Major nutrient pools and pathways of nutrient transfers crop atmosphere stable labile InorganIc ordanIc plants microbes labile soil stable InorganIc solution organIc leaching erosion
Major nutrient pools and pathways of nutrient transfers soil solution stable inorganic labile inorganic microbes plants stable organic labile organic leaching erosion crop atmosphere
The importance of different pools and transfers varies between nutrients Relative importance of global pools Significance of inorganic and organic pools and biological cycling Solubility of inorganic forms of nutrients Buffering capaci Movement of nutrients in soil solution Replenishment of nutrients in soil solution Concentrations of nutrients in solution close to roots
The importance of different pools and transfers varies between nutrients • Relative importance of global pools • Significance of inorganic and organic pools and biological cycling • Solubility of inorganic forms of nutrients • Buffering capacity • Movement of nutrients in soil solution • Replenishment of nutrients in soil solution • Concentrations of nutrients in solution close to roots
Importance of pools varies with nutrients Nitrogen (N) Almost entirely in organic form in soil(500- 5000kg/ha); exchange NH4 0-400kg/ha Soil solution: anion and cation(NO30.1 5mM) and NHa, 0.01-0. 5mM); very soluble low buffering capacity Large inorganic pool in atmosphere(N2);very inert(unreactive
Importance of pools varies with nutrients Nitrogen (N) – Almost entirely in organic form in soil(500- 5000kg/ha); exchange NH4 + 0-400kg/ha – Soil solution: anion and cation (NO3 - ,0.1- 5mM) and NH4 + , 0.01-0.5mM); very soluble; low buffering capacity – Large inorganic pool in atmosphere (N2); very inert (unreactive)
Importance of pools varies with nutrients Potassium(K) Inorganic pools in soil and plants Crystal-lattice K, 10-10,000kg/ha Soil solution: cation(K+),0.05-2mM; soluble EXchange K+, 10-500kg/ha Atmospheric pool negligible
◼ Potassium (K) ◼ Inorganic pools in soil and plants ◼ Crystal-lattice K, 10-10,000kg/ha ◼ Soil solution: cation (K+), 0.05-2mM; soluble ◼ Exchange K+, 10-500kg/ha ◼ Atmospheric pool negligible Importance of pools varies with nutrients
Importance of pools varies with nutrients Phosphorus (P) Both inorganic and organic pools in soil Organic P: 5-100kg P/ha Absorbed soil phosphate(inorganic P): 20 500kg soil solution: anions(H2PO4/HPO42-, depends on pH): 0. 1-2uM High buffering capacity
◼ Phosphorus (P) ◼ Both inorganic and organic pools in soil ◼ Organic P: 5-100kg P/ha ◼ Absorbed soil phosphate (inorganic P): 20- 500kg ◼ soil solution: anions (H2PO4 - /HPO4 2- ,depends on pH); 0.1-2μM ◼ High buffering capacity Importance of pools varies with nutrients