Purpose

Biochars exhibited considerable differences in chemical properties with different feedstocks and pyrolysis conditions. This study was to understand the effects of pyrolysis temperature on the availability of phosphorus in biochars and biochar-amended soils.

Materials and methods

Biochars from rice straw and canola stalk were produced at temperatures of 250, 350, 450, 550, and 650 °C, respectively, and then applied to two acidic soils (Ultisol and Alfisol). The availability of phosphorus in biochars and biochar-amended soils was evaluated.

Results

The contents of total P and Olsen-P of biochar increased with pyrolysis temperature, reaching the maximum at 650 °C. The canola stalk biochar had a higher amount of total P than rice straw biochar. The addition of biochar increased the contents of total P, Olsen-P, and inorganic P (except Ca-P in Ultisol) in soils, varied with pyrolysis temperature, feedstock, and soil type. The highest phosphorous availability appeared in soils amended by biochars produced at 450 °C. The inorganic P in soils increased in the order of Ca-P > Fe–P > Al-P. Biochars significantly increased the contents of Al-P and Fe–P in two soils and Ca-P of Alfisol. Correlation analysis showed that there was a positive correlation between biochar pH and Olsen-P in soils, soil pH, and inorganic P.

Conclusions

Biochar could largely affect the availability of phosphorus in soils. The amount and form of available P were dependent on pyrolysis temperature and feedstock. It was important to consider the most suitable pyrolysis temperature to improve the soil P availability better, which was essential to develop soil productivity on a large scale.

Graphical abstract

中文翻译：

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热解温度影响稻草和油菜秆生物炭和生物炭改良土壤的磷有效性

目的

生物炭在不同原料和热解条件下在化学性质上表现出相当大的差异。本研究旨在了解热解温度对生物炭和生物炭改良土壤中磷有效性的影响。

材料和方法

分别在 250、350、450、550 和 650 °C 的温度下生产稻草和油菜秆生物炭，然后施用于两种酸性土壤（Ultisol 和 Alfisol）。评估了生物炭和生物炭改良土壤中磷的有效性。

结果

生物炭的总P和Olsen-P含量随着热解温度的升高而增加，在650℃时达到最大值。油菜秸秆生物炭的总磷含量高于稻草生物炭。生物炭的添加增加了土壤中总磷、Olsen-P 和无机 P（Ultisol 中的 Ca-P 除外）的含量，随热解温度、原料和土壤类型而变化。在 450 °C 下生产的生物炭改良的土壤中出现了最高的磷利用率。土壤中无机磷的增加顺序为 Ca-P > Fe-P > Al-P。生物炭显着增加了两种土壤中 Al-P 和 Fe-P 的含量以及 Alfisol 的 Ca-P 含量。相关性分析表明，生物炭pH值与土壤中Olsen-P、土壤pH值、无机磷均呈正相关。

结论

生物炭可以在很大程度上影响土壤中磷的可用性。可用 P 的数量和形式取决于热解温度和原料。重要的是考虑最合适的热解温度以更好地提高土壤磷的有效性，这对于大规模发展土壤生产力至关重要。

图形概要