Effects of nitrogen and phosphorus fertilization on Douglas-fir nursery growth and survival after outplanting

Abstract

A 5N × 5P factorial fertilizer experiment was conducted on Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) seed beds at Campbell River nursery on northern Vancouver Island. Nutrient concentrations were measured in soil and seedlings. After 2 years of growth, trees were lifted from each treatment in mid-November and again in mid-February for storage. All were planted out in April and grown for 2 years. Seedling dry weight and height in the nursery were significantly affected by N fertilizer treatment, but not by P fertilizer, although seedling tissue P concentrations were low (0.09-0.17%) and available soil P was significantly increased by treatment. Largest seedlings resulted from application of 50-75 kg N/ha during the 1st year of growth and 100-150 kg N/ha during the 2nd year. Seedling dry weight was correlated with tissue N concentration (r = 0.73-0.75) and greatest dry weight was associated with a 1-0 shoot N or a 2-0 foliar N concentration of 2%. Survival and height 2 years after planting out were significantly affected by N fertilizer treatment in the nursery, and the nursery treatments resulting in largest seedlings yielded the highest survival and height. However the N concentration of 2-0 seedlings was not closely correlated with survival or height, and shoot dry weight was the most useful nursery measurement for predicting these values (r = 0.49). Fertilization did not affect cold hardiness and hardiness of trees was essentially the same at both lifting dates. Survival at 2 years after planting was unaffected by lifting date.