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Research Branch > Stand Management > Fertilization > EP 886.01e
Effects of Nitrogen Application Rate on the
Growth of Lodgepole Pine (EP 886.01e)
Although N deficiencies are widespread in interior forests, fertilized
trees may not necessarily respond positively to increased N application
rate. Evidence from lodgepole pine fertilizer screening trials indicates
that on some interior sites, large N applications may actually reduce growth
by inducing or aggravating secondary nutrient deficiencies.
In 2000, the BC Ministry of Forests, Research Branch established an
area-based experiment to determine the effects of N application rate on the
growth and development of lodgepole pine. The site is located south of
Houston, within the Dry Cool subzone of the SBS biogeoclimatic zone (SBSdk).
The lodgepole pine plantation was 21 years old at the time of installation
To determine the effects of two N application rates (200N and 400N), each
applied with and without other nutrients, on the magnitude and duration of
growth response in young lodgepole pine.
The treatments include two N application rates (200N and 400N), applied
alone and in combination with a "Complete Mix" fertilizer (100P, 100K, 75S,
38Mg, 3B), and an unfertilized control. Each of the five treatments is
replicated three times, for a total of 15 treatment plots. Each circular,
0.07-ha treatment plot consists of an inner assessment plot surrounded by a
treated buffer. Growth data are collected from 50 trees within each
assessment plot every 3 years. Measurements include diameter at breast
height, total height, height to live crown, tree form and damage. Foliar
nutrient data were obtained from all treatment plots prior to fertilization,
and will also be collected after 1, 3, and 6 years.