School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin, Heilongjiang 150030, China; Key Laboratory of Effective Utilization of Agricultural Water Resources of Ministry of Agriculture, Northeast Agricultural University, Harbin, Heilongjiang 150030, China; Heilongjiang Provincial Key Laboratory of Water Resources and Water Conservancy Engineering in Cold Region, Northeast Agricultural University, Harbin, Heilongjiang 150030, China.
School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin, Heilongjiang 150030, China; Key Laboratory of Effective Utilization of Agricultural Water Resources of Ministry of Agriculture, Northeast Agricultural University, Harbin, Heilongjiang 150030, China; Heilongjiang Provincial Key Laboratory of Water Resources and Water Conservancy Engineering in Cold Region, Northeast Agricultural University, Harbin, Heilongjiang 150030, China.
Sci Total Environ. 2023 Oct 1;893:164845. doi: 10.1016/j.scitotenv.2023.164845. Epub 2023 Jun 15.
Freeze-thaw cycles (FTCs) usually occur in the nongrowing season of crops, and the temporal mismatch between soil nitrogen (N) supply and crop N utilization increases the risk of N loss. Crop straw burning is a seasonal air pollution source, and biochar provides new alternatives for waste biomass recycling and soil pollution remediation. To investigate the effect of biochar on N loss and NO emissions under frequent FTCs, different biochar content treatments (0 %, 1 %, 2 %) were set, and laboratory simulated soil column FTC tests were conducted. Based on the Langmuir and Freundlich models, the surface microstructure evolution and N adsorption mechanism of biochar before and after FTCs were analyzed, and the change characteristics of the soil water-soil environment, available N and NO emissions under the interactive effect of FTCs and biochar were studied. The results showed that FTCs increased the oxygen (O) content by 19.69 % and the N content by 17.75 % and decreased the carbon (C) content by 12.39 % of biochar. The increase in the N adsorption capacity of biochar after FTCs was related to changes in surface structure and chemical properties. Biochar can improve the soil water-soil environment, adsorb available nutrients, and reduce NO emissions by 35.89 %-46.31 %. The water-filled pore space (WFPS) and urease activity (S-UE) were the main environmental factors determining NO emissions. Ammonium nitrogen (NH-N) and microbial biomass nitrogen (MBN), as substrates of N biochemical reactions, significantly affected NO emissions. The interaction of biochar content and FTCs in different treatments had significant effects on available N (p < 0.05). The application of biochar is an effective way to reduce N loss and NO emissions under the action of frequent FTCs. These research results can provide a reference for the rational application of biochar and efficient utilization of soil hydrothermal resources in seasonally frozen soil areas.
冻融循环（FTCs）通常发生在作物的非生长季节，土壤氮（N）供应与作物 N 利用之间的时间不匹配增加了 N 损失的风险。作物秸秆燃烧是季节性的空气污染源，而生物炭为废物生物质回收和土壤污染修复提供了新的选择。为了研究频繁 FTCs 下生物炭对 N 损失和 NO 排放的影响，设置了不同生物炭含量处理（0%、1%、2%），并进行了实验室模拟土壤柱 FTC 试验。基于 Langmuir 和 Freundlich 模型，分析了 FTCs 前后生物炭的表面微观结构演变和 N 吸附机制，并研究了 FTCs 和生物炭相互作用下土壤水-土环境、有效 N 和 NO 排放的变化特征。结果表明，FTCs 使生物炭的氧（O）含量增加了 19.69%，N 含量增加了 17.75%，C 含量减少了 12.39%。FTCs 后生物炭的 N 吸附容量增加与表面结构和化学性质的变化有关。生物炭可以改善土壤水-土环境，吸附有效养分，减少 35.89%-46.31%的 NO 排放。水填充孔隙空间（WFPS）和脲酶活性（S-UE）是决定 NO 排放的主要环境因素。作为 N 生化反应的底物，铵氮（NH-N）和微生物生物量氮（MBN）显著影响 NO 排放。不同处理中生物炭含量与 FTCs 的相互作用对有效 N 有显著影响（p<0.05）。生物炭的应用是减少频繁 FTCs 作用下 N 损失和 NO 排放的有效途径。这些研究结果可为季节性冻土区生物炭的合理应用和土壤水热资源的高效利用提供参考。
