Functions of Carbon, Hydrogen and Oxygen
- 1. Institute of Agriculture and Animal Science (IAAS) Prithu Technical College Deukhuri, Dang SSC-121 Assignment Planning Essential Elements: Forms, Occurance, Functions and Deficiency Symptoms Krishna Aryal Asst. Professor (Soil Science) [email protected] 1
- 2. Institute of Agriculture and Animal Science (IAAS) Prithu Technical College Deukhuri, Dang SSC-121 Assignment Planning 2 Forms and functions of carbon, hydrogen, oxygen in plants • C, H & O are obtained by plants from air & water. • C & H absorbed in combined form, O partly taken from molecular form. • These 3 elements for all life form about 95% of the dry weight of plants.
- 3. Institute of Agriculture and Animal Science (IAAS) Prithu Technical College Deukhuri, Dang SSC-121 Assignment Planning 3 Functions • They are major constituents of all organic chemical compounds of which the plant is made & they are concerned with different metabolic reactions vital for plant growth & development. • They provide structure & give shape to plants. • Required for photosynthesis. • They play key role in providing energy required for growth and metabolism of the plant. • The bulk of energy required for the plant metabolism is derived from oxidative breakdown of carbohydrates, fats, & proteins during cellular respiration.
- 4. Institute of Agriculture and Animal Science (IAAS) Prithu Technical College Deukhuri, Dang SSC-121 Assignment Planning 4 Nitrogen • N is foremost important element which limits crop prod. • Plants normally contain between 1-5% N by dry weight (1.5% Shoot DM) • Nitrogen may be taken up by plants as either an anion NO3- (nitrate) or a cation NH4+ (ammonium) • Plant preferences for nitrate or ammonium are species-specific & are usually related to the natural environment of the species, with plants adapted to bogs, marshes, cold, or acid conditions often preferring ammonium-N, & most other dryland species preferring nitrate-N.) • In moist, warm & well-aerated soils, NO3- form is dominant.
- 5. Institute of Agriculture and Animal Science (IAAS) Prithu Technical College Deukhuri, Dang SSC-121 Assignment Planning 5 N presence in soil • Surface soil contain 0.02 to 0.25%.; OM contains 5% N. • NO3-, NO2- & NH4+ forms available for plant nutrition • Minerals humus complex also accounts for much additional N of soils. • Appreciable amount of NH4+-N may be fixed in sub soil & rocks
- 6. Institute of Agriculture and Animal Science (IAAS) Prithu Technical College Deukhuri, Dang SSC-121 Assignment Planning 6 Gains of nitrogen • Layer silicate clays, rocks and minerals • Mineralization of organic matter. • Fixation i. Physical N fixation ii. Chemical N fixation/industrial fixation iii. Biological N fixation a) Symbiotic N fixation b) Non symbiotic/asymbiotic N fixation N Fluxes in soil Losses of nitrogen • Leaching • Volatilization • NH4 + fixation by crystal lattice • Surface runoff • Denitrification • Crop removal, microbial removal • Soil erosion and runoff
- 7. Institute of Agriculture and Animal Science (IAAS) Prithu Technical College Deukhuri, Dang SSC-121 Assignment Planning 7
- 8. Institute of Agriculture and Animal Science (IAAS) Prithu Technical College Deukhuri, Dang SSC-121 Assignment Planning 8