxes and popcorn bags. Given their widespread use and persistence, it stands to reason that PFAS are also present in many organic and synthetic products used in the turf industry, including biosolids and other composts. Research into plant uptake is ongoing, but current findings indicate that PFAS concentrations in compost are low. One study on lettuce found that compost amendments can actually reduce PFAS uptake by plants. It is important to remember that PFAS are ubiquitous, legally manufactured, and still present in thousands of materials. The US Compost Council, EPA and other stakeholders acknowledge the need for further research. Additionally, state, tribal, and local regulations may apply, so be sure to check for specific guidelines before starting a biosolid compost program.
There are two primary approaches to soil improvement with compost:
- Topdressing is ideal for fields with a solid grade that require additional organic matter. It is usually done manually, while larger areas may require specialized equipment. Spread high-quality compost across the turf surface to a depth of ¼ to ½ inch. Rake, drag, or brush the material into the sward. Water the material in. Topdressing is most effective when combined with core aerification to help the material integrate into the underlying soil. Applying seed before topdressing is also beneficial.
- Mixing compost into the top 4 to 6 inches of topsoil is best for complete field renovations where the soil quality is poor and the grade needs correction. The process involves removing existing turf to establish a new surface. Remove dead or old vegetation so that only bare soil remains. This can be done with a hard rake or by lightly rototilling. Spread 1 to 2 inches of high-quality compost over the soil surface and rototill to a depth of 4 to 6 inches. Perform this task when the soil is relatively dry. During tilling, remove rocks, wood pieces, and thick roots. Typically, two to three passes with the rototiller are sufficient to mix the materials thoroughly. After tilling, grade the soil surface to the desired slope (crown, side-to-side, etc.). The finished seedbed should have small aggregates; an even surface (without bumps or depressions); and a loose, friable texture.
Pamela Sherratt is a sports turf extension specialist at The Ohio State University.
Questions?
Send them to Pamela Sherratt at 202D Kottman Hall, 2001 Coffey Road, Columbus, OH 43210 or sherratt.1@osu.edu
Or send your question to Dr. Grady Miller, North Carolina State University, Box 7620, Raleigh, NC 27695-7620, or grady_miller@ncsu.edu