| In the past decades ,a great many study has been done on the supply ability of soil in internal and international, and some method has been formed and developed to determine soil available potassium. Different country or region, even different soil type use different method. Presently,the rutine methods only extract a part of all soil avaible potassium, the result are qualitative or semi-quantitative analysis.This study base on compare rutin methods, through several means to found a method which can measure the change of soil potassium exactly, discuss the feasibility of value the Kcapacity of soil with sodium tetraphenylboron (NaBPh4) method, to the effect that offer evidence for use the potassium of our countrywith reason.We accede different amount of K to wuxi soil and then extract potassium with various meanses.The result indicate that the reclaim percentage with current normal regulations methods are not satisfying.The K reclaim percet with ammonium acetate method, 2mol/L Nitric acid and lmol/L Nitric acid boi method is 20%,30% and 50%. The K cumulative reclaim percent extracted continuously by 2mol/L Nitric acid is 60%; K cumulative reclaim percent extracted continuously by lmol/L Nitric acid boil is 75%; K cumulative reclaim percent extracted continuously by lmol/L Nitric acid boil in autoclave is 80%.The K cumulative reclaim percent extracted continuously by 2mol/L Nitric acid with ultrasonic is 75%.The mechanism of current normal regulations method is far different with plant root ,but NaBPh4 can simulate the mechanism of plant root absorb soil nutrient well. We studied NaBPh4 method through change the extract condition, the concentration of NaBPh4 and GuCl2, the extract time , the temperature etc .The main results of this study were showed as follows:1.The amount of K extract with NaBPh4 is increasing with the increase of the NaBPh4 concentration during0.01mol/L-0.25mol/L.The max K amount extract is coming when the concentration of NaBPh4 is 0.25mol/L.2. The concentration of GuCl2 is also effect the amount of K extract with NaBPh4 method.The deposition appear during the experiment will not dissolve even boil when the concentration of CuCl2 is thin.The result of experiment showed that the prime concentrition of NaBPLt or CuCL2 is 0.25mol/Lor 0.14mol/L.3.Threr is no obvious difference between percentage recovery of K extract with NaBPh4 under ultrasonic or surge,both are about 80%.4. NaCl can accelerate potassium release from soil. The amount of K extract with NaBPh4 is increasing with the increase of the NaCl concentration.The max K amount extract is coming when the concentration of NaCl is 0.17mol/L.5. The amount of K extract with NaBPh4 is increasing as the time pass by, but the velocity of increase is gradually decline.There is a obvious inflexion when the extract time is 2 hours,it indticate that the K extract later is part of hardly extract K.6. Among accede calcium carbonate powder to soil, confect extracting solution withbuffer solution, drop several drop of NaOH solution, the effect of the last one is thebest, and the difference is very markedly.7.The effect of temperature on extract potassium with soil is very great, The amount of K extract with NaBPh4 is increasing from 500mg/kg to 3100 mg/kgwith the increase of temperature during10C-80C.The extract ability of NaBPh4 on 80C increase five times than on 10C.The amount of potassium extract will not increase when the temperature is beween 80C and 90 C, when the extract temperature is 100 C,the amount of K extract will not increase , decrease 100mg/kg on the contrary. The percentage recovery of potassium is low when the extract temperature is 10Cand 15 C,it is only 66.9% and 77.5%,the percentage recovery of potassium is fluctuated between 90% and 105%.8. There are much difference in the amount of potassium extract of different soils sampling from different region with current normal regulations methodsand NaBPh4 method for the clay mineral and other character are differentbut there are similar trend. The percentage recovery of...
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