Improving nitrogen management in turf

Nitrogen management, one of the most central turfgrass
maintenance practices, remains an art as much as a science.
Due to the dynamic nature of nitrogen in the soil, i.e., the
changing forms and amounts available to plants, there have
been no reliable objective testing measures that allow for
increased precision. As a result the subjective guessing of
when and how much N to apply remains the norm. This is not to say that professional turf managers can’t develop more precise N management. Rather that there is not a value that can be generated to determine when and how much N is required unlike what would occur if a soil test indicated K levels were below 50 lbs. per acre. Increasing precision through objective measurement has been the focus of the nutrient research at UConn for more than a decade. There were some successes using Anion Exchange Membranes, reflectance correlations using spectrophotometric measures, as well as tissue and soil testing, however adoption of any of these strategies has been limited by the technology and from industry reluctance. There are traditional approaches to N fertilization of turf that seem resistant to change due to the overall structure and logistics of the lawn care and grounds turf industry. Still, recent attempts using soil health measures and potentially mineralizable N have continue to provide insight into the complexity of managing a nutrient that changes availability rapidly in time and amount. Nitrogen Use Efficiency and Turfgrass Species

In addition to the dynamic nature of N in soils and the variety of situations where turf is grown the turfgrass we grow continue to be regarded as central to becoming more precise and sustainable with N management programs.

Studies dating back to the 1980’s indicated turfgrass species and varieties have a wide range of Nitrogen Use Efficiency (NUE), i.e., the amount of N required to increase growth and quality. Research by the late SUNY Cobleskill Professor Z. Jiang from Rhode Island found that Kentucky bluegrass varieties, such as Blacksburg, Conni, Dawn, Eclipse convert N more efficiently to top and root growth. In recent UConn research tall fescue as a species had higher NUE than Kentucky bluegrass. This was determined to be primarily related to increase rooting of tall fescue that absorbs greater volumes of soil N.—from Dr. Frank Rossi’s blog, shortCUTTS, quoting UConn Professor Karl Guillard