红壤交换性碱和交换性酸的研究 Ⅱ.与中性盐NaCl和Ba(NO3)2的关系

提出一个测定Cl- —交换性碱的方法。用自动控制pH的滴定装置定量地研究了一个砖红壤胶体和一个红壤胶体在NaCl和Ba(NO3) 2 溶液中的交换性酸的变化。结果发现 ,砖红壤和红壤胶体在两种盐溶液中 ,在测定pH范围内只出现交换性酸 ,红壤胶体的交换性酸量比砖红壤胶体的大。随着盐浓度的增高 ,交换性酸量的增幅由大变小 ,明确地出现一折点 ,NaCl在 30 0mmolkg- 1左右 ,Ba(NO3) 2 在 1 2 0mmolkg- 1左右。pH对交换性酸有显著影响 ,在Ba(NO3) 2 溶液中随pH升高而增大 ,在NaCl溶液中则出现一峰值。

EXCHANGEABLE ALKALINITY AND EXCHANGEABLE ACIDITY IN THE RED SOILS Ⅱ. RELATIONSHIP WITH NEUTRAL SALTS NaCl and Ba(NO3)2

WTBZ?1/2 Changes of exchangeable ?acidity? in the soil colloid of a latosol and a red soil with the presence of NaCl and Ba(NO 3) 2 solutions were studied quantitatively with an automatic pH control titration device. The results showed that in the two salt solutions only exchangeable ?acidity? appeared in the range of pH measured. The amount of exchangeable ?acidity? in the red soil is larger than that in the latosol. The increment of exchangeable acidity decreased with increase in concentration of the salt solutions. Turning points in the curve of the exchangeable ?acidity ?were observed when 300 mmol kga?a(c)-1aa of NaCl and 120 mmol kga?a(c)-1 of Ba(NO 3) 2 was added respectively. The exchangeable ?acidity?, which were significantly influenced by pH, increased with pH in the Ba(NO 3) 2 solution, but the peak value of the exchangeable ?acidity ?was found in the NaCl solution. A method of measuring the Cl --exchangeable ?alkalinity? was constructed. ?1/4WTHZ?1/2