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Soil acidity treatment with calcium carbonate
** Reasons for plant death or non-growth when soil acidity:
There are many factors present in the soil due to acidity. These factors eventually lead to weak or lack of plant growth. The most important of these factors are the following:
1- The effect of the difference in acidity number on the penetration of different cations through the root membranes (preventing the entry of some of them).
2- The entry of hydrogen ions into the roots of plants from the acidic solutions surrounding them, which causes the cessation of many vital processes within the plant.
3- Preventing the occurrence of enzymatic processes due to the extreme sensitivity of enzymes to changes in the pH number in plant sap.
4- Nitrogen enters plants in most cases in the form of nitrates and turns into ammonium before reaching the stem. Any disturbance in this process due to the acidity of the soil undoubtedly affects the ability of the plant to form green tissues.
5- Disruption of the ionic balance between the mineral substances that pass through the root and its effect on the anabolic process inside the plant body.
6- The toxic effect caused by the aluminum ion in cases of severe acidity.
The effect of adding lime to the soil:
First, a physical effect:
Calcium, when added to the soil, collects fine soil granules (raises the porosity of the soil) and helps improve the movement of water and air in the soil and gives the soil the desired granular structure. And it affects indirectly by encouraging organisms that decompose organic matter and thus contribute to the formation of humus, which has an important role in improving the physical, chemical and biological properties of the soil.
Secondly, a chemical effect:
The increase in the soil pH number is accompanied by the addition of lime from 5, for example, to the PH number of 6.5, for example, with important chemical changes that can be summarized as follows:
1- Reducing the concentration of hydrogen ions in the ground solution.
2- Reducing the solubility of iron, aluminum and manganese.
3- Increasing the ability to benefit from phosphates and molybdates.
4- Increasing the concentration of adsorbed calcium and magnesium, thus increasing the saturation percentage of bases
Therefore, its importance in terms of the availability of nutrients for the plant and the removal of the toxic effect of some elements.
Third, biological effect:
Lime has an encouraging and motivating effect on soil organisms, thus increasing the decomposition of organic matter and the availability of nitrogen in the soil. Pushing enzymatic processes encourages the formation of humus and removes some intermediate products that may have a toxic effect on growing plants. On the other hand, calcium, by raising the pH, accelerates the formation of amides, the formation of ammonium, and the oxidation of sulfur. The addition of lime also activates bacteria that fix atmospheric nitrogen and streptococcus bacteria on the roots of legumes. Due to the need of the bacteria that carry out the nitrification process to calcium, the addition of this element increases the speed of the nitrification process