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/442256
Field Science 16 SportsTurf | January 2015 www.sportsturfonline.com W ebster's dictionary defines soil as the upper layer of earth that may be dug or plowed and a medium in which something takes hold and develops. As sports turf managers, that holds true for us. We dig in it, plow it, plant in it, roll it, and expect the soil to serve as a medium to exchange water, air, and nutrients for turfgrass, all to provide the best playing surfaces possible. The type and quality of the soil influ- ences everything we do as turfgrass managers. It can dictate which species of turfgrass we grow and maintain, how often and how much we fertilize and irrigate, and influence how we modify the soil through our various cultivation techniques. Although there are days the soil appears to be one large "hunk of stuff " as we attempt to dig through it with a shovel, it is essentially one-half mineral and organic matter and another one- half pore space. Maintaining a balance between the two becomes crucial to the performance of the turf. The solid mate- rials provide stability and a storehouse for nutrients, while the pore spaces provide air for root health and places for water to percolate and be stored. Years ago I had a discussion with Mike Andresen, facilities & grounds director at Iowa State University. He stressed how important it was for him to maintain vertical air and water movement as a key to maximizing the performance of his turf. This is so true. Our key to success is to develop and maintain positive air and water movement throughout our soils. This includes water moving in all direc- tions; up, down, and laterally throughout the soil (figure 1). With native soil fields this may be a difficult task, however, the key is maximizing the potential each soil has. Soil texture Knowing your soil's texture (the rela- tive percentages of sand, silt and clay) becomes very important. How water moves throughout a clay textured soil will differ considerably from a sandy loam soil (figure 2). It is often stressed to water your turf deeply and infrequently, which may be interpreted as applying 1 inch of water or more per application, waiting a number of days and then doing it again. With most of our soils, this may not be pos- sible. Interestingly, you may irrigate a clay soil and a sandy soil similarly, but for different reasons. As you irrigate a clay soil, the pores fill with water and seal the surface, allowing no more water to infiltrate and runoff like concrete. As you apply water to a sandy soil, a larger volume of water applied may percolate through and beyond the rootzone and not benefit the plant. So, in each case, you may be required to apply smaller amounts in repeat applications. If your goal was to apply 1 inch of water, you may be required to apply three 1/3 inch appli- cations of water sequentially to maximize your irrigation efforts. Back to BaSicS: underStanding SoilS, Soil moiSture, and Soil teStS ■ By Brad JakuBowski Figure 1 Figure 2 texture (meq/100g) Sand 1-10 Silt Loam 14-20 Clay Loam Soil 25-30 Clay 80-120 Organic Matter 150-500