Fertilization of Western Redcedar (Thuja plicata) R.W. Negrave Coast Region, MFR

Western Redcedar Fertilization Fertilization studies Fertilization studies Harrington and Wierman Harrington and Wierman SCHIRP SCHIRP

Fertilization Studies Commercial thinning/ fertilization (WA) Commercial thinning/ fertilization (WA) SCHIRP: North Island, Kennedy Flats SCHIRP: North Island, Kennedy Flats WFP monitoring of operational trials WFP monitoring of operational trials

Harrington and Wierman (1990) Thinning and fertilization with different products Thinning and fertilization with different products Stands were 15 – 20 yrs old on poor sites Stands were 15 – 20 yrs old on poor sites Reported five years after treatment Reported five years after treatment

Harrington and Wierman: Seven Treatments Untreated Untreated Unthinned + NH4 + Ca + P + K + S Unthinned + NH4 + Ca + P + K + S Thinned, unfertilized Thinned, unfertilized Thinned + Urea-N Thinned + Urea-N Thinned + NH4 Thinned + NH4 Thinned + NH4 +Ca + P Thinned + NH4 +Ca + P Thinned + NH4 + Ca + P + K + S Thinned + NH4 + Ca + P + K + S

Harrington and Wierman: Application Rates 300 kg/ha N (urea; ammonium nitrate) 300 kg/ha N (urea; ammonium nitrate) 100 kg/ ha P (dicalcium phosphate) 100 kg/ ha P (dicalcium phosphate) 129 kg/ ha Ca (dicalcium phosphate) 129 kg/ ha Ca (dicalcium phosphate) 100 kg/ ha K (potassium sulphate) 100 kg/ ha K (potassium sulphate) 41 kg / ha S (potassium sulphate) 41 kg / ha S (potassium sulphate)

Harrington and Wierman: Results Height and diameter growth were significantly greater in all thinned or fertilized treatments, compared to untreated Height and diameter growth were significantly greater in all thinned or fertilized treatments, compared to untreated The best treatments for height (+65%) and diameter growth (+106%) contained ammonium nitrate and dicalcium phosphate The best treatments for height (+65%) and diameter growth (+106%) contained ammonium nitrate and dicalcium phosphate Ca and P additions increased growth over N alone Ca and P additions increased growth over N alone Thinning was also produced substantial diameter growth response Thinning was also produced substantial diameter growth response

SCHIRP Trials Kennedy Flats and N. Vancouver Island Kennedy Flats and N. Vancouver Island Kennedy Flats trial in general agreement with N. Vancouver Island trial Kennedy Flats trial in general agreement with N. Vancouver Island trial Scarification appears to have a positive effect on growth; slight interaction with fertilization Scarification appears to have a positive effect on growth; slight interaction with fertilization

SCHIRP NVI: Treatments Two sites: CH and HA Two sites: CH and HA Two species: Cw Hw Two species: Cw Hw Fertilized and unfertilized Fertilized and unfertilized 225 kg/ha as urea 225 kg/ha as urea 100 kg/ ha as triple superphosphate 100 kg/ ha as triple superphosphate NPK at planting NPK at planting Three establishment densities: Three establishment densities: 500, 1500 and 2500 sph 500, 1500 and 2500 sph

Volume Response to Fertilization

Summary of Effects Fertilization continued to increase height growth after 10 years Fertilization continued to increase height growth after 10 years Greatest volume response on HA Greatest volume response on HA Still deficient to very deficient in N Still deficient to very deficient in N

Future Growth? Growth pattern Growth pattern Magnitude of response Magnitude of response Nutrient concentrations and associations with growth Nutrient concentrations and associations with growth Foliage mass Foliage mass

Nutritional Response: 10 Years Later Fertilization increased foliar: N concentration on HA but not CH N concentration on HA but not CH P and Ca concentration in both species on both sites P and Ca concentration in both species on both sites

Favourable Indicators Volume response and total volumes greatest on HA Volume response and total volumes greatest on HA Indications of more sustained incremental height growth on HA Indications of more sustained incremental height growth on HA N, P, and Ca concentrations all increased on HA and associated with growth: No evidence of dilution N, P, and Ca concentrations all increased on HA and associated with growth: No evidence of dilution Crown closure associated with better incremental height growth response Crown closure associated with better incremental height growth response Stand-level nutrient demands generally stabilize with crown closure Stand-level nutrient demands generally stabilize with crown closure

Unfavourable Indicators Volume response less on CH Volume response less on CH Loss of foliar-N concentration effect on CH Loss of foliar-N concentration effect on CH Reduced height growth with increasing density on CH Reduced height growth with increasing density on CH

Individual Cw Foliage Mass Foliage mass increased with nutrient regime: Foliage Mass (kg) CH-F0:2.15a CH-F1:3.73b HA-F1:5.96c

Foliage - Growth Relationships

General Conclusions Magnitude and duration of Cw response to fertilization are comparable to Fd Magnitude and duration of Cw response to fertilization are comparable to Fd No indications of negative growth response: trajectories likely parallel or better at SCHIRP No indications of negative growth response: trajectories likely parallel or better at SCHIRP Cw appears to respond well at higher densities Cw appears to respond well at higher densities Greater response implied by higher application rates; ammonium; Ca Greater response implied by higher application rates; ammonium; Ca