Needles on trees in study plots fertilized with N were generally somewhat longer than those that had not been fertilized, with no consistent differences between trees receiving different N levels. However, those differences were not statistically significant on any of the study plots (Tables 2 and 6). In earlier studies with Douglas-fir (Brown and Vimmerstedt, 1983), needle lengths were significantly longer on trees receiving at least 100 pounds of N per acre than on unfertilized trees, with no significant differences between trees fertilized with 100 to 225 pounds of N.
As noted with shoot growth, lengths of needles were generally longest on trees on the better-drained sites (Pomerene 1 and 2) and shortest on the two most poorly drained areas (Wooster 2 and Pomerene 3). Similar results related to internal soil drainage have been noted in soil/site studies (unpublished data).