256-24 Comparing Aluminosilicates Adsorption Capacity of Nitrogen, Phosphorus and Potassium.

Poster Number 203

See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: General Soil Fertility and Plant Nutrition: II
Tuesday, October 18, 2011
Henry Gonzalez Convention Center, Hall C
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Alberto Bernardi1, Gilberto B. Souza2, Larissa Silva3, Marta Fujita3, Elaine Pereira3 and Caue Ribeiro4, (1)Soil Fertility, Embrapa Pecuaria Sudeste, Sao Carlos, Brazil
(2)Chemical Analysis, Embrapa Pecuaria Sudeste, Sao Carlos - SP, Brazil
(3)UFSCar, Sao Carlos - SP, Brazil
(4)Nanotechnology, Embrapa Instrumentacao Agropecuaria, Sao Carlos - SP, Brazil
Aluminosilicates with negative charges provide an exchangeable site for positive cations such as K, Ca and Mg, and positively charged groups such as water and ammonia. Due the weak attraction absorbed cations can be easily replaced using the standard ion exchange techniques, making these natural minerals good ion exchangers and their use may improve the fertilizers use efficiency by controlling nutrient retention and release. A laboratory study was undertaken to determine the adsorption capacity of nitrogen, phosphorus and potassium by the three natural aluminosilicates. Four experiments were carried out in laboratory for nitrogen and phosphorus/potassium adsorption study in a totally randomized experimental design with three replications. Adequate period for adsorption study were determined with two experiments where 1 g of clinoptilolite was shacked in 50 mL solutions of 0.001 mol L-1   (NH4)2SO4 and 0.001 mol L-1 K(H2PO4) for 0, 0.5, 1, 2, 4, 5, 8, 10 and 24 hours. Nitrogen adsorption were determined by shaking 1 g of clinoptilolite, zeolite and bentonite aluminosilicates at 5, 10, 20, 40, 60, 80 and 100 mg N L-1 in 50 mL solution of (NH4)2SO4 at water, 0.1 mol L-1 NaCl and 0.1 mol L-1 KCl, respectively, for a total of 30 min. Phosphorus and K adsorption were determined by shaking 1 g of clinoptilolite, stilbite and bentonite aluminosilicates at 0, 5, 10, 20, 40, 60, 80 and 100 mg L-1 of P an K in 50 mL solution of K(H2PO4) for a total of 30 min. After centrifugation N and P concentrations in supernatants were measured by spectrophotometry with flow injection analysis (FIA), and K concentrations with flame photometry. Maximum adsorptions were obtained with 30 min of shacking indicating ion exchange phenomena for N and K. Clinoptilolite adsorbed almost 100% of N and K in solution, bentonite 50% and zeolite 25%. Results showed N and K adsorption order was clinoptilolite, bentonite and stilbite. There was no difference on P adsorption, which was lower than 10% of total P in solution for all aluminosilicates. These results also indicate that aluminosilicates minerals probably are able to improve the efficiency of N and K through the control of ions retention and, therefore, enhancing plants absorption ability.
See more from this Division: S04 Soil Fertility & Plant Nutrition
See more from this Session: General Soil Fertility and Plant Nutrition: II
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