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二、磷肥的合理分配和施用 1.土壤供磷状况与磷肥的分配①土壤含磷量在0.08—0.10%以下,大多数情况下磷肥表现出增产效果;土壤有效氮与有效磷(P_2O_5)之比大于4时,施用磷肥大多有较好的增产效果;土壤有机质含量与土壤有效磷呈明显正相关,大体上每增加0.5%的有机质,可相应提高5ppm 的有效磷。②对大多数土壤来说,磷的有效性在 PH5.5—7.0范围最大。低PH 值(即酸碱度)情况下,铁铅及其水合氧化物对磷产生强烈吸持作用;高 PH 值时,磷与钙、镁离子及其碳酸盐反应产生化学沉淀。另外,土壤 PH 值还影响作物根的吸收性能。一般作物生育期的最适土壤 PH
Second, the rational allocation and application of phosphate fertilizer 1. The status of phosphorus supply and soil phosphorus distribution ① soil phosphorus content of 0.08-0.10% or less, in most cases showed increased yield of phosphate fertilizer; soil available nitrogen and available phosphorus (P_2O_5) The ratio of soil organic matter to soil available phosphorus was significantly positively correlated with the increase of yield. Mostly, for every 0.5% increase of organic matter, the available phosphorus could be increased by 5ppm. ② For most soils, the effectiveness of P is greatest in the range of pH 5.5-7.0. At low pH (ie, pH), iron and lead and their hydrated oxides strongly adsorb phosphorus; at high pH, phosphorus reacts with calcium and magnesium ions and their carbonates to produce chemical precipitates. In addition, soil pH also affects crop root absorption. The optimum soil PH for the general crop growth period