Please have a look at this ResearchGate link and PDF attachments.

https://www.researchgate.net/post/How_soil_pH_affects_nutrients_availability_to_plants#post-comment-editor

Soil pH is the measure of acidity (sourness) or alkalinity (sweetness) of a soil. The pH scale goes from 0.0 to 14.0. The most acid soil is 0.0 and the most alkaline is 14.0. Halfway along the scale, 7.0, is neutral, neither acid nor alkaline. A soil gets more acid as the pH values decrease from 7.0 to 0.0 and is more alkaline as pH values increase from 7.0 to 14.0. Soil pH can affect plant growth in several ways. Bacteria that change and release nitrogen from organic matter and some fertilizers operate best in the pH range of 5.5 to 7.0 making this the optimum pH range. Plant nutrients leach from the soil much faster at pH values below 5.5 than from soils within the 5.5 to 7.0 range. In some mineral soils aluminum can be dissolved at pH levels below 5.0 becoming toxic to plant growth. Soil pH may also affect the availability of plant nutrients. Nutrients are most available to plants in the optimum 5.5 to 7.0 range. PH can also affect the structure of the soil, especially in clay soils. In the optimum range clay soils are granular and easy to work with. However, if the soil is either extremely acid or alkaline clay, soils tend to become sticky and hard to cultivate.

http://archive.naplesnews.com/community/gardening-the-ph-of-your-soil-can-affect-plant-growth-and-health-ep-1071358042-331319431.html/

If the pH is less than 7, most of the elements are ready to be absorbed, the cultivar is cultured in pH 7 - 8 soil, while tobacco and cotton are found in pH 5 - 5 soil.

It seems very interesting details Mr Arvind , I appreciated it.

Yes Mr Mahesh Kumar you have opened a deep related specific information.

higher or lower PH than 7 can generally minimize soil microbial activity which affects decomposition process and nutrients release leading to a shortage of nutrients to plant.

thanks Nihad for answering this question and giving us nice information. why do you think that tobacco needs more acidic soil?

The binding of many elements on the soil depends on the pH. Some may be fixed in a non-absorbable form by changing the pH. Therefore, both deficiency and excess symptoms occur in part depending on the pH of the soil. It is true: on acidic soils you can find a lack of phosphorus, magnesium and molybdenum. There may be a surplus of manganese, aluminum, iron and boron. Alkaline soils can cause a shortage of manganese, iron, boron and phosphate for plants. These element are fixed in a non-absorbable form for plants.

In addition acid damage can occur in acidic soils. An example of this is: In the acidic soil however it breaks down into aluminum ions and water: Al(OH)3+ 3H+ →Al3+ 3H2O. The aluminum ions are toxic to plants.

Thanks petra for these valuable information.

As you said , more elements are fixed in the alkaline or acidic soil and could not be available for plant.

This is one conclusion, Salwan. As has been demonstrated, the damage caused to plants by unfavorable pH values mainly due to nutrient deficiency or poisoning. This applies to all plants. But: the individual plant species differ in their sensitivity. Therefore they each have different optimal pH ranges. Examples: Barley must not be grown in acidic soil. Yellow lupins and rye must not be grown in alkaline soils.

Plant is responded differentially to soil ph as you said and gave a good example for barely which likes the alkaline soil and can survive the high EC up to 12, while lupins and tobacco are planted in acidic soil.

Now petra what are the reasons behind a different responses of plant to soil ph?

I suspect that the different plants have a different internal buffering capacity and thus a different tolerance.

Soil pH also affects the soil microorganisms responsible for most nutrient transformations in soil, regenerating mineral nutrients that are available to plants. The higher abundance of beneficial microorganisms are positively related to higher soil quality including plant growth, lower disease incidence and higher nutrient contents. Soil acidity impacts beneficial soil microbes.

This is very nice note Arvind that Microbial communities are diminished to acidity and alkalinity and most microbes like nitrobacter and Azotobacter are not tolerated to such events although some microbes are adapted to both events since years. Higher abundance of microbies in soil, bigger benefits for plant growth will be recorded.