Turf

Polymer Coated Urea as Compared to Uncoated Urea fertilizers at excessive rates because of the mentality of "if some is good then more must be better." Over 90 percent of the soil samples identified as coming from turfgrass sites that are submitted to the BYU Environmental Analytical Laboratory contain available phosphorus concentrations that are in the high to excessive range— meaning that no phosphorus fertilizer is needed and that no negative impact on the turf growth will occur if not applied for several years. In fact, excessive phosphorus can create imbalances with other nutrients and favor certain weeds, such as annual bluegrass. To continue applying phosphorus when unnecessary is wasteful of resources and simply results in more water pollution that drives the desire for society to ban it all together. However, some sites still need phosphorus application to create a fertile soil conducive for plant health and banning fertilizer use altogether is nonsensical in light of the fact that there are tools available to govern its use (i.e. soil testing). Banning fertilizer use in these soils would be detrimental and eventually most soils would become depleted with plants suffering from nutrient deficiency. In most cases, we recommend soil testing for phosphorus and other nutrients every 3-5 years and then following appropriate fertilizer recommendations that are based on scientific research. In the case of nitrogen, soil testing is not the best answer. This is because Figure 2. Same results in turfgrass with half as much fertilizer when using polymer coated urea (tan fertilizer on left) compared to uncoated urea (white fertilizer on right). 100% 75% 50% 25% 0% verdure (greeness) mowing height nitrogen used Figure 1. Half as much nitrogen (2 pounds per 1000 feet2) results in near equal verdure and slightly less mowing for polymer coated urea than uncoated urea applied monthly. the nitrogen not used by plants is easily leached to groundwater or lost to the atmosphere. Therefore, nitrogen needs to be applied regularly but judiciously. New fertilizer technology allows nitrogen to be applied at lower rates than have been used in the past because more of it is taken up by the plant and very little is lost to the atmosphere. For example, a polymer coated urea (Duration, Agrium Inc., Loveland, Colo.) results in a controlled release of nitrogen steadily over the growing season to "spoon feed" the plants, which effectively take up the nitrogen as it becomes available, avoiding flushes of nitrogen in excess of plant needs. The results of recent research at BYU show that this fertilizer can be applied at half the normal recommended rate with- out reduction in greenness (see Figures 1 and 2). In addition, frequency and cost of mowing are slightly reduced and growth is more consistent (no flushes of growth); and losses to groundwater and to the atmosphere are virtually eliminated. High-quality, control-release fertilizers, such as Duration, only have to be applied once or twice during the year, which also reduces costs associated with the labor of application. We propose that all turfgrass managers be good environmental stewards so fertilizer bans are not initiated and that the data collected be used to educate communities pursuing fertilizer bans. Using the correct rate of fertilizer and the right product is the solution—not banning the use of essential nutrients. The real solution to nutrient pollution is responsibility and education. WT Bryan G. Hopkins, associate professor in the plant and wildlife sciences department at Brigham Young University in Provo, Utah, authored this article with research assistants Samuel A. Randall, Tiffany M. Rae, Curtis J. Ransom and Lloyd E. Sutton. Winter 2013 21

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