About Fertilizers

1. What is a fertilizer ?

A fertilizer is a chemical product either mined or manufactured material containing one or more essential plant nutrients that are immediately or potentially available in sufficiently good amounts.

2. Is application of fertilizers harmful to the soil/ plants/ humans ?

Fertilizer applications at the recommended rates are not at all harmful. It is wrong to carry such doubts to the farmers and the consumers of farm products. Fertilizers carry the similar chemical elements which a soil or atmosphere contain. Secondly, the raw materials used for manufacturing fertilizers are natural products. For example, the air we breathe contains 79% nitrogen and is used to manufacture nitrogenous fertilizers like urea. Natural minerals like sulfur, rock phosphate are used to manufacture phosphatic fertilizers like super phosphate.

3. Why people comment that fertilizers are harmful ?

Such comments are due to lack of sufficient knowledge about fertilizers. Farmers should clearly understand the role of fertilizers in crop production, use them where needed in a balanced way, and avoid excessive use of them even if they are given free not that they are harmful but it is waste of money to use for that crop.

4. What is fertilizer grade?

Fertilizer grade refers to the guaranteed content (analysis) of plant nutrient/s in a fertilizer. That is percentage of the major plant nutrients; NPK in that order, present in a fertilizer reflects the grade of that fertilizer. Thus 14-14-14-fertilizer grade refers to the fertilizer guaranteed to contain a minimum of 14% nitrogen (N), 14% of phosphorus (P₂O₅) and 14% of potassium (K₂O).

5. What types of fertilizers are available in the market ?

Three types of fertilizers are available in the market. They are straight fertilizers, Complex fertilizers, and Mixed Fertilizers.

Straight Fertilizers supply single plant nutrient either nitrogen (N), or phosphorus (P), or potassium (K). Example: Urea supplies 46% N; Super phosphate provides 7% P or 16% P₂O₅.

Complex Fertilizers supply more than one plant nutrient. Example: Di-Ammonium Phosphate (DAP) contains 18% N and 20% P (46% P₂O₅).
Mixed Fertilizers are physical mixture of two or more straight and/or complex fertilizers to supply particular combination of plant nutrients. Example: one can buy DAP and Muriate of Potash and mix them in a ratio to get a fertilizer mixture containing a grade of 12-32-16 of N, P₂O₅, and K₂O.

6. What are the advantages of Complex Fertilizers ?

1. The possibility of adulteration is generally less.
2. Each granule is homogenous in nutrient content.
3. Being granular, the drilling of fertilizer is easy.
4. They are cheaper than straight or mixed fertilizers.
5. Phosphorus availability is not affected (fixation is less) as the phosphorus in the granules will have less contact with soil particles.

7. Are there any disadvantages with Complex Fertilizers ?

The disadvantage with Complex Fertilizers is that the ratios of the nutrients are fixed and the farmers may have to supplement with straight fertilizers to meet the crop requirements.

8. What are the advantages of Mixed Fertilizers ?

1. There will be considerable saving in time and labor in application to the crops, as all the nutrients required are present in the same packing.
2. One can ensure balanced nutrient application if suitable mixture is chosen.
3. Micronutrients can also be included in the mixtures.

9. Are there any disadvantages with Mixed Fertilizers ?

1. There is possibility for adulteration with inert material.
2. Farmers themselves can mix the fertilizers provided they are knowledgeable about what fertilizers cannot be mixed together.

Compiled by Dr. Diwarkar : 30 August 2004