When you understand them, you use them right. Many farmers may be familiar with fertilizers, but what are their mechanisms and characteristics? We have some useful knowledge to share.

• What are fertilizers?

Fertilizers are organic, synthetic organic, inorganic, or microbes, whether natural or man-made, whose production is meant to be used as nutrients for plants, no matter by which means, or to cause chemical, physical, or biological changes in the soil to nurture and facilitate growth for plants¹

• How many types of fertilizers are there and what are they?

Types of fertilizers¹

1. Chemical fertilizer: fertilizers from inorganic or synthetic organic substances including straight, mixed, compound and organic chemical fertilizers, but excluding:

1.1 Lime, marl, plaster, gypsum, dolomite or any other substances determined by the Minister by declaring on the government gazette.

1.2 Inorganic or organic substances, whether natural or man-made, whose purposes are for industries or any other enterprises declared by the Minister on the government gazette.

2. Biological fertilizers: fertilizers that are made from live microbes which can produce or help utilizing nutrient elements or help utilizing for plants which are used to improve biological, physical or biochemical property of the soil, including leavening agents.
3. Organic fertilizers: fertilizers that are made from organic materials which is produced by moisturizing, chopping, fermenting, winnowing, extracting, or by other means, and the materials is completely digested by microbes, but is not a chemical or biological fertilizer.
4. Organic chemical fertilizer: fertilizers that have exact certified nutrients, whose amount of organic matters meet the amount declared by the Minister on the government gazette.

Chemical Fertilizers

• How many types of chemical fertilizers are there and what are they?

Types of Chemical Fertilizers

1. Straight fertilizers: chemical fertilizers containing one main nutrient element: nitrogenous, phosphatic or potassic fertilizer¹ 

^{Examples of straight fertilizers:}

1. Mixed fertilizers: a mix of different types of chemical fertilizers to include desired nutrients¹

Apart from that, mixed fertilizer can also be divided into two categories:

1. Bulk blended or tablet mixed fertilizers: mixed fertilizers containing all the primary macronutrient elements. The consistency may not be the same for every grain or tablet as this type of fertilizer is made by crushing different straight fertilizers and re-pressing the mix into tablets.
2. Inconsistently mixed fertilizers: mixed fertilizers which have different nutrient elements in different grains or tablets, made by simply mixing different types of straight fertilizers without crushing and re-making the tablets.

Examples of mixed fertilizers:

1. Compound fertilizers: chemical fertilizers made by combining at least two main primary macronutrient elements using a chemical process¹

Examples of compound fertilizers:

Apart from these three types of fertilizers, there is an addition category called complex fertilizers

1. Complex fertilizers: chemical fertilizers made by a chemical process combining a fertilizer with two primary macronutrient elements with another primary macronutrient element. This would create a fertilizer which contains all three primary macronutrient elements. For example: adding potassium to nitro-phosphate fertilizer to make a specific formula of an N-P-K fertilizer. This process is highly popular in Europe.

Examples of complex fertilizers:

¹/Fertilizer Act, B.E. 2518 (1975) as amended until Fertilizer Act (No. 2), B.E. 2550 (2007)