SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/183915
analysis on the back of the bag to determine the source of the N, and how much of it is soluble and/or slow-release. Urea to which nitrification inhibitors and/or ammonia volatilization inhibitors have been added. The majority of nitrogen must be taken up by the plant as nitrate-N or ammonium-N. Soluble N sources already have the N in that form, and slow-release sources either have that N "trickle" out via a physical barrier that degrades over time, or by being released from a chemical formula via hydrolysis or microbial breakdown. Sometimes, however, the plant available forms (nitrate or ammonium) can be converted into other N forms that are less desirable for the plant or surrounding environment. In one case, ammoniumN gets converted to nitrate-N by the microbial process called nitrification. The nitrate-N is still plant available, but because it is an anion it can be prone to leaching from the plant's rootzone. In the second case, another loss path is when N is lost as ammonia gas, out of the plant canopy to the atmosphere (this is volatilization, which is caused by the urease enzyme). To slow down these processes of nitrification and volatilization inhibitors are added to the urea fertilizer. There is a separate nitrification inhibitor and urease inhibitor, but some fertilizers may contain both. Additionally, there are several different nitrification inhibitors on the market and thus you should carefully read the label to see what your fertilizer may contain. The most common nitrification inhibitor in turfgrass fertilizers is dicyandiamide (DCD), www.stma.org while the most common urease inhibitor is N-(n-butyl) thiophosphoric triamide, (NBPT). Use of a fertilizer with a nitrification inhibitor may help to limit N leaching, and use of a fertilizer with a urease inhibitor may help reduce N loss to the atmosphere. So, those are six basic groups of N fertilizers. Things get more complicated when other nutrients are added and blends are created. With variations in nutrient ratios, coating types, type and proportion of slow-release N and other characteristics, you can see how the number of possible (and actual) products can become so large. So how do you pull all this information into a coherent plan for selecting a fertilizer? First, think about what you want your N to do. Do you need to heal worn spots and grow turf? In that case, use a soluble and readily available source to promote growth. Or, do you simply need a background green color with minimal growth? A long-chain MU or polymer coat with a long release pattern might work well. Do you have an environmentally sensitive area, one with a high sand content, in an area with intense rainfall? Consider adding slow-release or materials with inhibitors to protect the environment. Last, calculate your cost per pound of nutrient. Comparing N sources on a price per pound basis removes the percent N content from the equation, helping you make a cost effective decision. n Dr. Elizabeth Guertal is a professor of turfgrass management at Auburn University in Alabama. SportsTurf 11