Science Enrichment 2

Different Types of Fertilisers

Fertilisers are very important for the growth of plants. They provide them with nitrogen which gets converted into useful forms either for the plant itself of on the soil for other plants to use. Each plant requires different properties from the fertilisers and so it is very important for farmers to pick the right fertilisers for farming.

Acidic, fertilisers are made up of usually primary and secondary macronutrients. There are 3 primary macronutrients: nitrogen, phosphorous and potassium. The secondary macronutrients are calcium, sulfur and magnesium. One each from two types of macronutrients is usually combined together along with some other micronutrients like boron, chlorine, manganese, iron or zinc.

Rock Phosphate

Rock phosphate, basically PO₃, is actually the 20-million-year-old remnants from the remains of aquatic and land critters. It is in the form of clay, and will not leach out of the soil but be absorbed by roots of the plant. It releases the 30% of phosphorus at a very slow rate and can last for up to 5 years. It is often mixed together with other fertilisers and it can attract roots to the area spread with the fertiliser.

Ammonium Nitrate

Ammonium nitrate is made by combining nitric acid and ammonia. This reaction is very violent though many do not know it. Ammonium nitrate is made up of 27% nitrogen and is usually available in granule form. This is the most popular form of fertiliser because it does not affect the pH of the soil much. It constantly provides a large amount of nitrogen to the plants. However some there are some reservations on this type of fertiliser because it explodes and can be fatal.

Superphosphate

Superphosphate came about from tricalcium phosphate where the latter was too insoluble to form a fertiliser. It is thus reduced to monocalcium phosphate and added to sulfuric acid to form the superphosphate of lime. Superphosphate is usually used in the early stages of gardening. It is very concentrated and should be mixed to other fertilisers because the plants would die if not.

Potassium Chloride/Potassium Sulfate

Also known as the muriate of potash and the sulfate of potash respectively, potassium-based fertilisers are used only when there is a potassium deficiency in the soil. It is applied commonly when sowing. Potassium chloride is the most common potassium-based fertiliser and is also the cheapest. However, if such fertilisers are used in soil where there is an abundance of potassium, it can cause diseases such as root rot. Thus it is applied in small amounts unless there is no potassium in the soil.

Shao Xuan
(Post #9)