Adsorption-desorption of zinc in soils and its availability as influenced by phosphorus in maize
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Date
2016
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Punjab Agricultural University, Ludhiana
Abstract
An investigation was undertaken on three different treated soils from long term experiment of Maize-wheat cropping sequence (1971) to study the adsorption-desorption of zinc in soils and its availability as influenced by phosphorus in maize. Three soils selected were Soil I (100%N), Soil II (50% NPK) and Soil III (100% NPK) and were tested for pH, EC, OC, available P, available K, available N, microntutrients and texture. A pot experiment was conducted at screen house with application of different levels of P (0, 30, 60 and 120 mg kg-1 soil) and Zn (0, 6.25, 12.5 and 25 mg kg-1 soil). Plant samples were analyzed for P and Zn concentration and their uptake. Soil III had highest dry matter yield, highest P uptake and lowest Zn uptake. Available P and dry matter was significantly and positively correlated, where as Zn uptake and dry matter showed significant negative correlation. Soil III with highest content of phosphorus showed the higher adsorption of Zn, adsorptive capacity, extent of Zn adsorption (n), bonding energy constant (K) and adsorption maxima (Y). Zinc dynamics were studied at different times (5, 15, 30, 60, 120, 240, 360, 480 and 960) minutes. The faster rate of Zn desorption during the first four hour may be attributed to desorption of Zn from macro-aggregates or the outer surfaces of micro-aggregates, whereas, the slower rate of desorption after four hour may correspond to desorption and diffusion of Zn from inside macro or micro aggregates. Experimental data was fitted into four kinetic models among which Elovich model was considered to be best suited.