Whistler Biosolids Forest Fertilization Program (EP1177)


It was anticipated that forest biosolids fertilization could achieve the dual benefits of improved soil fertility and tree growth in nitrogen-deficient Douglas-fir plantations of the Whistler Interpretive Forest, while providing an economic and environmentally safe disposal for Whistler’s municipal sewage biosolids. This experiment was established as a co-operative study between the BC Ministry of Forests, the University of British Columbia and the Resort Municipality of Whistler, to determine if these results were achievable was established 


  1. To compare fertilization of Douglas-fir with biosolids at 750, 1000, and 1500 kg-Nitrogen/hectare (N/ha) and conventional fertilizer at 225 kg-N/ha, and 
  2. To compare the growth response with season of fertilizer application (spring, summer and fall).

The experiment was established in 1993 near Whistler, B.C. in a 15-year-old, nutrient deficient Douglas-fir plantation that had been thinned to 600 stems/ha and pruned to 3 m height the year before. Season of application was tested by applying the fertilizers in 3 areas (blocks) with each block fertilized in a different season: summer (August 1993), fall (September, 1993) and spring (June, 1994).  The five fertilizer treatments (750, 1000, and 1500 kg/N/ha applied as biosolids, a conventional fertilizer at 225 kg-N/ha, and an unfertilized control) were tested in 0.09-ha plots with 2 plots per block receiving the same treatments (10 plots per block or 30 plots in total). 


Completed 1999.


  • Girard, A. 2014. A five-year comparison, between fertilizer and biosolids, of yield in a coastal Douglas-fir plantation: an eighteen year post fertilization growth response assessment. BScF thesis. Univ. British Columbia, Vancouver, B.C.
  • de Montigny, L. and S. Stearns-Smith. 2001. Douglas-fir fertilization with biosolids: five-year results at Whistler, B.C. B.C. Min. For., Victoria, B.C. Exten. Note 50.
  • Zhong, A. 1998. Efficacy of secondary biosolids fertilization in a managed Douglas-fir forest in the Coastal Western Hemlock zone of British Columbia. PhD thesis. Univ. British Columbia, Vancouver, B.C.