蔗渣生物质炭对喀斯特农田石灰性土壤氮转化过程的短期影响

Study on short-term effects of sugarcane biochar on nitrogen transformation in calcareous soils in karst farmland

生物质炭对于土壤中不同形态氮库的含量影响已有较多研究,但对西南喀斯特区石灰性土壤氮素形态,尤其是控制氮素形态的转化过程研究较为缺乏。本研究设置土壤中添加1%(C1)和3%(C2)蔗渣生物质炭2个用量水平,并以不施用蔗渣生物质炭作为对照(CK),共3个处理,通过 15 NH 4 NO 3 和NH^15 4 NO 3 成对标记技术,结合MCMC氮素转化模型研究了不同用量的蔗渣生物质炭对石灰性土壤氮转化过程的短期影响,为该地区蔗渣资源化利用和土壤氮保持提供理论支撑。结果表明,与CK相比,添加蔗渣生物质炭能够快速提高土壤pH和有机碳含量。添加生物质炭并没有显著改变土壤氮的矿化、铵态氮(NH^+ 4 )和硝态氮(NO^- 3 )的微生物同化和异养硝化速率,但NH^+ 4 吸附速率随生物质炭用量的增加而提高,以添加量最高的C2处理最大。添加生物质炭同样提高了土壤NH^+ 4 释放速率,但C1和C2处理的土壤NH^+ 4 释放速率并无显著性差异。与CK和C1处理相比,施用高量蔗渣生物质炭通过抑制自养硝化速率而显著降低了硝态氮净产生速率。这些结果表明,施用高量蔗渣生物质炭于石灰性土壤中可快速实现对NH^+ 4 吸附,降低自养硝化速率,减少NO^- 3 产生,从而降低了其损耗和淋失风险。

The effect of biochar is related to the duration of soil retention. Biochar entering the soil has an effect on nitrogen transformation process, corresponding to agronomic and environmental effects on nitrogen. The researches on the effect of biochar on nitrogen transformation of calcareous soils in karst areas of Southwest China are scarce, especially the research on various pathways of nitrogen transformation. The 15 N tracing technique combined with the Markov Chain Monte Carlo(MCMC)algorithm-based numerical optimization model were used to investigate the effect of biochars on nitrogen transformation in calcareous soils, which provide theoretical basis for nitrogen transformation in this area. In this study, three treatments was designed which included biochar-1%(C1), biochar-3%(C2) and control (CK),with biochar extracted from sugarcane for the experiment to determine the gross soil N transformation rate. The results showed that biochar could rapidly increase soil pH and organic carbon. There was no significant difference in nitrogen mineralization, immobilization and heterotrophic nitrification with the addition of biochar. but the adsorption rate of NH^+ 4 increased with the increase of biochar. The addition of biochar also increased the NH^+ 4 release rate, but the NH^+ 4 release rate decreased with the increase of biochar. The autotrophic nitrification rate and dissimilation reduction rate of nitrogen can be reduced by adding masses of biochar. Therefore, the application of biochar in calcareous soil can quickly achieve NH^+ 4 adsorption, reduce the rate of autotrophic nitrification, and reduce the accumulation of NO^- 3 in soil, thus reducing its loss and leaching risk.