Biochar Affected by Composting with Farmyard Manure
- Katharina Prost *a,
- Nils Borchardac,
- Jan Siemensa,
- Timo Kautzb,
- Jean-Marie Séquarisc,
- Andreas Möllerd and
- Wulf Amelunga
- a Univ. of Bonn, Institute of Crop Science and Resource Conservation, Soil Science and Soil Ecology, Nussallee 13, 53115 Bonn, Germany
c Forschungszentrum Jülich GmbH, Agrosphere Institute, IBG-3, 52425 Jülich, Germany
b Univ. of Bonn, Institute of Organic Agriculture, Katzenburgweg 3, 53115 Bonn, Germany
d Federal Institute for Geo-Science and Natural Resources, Stilleweg 2, 30655 Hannover, Germany
Biochar applications to soils can improve soil fertility by increasing the soil’s cation exchange capacity (CEC) and nutrient retention. Because biochar amendment may occur with the applications of organic fertilizers, we tested to which extent composting with farmyard manure increases CEC and nutrient content of charcoal and gasification coke. Both types of biochar absorbed leachate generated during the composting process. As a result, the moisture content of gasification coke increased from 0.02 to 0.94 g g−1, and that of charcoal increased from 0.03 to 0.52 g g−1. With the leachate, the chars absorbed organic matter and nutrients, increasing contents of water-extractable organic carbon (gasification coke: from 0.09 to 7.00 g kg−1; charcoal: from 0.03 to 3.52 g kg−1), total soluble nitrogen (gasification coke: from not detected to 705.5 mg kg−1; charcoal: from 3.2 to 377.2 mg kg−1), plant-available phosphorus (gasification coke: from 351 to 635 mg kg−1; charcoal: from 44 to 190 mg kg−1), and plant-available potassium (gasification coke: from 6.0 to 15.3 g kg−1; charcoal: from 0.6 to 8.5 g kg−1). The potential CEC increased from 22.4 to 88.6 mmolc kg−1 for the gasification coke and from 20.8 to 39.0 mmolc kg−1 for the charcoal. There were little if any changes in the contents and patterns of benzene polycarboxylic acids of the biochars, suggesting that degradation of black carbon during the composting process was negligible. The surface area of the biochars declined during the composting process due to the clogging of micropores by sorbed compost-derived materials. Interactions with composting substrate thus enhance the nutrient loads but alter the surface properties of biochars.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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