Abstract Mixed-feedstock-biochars can increase both available soil organic matter (SOM) and inorganic nutrients, yielding a more valuable biochar for agricultural purposes. Since the agronomic benefits of biochar are dependent on its structural and physio-chemical characteristics, this study compares these properties for single- and mixed-feedstock-biochars using a range of analytical techniques. Six biochars were produced from wheat straw (Ws), and a combination of wheat straw and basalt (WsBs) at three pyrolysis temperatures, 450, 550 and 650 °C. The results showed that WsBs biochars contained higher ash contents, with considerably lower fixed carbon, volatile matter and electrical conductivity than the Ws biochars. Microscopic and spectroscopic analyses revealed increases in the concentration of Si on the surface of wheat straw particles during processing. A layer of Si on the surface of the C matrix appeared to prevent further reactions between C-rich phases and some mineral phases (mainly Fe and Ca-rich regions) at 650 °C. Other mineral compounds, such as those rich in K and Na, were adsorbed to both C and Si-rich phases. Basalt incorporation into the wheat straw particles also catalysed new functionalities. Surface C-N-based functionalities (amides) were only detected in wheat straw biochars, whereas ammonium-based groups were found in the WsBs biochars. Concentrations of dissolved organic carbon, which were affected by both feedstock composition and pyrolysis temperature, appeared to be higher in the Ws biochars, with the highest concentrations found at 450 °C. The WsBs biochars contained greater concentrations of biopolymers and humic-like substances than the Ws biochars. These organic fractions would increase the availability of micro-nutrients, reduce ions leaching and promote soil strength and resistance to erosion following the biochar application.

中文翻译：

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小麦秸秆与玄武岩单一原料与混合原料生物炭特性比较

摘要 混合原料生物炭可以增加可用土壤有机质 (SOM) 和无机养分，产生更有价值的农业生物炭。由于生物炭的农艺效益取决于其结构和理化特性，因此本研究使用一系列分析技术比较了单一和混合原料生物炭的这些特性。六种生物炭由小麦秸秆 (Ws) 以及小麦秸秆和玄武岩 (WsBs) 在三个热解温度（450、550 和 650 °C）下生产。结果表明，与 Ws 生物炭相比，WsBs 生物炭的灰分含量更高，固定碳、挥发性物质和电导率要低得多。显微和光谱分析表明，在加工过程中，麦秸颗粒表面的硅浓度增加。C 基体表面的一层 Si 似乎阻止了富 C 相与一些矿物相（主要是富铁和富钙区域）在 650 °C 下进一步反应。其他矿物化合物，例如富含 K 和 Na 的那些，被吸附到富含 C 和 Si 的相上。玄武岩掺入小麦秸秆颗粒也催化了新的功能。仅在小麦秸秆生物炭中检测到基于表面 CN 的官能团（酰胺），而在 WsBs 生物炭中发现了基于铵的基团。受原料组成和热解温度影响的溶解有机碳浓度似乎在 Ws 生物炭中更高，450 °C 时浓度最高。WsBs 生物炭比 Ws 生物炭含有更高浓度的生物聚合物和腐殖质类物质。在施用生物炭后，这些有机部分将增加微量营养素的可用性，减少离子浸出并提高土壤强度和抗侵蚀性。