为了揭示生物质炭作为土壤调理剂添加后对土壤矿质氮形态、含量等土壤性质的影响，该研究利用芒草分别在350和700℃裂解制得生物质炭，发现2个温度尤其是700℃制得的生物质炭，对NH4+有很强的吸附能力，但对NO3-的吸附能力很弱。将生物质炭分别加入到酸性（pH值为3.8）和碱性（pH值为7.6）土壤中，25℃下室内培养180d。结果表明，生物质炭提高了土壤全氮含量，酸性和碱性土壤分别平均提高了22%和17%；但使土壤铵态氮含量大幅降低至接近仪器检测限水平；生物质炭对土壤硝态氮含量的影响因生物质炭和土壤类型而异。生物质炭对土壤矿质氮形态和含量的影响，显然与生物质炭对铵的吸附作用、提高土壤 pH 值、增强氨挥发损失，以及形成微生物量氮等密切相关。该研究可为开展生物质炭基氮素新型肥料及制剂等方面的科学研究提供参考。%Biochar is the charred byproduct of biomass pyrolysis, the heating of plant-derived material in the absence of oxygen in order to capture combustible gases. Key chemical and physical properties of biochar are greatly affected both by the choice of feedstock (crop waste, energy crop, etc.) and the process conditions (mainly temperature and time). The effect of temperature on biochar properties shows that biochar created at low temperature may be suitable for controlling the release of nutrients, whilst high temperature biochars may be more suitable for use as activated carbon. The other key aspect of biochar is related to carbon sequestration and improvement of soil productivity. Soils amended with biochar in many centuries ago by pre-Colombian peoples in the Amazon Basin still retain higher plant-available nutrients than the adjacent unamended soils. Additions of biochar to soil have shown definite increases in the availability of major cations and phosphorus as well as total nitrogen concentration. The causes for high fertility of these soils are multiple, but the source of the large amounts of organic matter and their high nutrient retention has been attributed to the extraordinarily high proportions of black carbon. Besides, the high available nitrogen (N) is from both direct nutrient addition by the biochar and greater nutrient retention. It is also reported biochar can influence soil N concentrations via affecting soil process, such as N transformation. However, it remains largely unknown how biochar affect N transformations.In this study, biochars were produced at 350°C (BC350) and 700°C (BC700) by using Miscanthus giganteus, and applied with and without ryegrass into soils with low (pH=3.8) and high pH values (pH=7.6) incubated for 180 days. Our results showed that the addition of biochar to soils had an average increase of total N content of 22% and 17%, respectively in acid and alkaline soils. Biochars had obvious effect on NH4+-N in acid soil. After 87 days of incubation, NH4+-N was declined to very low concentration. BC350 had a slight increase of NO3--N in acid soil. Compared with BC350, soils with BC700 significantly (p<0.05) decreased the concentration of NO3--N. For BC700, NO3--N in acid soil declined from 96.23 mg/kg to 4.39 mg/kg. Results also showed that biochars had high adsorption on NH4+-N. but no NO3--N was adsorpted, showing different impact of biochar on NH4+-N and NO3--N. This can partly explain why NH4+-N was not detected within all biochar addition treatments while NO3--N differed between soils and biochar. In addition, the increased soil microbial biomass via pH changes and better micro-environment, which affect biochar N transformation, thus possibly benefit N use of plant. No significant difference (p>0.05) was observed in treatments with and without ryegrass, neither between day 87 and 180, suggesting mineralization was largely occurred at the early incubation time in the soil with biochar added. The effects of biochar on the form and content of soil mineral nitrogen were closely related to the biochar’s abilities including ammonium adsorption, enhancing soil pH value, enhancing ammonia volatilization, and microbial biomass nitrogen formation. In the practical application, using biochar as coating materials in producing the slow-release fertilizer to improve nitrogen use efficiency seems to be very promised, and more research is needed in this area in the near future.
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