Response of interior spruce to fertilization in the interior of British Columbia

In 1987, a research project, conducted in the interior of British Columbia, was undertaken in order to obtain preliminary fertilization response data for three interior species. In 1988, as part of this contract, 12 screening trials were established in young interior spruce stands in the north-central interior of B. C. using factorial combinations of nitrogen and "complete" mix fertilizer. Initial assessment of the unfertilized foliage obtained from the 12 installations indicated that all stands exibited low nitrogen and potentially low sulphur levels. After fertilization, the effects of the treatments were measured by needle weight response, nutrient concentration, and subsequent nutrient content response. In all 12 installations the largest needle weight response occured when the nitrogen and the "complete" mix fertilizers were combined.. In the treatments where nitrogen was applied alone, no significant change in needle size was recorded. Nutritionally, nitrogen fertilization resulted in large increases in nitrogen concentration, indicating this element was limiting. As well, nitrogen fertilization also produced large decreases in K, S, and S04-S concentrations. Nitrogen-only fertilization also caused large elevations in the N/S ratios to occur. This elevation in N/S ratios and the subsequent decreases in S and S04-S concentrations seem to indicate that nitrogen-only fertilization has a negative impact on the sulphur nutrition of interior spruce. The addition of the "complete" mix fertilizer was, in most cases, successful in returning the decreased nutrient concentration levels of K, S, and S04 and the elevated N/S ratios back to their original unfertilized status. From these results it appears that nitrogen fertilization of interior spruce should only be considered if it is accompanied by a mixture of other nutrients; the most important component being sulphur.Forestry, Faculty ofGraduat