BEST MANAGEMENT PRACTICES application under hot , humid , and / or windy conditions . After application , watering with 0.25 ” irrigation water reduces volatilization potential .
Ammonium converted from urea or applied as a fertilizer converts to nitrate within a few hours / days . The nitrate is prone to leaching below the rootzone with high precipitation and irrigation rates , particularly in sandbased soils . Nitrate is further lost to the environment due to emissions of nitrification / denitrification gases ( e . g ., nitrous oxide ), especially with prolonged soil saturation . Thus , proper irrigation and drainage can help minimize losses of nitrate . Use of fertilizers that are not “ quick release ” and become available over time can result in increasing nitrogen uptake and reducing losses . These fertilizers can effectively “ spoon feed ” plants by releasing or converting nitrogen in a steady manner rather than a flood of it entering the soil solution . These nitrogen sources can reduce losses to the environment , decrease foliar burn potential , and reduce labor with fewer required applications . Although complex , understanding these sources of nitrogen fertilizers can be simplified by separating into two types :
Slow / controlled release – Nitrogen is released slowly or , in some cases , engineered to release in a controlled rate . For example , long-chain molecules containing nitrogen ( e . g ., methylene urea and urea formaldehyde ) are broken down through microbial degradation — eventually resulting in ammonium and nitrate as breakdown products . Another example are the coated fertilizers , such as polymer-coated urea . Composted animal and plant biosolids and similar sources are included in this category as well .
Stabilized – Inhibitors are added to water-soluble nitrogen products and slow down the nitrogen cycle to decrease the chance of loss and increase the window of when the plant available forms of nitrogen ( ammonium and nitrate ) are available for uptake . Inhibitors include : o Urease inhibitors – The conversion of urea to ammonium is slowed as the enzyme that catalyzes this reaction is temporarily inhibited .
o Nitrification inhibitors – The conversion of ammonium to nitrate is slowed as microbes responsible for this conversion are temporarily inhibited in their activity .
While these enhanced-efficiency fertilizers are generally more expensive on a cost per pound of nitrogen basis as compared with quick-release materials , their benefits include increased efficiency ( lower rates can be applied ), reduced costs ( fewer applications ; reduced mowing needs ; reduced clippings ), reduced risk for nitrogen-related diseases , and reduced environmental impacts . Often , a blend including 30-50 % of these sources along with quickrelease nitrogen is affordable and effective .
Proper nutrition is imperative as plants are preparing for dormancy late in the season . Therefore , nitrogen fertilization is often necessary . As always , any local regulations should be followed when applying fertilizers late in the year . It is also noteworthy that some irrigation waters , especially waste waters , can be high in nitrogen and should be tested and accounted for to avoid excessive nitrogen applications .
PHOSPHORUS As with nitrogen , phosphorus deficiencies or excesses are detrimental to plants , and excesses are harmful to the environment . Phosphorus plays important roles sportsfieldmanagementonline . com January 2023 | SportsField Management
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