In descending order, by date published.
Recommended nutrient additions, based on a soil test, are only made when a crop yield or economic response has been measured for that crop under Kentucky soil-climatic conditions. Many field studies have been conducted by the Kentucky Agricultural Experiment Station under Kentucky farm conditions to determine the extent of any primary, secondary, or micronutrient needs. Yield and soil test data from these studies serve as guidelines for establishing recommendations contained in this publication. Recommendations in this publication strive to supply the plant nutrients needed to achieve maximum economic return assuming good management practices.
Nitrogen (N) fertilizer is required by turfgrass in larger quantities than any other mineral nutrient because the plant demand for N is high and the supply of N from the natural environment is normally low. In instances where N is not applied according to the University of Kentucky recommendations, applied N can increase the risk of surface and ground water contamination. The objective of this document is to describe the function of N in turfgrass, explain how soil and tissue tests can be used to manage N applications, and to describe the various N fertilizer sources available for application to turfgrass.
Iron (Fe) is commonly applied using granular or foliar sources to enhance turfgrass color. Iron applications can result in darker green turfgrass as a result of increased Fe uptake or Fe oxidation on the leaf surface. In many cases, Fe results in no turfgrass response at all. Understanding the dynamics of Fe both in the plant and in the soil can enhance your nutrient management programs. The objective of this publication is to explain the function of Fe within the plant, describe the Fe sources available for turfgrasses, and identify which Fe fertilizers are most effective.
Calcium (Ca) is the dominant cation in all soils of agronomic importance and Kentucky soils are no different. Kentucky soils are naturally high in Ca. Consequently, Ca deficiency in Kentucky turfgrasses is extremely rare, and the probability of observing a Ca response on golf courses, home lawns, sod production, or sports fields is very low. Applying Ca fertilizers to artificially increase soil Ca above the level necessary for proper plant growth normally does not result in an increase in plant uptake because Ca uptake is genetically controlled. Regardless, Ca is commonly applied in both granular and liquid forms.
Magnesium is an essential element for all plants. Soluble magnesium (Mg) exists in soils primarily as Mg2+, a positively charged divalent cation. Kentucky soils are naturally high in Mg and, thus, Mg applications to turfgrass are normally unnecessary. However, turfgrasses grown in sand-based rootzones, such as golf course putting greens and sand-based sports fields, are prone to Mg deficiency. When Mg is necessary, it is essential to understand the function of Mg in the plant, the dynamics of Mg in the soil, and the forms of Mg fertilizers.
Phosphorus (P) is an essential plant nutrient and a common component of many turfgrass nutrition programs. Although P application can improve turfgrass quality in some soils, most soils of Kentucky already have adequate plant-available P to support healthy turfgrass growth. What is the function of P within the plant, and how much P is required to sustain acceptable turfgrass in Kentucky? Also, if P applications are necessary, when and how should P be applied?
Soil acidity is one of the most important soil factors affecting crop growth and ultimately, yield and profitability. It is determined by measuring the soil pH, which is a measure of the amount of hydrogen ions in the soil solution. As soil acidity increases, the soil pH decreases. Soils tend to be naturally acidic in areas where rainfall is sufficient to cause substantial leaching of basic ions (such as calcium and magnesium), which are replaced by hydrogen ions. Most soils in Kentucky are naturally acidic because of our abundant rainfall.
Authors: Gregg Munshaw
Lawns require fertilizer to remain healthy. Proper fertilization practices will lead to a thick, dark green, uniform lawn that is competitive against weed and disease invasions. The nutrients contained in fertilizers are necessary to support many processes occurring within the plants. If any essential nutrient is limiting, the plants will not perform at their highest level.
Most homeowners desire an aesthetically pleasing landscape and will take steps to ensure success. Proper fertilizing, watering, and pest control are all steps that will lead to a quality lawn. However, some confusion surrounds when and why lime should be applied to a lawn. Many homeowners believe that lime needs to be applied on an annual basis for a quality lawn. The purpose of this publication is to explain why lime is needed and whether it is required on your lawn.
Soybean grows best on fertile soils. For decades, the University of Kentucky has conducted field studies to establish the relationship between soil nutrient supplies and soybean yield. Adequate soil fertility must be present so that yields are not limited.
Authors: Gregg Munshaw
How much fertilizer should you use on your lawn? Too much can result in turf burn, wasted product and money, and potential environmental concerns. Too little will result in a low-density lawn that will not be attractive or competitive against weed invasions. To insure that you apply the proper amount of fertilizer to your lawn, you must calibrate your fertilizer spreader. You should calibrate your spreader each time you use a new (different) fertilizer because not all fertilizers have the same particle size or density. The information on the fertilizer bag is a good starting point for the calibration process but remember that spreaders can differ significantly. Calibrating your spreader will take a little bit of work, but the series of fairly simple steps below will help you complete the task.
Alfalfa is a high quality, valuable forage crop that can be successfully produced on most well-drained soils in Kentucky for hay, silage, and grazing. Fertilizing alfalfa can be uniquely challenging because it is a high-yielding crop that removes a tremendous amount of soil nutrients when compared to other crops grown in Kentucky. A thorough understanding of alfalfa's growth habits, nutrient requirements, and soil nutrient supply mechanisms is necessary to effectively manage fertilizer inputs and maximize profitability while minimizing environmental impact.
Soil is a mixture of weathered rock fragments and organic matter at the earth's surface. It is biologically active--a home to countless microorganisms, invertebrates, and plant roots. Soil provides nutrients, water, and physical support for plants as well as air for plant roots. Soil organisms are nature's primary recyclers, turning dead cells and tissue into nutrients, energy, carbon dioxide, and water to fuel new life.
The soaring cost of fossil fuels is an indicator that nitrogen fertilizer prices are going to remain high for the foreseeable future. With higher N prices, many producers are trying to evaluate the usefulness of several N additive products in their production systems. High N prices make these products more attractive because it takes fewer pounds of saved N to offset the price of the additive. Producers should have a good understanding of how these products work in order to make informed decisions regarding their use.
Authors: Greg Schwab
There are a lot of misunderstandings regarding sulfur (S) nutrition for Kentucky crops. Sulfur is considered a seconda r y pla nt nutrient because, although the crop requirement for S is relatively large, it is usually found in soil at concentrations adequate for plant growth and yield so that no fertilizer S is needed. For many years, soil S was maintained by atmospheric deposition. However, more stringent clean air standards require greater removal of S during burning of fossil fuels. That fact, along with increasing crop yields, has caused many Kentucky grain producers to begin to question if S fertilization will increase yield.
The most important part of making fertilizer recommendations is collecting a good, representative soil sample. Soil test results and fertilizer recommendations are based solely on the few ounces of soil submitted to the laboratory for analysis. These few ounces can represent several million pounds of soil in the field. If this sample does not reflect actual soil conditions, the results can be misleading and lead to costly over- or under-fertilization. It is necessary to make sure that the soil sample sent to the laboratory accurately represents the area sampled.
9/1/1996 (minor revision)
Authors: Ken Wells
Authors: Monroe Rasnake
Authors: Lloyd Murdock