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Citric acid soluble phosphatic fertilizers

Citric acid soluble phosphatic fertilizers

Citric acid soluble phosphatic fertilizers are not soluble in water but are readily soluble in acidic water or weak acids like 2 per cent citric acid. They also contain phosphorus in available form, i.e., HPO4. The fertilizers are suitable for acidic soils where they can easily dissolve and become available to plants. The examples of  these fertilziers are:

a) Basic slag -18% phosphate (P20S)

b) Dicalcium phosphate -34-39% P20S

c) Rhenania phosphate -23-26% P20S

The first two are very important and are commonly used in a few pockets of the country.

a. Basic slag: Basic slag is a by-product of iron and steel industries. Original iron ore used as a raw material in iron industries contains appreciable amount of phosphorus as impurities. Purer form of iron is exracted from raw material leaving phosphorus and calcium rich basic slag as a by-product. Basic slag produced in India is of low quality. In contains only 3-8 per cent phosphorus in comparison to 14-18% phosphorus in basic slag produced in European countries. This is a grayish  black powder with a very high specific weight. , Its phosphorus is easily soluble in soil water of acidic soils. It exerts alkaline residual effect in the soil, therefore is useful for applying in acid soils. Basic slag is also used as liming material in our country.

b. Dicalcium  phosphate: Dicalcium phosphate has a excellent physical condition. It is also very rich in phosphorus (34% citrate soluble phosphates), therefore, less costly than basic slag in transport, storage and distribution. This fertilizer is suitable for a wide range of crops and soils because its phosphorus does not so easily convert into unavailable form as that of super phosphates.  Dicalcium phosphate is suitable for acidic soils.

c. Renonia phosphate: This is a citrate solube phosphatic fertilizer which contains alteast 24% available phosphorus (HPO4)' The production and consumption of this ferrtilizer in our country is negligible. However, in foreign countries this fertilizer is used in large amounts.

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Please note that this is the opinion of the author and is Not Certified by ICAR or any of its authorised agents.