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Sci Total Environ. 2019 Nov 10;690:1228-1236. doi: 10.1016/j.scitotenv.2019.07.116. Epub 2019 Jul 8.

Biochar incorporation increased nitrogen and carbon retention in a waste-derived soil.

Author information

1
Biogeochemistry Research Centre, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK. Electronic address: kate.schofield@plymouth.ac.uk.
2
Eden Project, Bodelva, Cornwall PL24 2SG, UK.
3
Biogeochemistry Research Centre, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK.
4
Camborne School of Mines, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Penryn, Cornwall TR10 9FE, UK.

Abstract

The synthesis of manufactured soils converts waste materials to value-added products, alleviating pressures on both waste disposal infrastructure and topsoils. For manufactured soils to be effective media for plant growth, they must retain and store plant-available nutrients, including nitrogen. In this study, biochar applications were tested for their ability to retain nitrogen in a soil manufactured from waste materials. A biochar, produced from horticultural green waste, was added to a manufactured soil at 2, 5 and 10 % (by weight), then maintained at 15 °C and irrigated with water (0.84 mL m-2 d-1) over 6 weeks. Total dissolved nitrogen concentrations in soil leachate decreased by 25.2, 30.6 and 44.0 % at biochar concentrations of 2, 5 and 10 %, respectively. Biochar also changed the proportions of each nitrogen-fraction in collected samples. Three mechanisms for biochar-induced nitrogen retention were possible: i) increased cation and anion exchange capacity of the substrate; ii) retention of molecules within the biochar pore spaces; iii) immobilisation of nitrogen through microbial utilisation of labile carbon further supported by increased soil moisture content, surface area, and pH. Dissolved organic carbon concentrations in leachate were reduced (-34.7 %, -28.9 %, and -16.7 %) in the substrate with 2, 5 and 10 % biochar additions, respectively. Fluorescein diacetate hydrolysis data showed increased microbial metabolic activity with biochar application (14.7 ± 0.5, 25.4 ± 5.3, 27.0 ± 0.1, 46.1 ± 6.1 µg FL g-1 h-1 for applications at 0, 2, 5, and 10 %, respectively), linking biochar addition to enhanced microbial activity. These data highlight the potential for biochar to suppress the long-term turnover of SOM and promote carbon sequestration, and a long-term sustainable growth substrate provided by the reuse of waste materials diverted from landfill.

KEYWORDS:

Biochar; Carbon; Manufactured soil; Nitrogen; Sustainability; Waste materials

PMID:
31470485
DOI:
10.1016/j.scitotenv.2019.07.116
[Indexed for MEDLINE]

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