layer allows the growth media to be suitable for play. Without sand mixed with the thatch layer, divots would readily kick out and the field would not be safe for any type of sport. Another common method of reducing thatch is vertical mowing. This consists of vertical blades tearing into the soil and pulling out organic matter. This can lead to a long recovery time for the turf. Reducing the amount of thatch at the surface allows nutrients and pesticides to penetrate into the soil. Nutrient management Nutrient management is essential in maintaining a healthy stand of turfgrass, and is much more difficult to achieve effectively in a sand-based system. Unlike with native soil fields, leaching of nutrients is a major concern when managing a sand-based turf system. Nutrient leaching occurs more readily in a sand-based system because sand has a relatively low cation-exchange capacity (CEC). This refers to the sand's ability to retain nutrient particles. Soil particle "hold on" to positively charged nutrient particles because they are negatively charged. The opposite charges cause the nutrients to adhere to soil particles which can then be taken up by plants. Sand has virtually no CEC, whereas clay and organic matter have relatively high CEC. This means that the higher the clay and organic matter of a soil, the more nutrients it will hold. Low CEC is a major concern when an athletic field is constructed with 100% sand because substantial amounts of nutrients will be unavailable to the turf. The pure sand base will not hold on to nutrients until there is substantial organic matter incorporated into the soil to keep nutrients from leaching. Eventually, organic matter levels will rise as the plants begin to mature and dead vegetative matter decomposes. The best way to avoid this problem is to incorporate some type of organic matter into the root zone mix during construction. The most common, as noted above, is peat moss. Mixing peat moss into the root zone mixture greatly increases nutrient holding capacity. This will greatly increase the chances of establishing a healthy stand of turfgrass because the soil will be able to retain both nutrients and water. Because the nutrient holding capacity is low, soil tests are crucial for sand-based athletic fields. Soil tests should be taken frequently to measure what nutrients are lacking. Fertility programs should then be based on the soil tests. Unlike a native soil