生物炭对土壤肥力与环境的影响

生物炭是生物体在完全或部分缺氧环境中经高温裂解后形成的含碳率较高的产物。目前对生物炭的研 究仍属于起步阶段，不同学科领域采用不同研究方法和手段，研究结论也不尽一致。阐述了目前生物炭对土壤结构、 土壤污染、土壤碳氮转化过程以及生物炭施用对土壤微生物群落、酶活性等方面的国内外研究进展，并且提出目前 生物炭在改土培肥研究过程中存在的问题，以期为今后生物炭的研究工作提供理论指导。

Effect of citrus intercropping with other crops on the nutrient status of rhizospheric soils

Effects of citrus/peanut, citrus/ginger intercropping, systems and peanut, citrus, ginger monocropping systems on the nutrients status of rhizospheric soils were investigated comparatively in Xinhui reclaimed wetlands, Guangdong province. Results showed that (1) The pH value of rhizospheric soil varied greatly in the five farming systems after 7 months cultivation. The pHs of rhizospheric soils in citrus/peanut and citrus/ginger farming systems were significantly lower than those under the peanut, citrus and ginger monocropping system. Especially, the pH of rhizospheric soil of citrus/peanut farming system was the lowest among the five kinds of planting systems; (2)The contents of available nitrogen in rhizospheric soil of citrus/peanut and citrus/ginger intercropping system were significantly higher than those of peanut and ginger monocropping system. No significant difference was found between the citrus/peanut and citrus/ginger intercropping systems. Also, the available nitrogen contents in the five farming systems all improved significantly after 7- month plantation;(3) The available phosphorus content of rhizospheric soil in citrus monocropping was significantly higher than that in citrus/peanut, citrus//ginger intercropping, and peanut monocropping systems. Meanwhile, The available phosphorus contents of rhizospheric soil in citrus/peanut and citrus/ginger interplanting systems did not show any significant differences from those in the peanut and ginger monocropping systems. (4) After 7- month planting, the available potassium content of rhizospheric soil in citrus/ginger farming system was significantly higher than that in the citrus monocropping systems; available potassium content in citrus/peanut intercropping was similar to that in citrus/ginger interplanting, and was significantly improved in 7 months.(5) The organic matter contents of rhizospheric soils in the five farming systems were very close and no obvious change with time in this study. It would be concluded that citrus/ginger and citrus/peanut intercropping systems could improve some nutrients status of rhizospheric soils. So citrus/ginger and citrus/peanut intercropping systems may be good examples for orchard land use in the study area.