Selected soil and biochar properties1.

1TN = Total nitrogen, TOC = Total organic carbon, TH = Total hydrogen, H/C = molar ratio, LOI = Loss on ignition. Untreated BC properties (Ash, CEC & base cations) and surface area data were obtained from Martinsen, Alling [41] and Smebye, Alling [42] respectively. All the other soil and BC data were measured in sub-samples from homogenized bulk samples used in the study. Soil and BC pH was measured in a 1:2.5 v/v slurry in water (n = 2) using a pH meter (Orion 2 Star, Thermo Fisher Scientific, Fort Collins, CO, USA) after overnight sedimentation and shaking. Base cations were measured in the eluate of ammonium acetate at pH 7 for BC and ammonium nitrate for soil (n = 1), with a flame spectrophotometer (Perkin Elmer, AAS 3300). CEC was determined as sum of base cations and exchangeable acidity in ammonium acetate pH 7 and ammonium nitrate extract for BCs and soil respectively. TOC, TN and TH were determined using CHN analyzer (n = 1) (CHN-1000, LECO, USA). The TOC for BCs were determined after acidification to remove carbonates.Selected soil and biochar properties1.本研究涉及的缩写定义如下：TN（总氮，Total nitrogen）、TOC（总有机碳，Total organic carbon）、TH（总氢，Total hydrogen）、H/C（摩尔比）、LOI（烧失量，Loss on ignition）。未经处理的生物炭（biochar, BC）的灰分、阳离子交换量（Cation Exchange Capacity, CEC）、盐基阳离子及比表面积数据分别引自Martinsen与Alling[41]、Smebye与Alling[42]。其余所有土壤与生物炭数据均取自本研究中经均质化处理的混合批量试样的分样。土壤与生物炭的pH值采用1:2.5体积比的水悬浮液，经过夜沉降与振荡后，使用pH计（Orion 2 Star，赛默飞世尔科技，美国科罗拉多州柯林斯堡）测定，平行重复次数n=2。盐基阳离子采用火焰原子吸收分光光度计（Perkin Elmer, AAS 3300）测定：生物炭样品使用pH 7的乙酸铵溶液洗脱提取，土壤样品则使用硝酸铵溶液洗脱提取，平行重复次数n=1。阳离子交换量（CEC）分别以如下方式测定：生物炭的CEC为pH 7乙酸铵提取液中盐基阳离子与交换性酸的总和；土壤的CEC则通过硝酸铵提取液计算得到。总有机碳、总氮与总氢采用碳氢氮元素分析仪（CHN-1000，力可公司，美国）测定，平行重复次数n=1。生物炭的总有机碳测定前需先经酸化处理以去除碳酸盐。部分土壤与生物炭性质如下：