Slow Release Nitrogen Fertilizer Demonstration Trials
Summary: The turfgrass response to the fertilizers was variable and strongly influenced by time of application and condition of the turfgrass at each golf course. None of the products demonstrated improved color at 10 or 12 weeks after treatment (WAT). Only 23-5-10 applied at 1.5 or 2.5 lbs N/1000 sq ft demonstrated color improvement at 6 or 8 WAT and only at the Arrowhead location. The initiation of the trial at Virginia Country Club on April 5th was too early and bermudagrass had not fully begun to grow. Future trials should be scheduled to begin no earlier than the middle of May or later in the summer to ensure that the bermudagrass has fully transitioned and is healthy. The early trial initiation date and cool spring confounded trial ratings. Recommendations are provided to help avoid these problems in the future.
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Principal Investigator: Larry Stowell
Cooperators: Raymond Davies, Virginia Country Club, John Martinez, Arrowhead Country Club, and Greg Swanson, San Luis Rey Down Golf Course
Sponsor: J. R. Simplot
Root zone sand survey
Summary: The objective this study was to determine the range of soil particle sizes found in golf course greens from Southern California and to gain a greater understanding of the nature of Southern California root zone sands.
A particle size distribution measure (PS) was developed to help characterize root zone sands. The PS value provides a single number that describes the range of particle sizes that comprise the root zone sand. A large PS (>1.2) indicates a higher composition of medium sand particles that is desirable. A small PS (<0.6) indicates a higher composition of smaller particles that is undesirable. The PS value was found to be significantly correlated with a number of other soil factors including organic matter content, percolation rate, bulk density, phosphorus, calcium, magnesium, potassium sodium, boron, iron, copper and interestingly, the age of the green. All of the significant correlations with the chemical composition and age of the soil were negative. A negative correlation means a large PS value sand will hold lower levels of nutrients. This relationship is expected and it is well known that higher sand content soils hold less nutrients than finer textured soils. The relationship between PS and age of the greens suggests that the greens are constructed using high sand content materials but the root zone degrades into lower quality finer soils after years of use and management. The reduction in PS may result from decomposition of the materials or addition of fine particles during management or from contaminants in irrigation water.
Based upon these results, some preliminary values have been identified to help understand the aging of greens in Southern California. For example, the correlations suggest that the initial percolation rate of materials used to construct Southern California greens is about 20 inches per hour. The initial PS value for new greens is about 1.6. Several other critical age points were also estimated using the PS model. For example, accelerated percolation rates, greater than 12 inches per hour, are desired in the intensively irrigated Southern California region. Based upon the PS and age relationship, a green may drop from the initial 20 inches per hour to 12 inches per hour in about 13 years. The critical low limit of 6 inches per hour percolation rate minimum for a USGA specification green will be reached in 23 years and an unacceptable percolation rate of 2 inches per hour will be attained in 30 years. These values suggest that after about 13 years of use, the root zone sand will no longer percolate adequately to satisfy the needs of golf play in Southern California.
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Principal investigator: Larry Stowell, Ph.D.
Cooperators: Raymond Davies, Virginia Country Club Jim Duffin, Los Amigos Golf Course John Martinez, Arrowhead Country Club Daniel McIntyre, Antelope Valley Country Club Don Parsons, Old Ranch Country Club Mark Phillips, Laguna Hills Country Club Steve Sinclair, Woodland Hills Country Club Reed Yenny Mesa Verde Country Club David Zahrte, Santa Ana Country Club
Sponsors: Above superintendents and PACE Consulting
Runoff water monitoring at Dove Canyon Country Club
Summary: Irrigation water and runoff water was monitored for three years at Dove Canyon Country Club to evaluate the impact of the golf course on down-stream water quality. When compared to the reclaimed irrigation water used throughout the development and the golf course, the runoff water was significantly lower in nitrates, total phosphorus, and total organic halogens. Oil and grease, total organic carbon, pH, and electrical conductivity of the runoff water were significantly higher than the irrigation water. There was no significant difference in the concentration of ammonia, nitrites, total Kjeldahl nitrogen in the irrigation and runoff waters. These results support the value of turfgrasses in capturing nitrogen and phosphorus, two key nutrients that can lead to eutrophication of waterways. The origin of the oil and grease, organic carbon, elevated pH and inceased salinity may be the golf course or the surrounding community that also drains into the same streams.
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Principal Investigator: Larry Stowell, Ph.D.
Cooperator: Eric Lover, Dove Canyon Country Club
Sponsor: Dove Canyon Country Club
