Abstract: The application of biochar could improve the efficiency of nitrogen absorption and utilization in soil. This study conducted field experiments to clarify the effect of biochar application on nitrogen uptake in the alfalfa (Medicago sativa L.) and maize (Zea mays L.) intercropping system. The experiment was divided into six treatments:maize monocropping (M),alfalfa monocropping(A),alfalfa and maize intercropping (MA). Biochar was applied to both alfalfa and maize intercropping (McAc),only maize intercropping (McA) and alfalfa intercropping(MAc). The results showed that the LER (land equivalent ratio) of different intercropping treatments was greater than 1,and McAc had the highest LER. Compared with MA,the application of biochar significantly increased the aboveground nitrogen content of alfalfa and corn plants by 11.63%~48.84%,and the soil alkaline nitrogen content of McAc increased by 24.95%,increaed the root surface area density by 34.23%~275.72%. In conclusion,the application of biochar can increase the content of soil available nitrogen and root surface area density,enhance nitrogen absorption in alfalfa/corn intercropping,and thereby increase crop yield. Compared with maize,alfalfa had more advantages when biochar was applied. Both alfalfa and maize had the best effect when Biochar was applied.

Key words: Biochar, Leguminous/gramineous intercropping, Soil nitrogen, The Land equivalent ratio

摘要： 施加生物炭有利于提高土壤氮素吸收利用效率。本研究通过田间试验，明确施加生物炭对紫花苜蓿(Medicago sativa L.)/玉米(Zea mays L.)间作系统氮吸收的影响。试验共有6个处理：玉米单作(M)，苜蓿单作(A)，玉米/苜蓿间作(MA)，间作均施生物炭(McAc)，间作仅玉米施生物炭(McA)，间作仅苜蓿施生物炭(MAc)。结果表明：不同间作处理土地当量比(Land equivalent ratio，LER)均大于1，McAc的LER最高；与MA相比，施加生物炭可显著提高紫花苜蓿及玉米单株地上部氮含量，且McAc的土壤碱解氮含量提高24.95%，根表面积密度增加34.23%~275.72%，进而提高了根系吸收氮素的能力。综上，施加生物炭可以提高土壤碱解氮含量和增加植物根表面积密度，提高紫花苜蓿/玉米间作氮吸收，进而提高作物产量。相比于玉米，施加生物炭对紫花苜蓿效果良好，紫花苜蓿和玉米都施加生物炭效果最好。

关键词: 生物炭, 豆/禾间作, 土壤氮素, 土地当量比