Growth and nutrient dynamics of Douglas-fir seedlings raised with exponential or conventional fertilization and planted with or without fertilizer

Abstract

The effects of two operational nursery fertilization regimes on the growth and nutrient dynamics of Douglas-fir ( Pseudotsuga menziesii var. glauca (Beissn.) Franco) seedlings after planting were compared. Seedlings were grown in a nursery with nutrients added at a constant rate (conventional fertilization) or at a rate that increased exponentially by 2%·day–1 (exponential fertilization) and planted near Barriere and Victoria, British Columbia. At the time of planting, half of the conventionally fertilized seedlings were planted with slow-release fertilizer packets. Growth and nutrient allocation was observed for 2 years following planting. Although the exponential fertilization regime provided 25% more N in the nursery compared with the conventional fertilization regime, exponentially fertilized seedlings were smaller at the time of planting, did not differ significantly in foliar N concentration, and showed no lasting benefits in growth or nutrient allocation. Two years after planting, there were no significant differences between the conventional and exponential fertilization regimes in seedling height, root collar diameter, total dry mass, or whole-plant N concentration. Seedlings fertilized at the time of planting had greater height and dry mass on the Barriere site but not on the dry Victoria site and whole-plant N concentrations did not differ 2 years after planting.