论文部分内容阅读
为了研究土壤电化学性质的微域变化,应用微电极,测定了氧化还原电位、pH 和电导。结果表明,在含氧化还原体系的标准液中,测得的电位值与理论值相符,在土壤中,数值可较大电极低2—5毫伏。在应用微氢醌电极法测定土壤的pH 时,对干土所得的结果与玻璃电极数值一致;对于还原性土壤,不能够应用。在应用微电极测定电导时,对于长1毫米,极间距离1.1毫米的电极,在不同浓度溶液中可得一致的电导池常数,对于更小的电极,电导池常数随溶液电阻的减小而增大。在土壤中长期磨擦时,可导致电导池常数的稍许增加。应用了标准线的方法校正了这些误差。土块表面的氧化还原电位,较其内部为高。表面的电导也可以较内部高10—20%。颗粒磷肥在土壤中的离子扩散,在一定距离范围内符合log C=log A-kx~2的Fick扩散定律。荞麦使根际土壤的pH 降低,电导升高,氧化还原电位升高;水稻使根际土壤的电位升高,pH 降低,电导降低;小麦和大豆使根际土壤的电位降低。水稻根系的电导,与土壤中者保持一基本固定的比例。
In order to study the micro-domain changes in the electrochemical properties of soil, the redox potential, pH and conductance were measured using microelectrodes. The results show that the measured potentials are in agreement with the theoretical values in the standard solution containing the redox system and in the soil the value can be 2-5 mV lower for larger electrodes. In the application of micro-hydroquinone electrode method for the determination of soil pH, the result obtained for dry soil is consistent with the value of the glass electrode; for reducing soil, it can not be applied. When using the microelectrode to measure the conductance, a consistent cell constant can be obtained for different electrodes with length of 1 mm and distance between electrodes of 1.1 mm. For smaller electrodes, the cell constant decreases with decreasing solution resistance Increase. Long-term friction in the soil can result in a slight increase in cell constant. The standard line method was used to correct for these errors. The redox potential of the soil surface is higher than its interior. The surface conductance can also be 10-20% higher than the interior. The ion diffusion of granular P fertilizer in soil conforms to the Fick diffusion law of log C = log A-kx ~ 2 within a certain distance. Buckwheat decreased rhizosphere pH, increased conductance and increased redox potential. Rice increased rhizosphere potential, decreased pH and decreased conductance, while wheat and soybean decreased rhizosphere potential. The conductance of rice roots maintains a substantially constant ratio to those in the soil.