Effects of Biochar Application on CO2 Emissions from a Cultivated Soil under Semiarid Climate Conditions in Northwest China

Abstract

Biochar amendments to soil have potential as a climate change mitigation strategy. However, their effect on carbon exchange in different ecosystems has not been well evaluated. Understanding how biochar affects carbon exchange from agricultural soil is essential for clarifying the contribution of biochar management to the carbon budget. We performed a laboratory and a two-year field experiment to investigate the short-and medium-term effects of biochar application on CO 2 emissions from semiarid farmland. There was no statistically significant alteration in the cumulative CO 2 emissions from the mixture of soil with biochar alone, while the emissions increased significantly with additional nitrogen amendment over the 46-day experimental period. Over the two-year experimental period, the cumulative CO 2 emissions from the field experiment decreased in the biochar-amended treatment, and the effects were significant at high application rates (20 and 30 t·ha −1 ) relative to the control in the MS. The seasonal CO 2 dynamics were strongly dependent on soil temperature, with a higher correlation with the temperature at a depth of 10cm than with the temperature at a depth of 0cm. Soil temperature, rather than soil water content, was the major environmental factor controlling the soil carbon exchange in the semiarid farmland of the Loess Plateau. In general, biochar additions enhanced aboveground dry matter accumulation in both the early and late stages of maize growth. The results suggested that biochar amendment was a preferable management practice to help maintain or increase carbon sequestration for this region with lower CO 2 emissions and higher dry matter production over a longer period.

Risk Evaluation of Pyrolyzed Biochar from Multiple Wastes

“…Consumption of rice contaminated with PTEs is a major pathway for human exposure to PTEs as revealed in China's so called "Cancer Villages"; hence, sewage sludge biochar was applied to suppress PTE (As, Cd, Co, Cu, Mn, Pb, and Zn) phyto-availability in soil to reduce PTE levels in rice grown in mining-impacted paddy soils [61]. Risk assessment indicated that 10% biochar (P ≤ 0.05) decreased the daily intake, associated with the consumption of rice by 68,42,55,29,43,38, and 22% PTEs, respectively [61]. Health quotient (HQ) indices for PTEs (except for As, Cu, and Mn) were <1, indicating a suppression of health risk pointing to the incremental lifetime cancer (ILTR) value for iAs (AsIII + AsV) associated with the consumption of rice significantly reducing (P ≤ 0.01) by 66% [61].…”

Weak Effects of Biochar and Nitrogen Fertilization on Switchgrass Photosynthesis, Biomass, and Soil Respiration

“…Switchgrass can grow in less productive soils under a broad range of environmental conditions, and requires minimal soil preparation and a relatively small amount of nitrogen (N) [8,9]. Numerous approaches have been proposed to improve switchgrass productivity while reducing environmental impacts [10][11][12][13][14].…”

“…Biochar, applied as a soil amendment, has been promoted as a climate change mitigation tool as it has the potential to reduce soil greenhouse gas emissions and increase soil carbon sequestration [14][15][16].…”

“…The relationship between soil respiration and biochar addition is critical to our understanding of the carbon sequestration potential of biochar-amended soil in cropland ecosystems [4,14,15]. Since soil respiration is one of the largest fluxes of the global terrestrial carbon cycle, soil management strategies such as biochar addition should be carefully evaluated with respect to changes in soil respiration [18].…”

Forest soil respiration and exoenzyme activity in western North America following thinning, residue removal for biofuel production, and compensatory soil amendments

“…For laboratory incubation studies, biochar decreases (Spokas, Koskinen, Baker, & Reicosky, 2009) or increases (Stewart, Zheng, Botte, & Cotrufo, 2013;Zheng, Stewart, & Cotrufo, 2012) CO 2 emissions. However comparisons of laboratory incubation studies and field studies show that CO 2 emission responses to biochar are consistently higher in incubation studies than in field or greenhouse studies (He et al, 2017;Shen, Zhu, Cheng, Yue, & Li, 2017). The response of exoenzymes to biochar amendments have largely been conducted in laboratory incubations with variable results (Awad, Blagodatskaya, Ok, & Kuzyakov, 2012;Bailey, Fansler, Smith, & Bolton, 2011;Demisie, Liu, & Zhang, 2014;Ouyang, Tang, Yu, & Zhang, 2014).…”