• vi
Comparative Effects of Foliar- and Soil-Applied Nitrogen Fertilizers on Douglas-Fir:
Phytotoxicity.
D.
C.
Young* and R.
E. Miller,
I.
Foliar Burning and
Union Oil Company of California and USDA Forest Service ,
Pacific
Northwest Forest & Range Experiment Station.
Urea prill and various nitrogen solutions were applied to individual Douglas-fir seedlings or 6- to 70-year­
old stands of Douglas-fir and hemlock,
Nitrogen-dosages ranged from 22 to 448 kg/ha
burning appears independent of solution concentration.
burning depends,
Needle damage and top kill were much greater when treatment was applied in mid-growing
season than when applied before the growing season.
moderate N-dosages
or mature stands of Douglas-fir or west ern hemlock
On newly planted Douglas-fir,
however, N-dosages should not greatly
especially if ammonium nitrate is used and treatment is applied during the growing s eason.
In:
•
Our results suggest that concentrated foliar sprays at
(179 to 224 kg/ha) can be applied to young
without serious foliar burning or top kill.
•
Foliar
degree of
primarily, on the absolute amount of solute per unit of needle surface and the osmotic pressure
of its saturated solution.
exceed 112 kg/ha,
(x 0.89 ; lbs/acre).
Under a given set of physiological conditions,
Agronomy Abstracts: 66th annual
meeting of the American Society of
Agronomy; November 10-15, 1974;
Chicago, IL. Madison, WI: American
Society of Agronomy; 1974: 180.
Abstract.