EFFECT OF IONIC STRENGTH FROM DIFFERENT SALT RESOURCES ON BORON ADSORPTION IN CALCAREOUS SOIL

Abstract

This study was conducted in the laboratories of Soil and water resources department, college of Agricultural sciences engineering, University of Baghdad for the purpose of disclosing the effect of ionic strength from different salt mixtures on the adsorption of boron in a silty clay calcareous soil taken from the prior location of the college of Agriculture in Abu Ghraib, after a quite equilibrium of boron solution prepared from Boric acid at 0, 1, 5, 7.5, 10 and 20 \uf06dmole B.ml-1 at 298 Kalvin. Three ionic strength solutions were used 0.1, 0.2, 0.3 mole.L-1 of four different salts CaCl2, MgCl2, NaCl. And composed salt of the three salts at 3:1:1 ratios respectively. Langmuir single surface line equation was used for better description of the reactions of Boron adsorption in soil and calculating the constants of this equation (Xm and K). Results showed a significant increase in Boron adsorbed quantity in soil with the increase of the applied Boron, where the highest adsorbed quantity of boron was 56 \uf06dmole B. gm-1 soil of CaCl2 treatment of the ionic strength 0.3 mole.L -1. The increase in ionic strength led to a significant increase in adsorbed Boron for all salts with different rates, where it was 16.61\uf06dmole B. gm-1 soil of CaCl2 treatment of 0.1 mole.L\xad -1 then increased to 24.31, 28.03 \uf06dmoleB. gm-1 soil of the ionic strength of 0.1, 0.2, 0.3 mole.L-1 respectively while it was 15.37\uf06dmole B. gm-1in MgCl2 treatment and increased to 22.68 and 26.85\uf06dmole B. gm-1 soil of the ionic strength 0.1 K 0.2 and 0.3mole.L-1 respectively.. In NaCl treatment, it was 13.78 then increased up to 14.63, 15.96\uf06dmoleB. gm-1 soil of the mentioned ionic strengths. In the mixture salt, adsorbed Boron was 16.70 then increased to 19.53 and 22.15\uf06dmole B. gm-1 soil for the same ionic strengths. These different salts showed significant differences in adsorbed quantity of Boron, where CaCl2 treatment was exceeded followed by MgCl2, mixture salt, then NaCl treatments as an averages of the three ionic strengths where it reached 68.95, 65.26, 58.38, then 44.37\uf06dmole B. gm-1 soil respectively and at maximum adsorption capacity (Xm) at 58.26, 55.92, 47.90, 46.17 mg B. Km-1 soil, while bonding energy to soil particles (K) was 0.279, 0.244, 0.244, 0.125ml \uf06dB for the mentioned salts respectively. In general, soil is considered to have a high maximum adsorption capacity (42.88 mg B. Kg-1 soil) and low bonding energy (0.216 ml \uf06d-1 B) .