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Understanding the dominant controls on biochar decomposition using boosted regression trees
Author(s) -
Chao L.,
Zhang W. D.,
Wang S. L.
Publication year - 2018
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/ejss.12534
Subject(s) - biochar , decomposition , pyrolysis , chemistry , incubation , charcoal , slash and char , environmental chemistry , agronomy , organic chemistry , biology , biochemistry
Summary Extensive studies have been carried out to investigate the decomposition of biochar. Biochar properties, soil characteristics and incubation conditions are considered key factors that control the rate of biochar decomposition. However, the relative contributions of these factors to its decomposition remain unknown. Approximately 812 individual measurements of the rate of biochar decomposition were collected from 23 studies involving 13 C or 14 C isotope techniques to evaluate the effects of incubation conditions, soil characteristics and biochar properties on its decomposition with a boosted regression tree (BRT) model. The BRT model accounted for 95% of the variation in biochar decomposition. Incubation conditions, soil characteristics and biochar properties accounted for 41, 31 and 28% of variation in the rate of biochar decomposition, respectively. The most important single predictor of biochar decomposition was incubation time (contributing 33% to the rate), followed by soil carbon: nitrogen (C:N) ratio (9%), pyrolysis time (9%), soil N content (8%) and biochar C content (7%). The rate of decomposition of biochar decreased with time for incubation times less than 1 year. Soil with a large C content and a small C:N ratio resulted in a large rate of biochar decomposition. Type of feedstock and biochar N content had little or no effect on biochar decomposition. Our results provide further insight into the factors that affect biochar decomposition and quantify the relative contributions of these factors to it. Highlights We studied the dominant factors that control biochar decomposition with BRT modelling. We quantified relative contributions of incubation conditions, soil characteristics and biochar properties to biochar decomposition. Rate of biochar decomposition explained by incubation conditions (41%), soil characteristics (31%) and biochar properties (28%). The most important predictor of biochar decomposition was incubation time.