A quantitative review of the effects of biochar application to soils on crop productivity using meta-analysis

Jeffery S, Verheijen FGA, van der Velde M, & Bastos AC (2011). A quantitative review of the effects of biochar application to soils on crop productivity using meta-analysis. Agriculture, Ecosystems & Environment 144 (1): 175-187. DOI:10.1016/j.agee.2011.08.015.

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Abstract

Increased crop yield is a commonly reported benefit of adding biochar to soils. However, experimental results are variable and dependent on the experimental set-up, soil properties and conditions, while causative mechanisms are yet to be fully elucidated. A statistical meta-analysis was undertaken with the aim of evaluating the relationship between biochar and crop productivity (either yield or above-ground biomass). Results showed an overall small, but statistically significant, benefit of biochar application to soils on crop productivity, with a grand mean increase of 10%. However, the mean results for each analysis performed within the meta-analysis covered a wide range (from -28% to 39%). The greatest (positive) effects with regard to soil analyses were seen in acidic (14%) and neutral pH soils (13%), and in soils with a coarse (10%) or medium texture (13%). This suggests that two of the main mechanisms for yield increase may be a liming effect and an improved water holding capacity of the soil, along with improved crop nutrient availability. The greatest positive result was seen in biochar applications at a rate of 100 t/ha (39%). Of the biochar feedstocks considered and in relation to crop productivity, poultry litter showed the strongest (significant) positive effect (28%, in contrast to biosolids, which were the only feedstock showing a statistically significant negative effect (-28%). However, many auxiliary data sets (i.e. information concerning covariables) are incomplete and the full range of relevant soil types, as well as environmental and management conditions are yet to be investigated. Furthermore, only short-term studies limited to periods of 1 to 2 years are currently available. This paper highlights the need for a strategic research effort, to allow elucidation of mechanisms, differentiated by environmental and management factors and to include studies over longer time frames.

Item Type: Article
Uncontrolled Keywords: Biochar; Soil; Crop productivity; Meta-analysis; Effect size; Crop yield
Research Programs: Ecosystems Services and Management (ESM)
Bibliographic Reference: Agriculture, Ecosystems & Environment; 144(1):175-187 (November 2011) (Published online 23 September 2011)
Depositing User: IIASA Import
Date Deposited: 15 Jan 2016 08:45
Last Modified: 19 Feb 2016 10:26
URI: http://pure.iiasa.ac.at/9536

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