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

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 – 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 – leaf litter, tree fine root senescence, crop residues, and tree row herbaceous vegetation – 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

Soil carbon sequestration in a Mediterranean agroforestry system

PresentationThe Earth’s soils are a large reservoir of carbon (C), containing about 1500 Pg C, which represents two to three times the C contained in the atmosphere. This reservoir is extremely sensitive to land use and can act as a source or as a sink of atmospheric CO2. Agroforestry systems are expected to sequester C into both above and belowground biomass. Such systems could also increase soil organic carbon (SOC) stocks due to higher organic inputs including leaf litter, pruning residues, tree fine roots’ turnover and root exudates. However, although tropical agroforestry systems have been thoroughly investigated, there are very few estimates of C sequestration in soils from temperate conditions. The objectives of this study were (i) to quantify the SOC stocks down to 2 m soil depth in an 18-year-old agroforestry system and in an adjacent agricultural plot, and (ii) to assess which SOC fractions are responsible for this additional storage. The experimental field was established in 1995 in Restinclières, South of France, on an alluvial carbonated Fluvisol. In the agroforestry system, hybrid walnuts (13x4-8m spacing, 85 trees ha-1) are intercropped with durum wheat, whereas in the adjacent agricultural plot, only durum wheat is cultivated. Spontaneous vegetation also grows on the tree row. About 200 soil cores were sampled from ten soil layers from 0 to 2m into the two plots of 625 m2 each. Bulk densities, texture and SOC contents were determined for each soil samples at each soil depth, using field spectroscopy. Carbon stocks were spatialized at the field scale. To determine which SOC fractions were affected by the agroforestry system, soil particle size fractionation was performed on 64 soil samples from 0-10, 10-30, 70-100 and 160-180 cm soil depth. C stocks were characterized by a high, but organized spatial variability. Spatial analysis showed doubled SOC contents on the tree row compared to the inter-row in surface soil layers, probably due to high inputs from the natural vegetation. Thanks to our extensive sampling scheme, we are able to provide the first quantification of soil C sequestration in these very representative agroforestry systems. After 18 years, this agroforestry system stored 4.9 ± 1.2 MgC ha-1 down to 30 cm, and 6.3 ± 1.8 MgC ha-1 down to 1 m. Annual additional soil carbon storage rates were estimated to be 272 ± 68 kgC ha-1 year-1 (0-30 cm) and 352 ± 98 kgC ha-1 year-1 (0-100 cm). This additional SOC storage was mainly due to the particulate organic matter fraction (50-200 and >200µm), whereas only 10 to 15% was associated to clay particles. The total annual carbon storage rate would be about 1 MgC ha-1 year-1 when trees’ biomass is taken into account, which is a lot compared to other techniques used to improve carbon storage in agriculture, like no-till farming or conservation agriculture