Acidic soil (IGKV RAIPUR C.G)

Acidic soil Effect of components (IGKV RAIPUR C.G)

1. ACIDIC SOIL

2. Introduction Soil acidity may be defined as the soil system’s proton (H+ ions ) donating capacity during its transition from a given state to a reference state. Soil having PH 5.5 are called acidic soil. Acid soil occupy approximately 60 % of the area of earth . When the concentration of some elements which are naturally acidic in reaction ,goes too high in soil ,soil become acidic and their PH goes down below 7.

3. Origin of Acidic soil CLIMATE: acidic soil are generally formed in humid region and high rainfall areas. In these regions, evaporation of water from the soil surface is less then precipitation . Excess amount of water moves downward in the soil and leaching of nutrients like calcium and magnesium takes place which results in formation of acid soil.

4. Continue … PARENT MATERIAL : soil developing from acidic rocks like igneous rocks results in formation of acidic soil. ACID FORMING FERTILIZERS: application of acid forming fertilizers such as Ammonium sulphate ,Urea, Ammonium nitrate etc. produce soil acidity.

5. Continue.. ORGANIC MATTER: During organic matter decomposition ,humus ,organic acids and different acid salts may also be produced and also concentration of Co2 increased . T he increased concentration of Co2 , hydrolysis of acid salts and various organic acids combinely increase the total acidity of soil.

6. Continue… HUMAN ACTIVITY : Excessive use of water or keeping the field submerged for long time accompanied by improper drainage may lead to the development of acidic soil.

7. Properties of Acidic Soil PHYSICAL PROPERTIES: Light texture. High permeability Poor water holding capacity. P oor organic matter Mainly kaolinite and some time illite clay minerals are present.

8. Continue… CHEMICAL PROPERTIES: More anion then cation . Availability of nutrients: Al,Fe,Mn,Cu,Co. BIOLOGICAL PROPERTIES: population of Fungi more then that of bacteria Rate of decomposition of biological materials , mineralisation and nitrification etc. are reducesd when acidity is increased.

9. Effect of soil acidity on plants DIRECT EFFECT: Toxic effect of H+ ions on root tissue. Phytoenzyme released by plant at root zone lose it effectiveness if hydrogen concentration goes to high. Mineralization process becomes slow. INDIRECT EFFECT: concentration of Al , Fe, Mg increased which cause plant toxicity.

10. Iron toxicity in Rice Mn Toxicity in cucurbits

11. Continue… Deficiency of Calcium occurs. The phosphate ion reacts with Aluminum or iron and insoluble phosphate of these element are formed and become unavailable to the plant. S ome essential micronutrient such as iron, manganese, copper etc. are required by plants in very low amount .they become highly soluble in acidic soil and become toxic to plants. Some disease causing fungi flourished well in acidic soil and cause root rot of tobacoo,blight of potato.

12. Aluminium toxicity in maize Late blight (Fungi disease) in Potato

13. Distribution of acidic soil Out of 146 million hectare of cultivable land in India ,49 million hectare of land are acidic ,of which 26 million hectare of land having soil PH less then 5.6(PH < 5.6) and the rest 23 million hectares of land having soil PH range 5.6 to 6.5. In India large area under acidic soil are Assam ,Manipur and Tripura .

14. Acidic soil found in India