| We examined the feasibility of foliar nitrogen application as an effective fertilizer in two shrub willows, Fish Creek (Salix purpurea) and Preble (Salix viminalis x (S sachalinensis x S. miyabeana)). Two objectives of the project were to determine if: (1) foliar application is an effective method of fertilization, and (2) different nitrogen sources are assimilated differently by the plants. We examined foliar and soil application of five forms of nitrogen (urea, ammonium nitrate, nitamin, GP787GP40 and arginine). Fresh weight, dry weight, polyamines, amino acids, soluble protein, and total nitrogen and carbon were analyzed. We concluded that: 1) foliar nitrogen leads to higher growth and assimilation, 2) different nitrogen sources are assimilated differently, 3) urea is the most effective foliar nitrogen fertilizer, and 4) foliar application leads to rapid uptake and metabolism of nitrogen. Thus foliar nitrogen can be used to increase its pool during fall for use in early spring. |
