In this experiment we investigated the influence of various anions including oxalic acid encountered as solution phase in soil on the adsorption and desorption of sulfate in Chungwon Bt soil. The effect of chloride and nitrate on the adsorption of sulfate was not significant, suggesting that sulfate was better able to compete for adsorption sites at concentrations studied, in contrast to the large reduction in the amount of chloride adsorbed in the presence of sulfate. The results of competition for sorption sites between sulfate and anion showed that the simultaneous presence of two anions in solution was effective in reduction of competing anion at a maximum value of adsorption, due to the similar adsorption mechanism for anion competition. Therefore, the variation in the buffer power of the acids will produce a change in the strength and amount of adsorption and the competitive ability.
To identify causes for drastic decrease in yield of tomato with repeated culturing number of the bag culture substrate of greenhouse tomatoes we investigated the physical and chemical properties of a coir used as the bag culture substrate to grow tomato at the Booyeo tomato experimental institute located in Booyeo, Chungnam Province for three years from 2012 to 2014. The results showed that total porosity ranged from 65.4 to 73.1% for the bulk densities of coir ranging from 0.12 to 0.14 g cm . The volumetric water contents measured at 0.01 bar as air entry point were 25% (before), 33% (1 st yr), 45% (2 nd yr), and 37% (3 rd yr). Organic matter contents ranged from 82.0 to 96.2% (highest in 1 st yr). pH and EC ranged from 4.47 to 6.47 (highest in 2 nd yr), and from 22.2 to 53.5 dS m -1 (highest in 1 st yr) and cation exchange capacity ranged from 71.0 to 191.7 cmol kg -1(highest in 3 rd yr). The surface structure observed with electrical microscope showed that the number of large pores decreased with increasing cultivating time while the proportion of smaller pores increased, indicating that the coir was consistently decomposed. Therefore, we could conclude that these changes of all physical and chemical properties of the coir may influence the holding capacities of water and nutrients, resulting in deterioration of quality of culture substrate of greenhouse tomatoes.
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