Dear Nadeem Sarwar

Slow release of fertilizers is one of the means of minimizing the fertilizer loss. This can be achieved by using different types of coatings,Urea is widely used as a fertilizer because of its high nitrogen content (46.6%). Unfortunately, urea is very water soluble and in regions with high precipitation the fertilizer may be leached from the soil before plants have an opportunity to assimilate it.Slow release of fertilizers is one of the means of minimizing the fertilizer loss. This can be achieved by using different types of coatings, Urea is widely used as a fertilizer because of its high nitrogen content (46.6%). Unfortunately, urea is very water soluble and in regions with high precipitation the fertilizer may be leached from the soil before plants have an opportunity to assimilate it.Sulfur-coated urea products can only be applied in granular form, and thus cannot be applied via liquid fertilization methods. It is not uncommon to find empty sulphur husks in turf once the nitrogen is released. Another disadvantage has to do with the relatively large particle size of sulphur-coated urea fertilizers, which makes their use on closely mown surfaces like putting greens impractical. However, more recently, materials with smaller particle sizes have been developed, permitting the use of sulphur-coated urea on putting greens. A spouted bed facility, which includes a 0.154 m ID x 0.91 m high bed with a 60° conical bottom, was used for the batch-wise production of sulphur coated urea. Molten sulphur was sprayed into the cone and the droplets froze upon impact with the cooler urea particles thereby forming coats which increased with time.

The quality of the coated urea was studied as a function of bed temperature (48–860 C), sulfur flow rate (34–260 g/min), atomizing air flow rate (0.402–0.785 m3/hr) and bed depth (0.28–0.47 m). No attempt was made to seal the product with wax or other materials. Bed temperature  the greatest effect on product quality, with quality improving up to approximately 800 C and then decreasing again. The quality also increased with the sulphur flow rate and decreased with the atomizing air flow rate. These measurements are explained in terms of the phase transition from monoclinic to orthorhombic sulfur and the sulfur droplet size which influences the spreading of liquid sulphur on impact with the urea particles.

please find attached related link and file,

Regards,

Prem Baboo

Article NEEM OIL & NEEM COATED UREA

 We have tried a bio-fertilizer made from neem which proved very effective in enhancing the growth of many crops including sugar cane, onion, chillies, paddy field of rice etc. It also has a pesticidal effect.

Presently we have a neem based bio-pesticide and looking for genuine parties for its marketting.

Coated urea fertilizers are a group of controlled release fertilizers consisting of prills of urea coated in less-soluble chemicals such as sulfur, polymers, other products or a combination. These fertilizers mitigate some of the negative aspects of urea fertilization, such as fertilizer burn. The coatings release the urea either when penetrated by water, as with sulfur, or when broken down, as with polymers.

Contents [hide]

1 Overview

2 Sulfur-coated urea

3 Polymer-coated urea

4 Combination products

5 See also

6 References

Overview[edit]

Further information: Controlled release fertilizer and Urea

Urea is widely used as a nitrogen fertilizer. Its high solubility in water makes it useful for liquid application, and it has a much lower risk of causing fertilizer burn than other chemicals such as calcium cyanide or ammonium nitrate. However, the risk of fertilizer burn with urea can be unacceptably high in some situations, such as higher temperatures. The high water-solubility of urea can be disadvantageous in some cases as well.[1]

One particular technique to mitigate these disadvantages has been to encapsulate prills of urea with less-soluble chemicals. These coatings permit the gradual release of urea in a controlled fashion, allowing for less-frequent applications.[1]

Sulfur-coated urea[edit]

Sulfur-coated urea, or SCU, fertilizers release nitrogen via water penetration through cracks and micropores in the coating. Once water penetrates through the coating, nitrogen release is rapid. The particles of fertilizer may in turn be sealed with wax to slow release further still, making microbial degradation necessary to permit water penetration. The size of fertilizer particles may also be varied in order to vary the time at which nitrogen release occurs. Sulfur-coated products typically range from 32% to 41% elemental nitrogen by weight. The sulfur coating process was originally developed by the Tennessee Valley Authority.[1]

Sulfur-coated urea products can only be applied in granular form, and thus cannot be applied via liquid fertilization methods. It is not uncommon to find empty sulfur husks in turf once the nitrogen is released. Another disadvantage has to do with the relatively large particle size of sulfur-coated urea fertilizers, which makes their use on closely mown surfaces like putting greens impractical. However, more recently, materials with smaller particle sizes have been developed, permitting the use of sulfur-coated ureas on putting greens.[1]

Polymer-coated urea[edit]

Polymer-coated urea, also called plastic-coated urea, or PCU, fertilizers can permit a more precise rate of nitrogen release than sulfur-coated urea products. It's possible to produce polymer-coated products where the nitrogen release can be delayed for 10 months after application. The primary disadvantage of polymer-coated urea products is their relatively high cost compared to sulfur-coated urea.[1]

Combination products[edit]

Products that use a combination of sulfur-coating and polymer-coating also exist. Typically, these products consist of urea, coated with a layer of sulfur, which is in turn coated with a layer of polymer. Each coating layer is generally less than the normal thickness for the individual processes. These products are generally used as less-expensive alternatives to purely plastic-coated products, while still providing precise nitrogen release characteristics.[1]