摘要
采用生物耗竭法和0.2 mol L-1四苯硼钠化学浸提法,利用不同动力学模型对我国8种主要土壤非交换性钾的释钾特性及其生物有效性进行定量评估。结果表明,供试土壤非交换性钾释放分为快速释放和稳定释放两个阶段,一级动力学模型、Elovich模型、双常数模型和扩散模型均能描述土壤非交换性钾的释放过程。根据双常数模型中参数(a)所表征的土壤非交换性钾释放速率常数,供试8种土壤的释钾能力按取土地区存在着自西向东、自北向南渐减的趋势。盆栽耗钾试验中,在累积释钾量高且释放速率快的土壤上,不施钾处理黑麦草累积生物量、累积吸钾量和相对含钾量较高,表现出强的供钾能力;与此相反,累积释放量低且释放速率慢的土壤上,其各项指标偏低,供钾能力较弱。四种动力学模型所表征的土壤非交换性钾释放速率与不施钾处理黑麦草含钾量及吸钾量极显著相关。以黑麦草钾素丰缺临界值34.0 g kg-1和土壤非交换性钾释放速率396 mg kg-1 h-1作为评价指标,供试8种土壤中,仅取自新疆的干旱土、陕西和黑龙江的均腐土在短期不施用钾肥的情况下能保证黑麦草丰产且不出现缺钾症状。
Release of non-exchangeable potassium （ NEK ） in soil is closely related to bioavailability of the potassium. The aim of this study was to characterize release and bioavailability of NEK in 8 soils, using pot K depletion experiments, 0.2 mol L^-1 sodium tetraphenylboron （ NaTPB ） extraction method and kinetic models. From each soil, 3 portions, 0.5 g each as replicate, were taken out for incubation in 3 ml of extracting solution （ 0.01 mol L^-1 EDTA and 0.2 mol L^-1 NaTPB ） separately for a period varying from 0.5 to 96 h. Four kinetic models （ First-order, Elovich, power function and parabolic diffusion ） were used to describe NEK release characteristics. Results show that NEK release rate in soil varied sharply with the agro-ecological region, being the highest in Northwest and Northeast China, and the lowest in Central and East China. NEK release in soil could be divided into two phases, fast and slow ones. The fast phase occurred at the beginning of the release, when NEK at the edges and wedge zones of clay mineral inter lattices broke up bondage of the minerals by diffusion, while the slow phase came late when NEK inside the inter lattices became the major source of K release. All the four models, the first-order （R^2=0.817 ~ 0.926, SE=11.9 ~ 215.1 ） , Elovich equations （R^2=0.952-0.997, SE=4.6-66.9） , power function （R^2=0.869-0.990, SE=3.9- 127.8） and parabolic diffusion （R^2=0.790- 0.963, SE=7.5- 211.4 ） , were good enough to describe NEK release kinetics. However, in choosing a proper one, it is essential not only to compare them in fitting degree, but also take into account their practicality and physical significance of the information they may provide. The Elovich equation failed to describe the early period of NEK release adequately, while the parabolic diffusion model yielded more than one NEK release rates. Thus, the NEK release rate described by the power function model might be a good indicator of NEK potential of soil. By such an indicator, the 8 soils were found
出处
《土壤学报》
CAS
CSCD
北大核心
2015年第5期1078-1087,共10页
Acta Pedologica Sinica
基金
公益性行业(农业)科研专项(201203013)
国家自然科学基金项目(NSFC40971176)资助
关键词
非交换性钾
释钾特性
动力学模型
供钾特性
生物有效性
Nonexchangeable potassium （NEK）
Potassium release characteristic
Kinetic model
Potassium supplying characteristic
Bioavailability
