不同种植条件下红壤性水稻土根区与非根区土壤钾素变化特征

Variation Characteristics of Potassium in Root Zone and Non-root Zone of Red Paddy Soils with Different Planting Pattern

采用分室根箱试验,研究了旱作(油菜)及水作(水稻)条件下红壤性水稻土根区与非根区土壤不同形态钾素变化特征。结果表明,无论旱作还是水作,根区与非根区土壤水溶性钾和交换性钾含量均有不同程度的降低,且根区降低幅度最大,与非根区相比差异达显著水平。根区对作物吸钾量的贡献最大,旱作和水作分别占39.6%和37.4%。非根区水溶性钾和交换性钾含量(y)与距根区距离(x)线性拟合达显著相关,距根区越近,含量越小。种植作物前后土壤各形态钾素含量变化状况表明,旱作时油菜吸收的钾主要来源于水溶性钾,其次是交换性钾;水作时水稻吸收的钾主要来源于交换性钾,其次是水溶性钾,水作促进了交换性钾的释放。当根区水溶性钾含量降低时,非根区钾逐渐向根区迁移,距根区距离越近迁移量越大,水作可促进非根区钾向根区的迁移。旱作时,由于非根区水溶性钾向根区转移速度较慢,根区土壤非交换性钾向水溶性钾转化,被作物吸收利用;而水作前后根区土壤非交换性钾含量变化不明显。

The variation characteristics of potassium （K） in root-zone and non-root zone of red paddy soils under upland （rapeseed） or waterlogged （rice） condition was studied using a rhizobox equipment. It was showed that soil water soluble K and exchangeable K in root-zone and non-root-zone soils both decreased irrespective of upland or paddy condition, and the decrease of K in root-zone was more significant than that of non-root-zone soil. Potassium uptake by crops mainly came from root zone （upland 39.6% and paddy 37.4%）. A significant positive linear relationship was observed in this study between soil water soluble K and exchangeable K in non-root zone （y） and the distance to rhizosphere （x）. Water soluble K was the main K source which rapeseed absorbed in upland condition, followed by exchangeable K, and exchangeable K was the main K source which rice absorbed in paddy condition, followed by water soluble K. Waterlogging promoted the transference of soil K from non-root zone to root zone. Soil non-exchangeable K in root zone in upland condition was absorbed by crop due to slower diffusion of K in non-root zone, but that in paddy condition was on the contrary.