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7.适当的土壤化学环境(1)酸硷度 水稻根系对酸硷度有着广泛的适应性,在pH4~9之间都可以生长,但以弱酸性至中性反应为最适宜.(2)亚铁 土壤在淹水情况下,空气隔绝,在嫌气性微生物活动下,把高铁还原成亚铁.土壤的pH值与Fe~(+2)的溶解度有关系,根据Ponnamperuma,F.N.1972,pFe~(+2)=2pH-10.8,即pH值每增减0.5,Fe~(+2)浓度(ppm)减增为原来的10倍.例如,pm6.5时,Fe~(+2)浓度为352ppm,pH7.0时,Fe~(+2)浓度就降到35.2ppm.
7. Appropriate soil chemical environment (1) pH The root system of rice has a wide range of pH adaptability, can grow between pH4 ~ 9, but weak acid to neutral reaction is the most appropriate. (2) Under flooded conditions, the ferrous soils were isolated from the air and the high iron was reduced to ferrous under the action of anaerobic microorganisms. The pH value of the ferrous soil was related to the solubility of Fe ~ (+2). According to Ponnamperuma, FN1972, pFe ~ (+2) = 2pH-10.8, that is, the value of Fe ~ (+2) When 352ppm, pH7.0, Fe ~ (+2) concentration dropped to 35.2ppm.