Fig. 5: Global synthesis of soil nitrous acid (HONO) emissions rates, gross nitrite (NO2−) production, and the contribution of biotic pathways to the soil NO2− pool.
From: Denitrification is the major nitrous acid production pathway in boreal agricultural soils
a Shows log-transformed HONO emission rates (ng N m−2 s−1) from the soils of a number of ecosystems under different management practices. Each yellow box denotes interquartile range (IQR; 25th percentile at lower end to the 75th percentile at upper end) with a central black line as median, lower whisker as a minimum (25th percentile — 1.5 × IQR), upper wisher as a maximum (75th percentile + 1.5 × IQR), and filled black circle as an outlier of sample numbers presented above the boxes of respective soil management practices. See Supplementary Data 1 for more details. Different letters in a indicate significant differences between means (F = 22.64, P < 0.05) in HONO emissions in different ecosystems. The correlation in b shows the relationship between gross nitrite production rates (µg N gdw −1 d−1) and soil pH in this study (pink triangle) and from synthesized data (light brown), i.e., Supplementary Data 2. The slope in b is marginally significant (P < 0.1), whereas the intercept is significant at P < 0.05. c Shows the percentage (%) contribution of different biotic pathways, organic nitrogen oxidation (white bar), nitrification (light gray bar), denitrification (dark gray bar), and ratio of denitrification to sum of nitrification and denitrification (black bar) to the soil NO2− pool. See Supplementary Data 2 for more details.
