Dear Prakash Chandra Srivastava, Thank you for supporting the needs of holistic analyses for defining nutrient strategy. One of the reasons I like vermicompost so much is not only Calcium is applied but also the material is rich in micronutrients such as Boron, Zinc, Manganese and others which can be limited as well as humic substances not to mention beneficial biology from the worm gut. In addition the humic components of the compost tea provides for chelation into solution of elements which are otherwise with mobility issues. In addition the humic material allows their ready  absorption into foliar surfaces. At these stages huge amount is not needed but often a Calcium suspicion is associated with Boron insufficiency and as you say both go together. We must not forget our micronutrient needs very critical in nuts and other crops. The use of foliar and soil analysis makes the black box of our plant soil system into one where the analysis lights the way for underlying situation in both the soil and the plant. The situation in particular shows alkaline and salt issues and working with the water source and pH of the soil can work together in remediating the issues. The underlying lack of Phosphorus and the low amount of organic matter and clay can be something taking into consideration to improve the environment. It is wonderful to plants like this that can produce nutritious healthful crops under otherwise challenging environmental conditions. Some thoughts, Paul 

Calcium chloride is the best source of calcium. the concentration in the range of 1000-2000 ppm. add Tween 20 as wetting agent at 0.1%v/v.

Dear Babak Malekian,    Under your conditions you may be suffering from a range of micronutrient issues especially if your soil is alkaline and sodic. I would suggest using leaf tissue analysis to determine how the nutrient balance in the foliage is and to provide a soil analysis. If you are low in micro nutrients and Calcium your best bet might well be to target the flower break and flowering stages with foliar application of vermicompost tea which would provide both Calcium and a range of micronutrients Zinc, Copper, Manganese, Iron and Boron along with Calcium. The use of tissue analysis and soil analysis would take the guess work out of the program. If you have soil and tissue analyses I would gladly give my opinion on your situation.  Sincerely PRH

Dear Dr.Hepperly

Thanks so much for your perfect answer.

Dear Dr. Babak,

The strategy suggested by Dr. Hepperly is perfect. It is important to know the limiting nutrients by soil and plant analysis. As a source of Ca, i would suggest calcium nitrate instead of Calcium chloride to be applied by foliar spray at critical fruit development stages like initiation of floral bud formation, early stage of fruit formation and fruit development. In case B is a limiting nutrient, you may go for foliar application of borax (2 g borax/ l). Borax needs to be dissolved in hot water before final dilution.

Dear Prakash Chandra Srivastava, Thank you for supporting the needs of holistic analyses for defining nutrient strategy. One of the reasons I like vermicompost so much is not only Calcium is applied but also the material is rich in micronutrients such as Boron, Zinc, Manganese and others which can be limited as well as humic substances not to mention beneficial biology from the worm gut. In addition the humic components of the compost tea provides for chelation into solution of elements which are otherwise with mobility issues. In addition the humic material allows their ready  absorption into foliar surfaces. At these stages huge amount is not needed but often a Calcium suspicion is associated with Boron insufficiency and as you say both go together. We must not forget our micronutrient needs very critical in nuts and other crops. The use of foliar and soil analysis makes the black box of our plant soil system into one where the analysis lights the way for underlying situation in both the soil and the plant. The situation in particular shows alkaline and salt issues and working with the water source and pH of the soil can work together in remediating the issues. The underlying lack of Phosphorus and the low amount of organic matter and clay can be something taking into consideration to improve the environment. It is wonderful to plants like this that can produce nutritious healthful crops under otherwise challenging environmental conditions. Some thoughts, Paul 

Endorsing some thoughtful comments from Paul, lets consider the fact , that calcium is a kind of nutrient  , which is in need throughout the crop growth , especially while addressing the perennial nut  fruit.  Leaf analysis is absolutely necessary , based on which an optimum value needs to be maintained . Importantly , calcium may not be maintained in higher proportion during early spring  due to lack of sufficient sink  , probably at later stages while seeds are in developing stage , a stronger sink for  calcium could physiologically be  developed , to be later  partitioned effectively accordingly to sink strength . Monitoring calcium concentration early in season would , therefore , be difficult , since most of the leaf analysis values address nutrient concentration at much later stages of crop growth....

Here is one nice PDF  for further reading....

Dear Folks, Sometimes the issues with Boron are attributed to Calcium issues. In fact both Calcium and Boron are needed in optimal rates to prevent the tip blast symptoms which can be quite common. Our interest in Pistachio may be very appropriate in the idea of concentrating on nut set. A crop like maize or wheat only need some 5 to 25 ppm Boron in their leaf tissues to be optimized. checking out Pistachio it is the highest for its Boron sufficiency according Borax company resource needing some 150 to 190 ppm in the foliage. I would really encourage that we take those Pitaschio leaf analysis and see where we are in relation to boron sufficiency range. If you take 20 to 30 leaves and dry them they can be send to a laboratory of atomic spectral analysis including the micronutrients and majors. Boron is relatively inexpensive to provide but in deficiency situations can cause sizable effects on nut production being expressed as aborted flowers and deformed nuts. 

Did You experienced with Ca deficiency in Pistachio, is really problem to aquire this element, lime forecrop it is common practice, soil Ca level too low? Maybe gypsum reliefs the problem, it is cheap and adds Ca ion and simultaneously fight with Na salinity  issue

Dear Krzysztof Gediga, The choice of Calcium sources is important if you have an alkalinity problem which might be found in semiarid and arid zones liming could make the situation worse. In that case gypsum may be more useful. If you are in acid soil liming may be fine but check for level of Magnesium to determine if Dolomite is your liming choice. The ability for Calcium to be used is often associated with Boron. Water, soil and plant analysis is your best friend and monitor how your measure impact the nutrient situation. Good Insights KG PRH

Clear cut Ca-deficiency in field , especially in perennial fruits is difficult to identify . we have hardly witnessed such symptoms. But . soil pH can throw enough clues on possibility Ca being one of the major fertility constraints. Paul has rightly hinted to use dolomite than lime in alleviating low soil pH-related plant nutritional issues, duly supported through soil-plant analysis.  Gypsum holds more promise in sodic soils , than using this source as Ca-source in acid soils. 

When  using soil readings my experience has shown that when Calcium is superior to 1000 and Magnesium is superior of 100 and Boron is 1 to 2 ppm there is little potential of issues with these components. Nutrients many times show a threshold response below the threshold you will have issues in the zone not  a problem. The emphasize on exact ratios I have less confidence in because many times to make those changes an ideal ratio may not be economic and additional input is probably neither warranted nor feasible. While soil readings are always a start fine tuning will ultimately need a tissue analysis to confirm what exactly is mobilized from the soil. Although there are cases where Calcium would not show outright deficiency symptoms there is potential benefit is using Calcium to address issues such as fruit softening and premature ripening. On acid soils if the pH is adjusted by appropriate liming there is rarely any issue with Calcium availability more common however on some ultisols and oxisols the soil is severely deficient with Magnesium and when in these acid soil situations Dolomite shoulb be  used as liming source and when done  the issues with both Calcium and Magnesium are resolved. My experience would also suggest Boron deficiency is quite widespread yet people do not address it based on fears of inadvertently causing toxicity issues.  Rarely in my experience with thousands of soil analysis do I see Boron in what I would consider the optimum range.