Cultural Practices on Athletic Fields: Soil Cultivation and Topdressing

Soil Cultivation

Soil cultivation is the process of breaking up and loosening the soil in a controlled fashion to allow air, water and nutrients to penetrate the rootzone. Soil cultivation is one of the most important cultural practices for maintained turfgrass areas, but also one of the most underutilized cultural practices. A field that is not aerated regularly will often exhibit poor turfgrass growth, compacted soil and high levels of thatch. Soil compaction is caused by foot and vehicular traffic and can create the following problems:

  • Decrease in total pore space. Large pore spaces between soil particles are essential for internal drainage, channels for root growth and air exchange.
  • Decrease in soil oxygen content. Oxygen is essential for root respiration and growth. Nutrient uptake by roots is an active process requiring oxygen. Therefore, nutrient uptake is limited by poor air exchange induced by compacted soils.
  • Reduces water infiltration and percolation.
  • Increases soil strength and density. Compacted soils reduce rooting density and depth.
  • Increase in water retention. Compaction can prolong wet soil conditions and contribute to puddles on sports field. Allowing traffic on a saturated field can also intensify compaction.

Cultivation practices to alleviate soil compaction, improve turfgrass growth and reduce thatch:

– Core Aerification

Core aerification is the single most important management tool for controlling compaction. Coring involves the use of a machine engineered to penetrate soil, extract cores and place them on the turf surface. Cores from 3/8 inch to 1 inch in diameter to a depth of 2-6 inches can be removed depending on the type of machinery used and maintenance needs. Extracted cores can be reincorporated into the turfgrass surface or removed.

Core when the turfgrass is actively growing so that it can recover from any injury. Fields should be cored a minimum of twice yearly.

On warm-season fields, core once in the spring (April or May), just before fertilization, and again in mid to late summer. For fields that see intensive practice and play, will be overseeded, or are constructed with a heavy soil profile, plan to core a minimum of 3 to 4 times per growing season. Begin in late April or early May and repeat monthly, or at least every other month, until cool fall temperatures halt bermudagrass growth or one month before anticipated fall overseeding time.

On cool-season fields, spring and early fall are the best times to aerate. Summer aeration of cool-season grasses is not generally recommended because these grasses are in a semi-dormant condition. A safe general rule for time of aeration is to aerate only when the desirable grasses are growing vigorously.

– Deep-tine Aerification

A major objective of deep-tine aerification is to loosen soils and create aeration channels to a depth well below that of conventional core aerification. Deep-tine aerification may provide the opportunity to relieve compaction that can occur in the soil just below the depth of routine core aerification. It is also used to improve air, water and nutrient movement through layered, poorly drained soils.

  • Hollow-tine, deep-tine aerification – Hollow tines from ½ to 1 inch or more in diameter and up to 12 inches in length remove much more soil than conventional coring. This allows the addition of large amounts of topdressing or organic matter to be added to amend the turfgrass rootzone.
  • Solid-tine, deep-tine aerification – Solid tines up to 16 inches in length and ½ to 1 inch in diameter are used to fracture the soil. Using solid tines lessens disruption to the turfgrass surface, but still creates aeration channels. Solid tines should not be used as a substitute for core aeration.

– Deep-drill Aerification

Soil is lifted to the turfgrass surface by drilling large, steel bits into the rootzone. Bits from ½ to 1 or more inches with a depth of up to 16 inches create deep channels and loosen the soil. Sand may be added to the holes to amend the soil and improve air, water and nutrient exchange in the rootzone.

– Water Injection Cultivation

Streams of pressurized water are directed through small diameter nozzles to penetrate thatch, loosen the soil and promote root growth. Water injection should not be substituted for traditional core aeration.

– Vertical mowing

Knives attached to a rapidly spinning, horizonal shaft are used to relieve grain, dethatch or cultivate turfgrass areas depending on the height setting. Vertical mowing should not be substituted for traditional core aeration.

– Spiking

Pointed blades attached to a horizonal shaft rotate above the soil surface. Spiking creates very little surface disruption, but will stimulate shoot and root growth to improve plant recovery from wear. Spiking should not be substituted for traditional core aeration.

– Slicing

V-shaped knives mounted on disks attached to a slowly-rotating steel shaft create deeper and longer perforations in the turfgrass compared to spiking. Slicing can be beneficial in promoting recovery of turf when core aeration would be too stressful to plants. Slicing should not be substituted for traditional core aeration.


Topdressing is a uniform application of a thin layer of soil or organic material over the turfgrass surface. Topdressing provides the following benefits:

  • Control thatch. Mixing soil with thatch gives beneficial soil microorganisms direct access to nutrient-rich organic matter, thereby speeding the decomposition of thatch. This can help accelerate water movement from the turfgrass surface into the soil below.
  • Level and smooth low spots or ruts on playing surfaces.
  • Amend the turfgrass rootzone. Physical properties of a rootzone can be improved if the appropriate topdressing material is used and the turfgrass is topdressed several times each year for many years. Topdressing is frequently used following core aerification practices.

Selecting the right topdressing material is critically important. The use of a topdressing material with a texture drastically different than that of the underlying soil often results in soil layering. This can restrict the movement of water within the soil profile.
The best time for topdressing is when turfgrass plants are actively growing. Turfgrass managers will typically pair a cultivation practice with topdressing.