SportsTurf

FIELD SCIENCE 12 SportsTurf | February 2016 www.sportsturfonline.com T urfgrass fertility management is a year round task, so a review of fertilizer basics may be helpful. Generally, fertilizer is defined as any substance containing one or more recognized plant nutrients that promote plant growth. Checking with the Department of Agriculture in a number of states results in a mixed bag of definitions. Many states include any substance that controls soil acid- ity or alkalinity, provides other soil enrichments or provides other correc- tive measures to the soil in the fertilizer definition. Most states exclude unma- nipulated animal or vegetable manure and some states exclude marl, lime, limestone, wood ashes, peat and/or compost that has not been shown to have value in promoting plant growth. There can be confusion over the terms natural organic, synthetic organic and organic fertilizer. Natural organicrefers to products that are derived from either plant or animal products containing one or more elements, other than carbon, hydro- gen and oxygen, which contribute to plant growth. These products are derived from living organisms and may include dried blood, composted manure, fish bi-products, bone meal and cottonseed meal. Synthetic organicrefers to prod- ucts that are manufactured chemically from elements or other chemicals. Synthetics go through some sort of manufacturing process, although they may come from naturally occurring mineral deposits. Synthetic products may also be referred to as inorganic fertilizer. Organic fertilizer, in the strict sense of definition, refers to a product containing carbon and one or more elements needed for plant growth, other than hydrogen and oxygen. Organic includes both natural and synthetic products. Hence the confu- sion, as most who desire an organic fertilizer really want a natural organic or non-manufactured product. This article will focus on synthetic products. Important considerations are the expectation on product release rate (how quickly turf greens up), prod- uct duration (how long the product produces a greening effect), and envi- ronmental impact (product leaching or volatilization). Nitrogen is the most critical nutrient source that promotes turf growth, so turf performance depends on the nitrogen source in the product. In general, there are three nitro- gen release sources: fast release, slow release and controlled release. That being said, there are many envi- ronmental and cultural factors that critically affect the ability of turf to uptake nutrients and produce accept- able turf quality. These factors must be evaluated, monitored and cor- rected, if necessary, before creating a fertilization plan. Soil tests are the basis for developing a fertilization plan and provide information on what the soil needs or does not need to pro- vide for turf nutrient requirements. Additionally, tissue testing can reveal whether the turf is effectively taking up the nutrients. Fast release sources are referred to as soluble due to their high solubility in water. Fast release nitrogen sources release nitrogen very quickly and may have a quick greening response that lasts just a few weeks. Multiple applica- tions are usually necessary to maintain turfgrass quality. Nitrogen deficiency symptoms may occur between appli- cations due to the cycling between high and low nitrogen levels. Fast release sources may promote excessive shoot growth and readily volatilize or leach. Common examples include urea, ammonium sulfate, ammonium nitrate and calcium nitrate. Slow release and controlled release sources provide nitrogen gradually over time and promote more consis- FERTILIZERS 101: BASICS YOU SHOULD KNOW ■ BY SUSAN HADDOCK

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