Dear Logesh nallasivivam,

Phosphate rich organic manure is a type of fertilizer used as an alternative to di ammonium phosphate and single super phosphate Phosphorus is required by all plants but is limited in soil, creating a problem in agriculture. In many areas phosphorus must be added to soil for the extensive plant growth that is desired for crop production.The solubilty depends upon PH of the soil, Ambient condition and becteria present in the soil. 

Phosphate Rich Organic Manure is produced by co-composting high-grade (32% P2O5 +/- 2%) rock phosphate in very fine size (say 80% finer than 54 microns). Needless to say, the finer the rock phosphate the better is the agronomic efficiency of PROM.. Research indicates that this substance may be a more efficient way of adding phosphorus to soil than applying chemical fertilizers. Other benefits of PROM are that it supplies phosphorus to the second crop planted in a treated area as efficiently as the first, and that it can be produced using acidic waste solids recovered from the discharge of biogas plants.

Organic fertilizer are able to enhances the solubility of many nutrient elements in soil. Hence for evaluating the effects of poultry manure on phosphorous solubility in two kinds of rock phosphate an experiment was carried out in a factorial design with three replication in lab condition . Treatment includes: 1- Moisture at two levels (F.C and S.P), 2- Poultry manure ratio to Rock phosphate at three levels (20, 40 and 60 percent), 3-incubation times (15,30 and 60 days). At final the phosphorous solubility of treatments was measured in water and Citrate. The results showed that citrate soluble phosphate had not significant variation with respect to times but water soluble phosphate had a negative trend with times. With increasing poultry manure levels, Water soluble phosphate increased but citrate soluble phosphate declined. Moisture had not significant effects on water soluble phosphate but citrate soluble phosphate showed a negative trend with increasing moisture. Water soluble phosphate was the most in F.C moisture content, 60 percent poultry manure and 15 days incubation times in concentrated rock phosphate but citrate soluble phosphate was maximum in S.P moisture levels, 20 percent poultry manure at 15 day incubation in concentrated rock phosphate. Key Words: Poultry manure – Rock Phosphate- Solubility.

Production of phosphorus rich organic manure (PROM) by composting of press mud and distillery waste with rock phosphate into a value added product standardized to contain 18% P2O5 with 22% moisture is a highly promising, natural, better and cheaper substitute of di-ammonium phosphate (DAP). The agronomic evaluation of PROM on paddy crop resulted in an enhancement of 29.41% yield over the DAP. The application cost of Simbhaoli PROM was 5% cheaper than DAP.

regards,

Prem Baboo

P solubility depends on

(i) soil pH (better around neutrality)

(ii) soil temperature (more than 20oC is needed)

(iii) availability of phosphate solubilizing bacteria

So, please look at those points and try to correct those factors for increased P availability

Please check this researchgate link.

https://www.researchgate.net/publication/279448107_Full_Length_Article_Effect_of_Recycled_and_Value-added_Organic_Waste_on_Solubilization_of_Rock_Phosphate_in_Soil_and_its_Influence_on_Maize_Growth

Article Full Length Article Effect of Recycled and Value-added Organ...

Dr. Biswas has highlighted good points.

Phosphate rich organic manure contains plant unavailable phosphorous both as inorganic and organic forms. You may increase the availability of unavilable inorganic phosphorous after introducing P solubilizer like Bacillus polymyxa or Pseudomonas striata and organic phosphorus by introducing phosphatase and phytase producing organisms like Aspergillus flavus, Chaetomium globosum, Curvularia lunata , Paecilomyces variotii etc.

The following review article  probably available online may provide good information on solubilization of P from rockphosphates using different approaches including  rockphosphate characteristics;soil properties including pH,Ca concentration ,water retention capacity and organic matter ;plant species including rootsystem,composting with organic manures/wastes and P solubilizing microbes.

Rock phosphate:its availability and solubilization in the soil-A review by Kiran Kumari and V.K.Phogat   Agric.Rev. ,29(2)108-116,2008.

The concept of using organic manure in any form or other modalities is of great need to sustain productivity these days. This as such gives an opportunity to use phosphorus rich organic materials. These propositions not only going to delete the cost of production of SSP or DAP, but use of mineral rock phosphate with organic manures will sustain phosphorus productivity in great way along with strains of Pseudomonas and Bacillus.  Apart from phosphorus nutrition, mineral rock phosphate will provide many other essential minerals as plant needs, which are generally eliminated during the process of SSP and DAP productions.

Good point Logesh has tossed up . Lets have have a precise answer .  If i take two manures , for example Farmyard manure and poultry manure . In these two manures , i want to hasten the release of tagged P. What kind of strategy , we need to adopt,  either with respect to microbial inoculation or addition of any other crop residue  having wide C:P ratio , or some inorganic phosphates or all three ....? The response of Dr Tarafdar is really impressive . 

I think realizing P from organic -P increased by using different biofertilizers (Bacteria and fungi)

Not only realizing P from organic fractions but also you may realize P from unvailable inorganic fractions by the help of soil microorganisms which are mainly releasing organic acids like citric, lactic, malic, formic etc. We found that if you can increase the organic acd concentration over 0.4M, then it will be possible to solubilize more than 70% inorganic P from the soil. But we could not find so far a single organism which can release so much organic acid concentration that can be used as inoculum.

Dear colleagues,If one desires to make phosphorus rich organic manure from rock phosphate , source of rock phosphate and organic material /manure  are important consederation,One has to first look in to the nature of rock phosphate,whether it is reactive or not,whether they have origin in igneous or metamorphic rocks or sedimentary deposits with -microcrystalline structure.Carbonate apatites are preferred over the fluorapatites and hydroxy apatites,as the former can decompose  easily compared to the latter.Second point is the rockphophates have to be composted with organic matreials with recommended methods,not simply mixed with manure.Efficient biocultures as mentioned by colleagues can be added to the compost after the thermophilic or cool phase of composting for their  better survival and prolification in the mature compost.Rock phosphate dissolution and removal of calcium from the medium encourages P solubilization(crop uptake of Ca especially by legumes may accelerate P dissolution).Poultry manure may contain more calcium than Farmyard manure and so the latter is more efficient in P solubilization than the former.Organic acids(through complexation and protons), H ions /protons and phosphatage and phytase enzymes of plant  root,manure,microorganism origin  may help in P dissolution/solubiliztion from insoluble/citrate soluble source.So,one has to manage plant/microbe-soil-manure/P source system for efficient use of P.

Dr. Subba you have cited very relevant and pertinent points.