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For more than a decade, studies have aimed to adapt the agronomy of organic no-till systems for the environmental conditions of Eastern Canada. Most research on organic no-till practices in Eastern Canada has been conducted in the province of Québec, where 4% of farms are certified organic, and results from these trials have been published in technical reports available in French. The objective of this review was to revisit previous research work on organic farming in Eastern Canada-the majority of which has been published as technical reports in the French language-in order to highlight important findings and to identify information gaps. Cover crop-based rotational no-till systems for organic grain and horticultural cropping systems will be the main focus of this review. Overall, a few trials have demonstrated that organic rotational no-till can be successful and profitable in warmer and more productive regions of Eastern Canada, but its success can vary over years. The variability in the success of organic rotational no-till systems is the reason for the slow adoption of the system by organic farmers. On-going research focuses on breeding early-maturing fall rye, and terminating cover crops and weeds with the use of bioherbicides.

Abbreviations: FRC, fall rye with compost; FRF, fall rye with inorganic fertilizer; MDL, minimum detection limit; ORC, oilseed radish with compost; ORF, oilseed radish with inorganic fertilizer; NCC, no cover crop with compost; NCF, no cover crop with inorganic fertilizer; CON, nonamended soil with no cover crop; WEOC, water-extractable organic carbon. P ost-harvest seeding of cover crops reduces the risk of wind erosion and nutrient loss through leaching and runoff during the non-growing season, but how cover crops affect C and N transformations during this time is poorly understood. Although soil microbial activity slows during the non-growing season, this period is particularly prone to N 2 O emissions in temperate regions (Wagner-Riddle and Thurtell, 1998;Dörsch et al., 2004;Ellert and Janzen, 2008;Hao, 2015). Whether cover crops reduce N 2 O emissions during the non-growing season by assimilating ammonium (NH 4 ) and NO 3 is uncertain. In part, this is because cover crops release labile C and N through root exudates and rhizodeposition during their growth phase and freeze-thaw cycles, which can stimulate microbial activity and increase N 2 O emissions (Petersen et al., 2011;Gul and Whalen, 2013;Mitchell et al., 2013). This may counter the crop N uptake and explain why there is no clear consensus on how non-legume cover crops effect N 2 O emissions (Basche et al., 2014 Core Ideas• Nitrous oxide emissions were greater in winter than spring or fall.• Tillage radish increased over-winter N 2 o fluxes.• Non-legume cover crops increased N 2 o fluxes under apparent No 3 limiting conditions.

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Several governmental programs have been established throughout Canada to foster agriculture sustainability. As a best management practice, cover crops (CCs) limit soil erosion and prevent nutrient losses in agroecosystems. Yet, the variable effects of CCs on cash crop productivity previously reported may limit their large-scale adoption by farmers. To address this variability, we conducted an unweighted meta-analysis including 2274 observations from 86 field studies conducted under humid temperate climate to evaluate yield response to CCs for three annual cash crops. Overall, CCs increased corn and small grain cereal yields by 13% and 22% respectively, but did not affect soybean yield. Legume CCs alone or mixed with grasses provided the highest small grain cereal and corn yield increases compared to non-legume broadleaf and grass CCs. CC benefits increased with N content in CC aboveground biomass but decreased when N fertilizer inputs applied to corn exceeds 60 kgN.ha-1. Greater precipitation and N fertilizer inputs reduced the negative effect of grass CCs on corn yield, while benefits of legume CCs were highly resilient to precipitation variations. CC benefits on corn yield increased through time, and at low soil organic matter content, especially at low N fertilizer inputs. These results evidence the complex interplay between cash crop productivity, CC management and environmental factors – related to N inputs from CCs, changes in soil properties (e.g., increased organic matter, improved soil structure or microbial activity) or potential competition for water under drier conditions – which provide new perspectives to promote CC inclusion in cropping systems.

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-Copper-mine tailings contain considerable amounts of copper (Cu) that may be extracted biologically or by organic ligands and may then become available to plants. A laboratory incubation experiment was conducted to assess the effect of a commercial garden growth substratum (GGS) containing natural mycorrhizae (Glomus intraradices) and peat moss in combination with lemon peel waste (LPW) on the evolution of labile Cu pool with time in a slightly alkaline Cu-mine tailing containing calcite. There were eight treatments combining four rates (0, 12.4, 50 and 100 g GGS kg -1 tailings) and two rates (0 and 100 g LPW kg -1 tailings). The amendments were thoroughly mixed with air-dry tailings in plastic bags. Distilled water was added to maintain the substrate at field capacity throughout the 8-week incubation period. The amounts of labile Cu in tailings increased with incubation time. Extractable Cu fractions as labile Cu (DTPA, Mehlich-3) were significantly increased after adding GSS and LPW. The smallest amount of labile Cu was found in the unamended tailings and the highest amount in the GGS-amended tailings.