Biochar Mitigated Yield-Scaled N2O and NO Emissions and Ensured Vegetable Quality and Soil Fertility: A 3-Year Greenhouse Field Observation

Abstract

Biochar amendments have been widely used in agricultural soil for lowering N2O and NO emissions while improving soil fertility and crop performance. However, a thorough understanding of the longevity of the favorable effects would be a prerequisite for large-scale biochar application in agriculture. We conducted a three-year greenhouse vegetable trial in Southeast China to systematically investigate the impacts of biochar mixed with nitrogen (N) on soil N2O and NO emissions, vegetable performance, and soil fertility at an interannual scale. The field experiment was established in November 2016 with biochar (0, 20 and 40 t ha−1; C0, C1, and C2, respectively), applied once without/with 240 kg N ha−1 urea (N0 or N1, respectively). Soil N2O and NO emissions were monitored during the spring vegetable cultivation period, and vegetable yield, quality, and soil properties were measured after harvests in 2018, 2019, and 2020. Results indicated that N application significantly increased N2O and NO emissions and vegetable yield throughout the trial period. Biochar combined with N generally reduced N2O and NO emissions and emission factors while increasing the vegetable yield, leading to lower yield-scaled N2O and NO emissions in 2018 and 2019. Biochar markedly enhanced soil pH and organic carbon and persisted, but generally had no significant effect on N use efficiency (NUE), vegetable quality, and soil fertility index (SFI) among treatments in over-fertilized vegetable fields. Based on our results, biochar application at 20 t ha−1 combined with N seemed to achieve the highest agronomic and environmental benefits for intensive vegetable production in Southeast China.

Ligneous amendments increase soil organic carbon content in fine-textured boreal soils and modulate N2O emissions

“…However, the long-term residual effects of biochar are still unknown, partly due to the lack of appropriate field experiments [27]. The current literature has shown that application of biochar has the potential to reduce soil N 2 O emissions [15,[28][29][30][31][32]. However, other studies have found transient or no discernible effects [28,33,34], or even occasional increases in N 2 O emissions [35][36][37][38].…”

Nitrous Oxide Emission and Grain Yield in Chinese Winter Wheat–Summer Maize Rotation: A Meta-Analysis

“…Soil N 2 O is primarily produced via microbial processes such as nitrification and denitrification [4]. It is well documented that soil aeration, the availability of N substrates, and soil organic carbon (SOC) content are among the most robust controllers of N 2 O fluxes from various agroecosystems [5][6][7][8]. These factors are closely related to climate (e.g., temperature and precipitation), soil properties (e.g., soil pH, texture, and organic matter content), and field management practices (e.g., N input rate, organic amendments, and tillage), thus leading to the large spatial and temporal variations in N 2 O emissions [9][10][11][12].…”