Topdressing is the application of a uniform thin layer of soil or finely granulated organic materials applied over the turf surface. It is used to level the playing field when minor variations or depressions are apparent, help to amend physical soil properties and create a better growing environment for the turf and help reduce thatch.
If you have access to a readily available topdressing material, the necessary application equipment and a budget that can afford this practice, topdressing can be an important part of your management program.
Timing and frequency
When conditions warrant it topdressing is done as a routine practice 1-2 times per year when the turf is actively growing, for example, in late spring, early fall and/or in late fall after the playing season.
Frequent applications can, over time, actually modify the soil profile. It is often combined with core cultivation practices.
Topdressing materials
Selecting the correct topdressing material is critical and depends on the purpose of the topdressing. The chosen topdressing material must be consistent in type and particle size and available for future applications. Variations in particle size can lead to layering which will disrupt drainage and rooting.
| Material | Use | Characteristics and Application Tips |
|---|---|---|
| Soil | All | When soil modification is not needed the existing soil or one similar in texture can be used. Pull cores, allow cores to dry on the surface and then drag to have soil fill in aeration holes. |
| Sand | L,C,P | Can use 100% sand should be angular or medium coarse. Make sure the sand source will be available for future use.
Can use a mix with 80% sand and 20% organic matter. The mix should not contain more than <5% fine gravel and <10% silt + clay or 2-5% very fine sand, 2-5% silt, 2-5% clay. After applying the topdressing material, first pull the drag mat making small circles then in large ovals so the material can filter into the aeration holes and also provide a level field. |
| Compost | All | Should be mature, screened, have a fine particle size, be within the pH range of 6.5-8.0 and have a low salt content. Compost should be tested. Apply no more than ¼ inch per application. |
| Crumb Rubber | Should have a small particle size: 0.05-2.0 mm. Apply at a ¼ inch depth per application until a cumulative depth of ¾ -1 inch depth is achieved over time. This material is expensive. | |
Uses:
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Amount needed
The amount of topdressing material needed will depend on the purpose of the topdressing. A light application, a 1/8″ – 3/8″ layer which is about ½ – 1¼ cubic yards for each 1,000 sq. ft., is usually used when seeding or overseeding.
Topdressing to amend the soil to relieve compaction will require a heavier application, enough to fill the aeration holes. To change the soil profile by actually building a sand cap will take much more material.
Topdressing amounts
| Approximate Depth (inches) | Approximate Amount Needed cubic yards/1,000 sq. ft. |
|---|---|
| 1/8 | 0.4 |
| ¼ | 0.8 |
| 3/8 | 1.2 |
| ½ | 1.5 |
| ¾ | 2.3 |
Several approaches to using sand to improve drainage include:
A short term approach involves punching holes in the soil using a core aerator, spiker, deep tiner or verti-drain to allow water and air to enter the soil. This practice will only last a week or two and the holes will seal over creating the previous situation.
A sand-cap can be built slowly over time by applying a 1 inch depth of sand over a 3½ month period with the goal of building a 2 inch layer within 2 growing season. See Sand Cap Build-Up Systems for Michigan High School Fields.
Once that level is reached an annual application of ¼” of sand along with core cultivation and/or vertical mowing will mitigate organic matter accumulation.