A Test of Close-Spaced, Short-Rotation Culture of Black Cottonwood

Abstract

Yield of black cottonwood (Populustrichocarpa Torr. and Gray) in 2-year rotations was affected in the first rotation by spacing and fertilization. Closest spacing (0.30 × 0.30 m) resulted in highest yield in the first rotation whereas in the second rotation, yield was not significantly affected by spacing. The average fresh weight yields were 13.4 tons/hectare/year in the first harvest and 20.9 tons/hectare/year in the second harvest. Initial fertilization with both N, and N, P, and K fertilizers improved growth in the first harvest but not in the second. During the first year, triazine herbicides controlled weeds but caused slight damage to the plants. Although there were no significant differences in yield between the herbicides, atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) reduced survival and first year height growth below that obtained with propazine (2-chloro-4, 6-bis[isopropylamino]-s-triazine) or simazine (2-chloro-4, 6-bis-ethylamino-s-triazine). Yield results and limited pulping studies show that short rotation black cottonwood has potential value for pulp fiber production.