Effects of Nitrogen Fertilization on the Growth of Container-Grown TreesRichard ReganExtension HorticulturistNorth Willamette Research & Extension CenterOregon State University

Ash Nitrogen Utilization 2005 – 2008 (Regan & Scagel)

Ash Nitrogen Trial 2005Winter Harvest

Ash Nitrogen Trial 2005Winter Harvest

Root system of 32g N CRF treatment.Note the large coarse roots and deformities.

Root system of 16g N CRF treatment (left) and 0g N treatment (right).

Root system of 32g N CRF treatment (left) and 0g N treatment (right).

Nitrogen DrawdownNDI75 estimated at 0.2 @ 2.5mg per 0.1 = 20mg per week

21.2 liters substrate per container.

21.2 L x 20mg = 424mg N week.

424mg N x 30 weeks = 12,720mg or 12.7 grams N per season.

12.7 x 36 = 457g 457/454 = 1.0 lbs N yd3

0g N16g N CRF

32g N CRF

16g N UF

32g N UF

Other Observations Main stem caliper was increased with

increasing rates of N from CRF and UF.0 N = 19% increase in caliper.32g N = 29 to 35 % increase in caliper.

Bud break the following spring was earlier with N treatments than no N treatment.0 N = April 2.32g CRF = March 4.32g UF = March 18.

Slight difference in the onset of dormancy.

LST for ‘Summit’ Ash Stems (2006-2007)LST is the lowest freeze test temp at which no visual browning occurred.

LST for ‘Summit’ Ash Buds (2006-2007)LST is the lowest freeze test temp at which no visual browning occurred.

N rates or formulation did not effect Phytophthora syringea canker growth on Malus ‘Spring Snow’