For the studies established in 1993 (Wooster 1 and Pomerene 1), for seven of the 10 sets of needle samples analyzed (one set per year for five years for each area), there were statistically significant increases in N levels for trees that had been fertilized at the 100-pound-per-acre rate of N when compared with unfertilized trees, while there were usually more moderate and usually statistically insignificant increases as levels of N application increased to 200 or 300 pounds per acre (Tables 5 and 7). For the three studies established in 1996, N levels were consistently higher for fertilized trees. However, differences were not statistically significant, quite possibly because the lower numbers of replications and treatments resulted in higher error mean square values in F tests.
Average N levels in needles of unfertilized trees ranged from 1.24 to 1.93 percent, with lowest levels for the two plantings at Wooster and highest levels for the 1993 study at the Pomerene Forest Lab (Tables 5 and 7); for fertilized trees, foliar N levels ranged from 1.54 to 2.18 percent, with lowest values for trees on the three more poorly drained sites (Wooster 1 and 2 and Pomerene 3) and highest for Pomerene 1.
|
Table 7. Effects of Nitrogen Fertilization on Foliage Color and Nitrogen Content of Needles of Trees in Studies Established in 1996. | ||||||||
|---|---|---|---|---|---|---|---|---|
| Fert. Level | Foliage Color | |||||||
| Upper Surface of Needles | Lower Surface of Needles | Needle N Content | ||||||
| Average | Range1 | |||||||
| 1996 | 1997 | 1996 | 1997 | 1996 | 1997 | 1996 | 1997 | |
| ---Rating2--- | ---Rating3--- | ---Percent--- | ||||||
| Wooster 2: Established 1996 | ||||||||
| 0 | 3.3 | 3.3 | 1.5-4.5 | 2.0-4.0 | 1.2 | 1.3 | 1.37 | 1.39 |
| 100 | 3.9 | 3.7 | 3.0-5.0 | 3.0-4.0 | 1.6 | 1.9 | 1.61 | 1.57 |
| 200 | 3.7 | 3.6 | 2.5-4.5 | 2.5-4.0 | 1.6 | 1.8 | 1.74 | 1.64 |
| Avg. | 3.6 | 3.5 | 1.5-5.0 | 2.0-4.0 | 1.5 | 1.7 | 1.57 | 1.53 |
| pF4 | 0.22 | 0.15 | - | - | 0.31 | 0.22 | 0.17 | 0.16 |
| LSD5 | - | - | - | - | - | - | - | - |
| Pomerene 2: Established 1996 | ||||||||
| 0 | 3.3 | 3.0 | 2.5-4.5 | 3.0-4.0 | 1.6 | 1.7 | 1.51 | 1.47 |
| 100 | 3.9 | 3.7 | 2.0-4.5 | 3.0-4.0 | 1.8 | 2.0 | 1.95 | 1.79 |
| 200 | 3.8 | 3.7 | 2.5-4.5 | 2.0-4.5 | 1.9 | 1.9 | 1.96 | 1.86 |
| Avg. | 3.7 | 3.5 | 2.0-4.5 | 2.0-4.5 | 1.8 | 1.9 | 1.81 | 1.71 |
| F4 | 0.25 | 0.23 | - | - | 0.34 | 0.27 | 0.24 | 0.17 |
| LSD5 | - | - | - | - | - | - | - | - |
| Pomerene 3: Established 1996 | ||||||||
| 0 | 3.0 | 3.1 | 2.0-3.5 | 2.0-4.0 | 1.3 | 1.4 | 1.38 | 1.36 |
| 100 | 3.5 | 3.5 | 2.0-4.0 | 2.5-4.5 | 1.7 | 2.1 | 1.68 | 1.60 |
| 200 | 3.3 | 3.6 | 2.5-4.5 | 2.5-4.0 | 1.6 | 2.0 | 1.72 | 1.62 |
| Avg. | 3.5 | 3.4 | 2.0-4.5 | 2.0-4.5 | 1.5 | 1.8 | 1.59 | 1.53 |
| pF4 | 0.23 | 0.27 | - | - | 0.17 | 0.23 | 0.06 | 0.13 |
| LSD5 | - | - | - | - | - | - | - | - |
| 1 Range in upper surface needle color for all individual trees in each fertility treatment (3 reps x 7-10 trees per plot).
2 Upper Needle Surface Color: 1.0 = Yellow; 2.0 = Green-Yellow; 3.0 = Yellow-Green; 4.0 = Green; 5.0 = Blue-Green. 3 Lower Needle Surface Color: 1.0 = Slightly Bluish; 2.0 = Moderately Bluish; 3.0 = Bluish. 4 pF: Probability of statistical significance of analysis of variance F test. 5 LSD: Least significant difference at 5% probability level for comparing differences between treatment means. | ||||||||
Only limited data is available for nitrogen levels in the foliage of trees of the West Virginia origins of balsam fir in other plantings. In soil-site studies established using the same source of seedling planting stock used in the studies reported here, N levels in foliage of unfertilized trees ranged from 1.00 to 2.23 percent, with lowest values for trees on very wet sites and those with inadequate weed control and highest values on fertile well-drained plots having good weed control; for fertilized trees, N levels in needles of trees ranged from 1.73 to 2.41 percent (unpublished data). In Ohio, N levels in needles of trees of grower-owned plantings of var. balsamea averaged 2.25 percent and ranged from 1.40 to 3.25 percent; for var. fraseri, the mean N level was 1.78 percent, with a range of 0.70 to 3.10 percent (unpublished data).