Summary 1.Genetically modified (GM), herbicide-tolerant crops have been adopted extensively worldwide, resulting in increased homogenization of agricultural practices. However, several countries still view GM crops with trepidation, citing potential risks to human health and the environment. We currently know little about how non-target biota responds to cultivation of GM crops under field conditions. 2. This study describes a series of microcosm and field experiments in Ontario, Canada, that estimated the effects of transgenic, glyphosate-tolerant (GT) crops and their management on the abundances of detritivorous soil biota and crop litter decomposition. 3. Absolute abundance of few of the measured biotic groups were affected by either the herbicide or variety treatments and, where significant effects were observed, the responses were not consistent across all years or for all sample dates within a year. More frequently, but not consistently, the GT herbicide system was associated with increased fungal : bacterial biomass ratios, suggesting a state of reduced enrichment. 4. Although the conventional and GT varieties studied differed in composition, we observed few effects of the modification for glyphosate-tolerance on maize Zea mays and soybean Glycine max litter decomposition. Overall, the herbicide system associated with GT crops reduced soybean-and corn-litter decomposition, but responses were inconsistent across Ontario, with many trials demonstrating no effect. Effects were probably underrepresented in this study as average daily precipitation was positively correlated with the magnitude of this system effect and many sites received well-below average levels of precipitation. 5. Synthesis and applications . Most concerns regarding the potential impacts of GM crops on non-target biota have targeted traits associated with the biotechnology itself. However, shifts in management practices associated with biotechnology are also widespread and have the same, if not greater, potential to alter the structure and functioning of agroecosystem biodiversity. The lack of observed permanent negative effects on soil biota in this study is heartening; however, more research is required to determine the functional consequences of observed transient effects and effects on other biota, as well as how altered crop litter decomposition affects agroecosystem nutrient cycling and carbon sequestration.

Renewed interest in natural fibres, decreasing subsidies to European producers, and high production costs have led the move to reintroduce fibre flax (Linum usitatissimum L.) production into eastern Canada. Research was conducted at the Macdonald Campus of McGill University, Que´bec, Canada in 1998 and 1999 and at Winchester and Kemptville, Ontario, Canada in 1998, to assess the performance of seven European fibre flax cultivars. Parameters evaluated included plant density, branching ratio, stem diameter, fresh and dry biomass, and mean harvest height. Data from all sites and years were subjected to a pooled anova where appropriate. The cultivar main effect was detected for all parameters measured, with the exception of mean fresh weight and mean height at harvest. There was also a site main effect for all parameters except for branching ratio. A cultivar-site interaction was found for all parameters except for mean stem diameter and mean dry weight. Results indicate a strong potential for producing fibre flax in eastern Canada using currently available European cultivars.

Research was conducted at the Macdonald Campus of McGill University (Que´bec, Canada) at three sites in 1997 and one site in 1998 to determine the effects and interactions of seeding depth (0, 1, 2, 4 or 6 cm) and seedbed preparation (i.e. soil rolling): none, rolling before or rolling after seeding on fibre flax (cv. Ariane) establishment, growth and yield. Seedbed preparation had little impact on the parameters measured while seeding depth had a variable effect on plant density, plant height, stem diameter and retted straw yield. Seeding depths of 1-4 cm provided consistently good establishment, growth and yield results. In 1997, there was an interaction between seeding depth and seedbed preparation on plant height, branching ratio and retted straw yield, although results were generally variable and tended to be site-specific. In 1998, there was an interaction between seeding depth and seedbed preparation on plant height and stem diameter prior to harvest, with the results varying for all seeding depth-seedbed preparation treatment combinations except for the 2-cm depth treatment. Rolling of the seedbed before seeding on lighter soils and at a depth of 2 cm on most soils can improve establishment, growth and yields of fibre flax under eastern Canadian growing conditions.

The feasibility of producing fibre flax in minimum tillage or zero tillage (ZT) systems was investigated. The results were variable between the sites, which differed in soil type and previous cropping history. Tillage regime had no impact on fibre flax phenological development including number of days to emergence, days to flowering and days to harvest at either site. However, tillage regime had a significant effect on mean stem diameter, dry matter content and plant height at all three sampling dates at the sandy loam site, and a significant effect on mid-season plant height at the clay site. At the sandy loam site, ZT plots had the highest populations of plants with the finest stem diameters, the lowest branching ratios, but the shortest plants by the end of the season. Overall, plant densities were greater, stem diameters thinner, and biomass production higher in the heavier soil of the clay site. These results indicate that under the growing conditions present in 1998, fibre flax can successfully be grown in minimum or ZT systems on different soil types in Eastern Canada. Moreover, the growth of fibre flax in these systems does not compromise the proportion of tall plants having thin stems and minimal branching, a critical quality parameter for fibre flax production.

A study was conducted to determine whether broadcast seeding of alfalfa (Medicago sativa L.) into a winter‐damaged alfalfa stand early in the spring would improve the stand and whether this seeding method could be a reliable alternative to conventional reseeding. In separate experiments conducted in 1986 and 1987 and followed for two growing seasons, alfalfa (‘Saranac’) seed was broadcast into winter‐damaged alfalfa plots, either as early in the spring as possible after the snow was gone (early April), or 2 wk later at the rate of 11 or 3.6 lb/acre. Stand improvement was evaluated on the basis of alfalfa density and dry matter yield. The effect of seeding date on density and yield was inconsistent and inconclusive. The recommended seeding rate of 11 lb/acre often resulted in better alfalfa populations and yields than the lower rate, although both seeding rates were generally better than leaving the plots unseeded. The effect of seeding rate on yield was only seen in the year following seeding. Success of reseeding was limited by poor germination, adverse effects of environmental conditions at seeding and later in the growing season, and possibly, by auto‐allelopathy. While there was some stand improvement, neither plant density nor yield was comparable to a vigorous alfalfa stand. The maximum density obtained was 6 plants/sq ft, but this was not maintained. Maximum total yield was only 2.83 tons/acre for three cuts. The results suggest that early‐spring broadcast seeding is not a good alternative to conventional reseeding on a large scale. It would, however, be suitable for repairing small areas of damage such as found in low spots in a field.

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