Herbicides increase growth responses to fertilizer in a 5-year-old Eucalyptus regnans plantation

A 5-yr-old Eucalyptus regnans plantation in the Napier district of the North Island of New Zealand was treated with 200kg diammonium phosphate (DAP)+250kg urea/ha or 200kg DAP+500kg urea/ha, and with a 2% solution of glyphosate applied at a rate of 3la.i./ha. Reduction of herbaceous/shrubby competition significantly increased 20-month dbh and volume increments but did not affect height increment. Fertilizer significantly influenced height increment, but did not affect diameter and volume increment. Neither herbicide nor fertiliser treatment significantly influenced foliar nutrient concentrations. -from Author