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以5个春大豆品种为材料,采用框栽方法对大豆秸秆还田与不还田时土壤磷、钾的盈亏量进行估算,研究了种植大豆对土壤磷、钾平衡的影响。结果表明:大豆成熟期有57.2%～70.1%的磷素、60.7%～74.7%的钾素转移到籽粒中,磷、钾的收获率较高。在大豆施磷酸氢二铵75～150kg·hm-2和硫酸钾40～120kg·hm-2水平下,土壤磷均有盈余,而土壤钾在施钾量低时亏损,高时盈余。大豆秸秆还田时,磷、钾的盈亏量分别为7.1～22.1kg·hm-2、-7.6～25.6kg·hm-2;秸秆不还田时分别为6.0～21.0kg·hm-2、-14.3～18.9kg·hm-2。大豆秸秆还田时,维持土壤磷、钾平衡的临界磷、钾肥用量为P2O518.4kg·hm-2、K2O 29.2kg·hm-2;秸秆不还田时,磷、钾肥的临界用量为P2O520.9kg.hm-2、K2O 37.3kg·hm-2。可见,优化肥料施用量和秸秆还田是保障土壤磷、钾素平衡的重要措施。
Five spring soybean cultivars were used as materials to estimate the amount of P and K in soil after returning and returning soybean straw. The effects of planting soybean on phosphorus and potassium balance were studied. The results showed that 57.2% ~ 70.1% of the phosphorus in the mature soybean and 60.7% ~ 74.7% of the potassium in the soybean were transferred to the grain, and the yield of phosphorus and potassium was higher. Under the condition of 75-150 kg · hm-2 of soybean diammonium phosphate and 40-120 kg · hm-2 of potassium sulfate, the soil phosphorus had a surplus while the soil potassium lost when the potassium was low and surplus when the potassium was high. Soybean straw returned to the field, phosphorus and potassium were 7.1 ~ 22.1kg · hm-2, -7.6 ~ 25.6kg · hm-2 respectively; straw was 6.0-21.0kg · hm-2, 14.3 to 18.9 kg · hm-2. The critical phosphorus and potassium fertilizers for the balance of phosphorus and potassium in soil when returning soybean straw were P2O518.4kg · hm-2 and K2O, 29.2kg · hm-2. The critical phosphorus and potassium fertilizer was P2O520 when the straw was not returned to the field. 9kg.hm-2, K2O 37.3kg · hm-2. Therefore, optimizing fertilizer application rate and returning straw to straw are important measures to ensure the balance of soil phosphorus and potassium.