Figure 1.
Cumulative 15N-N2O and 15N-N2 gas productions derived from Equation (1) from soil cores supplied with different forms of organic substrates or none (SOM-C).
(A) N2O-N and (C) N2-N gas productions for acetate, malic acid, butyrate and succinate treatments. (B) N2O-N and (D) N2-N gas productions for glucose, sucrose SOM-C and cysteine treatments. Values are means ±1 SEM (n = 4). The SOM-C treatment is the pooled results from 4 separate consecutive SOM-C experiments (n = 16).
Figure 2.
The N2/N2O ratios from the cumulative productions of 15N-N2 and 15N-N2O over time and slope coefficients form linear regressions.
(A–G) N2/N2O ratios for each treatment plotted alongside glucose for pair wise comparisons. Solid lines are linear regression, with 95% confidence bands (dashed lines). Values are means ± SEM (n = 4) and SOM-C n = 16. (H) Shows the slope coefficients (errors bars are ±95% confidence intervals) from regression analysis. The dashed red lines show the confidence intervals of the glucose treatment and the red symbols represent slopes which are not significantly different from glucose (ANCOVA and Tukey Kramer multiple comparison).