Figure 2.

Comparisons of soil total P in terms of its vertical distribution characteristics. (a) Soil total P with increasing soil depth. The lines across the boxes indicate the median values, and the lower and upper boxes shows the interquartile range (25th and 75th percentiles, respectively). (b) Density distribution of soil total P concentration in the different soil layers. The values of points and error bars indicate means ± SD for the different soil layers. − 10, − 20, − 30, − 50, and − 100 represents the 0–10 cm, 10–20 cm, 20–30 cm, 30–50 cm, and 50–100 cm soil depths, respectively.