Technical report CRMR-2018-SA-2-EN
Substrates containing biochar
for white spruce production (Picea Glauca sp.) in nursery:
Plant growth, economics and carbon sequestration
Production team: Authors: Sébastien F. Lange,
Suzanne E. Allaire,
Ph.D.,
Ph.D.,
Research associate,
Full professor,
Université Laval,
Université Laval, now at
now at Biopterre
GECA Environnement
Collaborators: Dany Paquet, Professionnal, Somival Inc. Lucie Turgeon, Traductions Ex Professo, linguistic revision Antoine St-Gelais, graphic design A co-production of Université Laval and GECA Environnement
Contact: Suzanne Allaire, Ph.D. CEO GECA Environnement
[email protected] 1-581-305-3374 www.GECA-Environnement.com © 2018
How to refer to this article : Lange, SF, Allaire SE. 2018. Substrates containing biochar for white spruce production (Picea Glauca sp.) in nursery: Plant growth, economics and carbon sequestration. CRMR-2018-SA3-EN. Centre de Recherche sur les Matériaux Renouvelables, Université Laval and GECA Environnement, Quebec, Qc, Canada, 32 p. DOI: 10.13140/RG.2.2.28019.84004.
Table of Content 1. Abstract
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2. Introduction
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3. Material and Methods
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3.1. Species and Biochar
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3.2. Treatments
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3.3. Growth Conditions
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3.4. Measured Parameters
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3.5. Statistical Analysess
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3.6. Economic Analysis
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3.7. Carbon Sequestration
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4. Results
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4.1. Biochar properties
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4.2. Substrate pH
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4.3. Germination
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4.4. Substrate Cores
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4.5. Seedlings
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4.6. Economic Analysis
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4.7. Carbon Sequestration
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5. Discussion
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6. Conclusion
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7. Acknowledgements
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8. References
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List of Tables
Table 1. Biochar properties
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Table 2. Treatment composition
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Table 3. Initial and final pH of the substrates
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Table 4. Seedling morphological parameters and N foliar concentration
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Table 5. Total production cost (CAD) of substrates containing biochar compared to the Control (nursery standard substrate) for white spruce in the nursery collaborating on the project
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Table 6. Potential C sequestration in soil (Cstable; tons year-1) compared to the production of white spruce in only one nursery and for Quebec production
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List of Figures
Figure 1. Initial conditions for seedling
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Figure 2. Experimental set up in greenhouse for spruce growth
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Figure 3. Plant evaluation based on quality parameters: height, diameter, root and above ground biomasses.
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Figure 4. Biochars (BC1, BC2, and BC3)
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Figure 5. Substrate initial and final pH as a function of biochar content
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Figure 6. Average percentage of germination on the total number of seeds (30) (T1 to T4 are the treatments, vertical bars are the standard deviation).
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Figure 7. Example of a carrot showing ecto-mycorhize proliferation
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Figure 8. Spruce growth during the experiment
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Figure 9. Effect of initial pH on plant growth parameters
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1. Abstract In Quebec, reforestation relies mainly on the production of 150 million seedlings, of which more than 80% are container-grown spruces. Because the price of substrate components increases and the forest industry tends to use more environmentally-friendly production processes, biochar seems an interesting alternative as a replacement for peat and perlite. The objective of this study is to evaluate the performance of three biochars manufactured from various forest residues incorporated at different rates (6.2; 12 and 25% v/v) into substrates used to grow white spruces over a one-year period. Switching from peat and perlite to biochar, at a rate up to 25% v/v, did not change plant growth. All the seedlings grown in these new production substrates complied with the strict Quebec government standards. Biochars could replace 100% of the perlite and 25% of the peat total volumes. The economic analysis, which included the cost of substrate components, revealed that switching to biochar resulted in 25% financial benefit, if the analysis was conducted today. The benefit is expected to rise over the years with the decreasing prices of biochar and
increasing prices of other substrate components. If we consider only white spruce in a single nursery, a complete replacement of perlite by biochar could induce an equivalent C sequestration of 6.0 to 7.3 T yr-1.So, for white spruce production only, if the same biochar application rate was used in all the forest nurseries in Quebec, C sequestration could reach 285 to 714 T yr-1, which could represent a simple and fast way to sequester carbon. If all horticultural perlite used in Quebec was replaced by biochar, this could induce a C sequestration equivalent to 4,000 T yr-1. Thus, biochar could be used as a substrate component in forest nurseries offering environmental and economic benefits up to an application rate of at least 25 % v/v while producing the same high-quality seedlings. Higher biochar application rates should be tested. We expect from these tests important production and economic gains compared to the standard substrate currently used, provided that pH, irrigation and fertilization are adjusted to the properties of these new biochar substrates. This was not done in this study.
Key Words Biochar, potting soil, forest nursery, finantial impact, carbon sequestration
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2. Introduction The Canadian province of Quebec has reforested vast portions of land during the last century. To accomplish this, high-quality seedlings were grown in forest nurseries. This effort continues, with more than 150 million seedlings produced annually (coniferous and hardwood trees), of which 25 million are white spruces (Picea glauca) (Boudreault et al. 2014), generating several millions dollars in nursery revenue (Colas and Lamhamedi 2011). About 90% of these seedlings are grown in containers for a period of one to two years. In Quebec, volume, quality, and price of each species used for reforestation is controlled by the MFFP (Ministère des Forêts, de la Faune et des Parcs), which publishes a guide on plant quality standards. Seedlings must be evaluated against these standards before being used for reforestation. For container-grown white spruces, seedlings taller than 35 cm are preferred. These seedlings are produced in multi-cell plastic containers with 310 cm3 cells (Boudreault et al. 2014). The production of white spruce that meets MFFP standards is a challenge because this specie is highly sensitive to substrate pH (range from 4.5 to 7.5) and drainage (CRPF and MRNO 1994). Root plug must be rigid and cohesive to remain intact during transportation, handling, and planting. In addition, because white spruce seedlings are sensitive to transplanting (CRPF and MRNO 1994), they must remain in the same container for one to two years while at the nursery. Most Quebec forest seedling nurseries use peatbased substrates that contain perlite or vermiculite to maintain desirable aeration, bulk density, water availability, and stability (Boudreault et al. 2014, Schmilewski 2008). However, the cost of perlite, vermiculite, and peat has increased and is expected to increase even more (USGS, 2016). In addition, perlite is generally imported, considered non-renewable and requires a lot of energy to be expanded for horticultural usage (Girault et al. 2010). In Quebec, peat is produced locally in large volumes and remains affordable. Nevertheless, its cost has also increased and, like perlite, peat is considered a non-renewable product (Girard
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2000). Its harvest involves wetland destruction (Barkham 1993) and high CO2 emissions to the atmosphere (Van den Akker et al. 2008). Several Quebec regions produce millions of tons of wood for the pulp and paper industry (Constantineau and Lacroix 2012), and millions of hectares of forest have been defoliated by spruce budworms, negatively affecting the quality of wood and resulting in decommissioning. In addition, the forest industry generates millions of tons of branches, bark, sawdust and other forest residues. All these residues can be valorized by pyrolysis to produce added-value products like biochar. Pyrolysis is the thermochemical transformation of organic materials, such as agricultural and forest residues, into biochar, a carbon-rich solid. Various pyrolysis technologies can be used to produce biochars offering different physicochemical properties (Allaire et al. 2018). Although their properties vary, general findings show that most biochars offer interesting physico-chemical characteristics for plant growth (Sohi et al., 2010). Biochar may stimulate soil particle cohesion, improve aeration (Cao et al. 2014; Steiner and Harttung 2014), increase pH (Steiner and Harttung 2014) and prevent root diseases (Laird 2008). It may also improve fertilization efficiency (Atkinson et al. 2010; Major et al. 2009; Yao et al. 2012), regulate water content (Cao et al 2014; Sohi et al. 2010; Steiner and Harttung 2014), as well as support microbial life in soil (Lehmann et al. 2011), resulting in increased plant productivity. In addition, biochar offers a high water retention capacity because pores between particles are small (Chan et al. 2007). Furthermore, biochar acts as a structuring component in soil and in substrates such as peat (Steiner and Harttung 2014). Some properties of biochar are similar to those of peat while others are similar to those of perlite. This suggests its possible use to replace perlite or peat in substrates (Nemati et al. 2015, Steiner and Harttung 2014). However, the effect of biochar as a potting soil component for white spruce is not well known. Few recent studies were found in the literature on
Photo by Victor Vorontsov on Unsplash
biochar used in forest soil experiments or for other tree species such as hybrid poplar (Populus nigra L. * Populus suaveolens Fischer subsp. maximowiczii A. Henry) (Headlee et al. 2014), Zelkova serrata (Cho et al. 2017) and Norway spruce (Picea abies [L.] Karst) (Heiskanen et al. 2013). Thomas and Gale (2015) and Gundale et al. (2016) have demonstrated that biochar applied directly in the field may have an interesting impact on tree growth, especially during the early development stage in the boreal forest. They also demonstrated with a meta-analysis that biochar can play an important role in forest restoration, specifically as a replacement product for other forms of organic matter and liming agents. Pluchon et al. (2014) studied the effect of a few types of biochars on the growth of various trees and showed that they have a neutral or positive effect on growth, but with a lot of variation depending on the type of biochar used. Headlee et al. (2014) have demonstrated that biochar made of oak feedstock and applied at a rate of 25% v/v yielded a total biomass equivalent to that of a potting mix containing vermiculite for hybrid poplar production. Heiskanen et al. (2013) have demonstrated that biochars added to an alluvial silty soil at a rate reaching 60% v/v have no deleterious effects on the growth of Norway spruce seedlings in a growth chamber. Growth parameters varied from one treatment to the other,
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indicating that different biochars may affect the growth of the Norway spruce differently. Cho et al. (2017) have used five different biochars at a rate of 20% v/v in container-grown seedling production of Zelkova serrata with two levels of fertilization. They demonstrated that three out of five mixtures containing biochars have produced seedlings with a significantly higher height (H) and collar diameter (D) than the Control made of a mixture of peat : vermiculite : perlite at a ratio of 1:1:1 v/v. They also demonstrated that the fertilization rate had a negligible effect on tree growth. Results of these studies may suggest that biochar improves forest seedling growth, while the response of seedlings and plants to biochar in potting soil may differ depending on species, potting mix as well as biochar type, properties and application rate. The purpose of this project was to test the potential of three biochars as a replacement of peat and perlite for white spruce production in multi-cell containers during the first year of production. Additionally, we compared the economic and carbon sequestration potentials induced by replacing peat and perlite with biochar into the substrate.
3. Material and Methods 3.1. Species and Biochar White spruce was used because it is the main species produced in Quebec forest nurseries. White spruce seeds (source EPB-V1-EST-1-3; lot 2004-021-3-1; calibre 123) were obtained directly from the collaborative nursery. Based on Allaire et al. (2018) and other measurements, we chose 3 biochars that would provide excellent water retention, stability over time and leaching criteria that we deemed important for the white spruce production in multi-cell containers. Special attention was paid to the size of biochar particles to ensure they would not be leached out of the substrate and to prevent substrate compaction. The residues used to manufacture the biochars came from the local forest industry. Because biochars can differ and present various properties depending on the feedstock and pyrolysis conditions, each biochar was characterized before its use in substrates.
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Biochar characteristics are given in Table 1. Briefly, they were made either from softwood bark residues (BC1), spruce sawdust (BC2) or hardwood charcoal residues (> 75% sugar maple) (BC3). BC1 was obtained from softwood barks sieved to keep only particles larger than 0.5 mm and dried to reach a water content between 0.08 and 0.15 g g -1. Pyrolysis was completed at 475°C for 15 min. The biochar was then stored outside in super sacks (polypropylene bags) for several months. BC2 was obtained from spruce sawdust previously ground, dried and sieved under 2 mm, then treated by fast pyrolysis at 454°C for a few seconds. BC3 was obtained after sieving (3.17 mm < x < 6.35 mm) hardwood charcoal production residues then completing pyrolysis for 24 to 48 h at 500°C. Physico-chemical properties of these biochars had been previously characterized following methods described in Allaire et al. (2018). These methods comply with certain standards of the IBI (International Biochar Initiative), EBC (European Biochar Certificate), ASTM, ISO or the Quebec and Canadian governments.
Table 1. Biochar properties BC1
BC2
BC3
Ashcontent (%)
9.9 (19)1
1.6 (23)
12.2 (38)
Ctotal (%)
60.2 (1)
74.9 (
