The attached paper titled " Application of Potential Phosphate-Solubilizing Bacteria

and Organic Acids on Phosphate Solubilization from Phosphate

Rock in Aerobic Rice" can be of great help to you

I think,  0.1mM concentration of  organic acids solution  of the amount equal to the 50% water holding capacity of the soil may serve your purpose. But you have to mix the solution with the soil at least 7-10 days in advance before planting.

thank you very much for your answer doctor. 

Dear Ehsan Akbarpour, If you are able to isolate the citrus rhizosphere bacteria and then screen them to solubilize insoluble oxidized iron you will be able to use through candidates for remediating iron chlorosis. It would be great to have a Bacillus for the ability to maintain inoculum as endospores and to simultaneous screen for iron and phosphorus solubilization and growth enhancement. I am not aware of people looking at the iron phosphorus and growth enhancement at the same time but do not see why it would not be feasible. Some Thoughts on your goal and how it might be achieved. Best Wishes on your studies. PRH

There will be sorption of undissociated acid and dissociated anions on soil surfaces so low concentration to the level of 0.1 mM may not result in sufficient increase in the concentration of these organic acids in soil solution. In submerged soils, there presence to the extent of 5-10 mM had been reported in soil solution so possibly you need to try concentration somewhere around 5 to 10 mM to have their sufficient concentrations in soil solution.  

Further, I wish to add that instead of resorting to external addition of these organic acids to soil (may be through drip) you may try a different strategy wherein the root stocks are inoculated with proton exuding microbial consortium culture prior to planting. The adaptability of the technique once proven would be easy  and cost-effective for the farmers.

Try simulate this process through organic matter decomposition instead of adding these chemicals.  This is neither advisable nor economical.

I very much endorse the views of Dr. PC Srivastava and Dr. HP Agrawal. There is no point in organic acid application to control iron nutrition of crops when there is a biological technique on hand being practical and everlasting. 

Thanks to Dr. K S Reddy. I agree with the views of Dr. H P Agarwal and Dr. Reddy. 

I agree to proposal of  Dr. Srivastava and Dr. Agarwal.

Yes I too agree with PC Srivastava & HP Agrawal....because if you apply organic acids as such then so many adverse affect  may be observed on soil nutrient cycling like absorption of heavy metals. Hence one of the alternative to use microbial resources because chelation is a complex process and only microbes have ability to release very precise amount of different kinds of organic acids with different concentration into the soil to perform that specific task. 

hi everyone.

i'd like to say thanks to all for your kind answers. they gave me a new vision on this field. specially Mr. Srivastava and Mr. Reddy.

wish you all the best.

hi everyone.

i'd like to say thanks to all for your kind answers. they gave me a new vision on this field. specially Mr. Srivastava and Mr. Reddy.

wish you all the best.

Suggestion of Agarawal is good and appropriate but he have already planned his experiment. May be he wants answer, good or bad?

Mr. Hussain is right. i have already started my project and samples are ready for stress phase. 

Organic acids such as citrate, malate and oxalate are able to desorb or solubilise fixed soil P, making it available for plant uptake. Organic acids also chelate Al3+to render it non-toxic, and are, therefore, involved in Al tolerance mechanisms. The role of organic acids exuded from roots in improving plant P uptake and Al-tolerance in acid soils has been documented. Several workers have attempted to understand how P deficiency or exposure to Al3+activates or induces organic acid efflux at the molecular level, with the aim of improving P acquisition and Al tolerance by conventional plant breeding and by genetic engineering. At the agronomic level, it is desirable that existing crop and pasture plants with enhanced soil-P uptake and tolerance to Al due to organic acid exudation are integrated into farming systems.

Interesting discussion . there could be two very effective ways to apply organic acids to peach rootstocks seedlings . Foliar application emerges to be the most ominous way to improve upon the rate iron absorption , since growing medium is treated with calcium carbonate , that will discourage iron to be effectively absorbed ( Lets consider the amount of foliage available for foliar spray as well,  in initial growth stages of peach seedlings). On the other hand ,  iron salt s could be allowed to react first with these organic acids , then could be applied into the soil treated with calcium carbonate . There could be third option as well, to chanelise the iron salts contained in organic acids through fertigation . It will be interesting to compare the absorption , translocation and utilization efficiency of iron  via these three methods of application . 

If I were doing this organic acid experimentation. I would apply the organic acid application in a weekly application for the 2 months of evaluation. I would use a concentration 500 to 1000 ppm organic acid. The key to the experiment would be using plant source and soil that would express the iron chlorosis as a baseline and then rate the chlorosis symptoms and take analaysis of chlorphyll rates along with the atomic analysis of the foliage and finally keep checking for the soil pH which can be involved.Good luck on the experiment. You may want to have a check in which you use Sulfur to adjust the soil medium to pH 6.5 as this would likely resolve the iron chlorosis issues without needing the organic acid treatment.  

Interesting points Dr. Paul. You mentioned the key point is rating of chlorosis symptoms. What are the other parameters as an indicator.

foliar application !

Dr  malhotra , i am enclosing on eexcellent PDF by  John  Morgan dealing with soyabean crop , where  iron deficiency chlorosis has been rated according to degree of chlororsis damaging the crop on  a scale of 1-6. 

It is important to consider three aspects of nutrient uptake in soybeans: bicarbonates in the soil and their relationship to plants, the important distinction of how Strategy 1 plants take up iron, and, finally, the relationship between

nitrogen and iron deficiency chlorosis.“Strategy 1 plants such as soybean,

blueberries, and azaleas must convert iron into an available form in order to allow for uptake. This is accomplished via the release of acids, which make the iron soluble, as well as reductants, or electrons, which reduce the iron present into a form that the plant can use. Strategy 1 plants can significantly differ in what types of pH they adequately grow in. Soybeans can grow in soils with pH levels near neutral or slightly alkaline better than a plant such as blueberries, which survive in very acid soils. When it comes to iron, most soils contain iron oxide or hydroxides. The problem is that in soils with adequate aeration, the form that iron will be in is Fe3+, which is not soluble and the plant cannot take it up. Strategy 1 plants rely on the release of acids and reductants to increase the availability and solubility of Fe in the soil. This is what happens when Fe3+ is converted to Fe2+.” So the crux of the IDC problem is truly due to an overabundance of bicarbonate in the soil and not a dearth of iron, and research shows that this most commonly occurs in soils that are saturated or where a lot of carbonates reside thanks to the soil’s parent material or a lack of aeration that will trap carbon dioxide in the soil profile. This is important because bicarbonate levels in the soil are proportional to the amount of carbon dioxide. Carbon dioxide is produced through microbial respiration.

The recommendation of using foliar application can have some limitations. For example experience in Hawaii the deficiency of Calcium and Boron in ginger is found in the growing points. As such the application of these nutrients will not be remedied in the roots from the application of the nutrients to the foliar and the roots are damaged by local underground deficiency affected marketability and storage quality. On the other hand if the soil nutrient level is optimized there will be not deficiency in either the roots or the shoots. When aggressive rooting is favored the nutrient issues in general are avoided. While foliar application can indeed have a economic role in managing the symptomatic expression to get optimized whole plant response in the whole plant cycle these issues are best addressed in the soil itself. Another issue with iron fertilization is that many pathogenic organisms are limited by iron scarcity when will make applications of foliar iron as chelates and conditions are moist the minor issues of bacterial disease such as soybean bacterial leaf blight can be fostered when the more nutrient scarce condition they are not problematic. When it comes to nutrition there are many interacting variables and a lot of care needs to exercised in the balancing act. In fact in many agricultural arenas there are issues with both deficiencies and excesses and the use of minimal application to come to adequacy and avoid excess application is available but only when a monitoring approach is used which is often beyond the scope of many workers and farmers.