Golf Course Management

JAN 2018

Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.

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122 GOLF COURSE MANAGEMENT 01.18 factorial combination of treatments. The en- tire study was maintained at a 1-inch (2.5-cm) mowing height because "it conforms to the general practice used on golf course fairways." For the next three years, the relative percentage of turfgrass species in each plot was counted. The first finding was that the relative per - centage of bentgrass or Kentucky bluegrass that was seeded had no effect on species com - position over time. That is, seeding bentgrass at 5% of the mixture did not affect species com - position change any differently than seeding the bentgrass at 20% of the mix. Additionally, acidity and soil phosphorus levels had little ef - fect on species composition, except in the es- tablishment year, when the Kentucky bluegrass used the higher levels of phosphorus to estab - lish at a greater percentage. After that establish- ment year, however, the same effect occurred over the range of soil phosphorus and soil pH found in the experiment — that is, the percent - age of the turfgrass that was Kentucky blue- grass declined steadily over the three years of measurement. The steady decline in Kentucky bluegrass occurred regardless of soil pH, the percentage of Kentucky bluegrass in the seed mixture, or the amount of applied phosphorus. It appeared that the selected bentgrasses used in this study (and one was browntop, which is aggressive) were simply able to outcompete the Kentucky bluegrass across a wide range of soil pH and phosphorus conditions. Under these 1938-type fairway conditions, the bentgrass was able to outgrow the Kentucky bluegrass, and it did this over the range of different acidi - ties and soil phosphorus conditions created in the experiment. Source: Musser, H.B. 1948. Effects of soil acidity and available phosphorus on popula - tion changes in mixed Kentucky bluegrass- bent turf. Journal of t e American Society of Agronomy 40:614-620. Beth Guertal, Ph.D., is a professor in the Department of Crop, Soil and Environmental Sciences at Auburn University in Auburn, Ala., and the president-elect of the Crop Science Society of America. She is a 20-year member of GCSAA. Beth Guertal, Ph.D. Twitter: @AUTurfFert Yep, we did that before (verdure) Several of the journals where turfgrass sci- entists publish their research are well over 100 years old. That includes Agronomy Journal, with Volume 1, Issue 1 covering agronomic topics published from 1907 to 1909. Turf - grass research (other than forage work) did not start to appear in these journals until the late 1930s, when explorations into the production of turfgrass for golf courses and lawns first ap - peared in what was then called the Journal of t e American Society of Agronomy. In 1948, the great turfgrass pioneer H.B. Musser published a research paper titled "Effects of soil acidity and available phosphorus (P) on population changes in mixed Kentucky bluegrass-bent turf." And that's a topical horse we beat to this day. Following up some research from the 1930s that had been published in the USGA Green Section, Musser wanted to examine how populations of Kentucky bluegrass and bent - grass changed because of their differing toler- ances to soil pH and fertility. So, in 1938, he modified a research area in State College, Pa., with sand and peat moss to "ensure a good physical condition." The area was halved, with one half treated with sulfur to lower soil pH, and the other treated with lime (CaCO 3 ) to increase soil pH. This resulted in respec - tive soil pH of 5.0 and 6.6 at the time of seed- ing. These blocks were further split into phos- phorus rates of 0, 2 or 12 pounds P 2 O 5 /1,000 square feet (0, 9.8 or 58.6 grams P 2 O 5 /square meter), with organic nitrogen (activated sew - age sludge) or inorganic nitrogen (nitrate of soda, pretty much our only inorganic nitrogen fertilizer at this time) applied at 3 pounds ni - trogen/1,000 square feet (14.7 grams /square meter) and potassium (as KCl) at 3 pounds K 2 O/1,000 square feet. In the fall of 1938, the blocks were seeded with mixtures of Kentucky bluegrass, creep - ing bentgrass and browntop (Agrostis tenuis). Equal percentages of the two bentgrasses com - bined to make up 5%, 10%, 15% or 20% of the mixture, and the rest was Kentucky blue - grass. In a statistical sense, the study was a 2 (levels of soil pH) × 5 (levels of fertilizer phos - phorus) × 4 (different percent seed blends) After that establishment year, the percentage of Kentucky bluegrass declined steadily over the three years of measurement.

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