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