{"id":553,"date":"2019-03-11T05:00:10","date_gmt":"2019-03-11T05:00:10","guid":{"rendered":"http:\/\/esp16.epgpbooks.inflibnet.ac.in\/?post_type=chapter&p=553"},"modified":"2019-04-25T07:38:46","modified_gmt":"2019-04-25T07:38:46","slug":"soil-ii-essential-macro-and-micro-elements-and-ion-exchange","status":"publish","type":"chapter","link":"https:\/\/ebooks.inflibnet.ac.in\/esp16\/chapter\/soil-ii-essential-macro-and-micro-elements-and-ion-exchange\/","title":{"rendered":"Soil- II (Essential, Macro and Micro Elements and Ion Exchange)"},"content":{"raw":"
\"epgp<\/a>\r\n<\/span><\/div>\r\n \r\n\r\nContents<\/strong>\r\n

1) Fertility of soil<\/p>\r\n

2) Essential elements<\/p>\r\n

3) Macronutrients and their functions<\/p>\r\n

4) Micronutrients and their functions<\/p>\r\n

5) Cation Exchange capacity<\/p>\r\n

6) Anion exchange capacity<\/p>\r\n

7) Exchangeable sodium percentage<\/p>\r\n

8) Significance of Soil Ion Exchange<\/p>\r\n

9) Soil pH<\/p>\r\n

10) Adjustment of soil acidity<\/p>\r\n11) Nitrogen cycle\r\n\r\n12) References\r\n\r\n \r\n\r\nFertility of Soil<\/strong>\r\n

Soil that produces abundant crops under the appropriate environmental conditions is coined the term \u201cfertile\u201d. Soil fertility reflects the soil- plant relationship with reference to<\/em> plant nutrients available in soil. Understanding the principles of soil fertility is vital to efficient nutrient management, profitable crop protection and environmental protection.<\/p>\r\n

By definition, soil fertility is defined as the innate capacity of soil to provide adequate amount of nutrients essential for plant growth during favorable conditions such as temperature, water and light, and the physical condition of soil while soil productivity is the economic concept that signifies the capability of soil to produce specified plants under well-defined and specified systems of management inputs and environmental conditions. It is a function of several factors rather than being a soil property alone.<\/p>\r\n \r\n\r\nEssential elements<\/strong>\r\n

For an element to be called as essential, it needs to meet the following criteria-<\/p>\r\n

The plant cannot complete its life cycle (seed to new seed) without it. If the element is specific in its physiological function in plants<\/p>\r\n

If the malady that develops in plant can be remedied only by that element.<\/p>\r\n

The element\u2019s function cannot be replaced by another element.<\/p>\r\n

The element is directly involved in the plant\u2019s growth and reproduction.<\/p>\r\n \r\n

Overall, 18 elements have been identified as essential for the growth of all plants. They are further classified not on their relative importance but on basis of their relative amounts into: Macronutrients<\/em><\/strong> (C, H, O, N, P, K, Ca, Mg, S) and Micronutrients<\/em><\/strong>(B, Cu, Fe, Mn, Zn, Mo, Cl, Co, Ni)<\/p>\r\n \r\n\r\nMacronutrients<\/strong>\r\n

The elements occurring in ample levels in plant biomass and fluids are known as macronutrients. They are divided into three classes: Structural (C, H, O), Primary (N, P, K) and Secondary (Ca, Mg, S).<\/p>\r\nTable 1: Macro-elemental nutrient, their uptake form and their plant mobility<\/strong>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
<\/td>\r\nNutrient<\/strong><\/td>\r\nUptake form<\/strong><\/td>\r\nMobility in Plant<\/strong><\/td>\r\nMobility in Soil<\/strong><\/td>\r\n<\/tr>\r\n
1.<\/strong><\/td>\r\nCarbon<\/td>\r\nCO2,H2CO3<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
2<\/strong><\/td>\r\nHydrogen<\/td>\r\nH+, OH-, H2O<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
3<\/strong><\/td>\r\nOxygen<\/td>\r\nO2<\/td>\r\n<\/td>\r\n<\/td>\r\n<\/tr>\r\n
4<\/strong><\/td>\r\nNitrogen<\/td>\r\nNO3-, NH4+<\/td>\r\nMobile<\/td>\r\nMobile as NO3-, immobile as NH4+<\/td>\r\n<\/tr>\r\n
5<\/strong><\/td>\r\nPhosphorous<\/td>\r\nHPO42-, H2PO4-<\/td>\r\nSomewhat mobile<\/td>\r\nImmobile<\/td>\r\n<\/tr>\r\n
6<\/strong><\/td>\r\nPotassium<\/td>\r\nK+<\/td>\r\nVery mobile<\/td>\r\nSomewhat mobile<\/td>\r\n<\/tr>\r\n
7<\/strong><\/td>\r\nCalcium<\/td>\r\nCa2+<\/td>\r\nImmobile<\/td>\r\nSomewhat mobile<\/td>\r\n<\/tr>\r\n
8<\/strong><\/td>\r\nMagnesium<\/td>\r\nMg2+<\/td>\r\nSomewhat mobile<\/td>\r\nImmobile<\/td>\r\n<\/tr>\r\n
9<\/strong><\/td>\r\nSulphur<\/td>\r\nSO4-<\/td>\r\nMobile<\/td>\r\nMobile<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n \r\n\r\nFunctions of Macronutrients<\/strong>\r\n\r\n \r\n

(1) <\/em><\/strong>Carbon, Hydrogen, Oxygen- It is the foremost component of carbohydrates, proteins and fats (94% of dry weight of plants). They aid in oxidative breakdown of carbohydrates, proteins and fats during cellular respiration. They also provide energy for the growth and development of plants. They are also called structural nutrients.<\/p>\r\n

(2) <\/em><\/strong>Nitrogen- It plays key role in, respiration and synthesis of proteins. It maintains fertility when bound to humus. It increases tillering and promotes vegetative growth of food crops. Deficiency <\/em>leads to decrease in rate and degree of protein synthesis, development of chlorosis<\/p>\r\n

\u00a0<\/em><\/strong>(3) <\/em><\/strong>Phosphorus- It makes up for structural component of membrane systems. Provides resistance to diseases in plants and also influences cell division, root growth, fruit and seed development. Deficiency <\/em>leads to restriction in root and shoot growth, shedding of leaves and delaying in flowering<\/p>\r\n

\u00a0<\/em><\/strong>(4) <\/em><\/strong>Potassium \u2013 It maintains water balance. It is an indispensable constituent of chlorophyll. It provides protection against fungal and bacterial diseases. Deficiency<\/em> leads to development of chlorosis and drying back tips of shoots and reduced growth of shoots<\/p>\r\n

\u00a0<\/em><\/strong>(5) <\/em><\/strong>Calcium- It controls soil acidity. It is involved in root elongation and cell division. It also acts as a buffer in plant system. It improves intake of plant nutrient by correcting the pH of soil. Deficiency <\/em>leads to wrinkled leaves, shorter roots, decrease in growth of plant.<\/p>\r\n

\u00a0<\/em><\/strong>(6) <\/em><\/strong>Magnesium- It is an important constituent of chlorophyll. It controls uptake of N and P from soil and also acts as a catalyst in activation of enzymes. Deficiency<\/em> leads to premature defoliation<\/p>\r\n

\u00a0<\/em><\/strong>(7) <\/em><\/strong>Sulphur- It promotes module formation, root growth and seed formation. It increases oil content in oil bearing plants. It is an essential nutrient for cereals, sugars. Deficiency<\/em> leads to brittle leaves and stems.<\/p>\r\n \r\n\r\nMicronutrients<\/strong>\r\n