Location: Hayden, Idaho
Initial Harvest: 2013
Second Harvest: Planned winter 2017
Land Restoration: Planned summer 2017
In spring 2012, a 65-acre poplar bioenergy farm was planted near Hayden in Idaho’s panhandle. The Hayden site was established with a planting density of 1,452 stems per acre with rows aligned on 10-foot centers and three feet intervals within each row. The site’s soil is silty loam with a coarse gravel fraction. At an elevation of 2300 feet, the Hayden demonstration site receives 26 inches of precipitation per year and is drip-irrigated with groundwater during the drier summer months. A weekly irrigation schedule was developed based on inputs of evapotranspiration, crop demand, and climate. The staff of the Hayden Area Regional Sewer Board (HARSB) facility, which neighbors the site, assists with irrigation operations and monitoring.
HARSB has used municipal effluent to irrigate poplar trees since the mid-1990s rather than discharging the treated wastewater into the Spokane River. For now, the poplars in AHB’s demonstration site are not irrigated with recycled wastewater, but HARSB is requesting the necessary permits so that irrigation with wastewater can occur on the site in the future.
The Hayden site includes commercial production trials featuring seven hybrid poplar varieties and research plantings. The commercial trials aim to demonstrate biomass yields, management practices, the cost of production, and harvesting logistics. The research trials include a biomass productivity trial, an alder intercropping trial, and a poplar bioenergy clonal screening trial. Researchers are also looking at wildlife populations and soil sustainability at the site. You can learn more about the research happening here.
Overall, growth and survival were very good during the first two growing season. After the first growing season, overall height at the Hayden site was 4.8 feet with 96% survival. The best clone averaged 5.7 feet in height. As the second growing season ended in 2013, the trees averaged 15 feet in height with a 95% survival rate. Post-harvest, the poplars in Hayden regrew vigorously reaching heights in excess of 20 feet by their second post-coppice year. Final yield estimates will be available after the next harvest in the winter of 2017.
The Hayden site underwent its initial harvest in the fall of 2013. This harvest averaged 7.2 green tons per acre of poplar biomass. The full yield potential of the poplars was not achieved in this initial harvest. Optimal harvest yields are anticipated during the sites next harvest in the winter of 2017 after three-years of coppice growth occurs from established root systems.