For insight into soil health, SportsField Management magazine recently spoke with Rebecca Knapp, CSFM. A Penn State Turfgrass alumnus, Knapp has prior experience in MLB, MLS, NCAA and MiLB. Knapp is also a member of the SFMA Editorial Committee.
SportsField Management (SFM): How can we effectively assess and monitor soil health in sports fields beyond standard soil nutrient testing?
Knapp: Soil health goes far beyond NPK values. While nutrient testing is essential, we need to gain an understanding of what’s happening below the surface if we want resilient, high-performing fields, especially under the stress of play and tight turnaround schedules.
One of the most critical challenges is soil compaction. Regular use of a penetrometer or a shear strength tester — especially in high-traffic zones such as goal mouths, position areas and sidelines — can provide real-time insights into rootzone resistance and whether aeration and topdressing programs are effective.
It is also important to monitor organic matter levels through annual physical soil testing not just for thatch, but for how it affects water infiltration and rooting. Caution must be taken when applying compost to sand-based fields. If organic matter exceeds 3%, water infiltration and percolation rates will be restricted.
Soil biology deserves a greater focus. Microbial activity or biomass testing are available and will present soil respiration. Results will vary with seasonality because soil temperatures and moisture levels affect microbial activity. Inputs such as carbon-based fertilizers, biostimulants, and molasses-based fertilizers are solutions that can be implemented to support beneficial microbial life.
Develop a consistent visual inspection routine. In addition, use a soil probe to assess rooting depth and evaluate soil moisture. Smell the soil, as healthy soil will smell earthy. These observations can help validate lab data and assist with field management decisions.
SFM: What are the best practices for improving soil structure in high-traffic areas such as goal mouths and sidelines?
Knapp: With high-traffic zones like goal mouths, sidelines and player bench areas, the key is being proactive and layering multiple strategies together.
Aeration remains an effective approach. Depending on available field recovery time, hollow- or solid-tine aeration can be effective. Aeration will relieve compaction and open up space for air and water to enter your soil profile and provide space for new root growth.
Topdressing complements this process, and is best managed through consistency. Use a sand blend that matches the existing rootzone. Light and more frequent applications tend to deliver the best results to maintain a uniform surface.
Being proactive with aeration and topdressing can prevent severe damage later in the season. If an area becomes worn, compacted and begins to thin, consider re-sodding or consider rotating fields to allow time for recovery. Thin areas can become a safety issue and affect playability.
SFM: How does organic matter management impact soil health and playability over the course of a sports season?
Knapp: Organic matter management plays a central role in both soil health and field playability. Excessive organic matter, especially in the upper inch of your soil profile can hold excess moisture, and limit oxygen exchange. The result is a soft, spongy surface that reduces footing and increases instances of disease and pest pressures.
When organic matter is managed effectively through aeration, topdressing and biological activity, the soil stays firm yet resilient. It drains efficiently after rainfall, recovers faster from wear, and supports healthy root growth.
From a season-long perspective, consistent organic matter management means the field stays more predictable with smoother ball roll, safer footing, and reduced mid-season decline.
SFM: What role do soil microbial communities play in turf health and recovery from stress or damage?
Knapp: Soil microbial communities are vital to long-term turf performance. These beneficial microbes decompose organic matter, cycle nutrients, and even protect roots from harmful pathogens. When the microbial population is active and balanced, the soil becomes a dynamic support system that helps turf recover faster after stress from play, heat or drought.
Microbes make nutrients more available, improve soil structure, and boost root resilience. Incorporating biostimulants such as humic acid, seaweed extracts or microbial inoculants strengthens and supports the soil ecosystem. Over time, turf supported by healthy microbial activity develops deeper roots, greater shoot density, and improved resilience.
Thriving soil biology separates a good playing surface from a great one. Turf will recover quicker, have consistent color and increased durability across the demand of sports schedules.
SFM: How can we balance soil moisture for optimal turf performance without promoting compaction or disease?
Knapp: Balancing soil moisture is one of the most precise aspects of sports turf management. This goes for both turf and infield skin management. It’s all about consistency and balance with weather conditions. Maintain moisture levels with the soil’s field capacity in mind while providing adequate moisture for root uptake and maintaining enough air space in the soil profile for gas exchange.
Dry soil puts turf under stress, limits rooting and slows recovery. Oversaturated soils promote compaction, encourage shallow rooting and increase disease pressure. Achieving the right balance requires both data-driven irrigation management and sound soil practices. Using weather data, evapotranspiration rates and real-time soil moisture sensors allows field managers to fine tune irrigation schedules with precision to match turf needs.
Humectant-based products can help stabilize soil moisture by extending the intervals between irrigation cycles, creating a more uniform environment for nutrient uptake, and supporting soil microbial life.
Improving infiltration rates through aeration and maintaining healthy organic matter levels also helps water move freely through the soil. This will reduce surface saturation and compaction risk. Balancing soil moisture is about understanding how water moves within your soil profile. Water movement will vary across your fields and even microclimates within a field. Giving the turf exactly what it needs, when it needs it will result in a firmer, healthier and more resilient playing surface all season long.