A meta-analysis and critical evaluation of influencing factors on soil carbon priming following biochar amendment
- 185 Downloads
Previous studies have found biochar-induced effects on native soil organic carbon (NSOC) decomposition, with a range of positive, negative and no priming reported. However, many uncertainties still exist regarding which parameters drive the amplitude and the direction of the biochar priming.
Materials and methods
We conducted a quantitative analysis of 1170 groups of data from 27 incubation studies using boosted regression trees (BRTs). BRT is a machine learning method combining regression trees and a boosting algorithm, which can effectively partition independent influences of various factors on the target variable in the complex ecological processes.
Results and discussion
The BRT model explained a total of 72.4% of the variation in soil carbon (C) priming following biochar amendment, in which incubation conditions (36.5%) and biochar properties (33.7%) explained a larger proportion than soil properties (29.8%). The predictors that substantially accounted for the explained variation included incubation time (27.1%) and soil moisture (5.0%), biochar C/N ratio (6.2%), nitrogen content (5.5%), pyrolysis time during biochar production (5.1%), biochar pH (4.5%), soil C content (5.2%), sand (4.7%) and clay content (4.1%). In contrast, other incubation conditions (temperature, biochar dose, whether nutrient was added), biochar properties (biochar C, feedstock type, ash content, pyrolysis temperature, whether biochar was activated) and soil properties (nitrogen content, silt content, C/N ratio, pH, land use type) had small contribution (each < 4%). Positive priming occurred within the first 2 years of incubations, with a change to negative priming afterwards. The priming was negative for low N biochar or in high-moisture soils but positive on their reverse sides. The size of negative priming increased with rising biochar C/N ratio, pyrolysis time and soil clay content, but deceased with soil C/N ratio.
We determine the critical drivers for biochar effect on native soil organic C cycling, which can help us to better predict soil C sequestration following biochar amendment.
KeywordsBoosted regression tree Incubation time Native soil organic matter Priming effect Pyrogenic organic matter Soil respiration
We are grateful to two anonymous reviewers for their insightful advice on an earlier version of this manuscript. We thank all the researchers whose data were included in this meta-analysis. This work was supported by the National Science Foundation of China (grant numbers 41601307, 31330011, 41630755), State Key Laboratory of Forest and Soil Ecology (grant number LFSE2015-06) and the National Key Research and Development Program of China (grant number 2016YFD0200304).
- Ciais P, Sabine C, Bala G, Bopp L, Brovkin V, Canadell J, Chhabra A, DeFries R, Galloway J, Heimann M, Jones C, Quéré CL, Myneni RB, Piao S, Thornton P (2013) Carbon and other biogeochemical cycles. In: Stocker TF et al (eds) The physical science basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, pp 465–570Google Scholar
- De'Ath G (2007) Boosted trees for ecological modeling and prediction. Ecology 88(1):243–251. https://doi.org/10.1890/0012-9658(2007)88[243:BTFEMA]2.0.CO;2 CrossRefGoogle Scholar
- Herath H, Camps-Arbestain M, Hedley MJ, Kirschbaum MUF, Wang T, van Hale R (2015) Experimental evidence for sequestering C with biochar by avoidance of CO2 emissions from original feedstock and protection of native soil organic matter. GCB Bioenergy 7(3):512–526. https://doi.org/10.1111/gcbb.12183 CrossRefGoogle Scholar
- Lehmann J, Joseph S (2009) Biochar for environmental management: science and technology. Earthscan, LondonGoogle Scholar
- Lehmann J, Gaunt J, Rondon M (2006) Bio-char sequestration in terrestrial ecosystems—a review. Mitig Adapt Strateg Glob 11:395–419Google Scholar
- Luo Y, Durenkamp M, De Nobili M, Lin Q, Devonshire BJ, Brookes PC (2013) Microbial biomass growth, following incorporation of biochars produced at 350 °C or 700 °C, in a silty-clay loam soil of high and low pH. Soil Biol Biochem 57:513–523. https://doi.org/10.1016/j.soilbio.2012.10.033 CrossRefGoogle Scholar
- Luo Y, Lin Q, Durenkamp M, Kuzyakov Y (2017) Does repeated biochar incorporation induce further soil priming effect? J Soils Sediments. https://doi.org/10.1007/s11368-017-1705-5
- Malghani S, Juschke E, Baumert J, Thuille A, Antonietti M, Trumbore S, Gleixner G (2015) Carbon sequestration potential of hydrothermal carbonization char (hydrochar) in two contrasting soils; results of a 1-year field study. Biol Fertil Soils 51(1):123–134. https://doi.org/10.1007/s00374-014-0980-1 CrossRefGoogle Scholar
- R Development Core Team (2012) R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. http://www.R-project.org
- Ventura M, Alberti G, Viger M, Jenkins JR, Girardin C, Baronti S, Zaldei A, Taylor G, Rumpel C, Miglietta F (2015) Biochar mineralization and priming effect on SOM decomposition in two European short rotation coppices. GCB Bioenergy 7(5):1150–1160. https://doi.org/10.1111/gcbb.12219 CrossRefGoogle Scholar
- Yousaf B, Liu G, Wang R, Abbas Q, Imtiaz M, Liu R (2017) Investigating the biochar effects on C-mineralization and sequestration of carbon in soil compared with conventional amendments using the stable isotope (δ13C) approach. GCB Bioenergy 9(6):1085–1099. https://doi.org/10.1111/gcbb.12401 CrossRefGoogle Scholar
- Yuan H, Lu T, Wang Y, Huang H, Chen Y (2014) Influence of pyrolysis temperature and holding time on properties of biochar derived from medicinal herb (radix isatidis) residue and its effect on soil CO2 emission. J Anal Appl Pyrol 110:277–284. https://doi.org/10.1016/j.jaap.2014.09.016 CrossRefGoogle Scholar