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Many athletic fields or home lawns that have been constructed on poor clay soils, such as subsoils, are often compacted, with poor drainage capabilities and low nutrient status. Adding a Compost material to a native soil field, either as a soil amendment or as a topdressing material offers many benefits:

* Improve nutrient status of soils

* Improved bulk density and water retention properties

* Extended color retention in the fall and quick spring green-up

* As a light mulch on new seedings to conserve moisture and provide seed:soil contact (see picture left)

Composts in sands:

Composted materials are also sometimes used as amendments in sand rootzones, as a replacement for peat. The content is usually quite low (~ 1% by wt.) and research has suggested that is doesn't offer any "value-added" attributes over peat (e.g. disease suppression) at the low amount at which is it used. It is not recommended that composted materials be used to topdress sand fields, as they could contribute to the organic accumulation on the surface and create problems such as reduced water infiltration rates and poor root growth. Most sand field managers work hard to keep organic matter off the surface so it makes sense not to apply it as a topdressing.

Source of Compost Material:

There are many composted materials on the market and some contain more organic matter than others. It is important to choose a material that is processed through strict quality control guidelines. One of the types commonly used in Ohio is a biosolid material - a composted sewage sludge (CSS) produced by the city of Columbus. It has a nutrient analysis of around 3-2-1 and it has been graded for both turf applications and flower beds. Some topdressing suppliers mix the CSS with sand or sandy-loam to produce a suitable topdressing for native soil athletic fields, or it can be used on its own as a light topdressing material.

There is sometimes concern with CSS containing heavy metals and salts. One recent study suggested that soil amended with less than or equal to 20% CSS showed all of the benefits listed above and there were no adverse affects on grass seedling development. Studies have also shown that at the 0.25 inch topdressing depth, CSS does not adversely affect newly seeded areas. At much higher rates (> 40%) heavy metals (Cu, Zn, Pb)were seen to accumulate in the perennial ryegrass plants and high salt concentrations in the soil affected seedling emergence.

Posted by Pam Sherratt & John Street