Study On Ratio Exchange Capacity Of The Exchangeable Cations In Purple Soil

Soil exchangeable cation is a direct source of the soil provided nutrients that needed by crop growth, Meanwhile, it also directly reflects the charge of soil colloids. Soil colloids exchangeable cations pecies composition and level of their content are in addition to influenced by the ion species and the content in the soil, but also take on the size of ion competition adsorbability on soil colloids. Currently scholars had deep exploration on the strength between soil exchangeable cation exchange capacity, and proposed impact strength of exchangeable cation exchange capacity factors. They ordered a sort on each exchangeable soil cation at the exchange capacity. From thecurrent study, People had a general perception on the exchangeable cation exchange capacity, but the relativeability of each exchangeable cation exchange between had not a specific metrics. This study was based on previous studies, using magnesium saturation-K+、Na+、Ca2+、H+exchange quantitative simulation methods, through the "Ratio law," the use of the exchange capacity oft he soil between the purple major comparative study of exchangeable cations to strike between the characterization of purple soil exchangeable cation exchange capacity of each strength parameters. The main results were as follows:(1) In the magnesium saturated soil sample preparation process,with the increase in the number of exchange, Mg2+ions, Na+ions, Ca2+ions content trends adsorbed on soil colloids have been significantly associated quadratic curve relationship. Then soil colloids adsorbed H+ions content is then obtained showed a significant correlation between a power equation.This shows that the use of10cmol(+)/L MgSO4solution of soil exchangeable cations followed each exchange, the variation of soil colloids cation adsorption capacity of each equation of the relationship between certain lawsare in line with the curve.(2) Research found that by replacing with10cmol(+)/L concentration of Mg2+ions on the size of the acidpurple soil cation exchange each exchange, with the Mg2+ions on the exchange of eight soil samples, which makes the pH of the soil samples increased only0.99units, and [H] concentration dropped8.77x10-5mol/L. This is mainly because the acid purple soil "Al3+buffers" dominated the soil pH buffer.(3) Mg2+ions were exchanged with the various exchangeable cations that adsorbed on the soil colloids. From the Mg2+ions content change curve in the soil adsorption after each exchange can be seen, during the fifth after the exchange, the curve has leveled off. This shows under the10cmol(+)/L of Mg2+ions concentration conditions Mg2+ions have basically completed the exchange of the soil samples in a variety of exchangeable cations.(4) When Mg2+ions exchanged Ca2+ions, Na+ions, K+ions that adsorbed in the soil colloids, from the curve for each ion adsorption can be seen, Mg2+ions in general in the first and second witching process has been exchanged substituted most of the exchangeable cations, but because each exchangeable cations Mg2+ions exchange capacity is different, not the same extent of its reach. And K+ions exchange is the most rapid and complete.(5) From the exchange process of Mg2+ions to the K+ions adsorbed in the soil colloids can be seen solutions till exists a certain amount of exchangeable K+ions in the exchange of post-exchange, and the total amount of K+ions swapped out were more than the total amount of K+ions in the original soil samples.This is because there are large amounts of hydration mica secondary2:1clay minerals in the soil clay minerals, and these minerals are relaesed semi-fixed part of the K+ions.(6) In the course of magnesium saturation, the trends of the total base ions adsorbed in the soil colloids are compliance with the quadratic equation, and showed increased first and then decreased. This is relevant with the Mg2+ions exchange capacity and Mg2+ions concentration range. Finally, because the Mg2+ions concentration limits and H+ions and Al3+ions exist in the system, the total amount of base cations did not reach base cations in the original soil samples.(7) According to the Ratio Law equation, we get ratio exchange equilibrium constants of the part of the exchangeable cations to Mg2+ions, and they were characterized the different exchange capacity of the part of the exchangeable cations to Mg2+ions. There are K+-Mg2+equilibrium constant is0.275; Na+-Mg2+equilibrium constant is0.0921; Ca2+-Mg2+equilibrium constant is1.25; H+-Mg2+equilibrium constant is1.18. Thus, the K+ions, Na+ions, Ca2+ions, H+ions exchange capacity between each other in the order of:Na+<K+4<Mg2+<H+<Ca2+,In the general cognitive, the H+ions due to smaller radius and weak hydration degree, its exchange capacity is greater than the Ca2+ions, but this conventional perception is contrary to this test. Therefore, the H+ion exchange capacity relative to other ions is limited to this experimental conditions to discuss.