耗竭条件下冬小麦的吸钾特点及其对土壤不同形态钾的利用

在耗竭条件下研究了冬小麦在我国11种主要土壤上的吸钾特点及其对不同形态钾利用。结果表明，冬小麦对钾的吸收具有明显的阶段性。拔节至齐穗期为吸钾高峰，成熟后出现排钾现象。耗竭条件下冬小麦各生育期土壤交换性钾含量变化不大，而缓效性钾从开穗后开始回升。冬小麦吸收的钾中，交换性钾占的比例较小，11种土壤平均为21.5％;1mol／LHNO3不能提取的钾占绝大部分，平均为78.5％。表明土壤经耗竭后，1mol／LHNO3不能提取的钟对作物钾营养的作用较大。耗竭后土壤交换性钾最低值出现的时期及数量大小是土壤重要的供钾特性之一。

THE PROPERTY OF POTASSIUM UPTAKE BY WINTER WHEAT AND THE UTILITY OF DIFFERENT POTASSIUM FRACTIONS OF SOILS AFTER DEPLETION

Pot experiment was carried out to sdudy the property of K uptake by winter wheat and the utillty of different K fractions after 5 cropping depletion on 11 main soils of China. The results showed that K uptake by wlnter wheat was obviously different at different growing stages. The peak of K uptake appeared at the Jointing full heading stage, while at the mature stage the wheat showed excretion of K. The exchangeable K of soils were low and stable at all growing stages, but the slowly availiable K increased after full heading of wheat. Most of the K absorbed by wheat was from the nonextractable K wlth 1mol/L HNO₃, averaging 78. 5%, and only small proportion from the exchangeable K, averaging 21. 5%. This indicated that the contribution of nonextractable K with 1mol/L HNO₃ to plant nutrlent has incresed after exhausted cropping. The date when the lowest value of exchangable K appeared and the lowest value was an important property of soil K supplying.