Graphical Diagnoses of Lodgepole Pine Response to Fertilization
1982
Weetman, G. F. | Fournier, R.
A combined use was made of “mini” plots and graphical analysis of shifts in nutrient concentration, unit fascicle weight, and nutrient content for needles grown in the first year following spring fertilizer application. Nitrogen, phosphorus, and potassium were applied, in factorial design with five replications, to 17 precommercially thinned lodgepole pine stands in the interior of British Columbia. The use of one bulked foliage sample from two sample trees per plot was sensitive to treatment differences. Phosphorous, potassium, calcium, and magnesium deficiencies were generally not diagnosed either with or without N additions. Mean fascicle weight increase for all trials was 20% for three N levels, suggesting a strong probability of appreciable 5-year volume increases. Response to N additions was variable and could not be readily explained by site conditions. Non-responsive stands showed luxury N uptake and suggested the presence of non-nutritional growth constraints. Additional screening trials are recommended to sample the wide range of sites and climates. The technique was found to be time and cost efficient with the advantage of producing both response data and nutrient status diagnosis within 1 year of fertilizer application.
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