Elwin G. Smith

Ongoing Development of Integrated Weed Management Systems on the Canadian Prairies

Abstract Herbicides are very effective tools to control weeds but there has been an overreliance on their use at the expense of other useful methods of weed management. Farmers are interested in alternative methods of weed management but are concerned about the risk of adopting such practices with current small profit margins. Research on the Canadian Prairies has found that cropping systems that utilize zero tillage, diverse crop rotations, competitive cultivars, higher crop seed rates, specific fertilizer management, and cover crops can effectively manage weed populations, especially when used in conjunction with targeted but limited use of herbicides. Farmers are gaining confidence in the merits of such agronomic practices in terms of sustainable weed management and are gradually adopting these integrated cropping systems on their farms. Further research and extension efforts are required to ensure that these integrated weed management systems are biologically and economically robust to facilitate greater adoption at the farm level.

Profitability and risk of organic production systems in the northern Great Plains

Organic crop production systems are increasingly being adopted by producers in the northern Great Plains. This study evaluated the expected net returns and risk of organic crop rotations, compared to conventional rotations. Field plot data of organic and conventional crop rotations were used to determine the net returns of the systems, using four different levels of premiums for organic produce. The risk of returns was evaluated using estimated cumulative density functions and stochastic dominance. The most profitable organic rotation required high price premiums to dominate the most profitable conventional rotation. However, the most profitable organic rotation dominated some conventional rotations that are commonly used in the northern Great Plains. The organic rotations had slightly higher risk, but the relative risk of rotations had little impact on the optimal rotation.

Factors Influencing Wheat Yield and Variability: Evidence from Manitoba, Canada

Production functions to explain regional wheat yields have not been studied extensively in the Canadian prairies. The objective of this study is to employ a Just-Pope production function to examine the relationship between fertilizer inputs, soil quality, biodiversity indicators, cultivars qualifying for Plant Breeders’ Rights (PBR), and climatic conditions on the mean and variance of spring wheat yields. Using regional-level wheat data from Manitoba, Canada, model results show nitrogen fertilizer, temporal diversity, and PBR wheat cultivars are associated with increased yield variance. Mean wheat yield is reduced by the proportion of land in wheat, the interaction of growing temperature and precipitation, and spatial diversity. By contrast, higher soil quality and PBR wheat cultivars increase mean yield. The wheat yield increases attributed to PBR range from 37.2 (1.4%) to 54.5 kg/ha (2.0%). Plant Breeders’ Rights may have enhanced royalties from increased certified seed sales, but the benefits in terms of higher wheat yield or lower yield variability are limited. Future research is required to understand the interactive effects of fertilization practices, genetic diversity, and environmental conditions on regional wheat yield stability.

Energy balances of biodiesel production from soybean and canola in Canada.

Biodiesel is currently produced in Canada mostly from recycled oils and animal fats. If biodiesel is to supply 5% of diesel usage, a government objective, first-time vegetable, likely from canola and soybean, oil will also be required to provide adequate feedstocks. In this review, we estimate the life cycle energy balances for biodiesel produced from soybean and canola oil under Canadian conditions. The three broad areas of energy inputs were crop production, oil extraction, and transesterification of the vegetable oil into biodiesel. Per unit seed yield, farm production energy inputs for canola were about three times higher than for soybean, mostly because of higher nitrogen fertilizer requirements for canola. Energy required for processing and oil extraction, per unit oil, was higher for soybean. Energy allocation for co-products was allocated using a system expansion approach. Protein meal was assigned about 12% of the energy expended for canola to grow the crop and extract the oil, and about 37% for ...

Blackleg disease of canola mitigated by resistant cultivars and four-year crop rotations in western Canada

Abstract In western Canada, canola is traditionally grown in rotation once every 4 years to restrict losses due to pests. Recently, growers have begun to produce canola more intensively due to market opportunities and cultivar improvements. This study was initiated to investigate the consequences of more intensive production of canola in rotations, integrated with currently available disease management practices, including blackleg resistant cultivars and fungicides. A 4 replicate split-plot experiment was established at Scott and Melfort, Saskatchewan with canola rotation treatments ranging from yearly to every second, third or fourth season in combination with pea, wheat and flax using a blackleg resistant and a blackleg susceptible cultivar. Sub-plots were fungicide treatments for blackleg and sclerotinia stem rot diseases. Blackleg incidence and severity was increased in rotations comprising more than one canola crop every four years, regardless of cultivar, although the blackleg resistant cultivar was much less affected than the blackleg susceptible cultivar. The yield of the blackleg resistant canola cultivar was similar among rotations that included canola every 2, 3 and 4 years. Fungicide application was of limited value to maintain canola yield. The results suggest that canola cultivars with strong blackleg resistance can be grown more intensively than once every 4 years with limited yield reduction. However, the increased severity of infection and amount of infested residue produced as canola rotations are intensified, which occurs even with resistant cultivars, increases the risk of inoculum carry-over, resistance breakdown and yield loss. Therefore, it would be prudent for western Canadian canola growers to adhere to less intensive inclusion of canola in rotations, such as one canola crop in 4 years, as an effective blackleg management strategy.

Cereal cover crops for weed suppression in a summer fallow-wheat cropping sequence.

Cropping systems in western Canada that include summer fallow can leave the soil exposed to erosion and require frequent weed control treatments. Cover crops have been used for soil conservation and to suppress weed growth. Experiments were conducted under rain-fed conditions at Lethbridge, Alberta to determine the effect of short-term fall rye (Secale cereale L.), winter wheat (Triticum aestivum L.) and annual rye cover crops in the fallow year on weed growth and subsequent wheat yield. Under favorable weather conditions fall rye was as effective as post-harvest plus early spring tillage or herbicides in spring weed control. Winter wheat and fall rye residues, after growth was terminated in June, reduced weed biomass in September by 50% compared to no cover crop in 1993 but had little effect on weeds in 1995. Fall-seeded cover crops reduced the density of dandelion (Taraxacum officinale Weber in Wiggers) and Canada thistle [Cirsium arvense (L.) Scop.] but increased the density of downy brome (Bromus tect...

The value of apple characteristics to wholesalers in western Canada: A hedonic approach

Sensory methods have been used to evaluate subjective apple characteristics such as juiciness, flavour, and texture. There is very little information to indicate the value wholesalers place on objective apple characteristics such as cultivar, grade, and fruit size. In this study, a hedonic price function for apples was estimated to evaluate the relationship between British Columbia (BC) apple (Malus domestica Borkh.) prices and the wholesalers’ perception of product quality characteristics. In this study, sales data and cultivar characteristics were obtained for three large wholesalers in western Canada that purchase BC fruit. Cultivar, fruit size, and grade were the most significant variables influencing apple prices. Wholesalers paid price premiums (

Diverse Rotations and Optimal Cultural Practices Control Wild Oat (Avena fatua)

2.25 to

Economic benefits of integrated weed management systems for field crops in the Dark Brown and Black soil zones of western Canada

5.25 per tray) for speciality cultivars such as Gala, Fuji and Braeburn compared with traditional cultivars such as McIntosh, Red Delicious and Spartan. Large fruit size earned a price premium (

Site-Specific Herbicide Decision Model to Maximize Profit in Winter Wheat

1.73 per tray) and small fruit were discounted (