Effects of Nitrogen
Fertilization on the
Growth of ContainerGrown Trees
Richard Regan
Extension Horticulturist
North Willamette Research & Extension Center
Oregon State University
Ash Nitrogen Utilization 2005 – 2008
(Regan & Scagel)
Ash Nitrogen Trial 2005
Winter Harvest
Ash Nitrogen Trial 2005
Winter 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 Drawdown
NDI75 estimated at 0.2 @ 2.5mg per 0.1 = 20mg per week
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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
16g N
CRF
32g N
CRF
0g N
32g N
UF
16g 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’