Golf Course Management

MAY 2019

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

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72 GOLF COURSE MANAGEMENT 05.19 mixed fertilizers is always an issue in fertilizer studies. In this case, the extra applied nutrients were not adjusted to uniformity across the vari - ous treatments and were simply applied as sup- plied in the various fertilizers. Even with these different rates of P and K addition, there were no increasing or decreasing trends in soil P or K over the length of the study, even in the treat - ments that consistently supplied P or K. e quality of turfgrass growing in the na - tive soil was almost always better than that of bentgrass growing in the USGA-type greens mix. e fertilizer treatments affected turfgrass quality in every year of the three-year study. However, there were some turf quality dif - ferences between the treatments from year to year. In the first year, quality was consistently highest in bentgrass to which granular urea had been applied. As the summer progressed, plots that received methylene urea, the foliar/gran - ular mix, or the higher rate of foliar fertilizer, also had similarly high quality. As the second and third years of the study were completed, bentgrass that received the twice-monthly ap - plications of the foliar/granular combination or the high rate of foliar fertilizer consistently had higher quality than that observed in bent - grass that received monthly applications of urea, methylene urea or organic fertilizer. So, for highest turfgrass quality, the key was apply - ing a higher rate of foliar fertilizer or a foliar/ granular application every two weeks, rather than monthly applications of granular prod - ucts. And the lower rate of the foliar product, which was also applied twice monthly? Well, even though it did not produce turf of the highest quality, it did produce bentgrass of ac - ceptable quality and was thus considered a suc- cessful treatment. Source: Xiao, M., K.W. Frank and T.A. Niko - lai. 2018. Foliar and granular effects on creep- ing bentgrass and soil nutrient levels. Crop, Forage and Turfgrass Management 4:170539 doi:10.2134/cftm2017.05.0039 Beth Guertal, Ph.D., is a professor in the Department of Crop, Soil and Environmental Sciences at Auburn University in Auburn, Ala., and 2019 president of the Crop Science Society of America. She is a 20-year member of GCSAA. Beth Guertal, Ph.D. guertea@auburn.edu Twitter: @AUTurfFert It's all in the delivery (verdure) Turfgrass fertilization sometimes seems to have devolved into two camps: the foliar folks and the granular gang. So, it's always nice when you find a research paper that examines those two methods for nutrient delivery. Re - cently, turfgrass researchers at Michigan State University used Penn A-4 creeping bentgrass putting greens to examine various combina - tions of granular and foliar fertilizers, and to determine their effects on turfgrass quality and soil nutrient status. e six fertilizer treatments were: 1) gran - ular organic fertilizer (soy protein and blood meal) (10N-2P-4K); 2) granular methylene urea (40N-0P-0K); 3) granular urea (46N-0P- 0K); 4) foliar nitrogen (N) (18N-3P-4K) ap - plied at 8 ounces product/1,000 square feet (2.5 milliliters/square meter), the recommended la - beled rate for the product; 5) the same foliar N product applied at 16 ounces/1,000 square feet (5.0 milliliters/square meter); and 6) a granu - lar and foliar fertilizer combination. All the granular products were applied at 0.5 pound N/1,000 square feet (2.4 grams/square meter) (per month, May–October) to supply a total of 3 pounds N/1,000 square feet (14.7 grams/ square meter) per year. e foliar products were applied twice weekly, applying 0.125 or 0.25 pound N/1,000 square feet per application (0.6 or 1.2 grams/square meter) to supply a total of 1.5 and 3 pounds N/1,000 square feet (7.4 and 14.7 grams/square meter) per year for the low and high rates, respectively. Finally, the foliar/ granular combination treatment had a total of 3 pounds N/1,000 square feet per year ap - plied, with half that N applied as split monthly granular treatments, and the remaining 1.5 pounds N divided as twice-monthly foliar ap - plications (at 0.125 pound N/1,000 square feet per application). So, with the exception of the lowest rate of the foliar-only treatment (which received only 1.5 pounds N/1,000 square feet/ year), all of the other treatments received 3 pounds N per year. Last, there was an unfer - tilized control treatment. All of this was done on two different putting green mixes: a native sandy clay loam root zone and a USGA-type root-zone mix. All of these various treatments also applied different rates of phosphorus (P) and potassium (K). Confounding nutrient application with The quality of turfgrass growing in the native soil was almost always better than that of bentgrass growing in the USGA-type greens mix.

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