Fertilization
Objectives
• What factors affect fertilization decisions
• How to find information needed
• How to calculate application costs
Silvicultural Tools
• Plant
• Kill
• Ameliorate site
Ameliorate Site
• Irrigate
• Drain
• Subsoil
• Fertilize
Fertilize
• What?
• How much?
• When?
• How?
The Details
• Fertilizer guide:
http://www.for.gov.bc.ca/tasb/legsregs/fpc/fpcguide/fert/ferttoc.htm
Written in 1995 (Forest Code)
What
• Law of the minimum
• Law of compensation
Law of the Minimum
• Growth is limited by whatever factor is most need
Nitrogen
Poten
tial Grow
th
Actu
al Grow
th
Law of Compensation
• The addition of one factor can increase the efficiency that a tree uses another factor
Law of Compensation
With P
Amount of N
Gro
wth
Rat
e
How Much?
• Rule of efficacy
• What is needed
• Cost
• Returns
Rule of Efficacy
• Diminishing returnsG
row
th
Amount of “X”
Nutrient Cycling
•Availability• CEC• Weathering• Mineralization• C:N• Nutrient capital• Translocation
Fertilization
• Affects trees
• Does not affect site
Ratings
• Amount (percentage) of elemental Nitrogen (N); Phosphorous pentoxide (P2O5); and Potassium oxide (K2O)
• Ex. 12-20-10 = 12%N; 20% (P2O5); 10%(K2O)
Ratings
• 100kg would then have 12kg N; 20kg (P2O5); 10kg (K2O)
• Atomic weights:
N=14.01 K=39.10
P=30.98 O=16.0
Ratings
(P2O5) = (2 * 30.98)
(2 * 30.98) + (5 * 16.0)
or 43.65% P
So 43.65% of 20kg = 8.7kg P
Analysis
• Soil
• Foliar
Effect
• Affects plants
• Does not affect site (response is shortlived)
• Affects stand dynamics
Target Species
• Non-trees can have more rapid uptake
• Can be detrimental (more competition)
When?
• Get above competition during establishment
• Increase diameter just before thinning or harvest
• Shorten rotation
How?
• “Teabags”
• Sidecast
• Helicopter
Cost
• Application plus fertilizer
• How much will reach trees?
• Most effective on medium site indicies
