连续秸秆还田对水稻土中钾素形态的影响

湖北省武穴市、荆州市和武汉市三个水旱轮作长期定位试验的基础上,研究了连续秸秆还田(三地秸秆还田时间分别为9、5和3年)对不同层次(0~20 cm和20~40 cm)土壤中各形态钾素(水溶性钾、特殊吸附钾、非特殊吸附钾、非交换性钾、矿物钾、全钾)的影响。结果表明:秸秆还田能显著增加0~20 cm土层中特殊吸附钾和非特殊吸附钾的含量,两者的增量分别为9.92%~138.35%和35.57%~143.79%,其中武穴试验点的增加效果相对最好。20~40 cm土层,各处理之间变化规律不明显。土壤全钾含量表现为武穴试验点最低(2.59~3.15 g kg~(-1)),与荆州和武汉试验点差异性较大(9.45~11.91 g kg~(-1))。武穴和荆州试验点供钾能力较低(速效钾含量100 mg kg~(-1)),武汉试验点供钾能力为中等(速效钾含量在100~150 mg kg~(-1))。矿物钾和全钾呈极显著正相关(武穴、荆州和武汉试验点的相关系数分别为0.994**、0.999**、1.000**),速效钾中各组分与速效钾的相关性在三个试验点存在差异,其中还田时间越长相关性越好。

Effect of Continuous Straw Incorporation on Forms of Potassium in the Paddy Soils

Based on the long-term experiments in Wuxue,Jingzhou and Wuhan of Hubei Province,the present study investigated the long-term effect of continuous straw returning (9,5 and 3 years respectively) under different crop rotation system on various forms of potassium (K,including water soluble K,specifically absorptive K,non-specifically absorptive K,non-exchangeable K,mineral K,total K) in the different soil layers (0-20 cm and 20-40 cm).Results showed that straw returning increased the contents of soil specifically absorptive K and non-specifically absorptive K with the increment of 9.92％-138.35％ and 35.57％-143.79％,respectively,in 0-20 cm layer.This increase effect was relatively most in Wuxue.No significant differences among treatments were observed in the 20-40 cm soil layer.Soil total K concentration was the lowest (2.59-3.15 g kg-1) in Wuxue,and its differences between Jingzhou and Wuhan (9.45-11.91 g kg-1) was significant.The supply capacity of soil K was low in Wuxue and Jingzhou (available K content ＜ 100 mg kg-1) and was middle in Wuhan (available K content of 100-150 mg kg-1).Correlation between mineral K and total K was extremely significant and the correlation coefficient was,respectively,0.994**,0.999**,1.000** in soils of Wuxue,Jingzhou and Wuhan.There were differences in the correlation between available K and available K among the three experimental sites.And the longer the term of straw returning was,the better the correlation was.