During the first full year of data collection (April 1998 to February 1999) at the floating green, leachate concentrations were observed to be low. The normal foliar applied fertilizer rate is 0.1 lb. N/1000ft2 as Nitro-K Plus II 24-0-24 (RSA MicroTech, Seattle, WA). Also, 0.3 and 0.6 lb. N/1000ft2 applications as Nitro-K Plus II 24-0-24 were made on August 5 and September 4, 1998, respectively. Nitrate nitrogen (NO3—N) ranged from 0.11 to 5.18 ppm, with the highest concentrations in early December 1998. Ammonium nitrogen (NH4+-N) levels were also low, ranging from 0.01 to 1.19 ppm. The 0.3 and 0.6 N/1000ft2 applications appeared to have little effect on the NO3—N and NH4+-N leachate concentrations. A 0.9 lb N/1000ft2 26-4-13 granular product was applied spring 1999 following core aerification. Leachate samples following the 0.9 lb N/1000ft2 26-4-13 application have not yet been analyzed.

During mid-season 1998 (June 15th to September 15th) nitrate concentrations never exceeded 3 ppm NO3-N, even after fertilizer treatments. Only during the winter and early spring, when turf growth is slow and environmental conditions favor mineralization, did leachate concentrations exceeded 3 ppm NO3-N. Throughout the first year of leachate collection, only 15 samples tested above 2.5 ppm NO3_N. Most of the samples over 2.5 ppm NO3-N occurred during the early spring 1998 or winter 1998-1999. The low leachate concentrations combined with the high leaf tissue (clippings) N (3.26 to 6.72%) suggests very efficient nitrogen uptake by the bentgrass plant.

Six microlysimeters were installed in mid-November 1998 and are currently being sampled once per month for comparison with the whole green leachate collection system. These microlysimeters were placed in sets of two at three different locations within the putting green soil profile. The locations included a low drainage area, a high plateau, and an intense traffic area. No samples were taken during the winter 1998-1999 to ensure the integrity of the ceramic microlysimeters. Microlysimiter sampling resumed in early March 1999 to measure nitrogen leachate caused by mineralization and early spring fertilization.

A new flow meter was installed spring 1999 by the golf course superintendent on the main irrigation line to the floating green. Daily readings will be taken from this flow meter and combined with precipitation data from the weather station to create a water balance for the entire putting green. The creation of the putting green water balance may lead to a better understanding and characterization of leaching in putting green rootzones and potentially provide information for computer modeling at a later date.

Proposed 1999 Research Schedule

July to Aug. 1999 - Site visits as needed. Data and sample collection and analysis.

Sept. to Nov. 1999 - Site visits as needed. Sample collection and analysis. Data analysis and summarized for the year. Research presentation at Northwest Turfgrass Conference annual meeting at The Resort at the Mountain, OR. November 1999 progress report to USGA.

Leachate samples collect last year will possibly be analyzed for PCNB.

Summary of Research to Date

1. Daily nitrate N ranged from 0.1 to 5.2 ppm, ammonium N ranged from 0.01 to 1.2 ppm.
2. Clipping dry weight ranged from 140 to 3481 g/day.
3. Clipping N ranged from 3.3 to 6.7%.
4. Light (0.1 lb. N/1000ft2), frequent (7 to 10 days) fertilizer applications resulted in low N leachate concentrations.
5. Uptake by the bentgrass plant appears to be highly efficient.
6. Clipping N ranged from 3.3 to 6.7%.

Recent Publications and Presentations

1. Johnston, W. 1998. Characterization of leaching at the Coeur d'Alene Golf Course floating green. Golf Course Management 67(2)74.
2. Johnston, W. J., C. M. Kleene, C. T. Golob, W. L. Pan, J. Anderson, and E. D. Miltner. 1998. Characterization of leaching at the Coeur d'Alene Golf Course floating green. Turfgrass Management in the Pacific Northwest 2(1):34.
3. Johnston, W. J., C. M. Kleene, W. L. Pan, and E. D. Miltner. 1998. Characterization of leaching at the Coeur d'Alene Golf Course floating green. Turf Line News 149:16-17.
4. Kleene, C. M., W. J. Johnston, W. L. Pan, C. T. Golob, E. Miltner, J. Anderson, and M. Moneymaker. 1999. Characterization of nitrate leaching on the floating green at the Coeur d'Alene Resort Golf Course. GCSAA Conf. Orlando, FL. (poster).
5. Kleene, C. M., W. J. Johnston, E. D. Miltner, W. L. Pan, and C. T. Golob. 1999. Characterization of nitrate leaching at the Coeur d'Alene Resort Golf Course. USGA May site visit. Puyallup, WA, May 1999. (presentation).
6. Johnston, W. J. 1999. The floating green research project and its impact on all sand grown turf. Western Canada Turfgrass Association Research Field Day, Pitt Meadows, BC, on July 14, 1999.

This is the presentation that Dr. Bill Johnston gave at the WCTA Annual Field Day at Swan e Set Bay Resort Golf Club, Pitt Meadows, BC, on July 14, 1999. The "Characterization of Leaching at the Coeur d'Alene Resort Golf Course Floating Green" is the project the W.J. Johnston, C.M. Kleene, W. L. Pan, and E. D. Miltner of Washington State University are doing on the Coeur d'Alene Golf Course floating green in Coeur d'Alene, ID. The project is cooperatively funded by the WCTA, USGA Green Section, Northwest Turfgrass Association, and the Superintendent association from Oregon, Western Washington and the Inland Empire.

Turf Line News October/November 1999