DESC:FIELD OF INVENTION:

An improved composition of Single Super Phosphate, a phosphate fertiliser with 14.5% Water Soluble P2O5 and 16% Citrate Soluble P2O5.

PRIOR ART AND BACKGROUND:

Single Super Phosphate (SSP) is a widely used fertilizer in India as it is an important source of phosphorus (P) and has a low unit price. The P content of SSP is expressed in terms of P2O5. SSP contains 16% P2O5.

It is well established that Indian soils are low in organic carbon (OC). The OC plays an important role in supporting soil microbial population which in turn produce organic acids that help in releasing P nutrient fixed in the soil.

Indian soils are deficient in organic carbon. The OC values are around 0.3-0.4% whereas they should be at least 1%. OC can be increased by adding manure, compost and decomposed biomass. However, not all farmers apply these sources of carbon because of the high cost.

Fertilisers can be effective carriers for additives that can rejuvenate the soil. Therefore, along with nutrients they can supply other beneficial elements to the soil. Single Super Phosphate is an ideal fertiliser for performing the role of a carrier. 60-70 kg of filler is added in every 1000 kg of SSP. This filler can be replaced by beneficial substances such as organic carbon.

US 2013/0104612 A1 describes a phosphate compound in which an organic source is added along with mineral acid. This invention relates to chemical modification of the phosphate compound through the addition of an organic source. The present invention differs from prior art as no claim in made with respect to the reaction of the organic material with phosphate compound as the role performed by the organic material is that of filler.

SSP is used for Sulphur loving crops such as soybean and groundnut. The Sulphur plays an important role in determining the amino acid profile in soybean and the oil formation in groundnut. Typically, SSP contains 11% Sulphur. It is possible to replace the inert filler with elemental Sulphur and thereby supply additional Sulphur to the crops.

Prior art in the form of commercially available products relates to the addition of elemental Sulphur to SSP to increase the Sulphur content. However, in all these products, the addition of Sulphur reduces the P2O5 content below 16% P2O5 and hence comes at the expense of P2O5. By replacing only the filler with elemental Sulphur, the P2O5 is maintained at 16% and value of the product is enhanced as it is supplying additional nutrients.

SUMMARY OF THE INVENTION

This invention relates to an improved composition of SSP that contains maximum of 70 kg of organic substances per 1000 kg of product. These organic substances contribute carbon to the soil. The preferred organic materials are those that are concentrated sources of carbon (50-70%). Thus, the SSP product will contain maximum of 5% organic carbon. Leonardite is the preferred source of organic carbon as it has highest carbon content among all organic sources.

In another embodiment of the invention, SSP contains upto 70 kg of Sulphur rich materials per 1000 kg of product. The Sulphur rich filler contributes additional Sulphur to the soil. The preferred Sulphur rich materials are Bentonite Sulphur or Sulphur sludge (50-70% Sulphur content). Thus, the SSP product will a maximum of additional 5% of Sulphur.

DESCRIPTION OF THE INVENTION

SSP is produced through the reaction of phosphate rock and sulphuric acid. The typical composition of SSP is as follows:

Component %
Mono Calcium Phosphate 28.5
Gypsum 55
Free acid 2
Silica 0.5
Metal phosphates 1.0
Filler 7
Moisture 6

TOTAL 100

As indicated above, the final product contains up to 7% filler which can be either sand or gypsum. The gypsum is added to the SSP powder after it has become cured. In the present invention, the filler used is an organic substance rich in carbon. Thus, while gypsum or sand do not offer any substantial benefit to the soil, the organic substance increases the carbon content of the soil. This is illustrated through the following example. A farmer who uses 100 kg of the improved SSP per acre can add 5 kg of carbon per acre to the soil which is equivalent to adding 40 kg of compost to the soil. If the farmer continues to use the improved SSP, the carbon content of the soil will gradually build-up. Farmers who use the normal SSP may or may not add compost and hence there is every likelihood that the carbon content of the soil may continue to remain low affecting the soil health and leading to low productivity.

Farmers who use 100 kg of improved SSP with additional Sulphur per acre can add up to 5 kg of extra Sulphur to the soil.

The inventive step lies in the following aspects of the invention

1) The use of SSP as a carrier for organic carbon, which is not known in prior art.
2) Addition of organic substance to SSP in place of inert filler to increase the carbon content.
3) Addition of organic carbon to SSP in the form of Leonardite or any other concentrated source of carbon (50-70%).
4) Maximum addition of organic substance at 70 kg per ton of SSP or 7%. The above dosage gives organic carbon content from maximum 5% in SSP
5) Organic substance can be mixed at any point of the manufacturing process starting from rock feeding to the end of curing.
6) The SSP with organic material can be bagged as powder or granulated.
7) The Water soluble P2O5 and Citrate Soluble P2O5 will continue to remain as 14.5% and 16% respectively as in the case of regular SSP.
8) Use of SSP as a carrier for additional Sulphur with a maximum Sulphur content of 16%.
9) Addition of Sulphur rich materials such as Sulphur sludge or Bentonite Sulphur as filler to increase Sulphur content.
10) Addition of Sulphur rich materials to the SSP after the curing stage.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A sample improved SSP composition with 1% Leonardite was produced and evaluated through trial in the research farm. The crop was soybean. 12-24-16 kg NPK per acre was applied through SSP, urea, MOP as basal. The results shown below demonstrate the superior performance of the improved SSP.

Parameters Improved SSP Regular SSP % increase over Regular SSP
Plant height in cm @ 30 DAS 20.77 19.77 5.06
Plant height in cm @ 45 DAS 26.60 25.67 3.62
NDVI @ 60 DAS 0.72 0.71 1.98
Root length in cm 17.22 14.62 17.78
No. of pods/plant 61.20 59.30 3.20
Pod weight/plant (g) 21.34 20.97 1.73
Grain weight/plant (g) 13.34 12.51 6.59
Shelling % 66.85 65.36 2.28
100 seed weight (g) 12.28 10.72 14.55
Total dry matter at harvesting (kg/ac) 2691.80 2543.00 5.85
Grain yield (kg/ac) 511.20 411.20 24.32

In a trial conducted on soybean in the research farm with SSP with additional 5% Sulphur, the yield obtained with regular SSP was 688 kg/acre and with improved SSP 804 kg/acre. The 16.7% improvement in yield demonstrates the benefit of adding additional Sulphur through SSP.

The advantages and novelty of the invention are:

It is an improved composition of Single Super Phosphate that contains up to 5% organic carbon.

The addition of carbon rich organic substances in SSP as filler in place of gypsum or sand.

The organic substances selected can be Leonardite, Biochar, Manure, Compost etc. The preferred organic filler is the one with the highest carbon content.

The improved SSP can be in powder or granular form. In the case of granular form, the SSP powder containing the organic filler is granulated.

The filler can also be replaced by Sulphur rich materials such as Bentonite Sulphur or Sulphur sludge to increase the Sulphur content of SSP from 11% to maximum of 16%.

The invention has been described with examples, embodiments etc. for the purpose of understanding the invention. All the modifications and variations are well within the scope of invention. The applicant intends to rely upon provisional specification and the drawings submitted alongwith provisional specification.
,CLAIMS:WE CLAIM:

1. A method of preparing an enhanced single super phosphate fertilizer comprising steps of:
a) reacting rock phosphate with sulphuric acid in a reactor to form single super phosphate,
b) allowing the reaction to reach completion by curing the mixture,
c) introducing a source of organic carbon matter or a source of sulphur matter into the same reactor or during curing for incorporation within single super phosphate and forming a single super phosphate characterized in the composition with 14.5% P2O5 water soluble P2O5 and 16% citrate soluble P2O5 alongwith either maximum of 5% organic carbon or maximum of 5% elemental sulphur and,
d) granulating the same single super phosphate by passing the powder through a drum granulator.

2. The method as claimed in claim 1 wherein the method includes selecting organic matter with 50-70% carbon such as Leonardite and Biochar.

3. The method as claimed in claim 1 wherein the method includes selecting sulphur matter which is Bentonite sulphur or sulphur sludge.

4. The method as claimed in claim 1 wherein the method includes adding selectively the organic carbon source as filler upto 70 kg/ton in the composition or adding selectively elemental sulphur source as filler upto 70 kg/ton in the composition.

5. A single super phosphate fertilizer composition prepared as claimed in claims 1-4 such that fertiliser composition with 14.5% P2O5 Water Soluble P2O5 and 16.0% Citrate Soluble P2O5 and maximum of 5% Organic Carbon.
6. A single super phosphate fertilizer composition prepared as claimed in claims 1-4 such that fertiliser composition with 14.5% P2O5 Water Soluble P2O5 and 16.0% Citrate Soluble P2O5 and maximum of 5% elemental sulphur.