Growing woody biomass for bioenergy in southern Ontario, Canada : a case study using tree-based intercropping

Paper presented at the 12th North American Agroforesty Conference, which was held June 4-9, 2011 in Athens, Georgia.In Ashton, S. F., S.W. Workman, W.G. Hubbard and D.J. Moorhead, eds. Agroforestry: A Profitable Land Use. Proceedings, 12th North American Agroforestry Conference, Athens, GA, June 4-9, 2011.During the spring of 2006, three willow varieties from SUNY-ESF (SV1, SX67 and 9882-41) were established on a marginal land in an agroforestry tree-intercropping arrangement where plots of short rotation willow were planted between rows (spaced 15 m apart) of 20-year-old mixed tree species. As a control, the same varieties were established on an adjacent piece of land without established tree rows. The study investigated the distribution of carbon and nitrogen pools, fine root biomass and clone yields in both tree-based intercropping (agroforestry) and conventional monocropping systems. Willow biomass yield was significantly higher in the agroforestry field, 4.86 and 3.02 odt ha-1 y-1 for the agroforestry and control fields, respectively. SV1 and SX67 had the highest yields and 9882-41 had the lowest. Willow fine root biomass in the top 20 cm of soil was significantly higher in the intercropping system (3000 kg ha-1) than in the conventional system (2500 kg ha-1). Differences in fine root biomass between clones followed the same order that was observed for differences in biomass yield: SV1 [greater than] SX67 [greater than] 9882-41. Leaf input was higher in the intercropping system (1900 kg ha-1) than in the monocrop system (1700 kg ha-1). Clonal differences in leaf inputs followed the same trends as those for root biomass and yield: SV1 [greater than] SX67 [greater than] 9882-41. Soil organic carbon was significantly higher in the agroforestry field (1.94 [percent]) than in the control field (1.82 [percent]). A significant difference was found between the three clones; 9882-41 had the lowest soil organic carbon of 1.80 [percent]. In December 2009, both fields were harvested (1st cycle) with Anderson bio-baler harvester. Harvesting process and bale yield data, harvest moisture content, field drying and loss of moisture etc. will also be discussed.R�mi Cardinael (1), Naresh Thevathasan (2), Andrew Gordon (2), Rachelle Clinch (3) and Idris Mohammed (2) ; 1. AgroParisTech, Paris, France. 2. School of Environmental Sciences, University of Guelph, ON, Canada. 3. Golder Associates Ltd., Mississauga, ON, Canada.Includes bibliographical references

Initial soil carbon losses may offset decades of biomass carbon accumulation in Mediterranean afforestation

Afforestation of degraded areas was suggested as CO2 sink, contributing to climate change mitigation. Yet, few studies have assessed this sink by combining measurements on carbon (C) in the biomass and the soil, despite it being crucial to properly estimate the mitigation potential. Here, we assessed the combined C stocks of afforestation plots of different ages on former cropland in a Cambisol landscape in Extremadura, Spain. The plots were afforested with two native tree species (Quercus ilex L. and Quercus suber L. in a density ratio of 3:1), planted at several occasions between 1998 and 2011. Stocks of afforested areas in 2022 were compared to non-afforested negative controls on arable land, to a closeby olive grove and a forest with signs of degradation. Tree biomass was estimated from allometric equations, soil organic carbon (SOC) stocks were measured to 30 cm depth, based on equivalent soil mass. The biomass C accumulation rate in afforested plots increased with tree density and elevation (p <0.05; range: 25 to 75 g C m2 yr 1). SOC stocks, in contrast, were not significantly different in afforested and non-afforested plots at any depth and in tendency even lower in afforested plots younger than 20 years. Consequently, total (biomass plus soil) C stocks in afforested plots were not significantly higher than in non-afforested ones. Nevertheless, SOC stocks and contents between the tree rows were significantly lower compared to soil next to the trees in the olive grove (about 1200 vs. 2200 g C m2 in the top 30 cm) and in tendency in the afforested plots (about 1200 vs. 1500 g C m2 in the top 30 cm; p <0.1). The fact that the degraded forest (about 6800 g C m2) and the olive grove (about 5300 g C m2) did have significantly higher total C stocks than the afforested and non-afforested sites (about 2300 and 1800 g C m2) could indicate that afforestation could soon become a C sink. However, our study clearly shows that afforestation is not automatically a C sink. Timing of different C pools` losses and gains affect net ecosystem carbon sequestration. While improved soil management in afforestation may reduce SOC losses, afforestation with Mediterranean Quercus trees under current management practices may require decades before being a C sink. This finding should temper expectations that afforestation with such tree species is a rapid solution to combat climate change

The input reduction principle of agroecology is wrong when it comes to mineral fertilizer use in sub-Saharan Africa

Can farmers in sub-Saharan Africa (SSA) boost crop yields and improve food availability without using more mineral fertilizer? This question has been at the center of lively debates among the civil society, policy-makers, and in academic editorials. Proponents of the “yes” answer have put forward the “input reduction” principle of agroecology, i.e. by relying on agrobiodiversity, recycling and better efficiency, agroecological practices such as the use of legumes and manure can increase crop productivity without the need for more mineral fertilizer. We reviewed decades of scientific literature on nutrient balances in SSA, biological nitrogen fixation of tropical legumes, manure production and use in smallholder farming systems, and the environmental impact of mineral fertilizer. Our analyses show that more mineral fertilizer is needed in SSA for five reasons: (i) the starting point in SSA is that agricultural production is “agroecological” by default, that is, very low mineral fertilizer use, widespread mixed crop-livestock systems and large crop diversity including legumes, but leading to poor soil fertility as a result of widespread soil nutrient mining, (ii) the nitrogen needs of crops cannot be adequately met solely through biological nitrogen fixation by legumes and recycling of animal manure, (iii) other nutrients like phosphorus and potassium need to be replaced continuously, (iv) mineral fertilizers, if used appropriately, cause little harm to the environment, and (v) reducing the use of mineral fertilizers would hamper productivity gains and contribute indirectly to agricultural expansion and to deforestation. Yet, the agroecological principles directly related to soil fertility—recycling, efficiency, diversity—remain key in improving soil health and nutrient-use efficiency, and are critical to sustaining crop productivity in the long run. We argue for a nuanced position that acknowledges the critical need for more mineral fertilizers in SSA, in combination with the use of agroecological practices and adequate policy support

The science base of a strategic research agenda: executive summary.

Identifying the challenges around soil organic carbon sequestration in agriculture. Questionnaire. Twelve Testable Hypotheses for Soil Organic Carbon Sequestration in Agriculture. Key research and innovation advances.European Union's Horizon 2020 Research and Innovation Programme Grant Agreement No 774378. Coordination of International Research Cooperation on Soil Carbon Sequestration in Agriculture

High organic inputs explain shallow and deep SOC storage in a long-term agroforestry system &ndash; combining experimental and modeling approaches

Agroforestry is an increasingly popular farming system enabling agricultural diversification and providing several ecosystem services. In agroforestry systems, soil organic carbon (SOC) stocks are generally increased, but it is difficult to disentangle the different factors responsible for this storage. Organic carbon (OC) inputs to the soil may be larger, but SOC decomposition rates may be modified owing to microclimate, physical protection, or priming effect from roots, especially at depth. We used an 18-year-old silvoarable system associating hybrid walnut trees (Juglans regia  ×  nigra) and durum wheat (Triticum turgidum L. subsp. durum) and an adjacent agricultural control plot to quantify all OC inputs to the soil &ndash; leaf litter, tree fine root senescence, crop residues, and tree row herbaceous vegetation &ndash; and measured SOC stocks down to 2 m of depth at varying distances from the trees. We then proposed a model that simulates SOC dynamics in agroforestry accounting for both the whole soil profile and the lateral spatial heterogeneity. The model was calibrated to the control plot only. Measured OC inputs to soil were increased by about 40 % (+ 1.11 t C ha−1 yr−1) down to 2 m of depth in the agroforestry plot compared to the control, resulting in an additional SOC stock of 6.3 t C ha−1 down to 1 m of depth. However, most of the SOC storage occurred in the first 30 cm of soil and in the tree rows. The model was strongly validated, properly describing the measured SOC stocks and distribution with depth in agroforestry tree rows and alleys. It showed that the increased inputs of fresh biomass to soil explained the observed additional SOC storage in the agroforestry plot. Moreover, only a priming effect variant of the model was able to capture the depth distribution of SOC stocks, suggesting the priming effect as a possible mechanism driving deep SOC dynamics. This result questions the potential of soils to store large amounts of carbon, especially at depth. Deep-rooted trees modify OC inputs to soil, a process that deserves further study given its potential effects on SOC dynamics

An efficient access to the enantiomers of α-methyl-4-carboxyphenylglycine via a hydantoin route using a practical variant of preferential crysallization AS3PC (Auto Seeded Programmed Polythermic Preferential Crystallization)

International audienc

Resolution of 5-(4-isopropylphenyl)-5-methylhydantoin by diastereomeric salt formation

International audienc