Spring Wheat and Soybean Variety Trials Under Organic Management

Hans G. Nass, Jerry A. Ivany, and John A. MacLeod

The most recent draft of the National Standard of Canada for Organic Agriculture encourages the use of crop varieties that are adapted to local conditions and that are resistant to the pests and diseases of the local region. The standard also specifies limitations on the use of non-organic seed, and farmers are required to use certified organic seed when it is readily available. These requirements are in keeping with the general philosophy of organic farming, which promotes the use of varieties that are adapted to local ecosystems and that have been selected to thrive under organic systems of management. It also helps ensure that seed has been produced under conditions that meet organic standards.

However, finding varieties that are appropriate for organic production under eastern Canadian conditions can be a challenge. Most cereal breeding research, for example, has been conducted in the prairie provinces where local conditions and pest and disease problems may be quite different from those in eastern Canada. Also, since much of the research in plant breeding has focused on selection for yield and performance under conventional management, it is not known which varieties will perform well in organic systems. For example, weed control can be a major problem on organic farms, and weed control methods are quite different on organic than on conventional farms. This may influence the relative performance of different varieties.

To provide information on a greater selection of locally adapted varieties, researchers at the AAFC Crops and Livestock Research Centre in Charlottetown have evaluated the performance of spring wheat and soybean varieties grown under organic management. The trial was conducted over two years (2000, 2001) at two sites on Prince Edward Island (Cherry Hill and Springfield). The spring wheat cultivars evaluated were AC Barrie, AC Walton, and Glenlea. Soybean cultivars were AC Proteina, OAC Vision, Alta, and Ugo. The trial also compared two weed control strategies in spring wheat:

• flame weeding at 10 days after seedbed preparation, when emerged weeds were in the cotyledon stage, followed by finger weeding 10 days later, when any newly emerged weeds were in the cotyledon stage; and
• finger weeding at 10 days after seedbed preparation, followed by a second finger weeding 10 days later, when newly emerged weeds were in the cotyledon stage.

The following is a brief summary of the results:

• When growing conditions were favourable (2000), spring wheat and soybean yields under organic management were comparable to yield estimates reported for these crops under conventional management. In 2001, drought conditions reduced spring wheat and soybean yields at both sites. The yield reduction was more severe in soybeans (50%).
• Varieties that perform well under conventional management did not necessarily perform as well under organic management. AC Barrie yields were higher than AC Walton yields at Springfield in 2000, whereas the reverse is usually true under conventional management. Thus, AC Barrie might be more suitable than AC Walton for organic production when growing conditions are favourable.
• In 2001 low soil temperatures early in the growing season limited the mineralization of soil and manure nitrogen, and drought conditions later in the season limited the uptake of nitrogen. As a result, none of the spring wheat cultivars at the Springfield site met the protein criteria for milling wheat (13.5% grain protein), and only AC Barrie met the criteria at the Cherry Hill site. AC Walton and Glenlea met the protein criteria for milling wheat in only one of the four site-years (Springfield, 2000).
• Soybean protein content was also reduced at the Springfield site in the drought year, but earlier seeding at the Cherry Hill site reduced the effect of the drought on soybean protein content.
• Spring wheat yield and protein content was not affected by weeding strategy. Weed competition was higher at both sites during the drought year, but there were no differences in weed densities or weed biomass (weight) between the two weeding strategies. However, because spring wheat grew faster than soybean early in the growing season, it provided better competition with the weeds than did the soybeans. Weed competition in the soybean plots was reduced because of the wider row spacing and slower establishment.

Researchers:

Hans G. Nass, Jerry A. Ivany, and John A. MacLeod
Crops and Livestock Research Centre
Agriculture and Agri-Food Canada,
440 University Ave,
Charlottetown, PEI, C1A 4N6
Contact: nassh@agr.gc.ca

References:

Nass, H.G., J.A. Ivany and J.A. MacLeod. (In Press). Agronomic performance and quality of spring wheat and soybean cultivars under organic culture. American Journal of Alternative Agriculture.

The National Standard of Canada for Organic Agriculture. The Canadian General Standards Board, Ottawa, Canada.

Related Links:

The following OACC article provides an excellent overview of plant breeding and seed production for organic systems:

Organic Plant Breeding and Seed Production: Importance and Challenges
Av Singh, Organic Agriculture Centre of Canada

Further information on mechanical and flame weeding strategies for organic systems can be found at:

Mechanical Weed Control in Organic Systems
Av Singh, Organic Agriculture Centre of Canada

Thermal Weed Control for Organic Production
Organic Agriculture Centre of Canada

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