Impact of biochar on greenhouse gas emissions and soil carbon sequestration in corn growth under drip irrigation with mulching

Authors: YANG, WEI - Inner Mongolian Agriculture University; Feng, Gary; Miles, Dana; GAO, LIHUA - Inner Mongolian Agriculture University; JIA, YONGLIN - Inner Mongolian Agriculture University; LI, CHANGJIAN - Inner Mongolian Agriculture University; QU, ZHONGYI - Inner Mongolian Agriculture University

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2020
Publication Date: 4/17/2020
Citation: Yang, W., Feng, G.G., Miles, D.M., Gao, L., Jia, Y., Li, C., Qu, Z. 2020. Impact of biochar on greenhouse gas emissions and soil carbon sequestration in corn growth under drip irrigation with mulching. Science of the Total Environment. 729:138752. https://doi.org/10.1016/j.scitotenv.2020.138752.
DOI: https://doi.org/10.1016/j.scitotenv.2020.138752

Interpretive Summary: Corn (Zea mays L.) is a major leading cash crop and is widely cultivated in arid and semiarid regions in northwestern China, due to local site-specific sunlight and heat resources. However, corn production in the region was greatly restricted by degraded soil characterized with little organic matter and poor water-holding capacity under low rainfall conditions. Rainfall and irrigation-water are easily lost below the root-zone, which limits the water and fertilizer productivity of corn plants. Drip irrigation under film-mulching are increasingly being used in the cropping systems in arid northwestern China due to these benefits and prospects: saving irrigation water, reducing nitrate leaching, restraining evaporation, and marketing requirements. To obtain acceptable crop yields and high economic outputs, a large number of commercial N fertilizers have been applied to corn production via the drip-irrigated approach under mulching. Excessive N input in corn upland soils has resulted in large increases in N2O and CO2 emissions in arid northwest China. With the increasing greenhouse gases (GHGs) in agriculture, the agricultural production and soil quality would be greatly limited globally.It is urgent to develop the effective agronomic practice to reduce GHGs emission from cropping system under drip-irrigation with film mulching. Biochar is commonly used as a soil additive to challenge climate change through restraining GHG production and increasing soil C sink in cropland soils. We adopted 2-yr field experiments to investigate the impact of biochar application on greenhouse gases (GHGs), soil organic carbon (SOC), and global warming potential (GWP) on sandy loam soil in Northwestern China. Biochar application rates of 0 (B0, control), 15 (B15), 30 (B30), and 45 (B45) t hm-2 were broadcasted onto the soil surface at the first crop growing season to a film-mulched and drip-irrigated corn production system. We found that biochar amendments of 15 and 30 t hm-2 reduced soil emissions of CO2, CH4, and N2O within two growing seasons, when it was only applied to sandy loam soil in the first growing season. However, the biochar amendment of 45 t hm-2 increased CH4 emission in the first year and reduced its emission in the second year, although these reductions of CO2 and N2O emissions were observed. Biochar amendments of 15, 30, and 45 t hm-2 also significantly reduced the total GWP of N2O and CH4 and greenhouse gas emission intensity. Biochar treatments with 30 and 45 t hm-2 significantly increased SOC sequestrations at the top 15-cm depth by 16 and 26% as averaged two growth periods. On average, biochar amendment with 30 t hm-2 should be recommended in terms of reducing GHG production, improving soil organic matter, and increasing corn yield under a mulched and drip-irrigated cropping system.

Technical Abstract: Biochar is widely used as a soil amendment to challenge climate change through restraining greenhouse gas production and increasing soil C sink in cropland soils, yet its effect was not studied well under drip irrigation with film mulching. A two-year field experiment was conducted to investigate the impact of biochar amendments on greenhouse gases (GHGs), soil organic carbon (SOC), and global warming potential (GWP) on sandy loam soil in Inner Mongolia, northwest China. Biochar application rates of 0 (B0, control), 15 (B15), 30 (B30), and 45 (B45) t hm-2 were broadcasted onto the soil surface, and then mixed into 30-cm soil depth with a rotary cultivator at the first crop growing season to a film-mulched and drip-irrigated corn production system. Soil emissions of CO2, N2O, and CH4 were measured using a closed static chamber approach at approximately 15-day intervals. SOC concentrations were determined around sowing and harvesting dates. Compared to control plots, biochar amendments reduced total CO2 emission by 18~25% at the first growing season, and 19~41% at the second growing season. The highest and lowest CH4 emissions were from B45 and B15 treatments in the first year, and B45 and B30 treatments in the second year, respectively. Relative to the control, B15 and B30 amendments reduced CH4 emission by 124% and 132% as averaged over 2-yr. With biochar amendments, total N2O emission was decreased by 71~110% and 39~47% in the first and second year. Among these biochar amendments, B30 was the best amendment limiting the GWP of N2O and CH4 in any of the two years. Amendments B30 and B45 significantly increased SOC sequestration in the top 15-cm depth by 19% and 37% in the first growing season, respectively, and by 12% and 15% in the second growing season. Biochar amendment B30 also significantly increased corn yields. Results demonstrate that biochar shows the greatest potential to mitigate greenhouse gas emissions in the first year and increase soil C sequestration. Results also show the greatest reductions with biochar application 30 t hm-2 in corn.