Yogy's biology

07 Plant Growth and Mineral Nutrition - part 17 - Nitrogen cycle Nitrogen cycle:  It is series of natural processes by which  Nitrogen enters successively from air to organisms through soil and back to environment.  Plants use photosynthetic product, the  sugars to make proteins.  To do this, they need nitrogen.  Unfortunately, it is very  innert  (nonreactive). Plants need nitrogen in a reactive form usually as  nitrate ions. Nitrogen is a  limiting nutrient  in the agricultural ecosystems.  It exists as nitrogen atoms with a strong triple covalent bond  (N≡N).  A regular supply of nitrogen to the plants is maintained through biological and physical process.  Nitrogen fixation : Atmosphere is the source of nitrogen.  Can not be used directly.  Combines with  C, H, N and O  to form compounds before being used. Conversion of  free nitrogen (N 2 )  of the atmosphere into nitrogenous sa...

07 Plant Growth and Mineral Nutrition - part 16 - Mineral nutrition Mineral nutrition :  Minerals constitute most commonly  -  Occuring solid Inorganic materials obtained from the earth's crust.  Plant absorbs mineral elements from surroundings (soil, air and water) for its use.  About  36 to 40  different elements of periodic table are used as minerals by the plants.  These are absorbed in ionic (dissolved) form as  PO 4  , CO 3  , SO 4   , etc.,usually through roots ( regions of elongation and growth ).  Sources of minerals :  Carbon  enters the plant as  atmospheric carbon-dioxide.  Source of  hydrogen  is  water  and  oxygen  comes from  air and water.  Carbon, Hydrogen and oxygen are not minerals in origin.  Source of  nitrogen  is the  soil.  Plant derives nitrogen from both mineral and non-mineral origin.  Classificaion of mine...