Effect of backfill composition on net photosynthesis (Pn), evaporation rate (E), and water use efficiency (WUE) of Quercus robur trees (Pn: μmol m−2 s−1 CO2; Evaporation rate: μmol m−2 s−1 H2O; WUE: Pn/evaporation rate). Data are the average of four sampling dates in the first and second year and six sampling dates in the third year.
| Treatment | 1st year | 2nd year | 3rd year | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Pn | E | WUE | Pn | E | WUE | Pn | E | WUE | |
| Compost | 8.15 ns* | 1.50 ns | 5.43 ns | 9.92 c | 2.54 c | 3.90 b | 15.03 a | 5.30 ns | 2.83 ns |
| Fertilization | 7.69 | 1.00 | 7.69 | 12.24 a | 2.64 c | 4.63 a | 16.05 a | 5.40 | 2.97 |
| Leonardite | 7.61 | 1.10 | 6.45 | 11.10 b | 3.06 a | 3.62 b | 13.32 b | 5.21 | 2.55 |
| Control | 7.52 | 1.05 | 7.16 | 11.02 b | 2.85 b | 3.86 b | 13.18 b | 5.04 | 2.62 |
↵* Values differ significantly when followed by different letters at P ≤ 0.05 (LSD test); ns = not significant.