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/56877
FieldScience | J. Scott Ebdon, PhD & Michelle DaCosta, PhD >> PERENNIAL RYEGRASS STUDY AREA at the University of Massachusetts-Amherst used to eval- uate the effects of five rate levels of nitrogen on shoot and root growth under simulated traffic. Enhancing nitrogen use efficiency of sports grass natural resource that must be conserved and protected. To that end, pro- fessional turf managers need to limit the use of N in order to protect sur- face and ground water from unnecessary contamination associated with the use of nitrogenous fertilizers when applied to turfgrass systems. A The conservation of N and water ap- plied to turfgrass systems are closely related because the acquisition of water and N from the soil is dependent on rooting depth and density. As such, any cultural factors or conditions that inhibit rooting may reduce the turf system's ability to ex- ploit the soil for these growth limiting re- sources. Eliminating any stresses that create an unfavorable environment for rooting will in turn allow the community of turf- grass plants to maintain turf function with less water and N. Sustaining turf function with less input from water and N fits nicely into "sustainable" turfgrass manage- ment practices, which is a term that has grown in popularity among turfgrass scien- tists and turf practitioners. 18 SportsTurf | March 2012 NUMEROUS OPPORTUNITIES The opportunities to enhance N uptake by promoting rooting are numerous. All as- pects of turfgrass maintenance practices such as height of cut (HOC), irrigation, and N fertilization directly influence rooting. In addition, there are as many conditions that exist in turf systems that are unfavorable to rooting such as excessive thatch, soil com- paction, and strongly acidic soil pH, which can further impede rooting and reduce ni- trogen use efficiency (NUE) of the turfgrass system. These unfavorable conditions and practices when considered alone may be harmful to rooting. Moreover, when these root-related stresses are active in combina- tion they can interact and can be more in- hibitory to rooting depth than any one MAJOR CONCERN of society is to limit the application of water and nutrients such as nitrogen (N) to grassy surfaces in- cluding residential lawns and recreational turf. Water is a limited practice or condition when considered alone. In addition, many conditions (thatch and soil compaction) or practices (excessively close HOC, excess N and over-watering) that inhibit rooting and the efficiency of the turf system to acquire water and N can also pro- mote waste as runoff and leaching. While runoff and leaching events are wasteful of water, these same practices or conditions can move fertilizer N into surface and ground water, respectively. By maximizing rooting depth and the turf system's NUE, the ability of the turf system to minimize N leaching is also enhanced, especially for irrigated turf in summer, when high soil temperature stress inhibits rooting of cool-season turfgrass. The key to sustainable turfgrass manage- ment is to keep costly inputs such as N and water to their lowest possible level while sus- taining optimal turf function. For optimal function under intensely trafficked sports fields, good shoot density and vigor is essen- tial for wear tolerance and recovery. Further- more, high turf density is also critical for keeping field related injuries to their lowest possible level. Nitrogen has competing affects on shoot growth and root growth and there- fore "balancing N" to achieve optimum turf density and wear tolerance without diminish- ing rooting depth and NUE of the turfgrass system is important. Five years of study was conducted at the University of Massachusetts-Amherst to eval- uate the response of perennial ryegrass to in- cremental increases in N from 1 to 9 pounds per 1000ft2 per year. Perennial ryegrass was maintained at 1.25 inch HOC, irrigated to prevent drought stress and fungicides were applied to prevent disease. Our published re- search indicated a linear response to N in shoot growth (leaf growth rate and shoot density) and root growth (total mg root dry wt. cm-3 to a soil depth of 18 inch). Each incremental increase in N caused sig- While the gains in leaf growth are large in response to N there are diminishing returns with added N. www.sportsturfonline.com By