解钾细菌C_6X对不同富钾矿物含量土壤钾素迁移的影响

Effects of potassium-solubilizing bacteria C_6X on potassium migration in soils with different content of potassium-rich minerals

为了改善黄土高原地区煤炭开采引起土壤质量急剧退化的现状,该文以玉米为供试植物,通过日光温室短期盆栽的方式,系统研究解钾细菌C_6X和玉米生长对土壤钾素迁移的影响。结果表明:1)玉米生长条件下,解钾细菌在富钾矿物质量分数45%上层土壤(0~20 cm)中对速效钾增量的促进作用最佳。2)解钾细菌和玉米生长协同提高上层土壤钾素固定能力,缓效钾增量在土壤富钾矿物质量分数68%为最大值。3)解钾细菌和玉米生长协同促进土壤钾素上移能力,在富钾矿物质量分数45%水平,土壤上移速效钾呈最大值;同时,解钾细菌促进土壤上移速效钾和玉米钾素积累量二者趋于线性稳定,利于土壤钾肥长期管理。因此,解钾细菌和玉米生长协同促进土壤钾素的释放和固定,并促进土壤钾素上移。

There is the severe agricultural environmental problem of cultivated soil potassium leaching caused by soil erosion in Loess Plateau, where the soil quality is rapidly degenerating caused by coal mining for a long time. It is necessary to rationally develop and utilize soil potassium in Loess Plateau for ecological restoration in the mining area of northwest China. In order to understand the effect of potassium-solubilizing bacteria C_6X on soil potassium migration under the conditions of maize（zea mays） planted in the mining area of northwest China, this study was performed by short-term pot cultures in helio-greenhouse with or without maize planting in artificial soils with different contents of potassium-rich minerals which simulated the soils in the studied area. The artificial soil was composed of quartz and two kinds of potassium-rich minerals, including feldspar and hydrous mica which are common minerals in the soil of northwest mining area in China. The artificial soils used in the experiment were treated with six levels of potassium-rich minerals, which were 18%, 25%, 38%, 45%, 68% and 75% by mass fractions of total potassium-rich minerals in soils. Each level of potassium-rich minerals treated with inoculation with active C_6X or sterilized C_6X. The C_6X is the tested strains of potassium-solubilizing bacteria Phyllobacterium ifriqiyense which was isolated from the garden soil in Beijing suburbs by microbial reclamation laboratory in China University of Mining and Technology. Also, nylon mesh（30 μm, dia.） was laid at 20 cm depth below the soil surface to block the downward growth of the root system of maize. We investigated to the relationship among the potassium-solubilizing bacteria, potassium-rich minerals ratios in soils and the growth of maize, and the synergistic effect of them on the soil potassium migration,which included the increment of available potassium in topsoil and subsoil, the increment of slowly available potassium in topsoil and subsoil, and the upward migratory available potassium. Also, linear regression analysis was used for data analysis which involving potassium accumulation in maize and upward migratory available potassium in soils with active C_6X or sterilized C_6X. The results showed that： 1） With maize planting, potassium-solubilizing bacteria increased available potassium in the soil with 45 % potassium-rich mineral mass fraction. Without maize planting, potassium-solubilizing bacteria significantly（P〈0.05） increased soil available potassium in the soil with 18 % or 25 % of the mass fraction of potassium-rich minerals. 2） Potassium-solubilizing bacteria and maize growth synergistically increased potassium fixation capacity in topsoil due to more potassium released from minerals and used by maize. Soil slowly available potassium increment was the maximum value in the soil with 68 % mass fraction of potassium-rich minerals. Without maize planting, potassium-solubilizing bacteria significantly（P〈0.05） improved soil slowly available potassium in the soil with 45% mass fraction of potassium-rich minerals. 3） Potassium-solubilizing bacteria and maize growth synergistically promoted ability of potassium translocation in soil. The upward migratory available potassium was to the maximum value in the soil with potassium-rich mineral mass fraction of 45%. Also, potassium-solubilizing bacteria promoted a linear relation between upward migratory available potassium in soil and potassium accumulation in maize, which has implication for the long-term management of soil potassium. In addition, the factor of potassium-rich mineral content in soils had no directly effect on soil potassium migration, but it could affect the metabolism of potassium bacteria at various degree, through which it finally could affect the soil potassium migration. To generalize, potassium-solubilizing bacteria and maize growth synergistically promoted soil potassium migration, and this is of great significance for the rational use of potassium-solubilizing bacteria to repair the ecological environment of the coal mining subsidence area in the Loess Plateau of Northwest China.