SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/141613
FieldScience | By Pamela J. Sherratt Figure 1 Figure 2 Figure 3 Improving Native Soil Fields T HE QUALITY AND LONGEVITY of an athletic field is directly related to the drainage capability of the soil. How fast water drains into and through the soil (infiltration rate, KSat) is the best indicator of how many games can be played and how the field will react during a rain game. Ideally, fields should have a minimum infiltration rate of 1 inch/hr., but it is not uncommon to see soils with infiltration rates of 0.01 inches/hr. or less. The infiltration rate of a soil is influenced by the soil texture and the level of compaction the soil is subjected to. Fields with low infiltration rates create very poor playing conditions. When wet, they turn to mud, when dry they turn to concrete (Figure 1). Turf plants will not grow in these soil conditions and so the field gets taken over by weeds like prostrate knotweed, 12 SportsTurf | July 2013 clover, dandelions and Poa annua. Turf growth is so poor that nutrients are not taken up, so the turf becomes chlorotic/yellow and does not recover from wear. Slow turf growth is more susceptible to diseases like red thread and rust. It is also impossible to get seed established on hard, compacted soils (Figure 2). Improving the infiltration rate of the soil therefore is the key to improving field conditions. There are short term fixes to improve infiltration. These include using aeration equipment like a core aerator, spiker, deeptiner or verti-drain. These machines punch holes in the soil, allowing water to enter and O2 and CO2 to enter and exit. After a period of a couple of weeks or less however, those holes seal over and the previous conditions return. A long-term fix is to amend the soil with a material that improves the infiltration rate, namely sand. As well as improving in- filtration rates, topdressing evens out the playing surface and fills holes that could cause athlete injury (Figure 3). Applying 50 tons of sand to a field per year via topdressing appears to be an effective rate. It is possible to apply higher rates of 60-100 tons, especially if the sand is applied in two increments (spring & fall). The sand is either applied alone or in combination with soil or compost. The soil &/or compost typically makes up 10-30% of the mix. Adding compost to the mix is a good way to get some organic material into the soil if it is lacking. Compost improves the soil health (increased oxygen, reduced bulk density, increased water holding capacity) and also adds nutrients. The soil component in a topdressing mix helps to maintain surface stability (sand alone does not have good shear strength) and also retains moisture, which is important for seed establishment. The soil &/or compost typically makes up 10-30% of the mix. Adding compost to the mix is a good way to get some organic material into the soil if it is lacking. www.sportsturfonline.com