Research and Studies

Tree Growth

RDN biosolids are applied to forest stands with nutrient poor soils. The biosolids Forest Fertilization Project has demonstrated increases in tree growth from 50% to 400%. Biosolids helps trees in nutrient poor areas to achieve their maximum natural potential as though they were growing in ideal conditions. Trees treated with biosolids also appear healthier; needles and buds are longer, greener and more numerous.

Comparison of tree growth rings
Comparison of tree growth rings before and after biosolids application.
Comparison of Douglas-fir tree branches from a stand applied with biosolids (left) and unapplied (right).

Groundwater Studies

In 2003 and 2012, studies were done which concluded that past and proposed future application of biosolids within the Application Area will not impact groundwater quality in any of the wells located in the region. It is important to note that biosolids in this project are not applied over drinking water aquifers.

This confirmed previously, monitoring results from 1992 that showed biosolids had:

  • No measurable impact on ground water
  • No measurable impact on nearby surface waters
  • No detectable impact on the five nearest residential water wells.
Extensive research from the 1992 biosolids pilot project showed that trace elements introduced into the soil through biosolids applications generally do not move far below the soil surface - usually within 5-10 cm. Even during a very severe rainstorm, biosolids that have not yet been absorbed into the soil will only move a few meters.

Past research projects include:

The private forest lands used in the Forest Fertilization Program were formerly leased to Vancouver Island University, a past participating partner in the Biosolids Program. As such they conducted a number of research project on biosolids.
1992 - 1994 GVRD / VIU Operational Research Project - This joint research project focused on the movement of biosolids in ground and surface waters. Local residential wells were also monitored.

1992 - 2017 VIU Growth and Yield Research Project - 14 growth and yield plots were monitored regularly. Results show the long term effects that biosolids applications have on coniferous trees' growth and yield.

1998 - 2017 VIU /Ministry of Forests Biosolids Research and Demonstration Project - This research site was established in a recently-harvested area. The effect of biosolids applications on coniferous trees' growth rates and wood quality was tracked. Vegetation measurements, which are taken every three years, show that biosolids applications have greatly increased tree growth rates.

2012 - 2017 VIU / RDN Carbon Sequestration Research Project - This project focussed on recently-established forest plantations, and has the goals of determining:

  1. How biosolids applications in both high and low nutrient sites affect the survival, growth and productivity of Douglas-fir and competing vegetation
  2. How applications affect the forest's development and its nutritional status over time
  3. How these changes affect the carbon balance of the plantations, i.e. the amount of carbon that will be stored in soil and vegetation over time.

Wastewater Services | 6300 Hammond Bay Road | Nanaimo, BC V9T 6N2 | E-mail: rcu@rdn.bc.ca
Telephone: 250-390-6560 (Nanaimo) 250-954-3792 (Oceanside) 1-877-607-4111 (Toll Free)
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