土壤硼不同化学库特性研究　Ⅱ．钙在土壤硼转化过程中的作用初探

STUDIES ON PROPERTIES OF DIFFERENT CHEMICAL POOLS OF SOIL Ⅱ.INVESTIGATION INTO THE EFFECT OF CALCIUM ON THE TRANSFORMING PROCESS OF SOIL BORON

土壤培养和向日葵幼苗试验结果表明，土壤热水溶性硼（ＨＷＳＢ）在培养和种植作物幼苗后，比原测定值明显下降，而且施肥培养处理比未施肥培养和施肥种植作物幼苗处理的土壤热水溶性硼（ＨＷＳＢ）都低。其原因：中、酸性土壤的有效钙含量因施肥引入钙离子后而提高，进入土壤胶体的钙交换出的土壤潜在性酸使土壤ｐＨ值下降；对于石灰性土壤，活性钙可能与施入的磷酸盐形成沉淀，这类土壤中的硼在被碳酸钙吸附的同时，还可与磷酸氢钙发生共沉淀。土壤发生的这些化学反应均使ＨＷＳＢ下降。而作物幼苗对土壤有效钙的强烈吸收，削弱了土壤固定硼的能力，土壤ＨＷＳＢ会有所上升。

The results of a soil culture experiment and sunflower seedling test indicated that the HWSB content in soils decreased sharply under the condition of cultivation and crop seedling planting, The HWSB content in soil treated with fertilizer was lower than that in soil without, or soil samples with seedlings. This is because that the calicium ion of the inorganic fertilizer enriched the available calcium in natural and acidic soils, The excess of calcium reacted with soil colloid releasing hydrogen ion, which decreased the pH of the soil. In the calcareous alluvial soils, the available calcium in the from of CaHPO4 and B-CaHPO4 coprecipitates, which occured as boron, was adsorbed by CaCO3. This chain of chemical reactions resulted in a reduction of HWSB. On the other hand, the crop seedlings absorbed the available calcium, which significantly affected the boron fixating capacity of soil, leading to an increase in HWSB content.