After reading this article you will learn about the influence of lime on soil properties in relation to plant nutrition.
(i) Toxicity of aluminium and manganese is the most important growth limiting factor in many acid soils and this toxicity effect can be reduced by the application of liming materials. Besides this, the reduced uptake of calcium (Ca2+) and magnesium (Mg2+) in the soil solution can also be alleviated with the application of lime.
(ii) Removal of hydrogen (H+) ion toxicity which damages root membranes and also causes detrimental effect for the growth of beneficial microorganisms like bacteria can also be removed through lime application.
Many of the following indirect benefits may be derived through the application of lime during the amelioration of soil acidity.
(i) Phosphorus Availability:
At low pH values and on soils high in aluminium and iron, phosphates are rendered less available because of their reaction with these compounds. The application of liming materials to such soils will inactivate the iron and aluminium, thus increasing the level of plant available phosphorus.
If the soil pH is greatly increased by the application of excess amounts of lime, the availability of phosphorus will again be decreased due to precipitation as calcium or magnesium phosphates. So liming programme should be planned in such a way so that the pH can be kept between 5.5 and 6.8 to 7.0 in order to derive maximum benefit from the applied phosphatic fertilizers.
(ii) Micronutrient Availability (Fe, Mn, Cu, Zn, B and Mo etc.):
With the exception of molybdenum (Mo), availability of micronutrients increases with a decrease in soil pH. This can be detrimental because of the toxic nature of many of the elements in anything other than minute concentrations. The toxic effects of most of the micronutrients can be prevented by the application of lime.
Most of the organisms responsible for the conversion of ammonia to nitrates (NH3 â†’ NO3) require large amounts of active calcium. As a result nitrification is enhanced by liming to a pH of 5.5 to 6.5. Decomposition of organic matter and other plant residues can also be improved with the application of lime by increasing the activity of micro-organisms.
(iv) Nitrogen Fixation:
The process of nitrogen fixation both symbiotic and non-symbiotic is favoured by adequate liming.
(v) Soil Physical Condition:
The structure of fine textured soil may be improved by liming. This is largely the result of an increase in the organic matter content and to the flocculation of calcium-saturated soils. Liming decreases the bulk density of soils, increases infiltration and percolation rates of water. Liming checks soil erosion.
The amelioration of soil acidity by liming may have a significant role in the control of certain plant pathogens. Club root disease of cole crops can be reduced with the application of lime.
(vii) Efficiency of Fertilizers:
Liming increases the efficiency of different fertilizers especially nitrogenous and phosphatic fertilizers by modifying the soil reaction favorably.