Table 5.
Soil total nitrogen (TN) (g kg−1) in rubber and rubber–Flemingia macrophylla plantations from April 2014 to January 2017 (mean ± SD, n = 3).
| Soil depth (cm) | Treatments | Apr 2014 | Jun 2015 | Jan 2016 | Aug 2016 | Jan 2017 |
|---|---|---|---|---|---|---|
| 0–10 cm | R1 | 1.48 ± 0.03aA | 1.50 ± 0.10aA | 1.44 ± 0.06abA | 1.50 ± 0.06aA | 1.45 ± 0.04aA |
| RF1 | 1.45 ± 0.20abA | 1.45 ± 0.07aA | 1.42 ± 0.15abA | 1.55 ± 0.35aA | 1.46 ± 0.1aA | |
| R2 | 1.48 ± 0.04aA | 1.45 ± 0.07aA | 1.52 ± 0.06aA | 1.46 ± 0.11aA | 1.55 ± 0.05aA | |
| RF2 | 1.48 ± 0.11aA | 1.43 ± 0.11aA | 1.50 ± 0.04aA | 1.41 ± 0.13abA | 1.47 ± 0.14aA | |
| 10–30 cm | R1 | 1.15 ± 0.10cA | 1.12 ± 0.03bA | 1.17 ± 0.07cA | 1.16 ± 0.10bcA | 1.17 ± 0.06bA |
| RF1 | 1.15 ± 0.07cA | 1.18 ± 0.09bA | 1.19 ± 0.12cA | 1.12 ± 0.16cA | 1.10 ± 0.06bA | |
| R2 | 1.28 ± 0.07cA | 1.21 ± 0.03bAB | 1.29 ± 0.05bcA | 1.17 ± 0.04bcB | 1.22 ± 0.04bAB | |
| RF2 | 1.29 ± 0.08bcA | 1.24 ± 0.06bA | 1.23 ± 0.09cA | 1.18 ± 0.12bcA | 1.23 ± 0.09bA |
R1: rubber plantations established in 2006; R2: rubber plantations established in 1994; RF1: Flemingia macrophylla introduced to R1 in 2010; RF2: Flemingia macrophylla introduced to R2 in 2010. Values within a column followed by the same letter (lower case) or within the same row (upper case) do not differ significantly at P ≤ 0.05.