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一、硝酸盐与土壤次生盐渍化栽培蔬菜的土壤,特别是保护地栽培的土壤,由于连年集约化生产,造成有机肥和化肥,特别是氮肥施用量超标,加之保护地土壤得不到充分的降雨淋洗,使得土壤产生次生盐渍化。蔬菜土壤次生盐渍化的主要原因是硝酸钙积累,硝酸根离子占全阴离子的67%～76%,阳离子则以钙离子为主。保护地栽培土壤次生盐渍化使水势降低,钙离子积累使土壤中氢离子浓度提高,这是钙离子代换了土壤颗粒表面氢离子的结果。而氢离子浓度的提高,使土壤中一些金属离子溶解,如锰离子。据报道,当土壤中硝酸钙超过0.25%时,辣椒叶片中锰离子浓度增加,植株生长受到明显抑制。
First, nitrate and soil Secondary salinization of soil cultivation of vegetables, especially the cultivation of protected soils, due to intensive production year after year, resulting in excessive use of organic and chemical fertilizers, especially nitrogen fertilizer, combined with the protection of the soil can not get Adequate rainfall leaching, making the soil secondary salinization. Vegetable secondary salinization of soil is mainly due to the accumulation of calcium nitrate, nitrate ions accounted for 67% to 76% of the total anions, calcium ions are the main cation. Protected cultivation of soil secondary salinization so that the water potential decreases, the accumulation of calcium ions to increase the concentration of hydrogen ions in the soil, which is replaced by calcium ions on the surface of soil particles hydrogen ions results. The increase in hydrogen ion concentration, so that some of the soil dissolved metal ions, such as manganese ions. It is reported that when the soil calcium nitrate more than 0.25%, the pepper leaves of manganese ion concentration increased, plant growth was significantly inhibited.