Joseph Heckman, Extension Soil Fertility

Whatever the crop, soil testing and record keeping are guides to sustainable soil fertility and nutrient management.  When soil tests levels are low, Christmas tree growers should attempt to build soil fertility levels into the optimum range.  And once that goal has been achieved, growers should focus on maintaining soil test levels in the optimum range.

This practice requires information on balancing fertilizer amendments with crop nutrient removal.  In the case Christmas Trees, this means nutrients associated with harvest of cut trees.  Rutgers NJAES has this type of data already built into an extension fact sheet: Soil Fertility Recommendations for Christmas Trees   https://njaes.rutgers.edu/fs1187/

For nutrient management purposes it is useful to know what a harvested or cut Christmas Tree removes from the soil.  On average, a harvest of 100 cut Christmas Trees contains 29 lb. Nitrogen, 3 lb. Phosphorus, 8 lb. Potassium, 12 lb. Calcium, 2 lb. Magnesium, and 1 lb. Sulfur.

An average fresh cut Christmas Tree that is 92 inches tall may be expected to have a fresh weight of about 48.5 lb.  Water typically makes up about 54% of a fresh cut tree weight.  Thus, on a dry basis a cut tree would have a weight of about 22.4 lb.

Tree recycling and mulch making are now common in many communities.  If the trees are shredded the nutrient content data above can be used to estimate the nutrient density of the resulting wood chips.

Reference:

Zinati, G., J.R. Heckman, and M. Vodak. 2016. Nutrient Removal by Christmas Tree Harvest. Journal Plant Nutrition. 39: 1506-1512.