First rotation biomass production and nutrient cycling within short-rotation coppice willow plantations in Saskatchewan, Canada

Although numerous studies have quantified different social, economic, energetic, and environmental benefits associated with short-rotation coppice (SRC) willow plantations, comprehensive assessments of nutrient cycling are rare. The objective of this study was to examine the biomass production and attendant biogeochemical cycling of nitrogen (N), phosphorus (P), potassium (K), sulphur (S), calcium (Ca), and magnesium (Mg) during the initial four-year rotation of six willow varieties grown at four locations along a 500 km north-south pedoclimatic gradient within Saskatchewan, Canada. Nutrient budgets consisted of quantifying various nutrient inputs (e.g., atmospheric deposition and soil mineral weathering), outputs (e.g., fine and coarse root biomass, leaf biomass, harvested biomass, leaching, and denitrification), and transfers (e.g., soil organic matter mineralization, canopy exchange, leaf litter decomposition, and fine root turnover) associated with the plant available soil nutrient pool. Total above- and below-ground production during the rotation was approximately 40 Mg ha-1, with calculated soil nutrient budget deficits (i.e., nutrient outputs > inputs + transfers) of 17, 39, 112, 271, and 74 kg ha-1 for N, P, K, Ca, and Mg, respectively, averaged across the varieties and sites, but a soil S surplus of 60 kg ha-1. While soil nutrient budget deficits varied among sites, there were no significant differences (P >0.05) among willow varieties. Despite the relatively low nutrient-demanding nature of willow and negligible leaching or denitrification losses, nutrient export in harvested biomass over multiple rotations will require soil nutrient amendments to maintain SRC willow productivity, particularly N and P, albeit a fraction of the amount required for annual agronomic crops

Willow short-rotation production systems in Canada and Northern United States: A review

Willow short rotation coppice (SRC) systems are becoming an attractive practice because they are a sustainable system fulfilling multiple ecological objectives with significant environmental benefits. A sustainable supply of bioenergy feedstock can be produced by willow on marginal land using well-adapted or tolerant cultivars. Across Canada and northern U.S.A., there are millions of hectares of available degraded land that have the potential for willow SRC biomass production, with a C sequestration potential capable of offsetting appreciable amount of anthropogenic green-house gas emissions. A fundamental question concerning 1 sustainable SRC willow yields was whether long-term soil productivity is maintained within a multi-rotation SRC system, given the rapid growth rate and associated nutrient exports offsite when harvesting the willow biomass after repeated short rotations. Based on early results from the first willow SRC rotation, it was found willow systems are relatively low nutrient-demanding, with minimal nutrient output other than in harvested biomass. The overall aim of this manuscript is to summarize the literature and present findings and data from ongoing research trials across Canada and northern U.S.A. examining willow SRC system establishment and viability. The research areas of interest presented here are the crop production of willow SRC systems, above- and below-ground biomass dynamics and the C budget, comprehensive soil-willow system nutrient budget, and soil nutrient amendments (via fertilization) in willow SRC systems. Areas of existing research gaps were also identified for the Canadian context

Relationship of soil properties to pyroxasulfone bioactivity in a range of prairie soils

The relationship between pyroxasulfone bioactivity and soil properties has not been investigated in a wide range of soils typical of western Canada. In this study, 47 soils from Saskatchewan, Manitoba and Alberta, with varying organic matter content (1.5%–22.1%), pH (5.0–7.9), and clay content (6.8%–59.4%) were used to evaluate the effect of soil properties on pyroxasulfone bioactivity and its relevance to field application rates. Bioactivity was assessed by measuring the reduction of sugar beet shoot length after 7 days in response to 0, 92, 184, and 368 µg ai kg−1 pyroxasulfone concentration in soil. Multiple regression analysis showed that pyroxasulfone bioactivity was related to soil organic matter content, pH and clay content. Grouping the soils according to these properties allowed for a summarization of pyroxasulfone field application rates required to achieve bioactivity based on the magnitude of sugar beet shoot length inhibition (%). The estimated field application rates ranged from less than 120–480 g ai ha−1

Chemical and molecular scale speciation of copper, zinc and boron in agricultural soils of the Canadian prairies

The general incidence of copper (Cu), zinc (Zn), and boron (B) deficiencies in soils of the Canadian prairies may be related to identifiable, highly variable inherent soil attributes. The objective of this study was to investigate the variability of selected properties, and their relationship with the bioavailability, forms and distribution of Cu, Zn, and B in a range of prairie soils. The nature of these micronutrient distribution was evaluated by measuring extractable concentrations, supply rates, and separation into various chemical pools through sequential extraction and spectroscopic speciation analyses. Soil pH was found to be the least variable property (CV=The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Growth, Survival, and Yields of 30 Short-Rotation Willow Cultivars on the Canadian Prairies: 2nd Rotation Implications

Willow biomass yields from short-rotation coppice bioenergy systems have been reported across multiple rotations in Europe, USA, and eastern Canada, but data are lacking for the Canadian Prairies. The goal of this study was to evaluate the second rotation biomass yields and stem growth for 30 willow cultivars established in Saskatchewan, Canada in 2007, and coppiced at the end of the first growing season. Detailed stem measurements were collected and all biomass was harvested at the end of the 2010 (first rotation data) and 2013 (second rotation data) growing seasons. The average 3-year cumulative biomass production across all cultivars was 8.1 oven-dry (OD) Mg ha−1 in the second rotation (ranging from 0.6 to 21.3 OD Mg ha−1). The three highest yielding cultivars were Taberg, Tully Champion, and Otisco, with annual production of 6.4–7.1 OD Mg ha−1 year−1 in biomass, which was an increase by 12–44% from the first rotation, and more than double the average for all 30 cultivars (2.7 OD Mg ha−1 year−1), and had an average stool-within-plot survival rate of 81–94%. The 20 lowest clones suffered from higher mortality, which resulted in lower biomass production in the second rotation. These data suggest that the top 10 willow cultivars have a promising potential as a bioenergy source, but more data are needed from the third and successive rotations before a sustainable biomass industry could be established in the Canadian Prairies

First-rotation yields of 30 short-rotation willow cultivars in central Saskatchewan, Canada

The Government of Saskatchewan is evaluating whether biomass crops can be successfully used as an affordable, reliable, and environmentally sustainable bioenergy source. The objective of this study was to determine the first 3-year-rotation biomass yields of 30 willow cultivars planted in central Saskatchewan. Annual willow morphological data were collected throughout the first rotation, and stem biomass equations were developed. A willow yield map was produced for the SV1 cultivar across climates and soils of Saskatchewan. The majority of willow biomass equations were with high R 2 values (>0.90), and there was a strong agreement between equation-derived yield and harvested biomass (RMSE = 13.6 %; bias = -3.3 %). The average diameter, height, and stem count of 3-year-old stems were 14.1 (standard deviation (SD) =1.7) mm, 304.7 (SD = 45.4) cm, and 8.7 (SD = 1.8), respectively. The average first-rotation harvested yield was 10.5 (SD = 3.3) Mg ha−1, and the average survival rate was 81 %. Simulated SV1 productivity was 13.6 and 11.8 Mg ha−1 across marginal agricultural lands of the Prairies (1.7 million ha) and Boreal Plains (0.4 million ha) ecozones, respectively. Low growing degree days, heavy clay soils, low nitrogen availability, and winter stem dieback at these northern latitudes were the main factors to influence willow production at relatively lower yields observed in this study. Based on first-rotation results, the Tully Champion cultivar had the highest potential to be utilized as biomass feedstock in Saskatchewan, producing 17.4 Mg ha−1, which was 70 % greater biomass than the average yield of the other 29 cultivars. The use of willow as a bioenergy source appears promising, but further research is needed