Any organic amendment , by and large , has encouraging effects on bioavailblility of boron on calcareous soils , dpending upon the reduction in soil pH and dissolution of calcium carbonate , since both crops are sulphur loving in nature.

Dear Sukhvir,

Calcareous soils have free calcium carbonate (CaCO3) in the profile. The carbonates, due to their relatively high solubility, reactivity and alkaline character, buffer the pH of most calcareous soils within the range of 7.5 to 8.5. These soils generally have 100% base saturation, and the exchange complex is dominated by calcium. Nutrient management in calcareous soils differs from that in non-calcareous soils because of the effect of soil pH on soil nutrient availability and chemical reactions that affect the loss or fixation of almost all nutrients.Nitrogen fertilizers should be incorporated into calcareous soils to prevent ammonium-N volatilization. The availability of phosphorus and molybdenum is reduced by the high levels of calcium and magnesium that are associated with carbonates. In addition, iron, boron, zinc, and manganese deficiencies are common in soils that have a high CaCO3 due to reduced solubility at alkaline pH values.

Boron: Soil pH affects B availability more by sorption reactions than by formation of less soluble compounds. Availability of B is highest in the pH range of 5.5-7.5. Boron is sorbed to Fe and Al oxides in soils and is lowest in the pH range of 6-9

Responses to boron application in sandy calcareous soils have been reported for sugar beet and bitter orange .In deficient soils, B is most applied in the form of sodium borates (Na2B4O7 xH2O). Excess and toxicity of B usually occur in soils with high levels of B or due to additions of B in irrigation water

In addition, iron, boron, zinc, and manganese deficiencies are common in soils that have a high CaCO3 due to reduced solubility at alkaline pH values.Boron (B) availability is regulated by its equilibrium concentration that in turn is buffered by adsorption and desorption reactions. Ionic strength, pH, OM content, and the type and amount of minerals are the major factors affecting B sorption reactions. To evaluate the influence of calcium carbonate equivalent (CCE) and ionic strength on B chemical behavior, its adsorption and desorption isotherms were measured in eight calcareous soils differed in CCE (0–85%). Adsorption and desorption data were described by the Langmuir and the Linear adsorption equations, respectively.

Regards,

Prem Baboo

Boron availability is affected by alkaline pH, coarse soil texture, low organic matter.

If your soil analysis has 1 to 2 ppm B it will be sufficient for soybean production.

If soil reading is less than 1 ppm especially under 0.7 ppm Boron might be a problem  in terms of deficiency for soybean. soil boron over 2 ppm can reach toxicity levels so care needs to be taken.

Alternatively you can also analyze the soybean for the foliar Boron content. If the foliar level is over 60 ppm Boron deficiency should not be problematic.

Excessive Calcium carbonate can reduce Boron toxicity but in a sandy alkaline low organic matter soil organic amendment it could be beneficial to amendment and adjust to optimize soybean nutrition.

In an alkaline soil with high carbonate it is likely you may experience Iron chlorosis deficiency.

Start your quest by getting a complete soil test and complementing with tissue tests. If the soil is very alkaline you can address some of the issues by banding sulfur to help adjust the soil reaction to improve B and  Iron availability.

When the soil organic matter is less than 1% you are likely in need for addressing deficiency situations. Liming a neutral pH soil can easily lead to iron and boron deficiency.

In sandy low organic matter soils the ability to use silt and clay in the compost mix can be useful for stabilizing organic matter and improving the long term modification of a coarse soil. The ability to retain and recirculate water from the soil lessens the Boron deficiency issues and improves plant nutrition generally.

if you have a soil analysis and or foliar analysis I would be glad to give an opinion on the limiting factors you might experience. I have over 35 years experience working with soybean.

I very  appreciate the very good replies/comments of Dr. Baboo and Dr .Hepperly .I have also quickly gone through the write up of Dr.Hepperly. Three points are very clear.We should not encourage practices that lead to soil acidification. Legumes and organic manures will definitely help to control and buffer soil pH.Our staple food crops are low in Boron.Relating micronutrient deficiencies to human diseases is very important and deserve great attention.I liked the write up pertaining to osteoporosis and arthritis.I think  crop boron nutrition in relation to human arthritis need great attention.

I made most comments related to soybean but Brassica plants have higher demand for Boron and also have a sizable Sulfur demand related to their defensive compounds. The Brassicas are good bioindicators as under low condition hollow heart is common.

Dr Hepperly , nice comments as usual . How do you see the emergence of boron -deficiency in alkaline soils ?. Like many other micronutrients , boron  is also a very poor sink for edible plant parts , but accumulates nicely in leafy parts. But boron has one extra-ordinary biochemical  property that it can easily move inside the plant as sugar-borate complex.

Dear Folks,

Boron is recommended in soil at 1 to 2 ppm.

However, in the extensive testing I have seen it seldom is at that level but mostly below 1 ppm. We see that Boron deficiency in sandy acid soils and in alkaline soils. The symptoms are mostly expressed as a deficiency in the tips causing necrosis tip dieback and stem proliferation or witches broom.

I believe the crucifers that readily show hollow stem are a good indicator but by that time losses have already occurred.

Therefore, by doing a foliar analysis is a patently good idea and using foliar remediation before damage to crop performance is acute.

Boron can be high in well water and for irrigated crops I have seen deficiency in the soil and toxicity related to irrigation water.

End opinion is that Boron deficiency and toxicity can be happening in alkaline soils because of the same window of deficiency to toxicity monitoring and testing is paramount. In fact I believe Boron deficiency is often a hidden one where people are unaware of a compromised situation.

As Dr. Anoop Srivastava says the Boron connection to sugar movement is well documentent. This probably explains how  Boron can have a marked beneficial effect on grape and fruit brix.

What is your experience Doctor in citrus?

Varieties and species can vary markedly in their reactions to deficiencies and toxicities according to my experience.

In relation to fertilizer for Brassica the use of Sulfur is very important as the cabbage family defensive biochemical are based on isothiocyanates. If I were planting such crops the use of 80-30-60 with appropriate micronutrients might be ball park goal for a conventional crop. Of course the recommendations can be fine tuned with soil testing and confirmations with foliar tests.

A very important role of crucifer family in plant rotations is their fumigant effect which can lower nematode, fungi, bacteria and weed seed levels. Care in this biofumigant approach is that the crucifers are notably not mycorrhizal and the level of benefical fungi can be affected.

Life is complicated!!

Thanku Dr Sahib.