Using soil content of plant-available nitrogen as a tool for diagnosing turfgrass damage. (4530)
Authors:
W.D. Gelernter* - PACE Turfgrass Research Inst., San Diego, CA L.J. Stowell - PACE Turfgrass Research Inst., San Diego, CA
Abstract:
Excessive levels of nitrate and ammonium in the soil can result in significant
damage to turfgrass roots and foliage that can resemble damage due to turf diseases.
Use of high-nitrogen content recycled water, anaerobic conditions in the soil, high soil organic matter, and over-fertilization are some of the culprits in cases of nitrogen toxicity. To develop guidelines for soil nitrogen levels, soil samples from golf courses around the U.S. were evaluated by Brookside Laboratories, New Knoxville OH using a 1M KCl extraction and a Lachat Quick Chem 8000 flow injection analyzer. Good performing greens (N=534) had mean nitrogen values of 3.24 ppm (standard error [SE] = 0.15) from ammonium; 5.88 ppm (SE = 0.26) from nitrate and 9.12 ppm (SE = 0.34) total plant available nitrogen (TPAN). Good performing tees (N= 68) had mean nitrogen values of 3.74 ppm (SE = 0.36) from ammonium; 7.05 ppm (SE = 1.08) from nitrate and 10.80 ppm (SE = 1.17) TPAN.
Good performing fairways (N= 220) had mean nitrogen values of 5.00 ppm (SE = 0.28) from ammonium; 18.61 ppm (SE = 1.57) from nitrate and 23.61 ppm (SE = 1.73) TPAN. From this survey and from data on laboratory and field diagnostic samples, we have determined that turf damage is most likely when TPAN levels in the soil exceed 20 ppm and/or when ammonium levels exceed 7 ppm. TPAN levels below 3 ppm can also result in poor turf performance.
Speaker Information: Wendy Gelernter, PACE Turfgrass Research Inst., San Diego, CA, 1267 Diamond St., San Diego, CA 92109; Phone: 858-272-9897; E-mail:
Session Information: Thursday, November 4, 2004, 7:55 AM-10:35 AM Presentation Start: 8:45 AM
Keywords: turfgrass; nitrogen; ammonium; nitrogen toxicity