Purpose

The recent literature indicates that, depending on the feedstocks and pyrolysis temperature, biochar can be a good source of nutrients. On the contrary, some biochars are not good sources of available carbon and other nutrients, but their porous structure seems to be a suitable microenvironment for microbial colonization. We investigated the response of soil biological parameters, microbial biomass carbon and nitrogen (MBC and MBN), in relation to mobile N species.

Material and methods

Five different biochars were produced at different temperatures (300, 350, 400, 450, and 500 °C) from the same feedstock (woodchips). The physicochemical and morphological characteristics of the individual biochar samples were described, and incubation was carried out with the application of 2% biochar to two different soil types (luvisol and fluvisol).

Results and discussion

The addition of 2% biochar did not change the pH in the slightly acid soils used in the experiment, in spite of the alkaline character of biochar. The increasing amounts of total and nitrate-available nitrogen during the experiment are probably related to changes in soil microbial activity. The amount of soluble carbon was constant during the experiment, confirming its stability in the soil, most likely because of the high amount of lignin in the feedstock. The influence of biochar on the soil microbiome was determined on the basis of the concentrations of MBC and MBN. Microbial biomass was increased in both soils treated with biochar produced at lower temperatures.

Conclusions

The physicochemical characteristics of the biochar as well as the sorption behavior of N-NO₃⁻ and N-NH₄⁺ indicate that at a pyrolysis temperature of 400 °C, biochar properties change substantially. However, these findings are only valid for biochar produced from woodchips, and the long-term effects of biochar application on soil properties need to be investigated in further studies.

中文翻译：

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施用不同形态和物理特性的生物炭改变土壤碳和氮的可及性

目的

最近的文献表明，取决于原料和热解温度，生物炭可以是营养的良好来源。相反，某些生物炭不是可利用的碳和其他养分的良好来源，但它们的多孔结构似乎是微生物定殖的合适微环境。我们调查了土壤生物学参数，微生物生物量碳和氮（MBC和MBN）与可移动N物种相关的响应。

材料与方法

使用相同的原料（木片）在不同温度（300、350、400、450和500°C）下产生了五种不同的生物炭。描述了单个生物炭样品的理化和形态特征，并在两种不同的土壤类型（卢维索和氟维索尔）上应用2％生物炭进行了培养。

结果和讨论

尽管生物炭具有碱性，但添加2％的生物炭不会改变实验中所用的弱酸性土壤的pH值。在实验过程中，总氮和可利用硝酸盐的氮量的增加可能与土壤微生物活性的变化有关。在实验过程中，可溶性碳的量是恒定的，这证实了其在土壤中的稳定性，这很可能是因为原料中木质素的含量很高。生物炭对土壤微生物组的影响是根据MBC和MBN的浓度确定的。在较低温度下生产的生物炭处理过的两种土壤中，微生物的生物量都增加了。

结论

生物炭的物理化学特性，以及N-NO的吸附行为₃ ^-和N-NH ₄ ⁺表示在400℃的热解温度，生物炭性能显着改变。然而，这些发现仅对木片生产的生物炭有效，需要进一步研究生物炭对土壤性质的长期影响。