Impacts of 120 years of fertilizer addition on a temperate grassland ecosystem - Fig 3

<p><b>Effect of fertilizer treatment plot on (a) soil organic carbon stocks at 0–5 cm and (b) soil organic carbon stocks at 5–10 cm.</b> Error bars represent ±1 standard error of the treatment plot mean and contrasting letters denote significant differences between treatment plots. H is the Kruskal-Wallis test statistic. Filled ellipses with error bars represent the mean and ±1 standard error for the O horizon in plots 7 (N) and 11 (NK).</p>