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Fertilization of Western Redcedar ( Thuja plicata ). R.W. Negrave Coast Region, MFR. Western Redcedar Fertilization. Fertilization studies Harrington and Wierman SCHIRP. Fertilization Studies. Commercial thinning/ fertilization (WA) SCHIRP: North Island, Kennedy Flats
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Fertilization of Western Redcedar (Thuja plicata) R.W. Negrave Coast Region, MFR
Western Redcedar Fertilization • Fertilization studies • Harrington and Wierman • SCHIRP
Fertilization Studies • Commercial thinning/ fertilization (WA) • SCHIRP: North Island, Kennedy Flats • WFP monitoring of operational trials
Harrington and Wierman (1990) • Thinning and fertilization with different products • Stands were 15 – 20 yrs old on poor sites • Reported five years after treatment
Harrington and Wierman: Seven Treatments • Untreated • Unthinned + NH4 + Ca + P + K + S • Thinned, unfertilized • Thinned + Urea-N • Thinned + NH4 • Thinned + NH4 +Ca + P • Thinned + NH4 + Ca + P + K + S
Harrington and Wierman: Application Rates • 300 kg/ha N (urea; ammonium nitrate) • 100 kg/ ha P (dicalcium phosphate) • 129 kg/ ha Ca (dicalcium phosphate) • 100 kg/ ha K (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 • 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 • Thinning was also produced substantial diameter growth response
SCHIRP Trials • Kennedy Flats and N. Vancouver Island • Kennedy Flats trial in general agreement with N. Vancouver Island trial • Scarification appears to have a positive effect on growth; slight interaction with fertilization
SCHIRP NVI: Treatments • Two sites: CH and HA • Two species: Cw Hw • Fertilized and unfertilized • 225 kg/ha as urea • 100 kg/ ha as triple superphosphate • NPK at planting • Three establishment densities: • 500, 1500 and 2500 sph
Summary of Effects • Fertilization continued to increase height growth after 10 years • Greatest volume response on HA • Still deficient to very deficient in N
Future Growth? • Growth pattern • Magnitude of response • Nutrient concentrations and associations with growth • Foliage mass
Nutritional Response: 10 Years Later Fertilization increased foliar: • N concentration on HA but not CH • P and Ca concentration in both species on both sites
Favourable Indicators • Volume response and total volumes greatest 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 • Crown closure associated with better incremental height growth response • Stand-level nutrient demands generally stabilize with crown closure
Unfavourable Indicators • Volume response less on CH • Loss of foliar-N concentration effect 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
General Conclusions • 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 • Cw appears to respond well at higher densities • Greater response implied by higher application rates; ammonium; Ca