Effect of Biochar on Soil Greenhouse Gas Emissions at the Laboratory and Field Scales

Abstract

Biochar application to soil has been proposed as a means for reducing soil greenhouse gas emissions and mitigating climate change. The effects, however, of interactions between biochar, moisture and temperature on soil CO2 and N2O emissions, remain poorly understood. Furthermore, the applicability of lab-scale observations to field conditions in diverse agroecosystems remains uncertain. Here we investigate the impact of a mixed wood gasification biochar on CO2 and N2O emissions from loess-derived soils using: (1) controlled laboratory incubations at three moisture (27, 31 and 35%) and three temperature (10, 20 and 30 °C) levels and (2) a field study with four cropping systems (continuous corn, switchgrass, low diversity grass mix and high diversity grass-forb mix). Biochar reduced N2O emissions under specific temperatures and moistures in the laboratory and in the continuous corn cropping system in the field. However, the effect of biochar on N2O emissions was only significant in the field and no effect on cumulative CO2 emissions was observed. Cropping system also had a significant effect in the field study, with soils in grass and grass-forb cropping systems emitting more CO2 and less N2O than corn cropping systems. Observed biochar effects were consistent with previous studies showing that biochar amendments can reduce soil N2O emissions under specific but not all, conditions. The disparity in N2O emission responses at the lab and field scales suggests that laboratory incubation experiments may not reliably predict the impact of biochar at the field scale.

Role of Nutrient-Enriched Biochar as a Soil Amendment during Maize Growth: Exploring Practical Alternatives to Recycle Agricultural Residuals and to Reduce Chemical Fertilizer Demand

“…As a soil amendment, biochar has been reported to offer several benefits, which include increased soil texture, soil carbon, nutrient retention, and cation exchange capacity, beside support to microbial diversity that increases mineralization and availability of nutrients in amended soils [19][20][21]. In a recent study, Fidel et al [22] evaluated the potential reduction of greenhouse gases (N 2 O and CO 2 ) emissions from biochar-amended soils based on laboratory soil incubations experiments and field scale studies under continuous cropping with four crop systems namely; no-till continuous corn, switch grass, forb mix, low-diversity and high-diversity grass mix. Their results highlighted that biochar had no effect on long term (>60 days) soil CO 2 emissions, but was able to suppress by 27% for the entire growing season of maize growing.…”

Effect of Woodchips Biochar on Sensitivity to Temperature of Soil Greenhouse Gases Emissions

“…It has to be considered that the short experimental duration of this study might limit the validity of the results to the first period after the application of biochar [76,77]. Therefore, these results may not be representative of the effect of biochar on long-term GHG emissions from soil in field application.…”

Formation and Fluxes of Soil Trace Gases

“…Multiple challenges exist in reconciling gas flux estimates and measurements based on laboratory investigations relative to field measurements, as shown by Fidel et al (2019) in this Special Issue [10]. Although the laboratory incubations they performed were made with soil from the same field plots and the same type of biochar as the field experiment, they were unable to obtain consistency between biochar effects on N 2 O and CO 2 emissions as measured in the lab relative to the field.…”