麦玉轮作体系中秸秆钾对土壤钾库平衡的影响

应用土壤养分状况系统研究法,对麦玉轮作体系中连续秸秆与氮、磷化肥配施对土壤钾素肥力影响进行长期定位研究。试验表明,秸秆还田对土壤速效钾、非交换钾的影响最大,对矿物钾和全钾的影响很小。秸秆还田量与溶液钾、非特殊吸附钾、特殊吸附钾和非交换钾含量呈正相关,与矿物钾呈负相关。在连续14～18年不施任何化学钾肥的耗竭状态下,秸秆还田能及时补给有效钾的损耗,但却促进了矿物钾的自然释放速率。在秸秆还田量2250～6750kg/hm2的情况下,难以维持土壤钾素平衡,需配施适量的化学钾肥。

Effect of Straw Potassium on Balance of Soil K in Wheat/Maize Rotation System

Effect of successive straw plus NP on soil K content in wheat/maize rotation system was studied according to the system methods from soil nutrition. The results showed that the effect of straw returning on available K and non-exchangeable K were more notable than mineral K and total K. Water soluble K,non-specifically absorbed K,specifically absorbed K and non-exchangeable K had positive correlation to amount of straw, but mineral K had opposite. In the exhausted condition -non-application of K-fertilizer for 14～18 years, straw plus NP could supply with available K timely, but speed up the natural release rate of mineral K. As straw application rate at the range of 2 250～6 750 kg hm-2, straw returning couldn't keep the balance of soil K, its combination to potash would slow down the decline of soil K content to some extent.