Open AccessWoody biochar's greenhouse gas mitigation potential across fertilized and unfertilized agricultural soils and soil moisture regimes
Author(s) -
Ramlow Matt,
Cotrufo M. Francesca
Publication year - 2018
Publication title -
gcb bioenergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.378
H-Index - 63
eISSN - 1757-1707
pISSN - 1757-1693
DOI - 10.1111/gcbb.12474
Subject(s) - biochar , soil water , greenhouse gas , environmental science , carbon sequestration , mineralization (soil science) , slash and char , environmental chemistry , moisture , nitrification , agronomy , chemistry , pyrolysis , carbon dioxide , soil organic matter , nitrogen , soil science , ecology , organic chemistry , biology
Biochar has been widely researched as an important technology for climate smart agriculture, yet work is still necessary to identify the magnitude of potential greenhouse gas ( GHG ) mitigation and mechanisms involved. This study measured slow‐pyrolysis wood‐derived biochar's impact on GHG efflux, mineral N dynamics, and soil organic C in a series of two incubations across fertilized and unfertilized agricultural soils and soil moisture regimes. This research explored the magnitude of biochar's full GHG mitigation potential and drivers of such impacts. Results of this incubation indicate slow‐pyrolysis wood‐derived biochar has potential to provide annual emission reductions of 0.58–1.72 Mg CO 2 ‐eq ha −1 at a 25 Mg ha −1 biochar application rate. The greatest GHG mitigation potential was from C sequestration and nitrous oxide (N 2 O) reduction in mineral N fertilized soils, with minimal impacts on N 2 O emissions in unfertilized soils, carbon dioxide ( CO 2 ) emissions, and methane ( CH 4 ) uptake. Analysis of mineral N dynamics in the bulk soil and on biochar isolates indicated that neither biochar impacts on net mineralization and nitrification nor retention of ammonium ( NH 4 + ) on biochar isolates could explain biochar's N 2 O reduction. Instead, biochar amendments exhibited consistent N 2 O emission reductions relative to the N 2 O emission in the control soil regardless of soil type and fertilization. Results across a soil moisture gradient suggest that woody biochar may aerate soils shifting redox conditions and subsequent N 2 O production. Understanding the magnitude of biochar's GHG reduction potential and the mechanisms driving these effects can help inform biochar modeling efforts, explain field results and identify agricultural applications that maximize biochar's full GHG mitigation potential.