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Similar to Nutrients soil fertility
Nutrients soil fertility
- 1.
- 2. Ability of soilto supply nutrients for plant growth
- 3. Soilis storehouse of nutrients Some available, some not
- 4. Soilfertility: quantity of nutrients soil contains how well protected from leaching how available to plant how easily roots can take them up
- 5. Plantnutrients Essential elements needed for plant growth
- 6. Plant nutrients Plantsabsorb 90 elements Only a few needed for growth Some not needed by plants but by animals that eat plants (cobalt) Others not needed, can be toxic (lead)
- 7.
- 8. How to determinewhich are essential?
- 9. Essential plant elements1. lack of element stops plant from growth or reproduction 2. element is directly involved in plant processes 3. shortage of element can only be corrected by supplying that element
- 10. 17essential elements 3 account for 95% plant needs carbon, oxygen and hydrogen come from water, air
- 11. Non-minerals Macronutrients Air and Water Carbon (C) Hydrogen (H) Oxygen (O)
- 12. 14come from soil 6 used in large amounts: macronutrients Nitrogen Calcium Phosphorus Magnesium Potassium Sulfur
- 13. PrimaryMacronutrients Nitrogen Phosphorus Potassium Not always available in large enough quantities Add by fertilizing
- 14. Secondary Macronutrients Calcium Magnesium Sulfur Soil usually has plenty
- 15. Micronutrients 8 nutrients left Used in small amounts Plant won't grow normally without them
- 16. NUTRIENT IONSPlants absorb some of the nutrients as ions instead of elements Ion has positive or negative charge
- 17. Ion has: positivecharge cation negative charge anion
- 18. Ions formin soil when compounds dissolve in water Example: Potassium nitrate (fertilizer) dissolves in water, molecule breaks down into potassium ion and nitrate ion
- 19. Plant roots absorb ions - soak like a sponge Soil particles adsorb ions - hold on to them - stick to it
- 20.
- 21. SOURCES OF ELEMENTSIN SOIL Nutrient elements present in soil in four places (pools)
- 22. SOURCES OF ELEMENTSIN SOIL 1. soil minerals major source released slowly by weathering not source of nitrogen
- 23. SOURCES OF ELEMENTSIN SOIL 2. organic matter large amounts of nitrogen nutrient anions released by decay
- 24. SOURCES OF ELEMENTSIN SOIL 3. adsorbed nutrients held by clay and humus particles relatively available to plants
- 25. SOURCES OF ELEMENTSIN SOIL 4. dissolved ions ions in soil solution plants absorb directly may be leached
- 26.
- 27. Soilcolloids Tiny particles of clay and humus with slight electrical charge This charge attracts plant nutrient ions
- 28.
- 29. adsorption Negatively charged colloid attracts swarm of cations from soil solution
- 30.
- 31.
- 32. Cation Exchange Whenone ion taken up by plant (pulled off soil particle), replaced by another. Replacement of one cation for another
- 33. Ability ofsoil to hold nutrients – directly related to the number of cations it can attract to soil colloids Determined by the amount of clay and humus in soil mix
- 34. Displacement of cationsdepends on: Relative concentration high concentration displaces low The number of charges on a cation
- 35. high CHARGE displaceslow Al>Ca>Mg>K>Na
- 36.
- 37. Plant roots havenegatively charged surfaces positively charged hydrogen ions attached Cation exchange takes place when plant roots exchange positive hydrogen ions for cations on soil colloids or in solution
- 38. CationExchange Capacity (CEC) The ability of soil to hold exchangable ions CEC expressed in milligram equivalents per 100 grams of soil (mEq/100g)
- 39.
- 40. Bonding strength If two cations are present in soil in equal numbers one that bonds most strongly will be adsorbed others will be leached out
- 41. Mass action moreions in soil, more exchange sites it will occupy
- 42. Weakly heldcations are more available for plant uptake
- 43. A clay particleis covered with negative charges Opposites attract, ions with positive charge(s) stick all over surface of clay root hairs secrete H+ into water around clay particles Smaller H cations replace larger cations
- 44. Several nutrientsavailable to plants as negatively charged ions – anion exchange Negative charge means it is repelled from cation exchange site Anion exchange greatest in acid soils
- 45. Implications for Growing High CEC soils have more clay Low CEC soils more sand
- 46.
- 47. Herbicide CECdetermines how much herbicide should be used. Colloids absorb pesticides also, tie them up. High CEC, clay soils usually need more to get effect you want
- 48. Fertilization High CEC soils have greater ability to hold nutrients - larger amounts, less frequently Low CEC - smaller amounts more frequently - leach out
- 49. Golf courses- all sand - low CEC - fertilize lightly and often Greenhouses - soilless - low CEC - fertilize lightly and often
- 50. Improve CECby adding organic matter Clay soils need less organic matter except to aerate soil
- 51.
- 52. Nutrientabsorption Nutrient ions cross cell membranes of root cells and move into vascular system
- 53. Some uptake ispassive Most uptake is active - takes energy to pull nutrients into high concentration already in plant
- 54. Roots produceenergy by respiration Waterlogged soil limits respiration - limits nutrient uptake
- 55. Root hairsget ions from soil solution by their own form of cation and anion exchange
- 56. As roottips grow, move through solution, constantly finding more nutrients
- 57. Capillary actionmoves nutrients through solution toward plant roots
- 58. Diffusion moves ions through soil solution – higher concentration to lower concentration
- 59. Factors affecting uptake Anything interfering with photosynthesis - slows growth, slows uptake --low light --poor drainage --soil compaction --dry soils --soil temperature
- 60.
- 61. Luxury Consumption Plants can sometimes store nutrients for when growth may be slowed
- 62. Plantswith deep roots, healthy roots need less fertilization