1. Fertilizer Concerns
  2. N Fertilizer
  3. P Fertilizer
  4. K Fertilizer
  5. Other Fertilizers
    1. Factors to consider when applying fertilizers:
      1. Crop to be grown

        1. economic value

        2. Nutrient removal of crop

        3. Absorbing ability of the plant


      2. Chemical condition of soil in respect to:

        1. total nutrients

        2. available nutrients

      3. Physical state of soil, especially

        1. moisture content

        2. aeration

        3. pH

      4. Other principles that are important:

        1. The most limiting nutrient will restrict the growth of the plant. This is the same idea as the weakest link in a chain, the shortest stay in a barrel etc....

        2. At some point the addition of fertilizer will no longer cause large increases in growth.

        3. This may also be determined for each fertilizer by fertilizer response curves.

        4. The main idea here is that maximum profit is obtained at less than maximum yield.

        5. Soil testing helps determine economical rates of application.

        6. This testing helps determine the point at which yield will be controlled by factors other than just nutrient supply. This may be growing days, water supply, bulk density of soil etc...

        7. These ideas are discussed to show that moderate rates of fertilization should be used unless the amount needed for maximum profit is known and that that profit will be great.

        8. The biggest problem is that maximum profit rates are not known for all soil types and different crops, therefore the soil test reports give nutrients levels for economical yields.

    2. Nitrogen sources for fertilizers

      1. NH4+ and N03- forms of N are both plant available.

        1. The N03- form is the meet easily taken up by the plant.
        2. Microorganism convert NH4+ to N03-: nitrification.

      2. 2 crops are specific for the form of N that is applied.
        One of the crops is very important here in N.C.

        Flue-cure tobacco
        This plant cannot tolerate high NH4+ levels in either the soil or fertilizers.
        Because the soil conditions for plant growth in tobacco do not lead to a good environment for microorganisms, N03- is the best form of N to apply.

      3. Cool season crops

        If it is possible, it is wise to use fertilizers high in N03-.

        1. Nitrification is reduced in cooler weather because the soil microorganisms are not as effect.

        2. the plant uses N as No3- in the plant so if NH4+ is applied it will be converted to N03- in the plant. This is an energy using reaction and will use some of the plants carbohydrate reserve.


      4. Lawn and Turf grasses

        Slow release nitrogen fertilizers are preferred. This cuts down on fertilizer burn and allows the effects of the fertilizer to last over a longer period of time.

      5. Acid forming Fertilizers

        Nitrogen fertilizer may be adverting as non-acid forming. This means that they do not contain NH4+ (ammonium) or that limestone has been added to neutralize the H released during Nitrification.

        acid forming fertilizers are not a problem as long as the soil manager soil tests regularly. The acidity released by these fertilizers may be corrected for with liming. m is may be cheaper than buying no-acid fertilizer.

    3. Sources of N Fertilizer

      • Anhydrous ammonia (NH3): formed by reacting atmospheric N with a source of H ( usually natural gas). This NH3 is 82.5% N.

        • This may be applied directly to the soil or may be used as a base for other N fertilizers.

  6. 4. Phosphate Fertilizers

    • Rock phosphate is finely ground apatite and contains 1-2% P.This may only be used on acid soils and soils with large amounts of organic matter.

    • Ordinary Superphoaphate : 17 to 20% P205. 0-20-0 is one of the most common P fertilizers but it is giving way to

    • Concentrated Superphosphate: 45 to 54 % P205 and is sold as 0-46-0. This is gaining much popularity.

    5. Potassium Fertilizers

    KCl is the common K fertilizer. This is also known as muriate of potash. This is the material used in most mixed fertilizers. However, tobacco is sensitive to large amounts of Cl so you must be careful when using large amounts of this fertilizer with tobacco.

    • KCL 0-0-60: Most common and cheapest of the K2O fertilizers

    • Potassium Sulfate; sulfate of potash. This must be used on crops that are sensitive to chloride. This is used most commonly with tabacco.

    6. Nutrient Management and Animal Wastes

    study module 1 Powerpoint or PDF


7. Fertilizer Best Management Practices for Golf Courses and Other Turf

See fertilizer BMP'S