TYPES OF FERTILIZERS

** UREA FERTILIZERS

Urea is the most widely used solid nitrogen fertilizer and is usually applied as granules, although it is sometimes mixed with ammonium nitrate and dissolved in water to form urea ammonium nitrate solution. When applied to soil, urea reacts with water to form ammonia, which makes the nitrogen within the fertilizer available to plants. Urea fertilizers deliver one of the highest amounts of nitrogen at 46 percent, with no phosphorus or potassium.

* AMMONIUM NITRATE

A solid fertilizer typically applied in granular form; ammonium nitrate provides substantial amounts of nitrogen to the soil. The Fertilizer Institute indicates that ammonium nitrate is particularly effective at fertilizing specialty crops such as citrus and pasture lands. Ammonium nitrate typically provides 33 percent nitrogen.

* Fertilizers are chemical substances that are used to enrich soils with specific nutrients to help plants grow.

* When applied to soil, urea reacts with water to form ammonia, which makes the nitrogen within the fertilizer available to plants.

* POTASSIUM NITRATE POTASSIUM

Potassium nitrate, also called nitrate of potash, is frequently used on vegetable crops including celery, potatoes, leafy green vegetables, tomatoes and several fruit crops, according to the Michigan State University Extension. The nitrate component of this chemical fertilizer works well with these crops. Potassium nitrate provides 44 percent potassium.

* Another phosphorus fertilizer, monoammonium phosphate delivers even more phosphorus than diammonium phosphate, at 48 percent.

** POTASSIUM CHLORIDE

Sometimes called muriate of potash, potassium chloride is a significant source of the element potassium as a fertilizer. Directly applied to soils or combined into multiple endings of mixed fertilizers, potassium chloride is also highly soluble and can be applied in liquid fertilizers. The chemical typically provides 60 to 62 percent potassium.

*AMMONIUM SULFATE

A by-product derived from the waste generated by coke ovens, ammonium sulfate forms when sulfuric acid is used to remove ammonia from the coal used to make coke. Ammonium sulfate is a solid material that contains 21 percent nitrogen.

*Nitrogen Fertilizer

A by-product derived from the waste generated by coke ovens, ammonium sulfate forms when sulfuric acid is used to remove ammonia from the coal used to make coke. Ammonium sulfate is a solid material that contains 21 percent nitrogen.

Other straight nitrogen fertilizers include ammonium sulphate and ammonium sulphate nitrate, calcium nitrate, sodium nitrate, Chilean nitrate and anhydrous ammonia.

* NITROGEN FERTILIZERS WITH INHIBITORS

Certain weather and soil conditions can lead to nitrogen immobilization, denitrification, volatilization or leaching, all reducing fertilizer efficiency. In response, the industry has developed special types of fertilizers designed to reduce these effects. They include foliar, slow and controlled release fertilizers, as well as fertilizer additives such as urease and nitrification inhibitors.

* PHOSPHORUS FERTILIZERS

The most common phosphate fertilizers are single superphosphate (SSP), triple superphosphate (TSP), monoammonium phosphate (MAP), di-ammonium phosphate (DSP) and ammonium polyphosphate liquid.

Different fertilizer products have different release profiles and need different spreader settings for efficient application.

* DIAMMONIUM PHOSPHATE

Where soils do not have enough phosphorus, diammonium phosphate can provide significant amounts of this chemical, at around 46 percent. The ammonia component of diammonium phosphate also delivers around 18 percent nitrogen. Highly water soluble, diammonium phosphate is often applied in liquid form.

* Where soils do not have enough phosphorus, diammonium phosphate can provide significant amounts of this chemical, at around 46 percent.

** MONOAMMONIUM PHOSPHATE

Another phosphorus fertilizer, monoammonium phosphate delivers even more phosphorus than diammonium phosphate, at 48 percent. The amount of nitrogen in fertilizer provides is somewhat less at 11 percent. The lower level of the ammonia component of this chemical lessens the risk of damage when applied to new seedling growth.

* POTASSIUM FERTILIZERS

Potassium is also available in a range of fertilizers which contain potassium only or two or more nutrients and include Potassium chloride (KCl), Potassium sulphate (K2SO4) or sulphate of potash (SOP), Potassium nitrate (KNO3), known as KN.

* CALCIUM, MAGNESIUM AND SULPHUR FERTILIZERS

Calcium (Ca), magnesium (Mg) and Sulphur (S) are essential secondary plant nutrients. They are not usually applied as straight fertilizers but in combination with the primary nutrients N, P, and K.

Sulphur is often added to straight N fertilizers such as ammonium nitrate or urea. Other sulphur sources are single superphosphate (SSP), potassium sulphate (SOP) and potassium magnesium sulphate (Kainite), the latter also containing magnesium.

Kieserite is a magnesium sulphate mineral that is mined and also used as fertilizer in agriculture, mainly to correct magnesium deficiencies. Calcium is mainly applied as calcium nitrate, gypsum (calcium sulphate) or lime/dolomite (calcium carbonate), of which calcium nitrate is the only readily plant available source of calcium.

MICRONUTRIENT FERTILIZERS

Today, a large number of special fertilizers are available to supply plants with important micronutrients such as iron, manganese, boron, zinc and copper. These can be either inorganic or organic compounds, with the inorganic varieties further divided into water- soluble and non-soluble products.