N2O Emissions Mitigation in Acidic Soil Following Biochar Application Under Different Moisture Regimes

Abstract

Managing soil pH has been recognized as one of the promising options for N 2 O emission mitigation in acidic soils. Rice-straw biochar (BC) application to acidic soils can not only ameliorate soil acidity but also influence N 2 O emissions. We investigated the impact of various levels of rice-straw-derived biochar, a control (no biochar), 2% biochar, and 4% biochar under 50% and 90% water-filled pore space (WFPS) values. In comparison with the application of biochar at 2%, the application of biochar at 4% more pronouncedly altered soil properties (pH, ammonium (NH 4 +-N), nitrate (NO 3-N), microbial biomass carbon (MBC), and abundance of nosZ and nirK genes). Similarly, more noticeable changes in soil properties were noted under 90% WFPS than under 50% WFPS. The soil pH increased from 5.67 to 7.29 with the 4% biochar application. In comparison with those following the 2% biochar application and the control, soil mineral N and the abundance of nosZ and nirK genes following the 4% biochar application were more augmented, thereby leading to a remarkable reduction in soil N 2 O emissions. The MBC content in the soil also increased with the BC applications, and the maximum MBC contents of 655 and 428 mg kg −1 dry soil were recorded with the 4% biochar application under 50% and 90% WFPS, respectively. Moreover, in comparison with the control, 4% BC mitigated soil N 2 O emissions by 83%, whereas cumulative N 2 O emissions were mitigated by 49%. In comparison with 90% WFPS, 50% WFPS produced 35% more N 2 O emissions. However, the biochar applications significantly (p < 0.05) reduced N 2 O emissions under both WFPS values owing to an increase in soil pH, which activated mineral N (NH 4 +-N and NO 3 −-N) and enhanced the abundance of nosZ and nirK genes. These results suggest that biochar applications can substantially diminish soil N 2 O emissions by triggering soil pH, soil C and N pools, and the abundance of nosZ and nirK genes.

Meta-Analysis for Quantifying Carbon Sequestration and Greenhouse Gas Emission in Paddy Soils One Year after Biochar Application

“…Soil types and P and K fertilizers were the key factors affecting N 2 O emissions from paddy soils. Soil type affecting N 2 O emissions was a reasonable finding because varied pH values, nutrient status, and textures would influence N 2 O emissions, and the K fertilizer application rate affected N utilization for the plant to grow, thus potentially changing the N 2 O emission response to N fertilizer [14,46,47]. Neutral to slightly acidic soil pH favored N 2 O emissions (Supplementary Materials Figure S10).…”

The Effect of Biochar and Straw Return on N2O Emissions and Crop Yield: A Three-Year Field Experiment

“…In addition, our research found that biochar application increased soil pH (Figure 2). The increased pH in the FB treatment enhanced the activity of nitrous oxide reductase and promoted the reduction from N 2 O to N 2 [44,45]. Moreover, biochar played an important role in transferring electrons to denitrifying microorganisms, promoting the conversion of N 2 O to N 2 , and thus reducing N 2 O emissions [46].…”

Obtaining Biochar From Rice Husk and Straw

“…The paper provides data that the use of biochar together with nitrogen fertilizers in rice sowing increases the yield of rice up to 44.4% [18]. Biochar obtained from rice straw normalizes the pH of acidic soil, reduces N 2 O emissions into the environment by 83% and activates mineral nitrogen [19]. The authors have studied the nature of sorption/desorption of biourea by biochar obtained from rice husk and straw at different pyrolysis temperatures (300, 450, 600°C), it has been found that the maximum adsorption of urea has been shown by biochar from rice straw and husk obtained at a pyrolysis temperature of 450°C, and these composites have the potential to enhance agricultural yield through the efficient use of nitrogen.…”