| Table 1. Description of the data used for testing the fertilization functions. Basal area, volume, age and current annual increment (CAI) refer to values at time of fertilizer application. AN is ammonium nitrate. Observed response (m3 ha–1 5 yr–1) is over bark. | ||||||||||||||||
| Total (n = 721) | Spruce (n = 301) | Pine (n = 420) | AN (n = 521) | Urea (n = 200) | ||||||||||||
| Variable | Mean | SD | Range | Mean | SD | Range | Mean | SD | Range | Mean | SD | Range | Mean | SD | Range | |
| Experiment start (year) | 1963 | 3.73 | 1959–1971 | 1962 | 3.21 | 1960–1971 | 1964 | 3.99 | 1959–1971 | 1963 | 3.57 | 1959–1971 | 1964 | 3.99 | 1960–1971 | |
| Basal area (m2 ha–1) | 19.8 | 6.41 | 3.3–41.2 | 22.4 | 6.74 | 3.3–41.2 | 18.0 | 5.47 | 5.1–37.7 | 19.4 | 6.24 | 3.29–41.2 | 20.9 | 6.72 | 5.1–39.5 | |
| Volume (m3 ha–1) | 166.7 | 76.37 | 20.4–482.9 | 206.5 | 83.56 | 20.4–482.6 | 138.2 | 55.45 | 23.5–373.2 | 161.5 | 72.32 | 20.4–482.9 | 180.3 | 84.72 | 23.5–467.6 | |
| Age (breast height yrs) | 91.2 | 20.71 | 42–139 | 89.7 | 18.91 | 57–139 | 92.4 | 21.86 | 42–127 | 91.2 | 21.21 | 42–139 | 91.3 | 19.4 | 57–127 | |
| CAI (m3 ha–1 yr–1) | 2.90 | 1.66 | 0.27–10.3 | 3.78 | 1.72 | 0.6–10.3 | 2.27 | 1.29 | 0.27–10.3 | 2.83 | 1.63 | 0.27–10.0 | 3.1 | 1.71 | 0.39–10.3 | |
| H40 (m) | 11.0 | 2.73 | 6.5–17.8 | 11.6 | 3.32 | 6.5–17.8 | 10.5 | 2.12 | 7.4–16.7 | 10.9 | 2.67 | 6.5–17.8 | 11.3 | 2.88 | 6.5–17.8 | |
| H100 (m) | 18.2 | 3.92 | 12.6–27.9 | 19.8 | 4.48 | 12.7–28.0 | 17.0 | 2.95 | 12.6–25.4 | 18.0 | 3.8 | 12.6–28.08 | 18.6 | 4.19 | 12.6–27.9 | |
| Latitude (° N) | 61.3 | 1.84 | 58–66 | 62.1 | 2.24 | 59–66 | 60.6 | 1.11 | 58–64 | 61.3 | 1.94 | 58–66 | 61.1 | 1.52 | 58–65 | |
| Altitude (m) | 269.9 | 169.5 | 10–630 | 221.5 | 145.3 | 10–500 | 304.5 | 177.12 | 50–630 | 262.3 | 167 | 10–630 | 289.5 | 174.74 | 10–630 | |
| Nitrogen (kg ha–1) | 110.1 | 56.25 | 31–250 | 105.0 | 55.67 | 31–225 | 113.7 | 56.45 | 31–250 | 104.5 | 56.15 | 31–250 | 124.5 | 54.05 | 50–250 | |
| Phosphorus (kg ha–1) | 9.0 | 15.19 | 0–60 | 7.7 | 13.61 | 0–54 | 10.0 | 16.18 | 0–60 | 10.0 | 15.33 | 0–60 | 6.4 | 14.53 | 0–60 | |
| Potassium (kg ha–1) | 23.0 | 38.81 | 0–144 | 18.8 | 35.82 | 0–123 | 26.1 | 40.59 | 0–144 | 28.8 | 41.8 | 0–144 | 8.0 | 23.86 | 0–123 | |
| Share AN | 0.72 | 0.45 | 0.00–1.00 | 0.71 | 0.45 | 0.00–1.00 | 0.73 | 0.44 | 0.00–1.00 | 1.00 | 0.00 | 1.00–1.00 | 0.00 | 0.00 | 0.00–0.00 | |
| Share Spruce | 0.42 | 0.49 | 0.00–1.00 | 1.00 | 0.00 | 1.00–1.00 | 0.00 | 0.00 | 0.00–0.00 | 0.41 | 0.49 | 0.00–1.00 | 0.44 | 0.50 | 0.00–1.00 | |
|
Observed response (m3 ha–1 5 yr–1) |
5.1 | 4.63 | -12.2–22.1 | 4.2 | 4.53 | -12.2–22.1 | 5.8 | 4.61 | -5.8–22.1 | 5.4 | 4.64 | -12.2–22.1 | 4.4 | 4.57 | -9.1–18.5 | |