Open AccessDoes biochar enhance soil organic matter formation in tropical soils?
Author(s) -
Laura S. Schnee,
Albert Ngakou,
Juliane Filser
Publication year - 2021
Publication title -
iop conference series. earth and environmental science
Language(s) - English
Resource type - Journals
eISSN - 1755-1307
pISSN - 1755-1315
DOI - 10.1088/1755-1315/648/1/012195
Subject(s) - biochar , oxisol , ultisol , soil water , amendment , organic matter , environmental science , soil organic matter , nutrient , agronomy , chemistry , soil science , environmental chemistry , biology , law , organic chemistry , pyrolysis , political science
Tropical soils are often deeply weathered and vulnerable to degradation. Biochar is a promising means to improve physico-chemical characteristics such as pH or bulk density. Sustainable soil amelioration is best achieved by improving biological activity, resulting in enhanced soil organic matter (SOM) stocks. In a meta-analysis, we investigated, if biochar amendment to tropical soils led to native SOM stock increases. We found a mean additional C accumulation (MAC) of 0.29% soil dry weight (% dw). MAC was independent of study duration, climate, and biochar addition rate, but strongly linked to soil type and nutrient status prior to the experiment: In Nitisols, MAC was highest (0.99% dw) and initial C and N contents were higher in these soils. MAC was negative in Ferralsols and Oxisols (–0.01% dw and –0.2% dw respectively). MAC as a percentage of initial C content was <50% for most soil types, but –50% in Ferralsols, Oxisols and Ultisols. We conclude that while biochar can enhance SOM stocks, attention has to be paid to the soil environment it is amended to. In low-activity clay soils, biochar amendment can lead to C mining and should therefore be co-amended with nutrient-rich organic amendments.