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Water soluble phosphatic fertilizers

 Water soluble phosphatic fertilizers

Water soluble phosphatic fertilizers contain phosphate in very easily dissolvable form (-H2PO4) in water and, therefore, are readily available to the plants. These fertilizers are highly prone to fixation, and therefore, their leaching loss from the soil is minimal. But, the fixed form of phosphorus is not available to the plant. The problem of fixation is severe in highly acidic or alkaline soils. The examples of these fertilizers are:

Single superphosphate (SSP)                        16-18% phosphate (P205)

Double superphosphate (DSP                        32% (P205:)

Tripple' superphosphate (TSP)                       42% (P205:)

Some important characteristics of these fertilizers can be highlighted individually.

a. Single superphosphate (SSP): Single superphosphate is grey coloured, dry, granular or powdered phosphatic fertilizer. It is sold in gunny bags with polythene lining inside or plastic bags. When super phosphate is applied in moist soil or in dry soil after rain or irrigation, phosphate part (H2PO4) is dissolved in the soil water. The roots of growing plants easily take up this form of phosphorus. There are a few tips to get the maximum benefit from the application of single superphosphate. Superphosphate should be applied just before sowing to enable the proper placement and also to ensure sufficient supply of phosphorus in early stages of plant growth when its requirement is the highest.

The entire dose should be applied before i sowing to short duration crops like paddy, [ wheat, ]owar, cabbage, cauliflower, potatoes, etc. For a long duration crop like  sugarcane, the entire amount should be split  in two doses: the first half before sowing  and the remaining half with the first earthing up. For sugarcane, SSP is placed in between the rows, 2-3 inches deep in the soil.

Phosphates of these fertilizers are not mobile in the soil. It is, therefore, necessary that superphosphate is placed in the root zone or in the soil layer where the roots are most active. In fruit trees. it should be deep placed.In highly acidic soils, SSP should not be applied. If necessary, it could be applied along with lime.SSP is suitable for short duration crops and acid when a crop requires quick start.

b. Double superphosphate (DSP): Single superphosphate is gradually becoming the: obsolete because of its low nutrient content and high cost of production. Double superphosphate a) contains two times more phosphorus than SSP. The characteristic, appearance and mode of action b) of this fertilizer are very similar to those of SSP.

c. Triple superphosphate (TSP): Triple superphosphate is a highly enriched, water soluble phosphatic fertilizer. It is the a. least costly in production, handling, storage and distribution. For maximum yield of short duration, fast growing crops like high yielding inc varieties of cereals, potatoes and certain other ma vegetable crops, TSP is superior to other am fertilizers provided the soil is neutral. The of trips to maximise utilization, discussed under  SSP, are also applicable to TSP.

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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.