Canola / Rape

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Seeding Rate

Canola should be seeded at 5-8 lbs/acre (Johnny's Selected Seeds, 1983).

Seeding Depth

Canola should be seeded at a depth of 1 inch (Johnny's Selected Seeds, 1983).

Seeding Dates

Spring- and fall-sown types of canola are available (Johnny's Selected Seeds, 1983).

Days to Maturity

Canola grows rapidly (Johnny's Selected Seeds, 1983).

Incorporation

Canola decomposes rapidly when tilled under (Johnny's Selected Seeds, 1983).

Uses

Canola can be grown for organic matter, weed suppression, or to enhance soil life (Johnny's Selected Seeds, 1983).

It also may be useful as a catch crop, as shown by Raderschall and Gebhardt (1990), who grew three different winter crops (barley, rapeseed, and Italian [annual] ryegrass) were grown following faba bean (cv 'Alfred') in order to evaluate their abilities to accumulate residual nitrogen. Accumulation of nitrogen was as follows (kg/ha): barley ('Cosina') - 36.2, rapeseed (cv 'Buko') - 52.1, and Italian [annual] ryegrass of Welsh origin (cv 'Deltex') - 22.9. Carbon/Nitrogen ratios were: barley - 20.3, rapeseed - 22.0, and Italian [annual] ryegrass - 31.0. Dry matter (biomass) accumulation was (tons/ha): barley - 17.2, rapeseed - 25.4, and Italian [annual] ryegrass - 14.8. Rapeseed was superior in retaining nitrogen that might otherwise be leached as nitrate.

Biomass

Raderschall and Gebhardt (1990) grew three different winter crops (barley, rapeseed, and Italian [annual] ryegrass) following faba bean (cv 'Alfred') in order to evaluate their abilities to accumulate residual nitrogen. Accumulation of nitrogen was as follows (kg/ha): barley ('Cosina') - 36.2, rapeseed (cv 'Buko') - 52.1, and Italian [annual] ryegrass of Welsh origin (cv 'Deltex') - 22.9. Carbon/Nitrogen ratios were: barley - 20.3, rapeseed - 22.0, and Italian [annual] ryegrass - 31.0. Dry matter (biomass) accumulation was (Mg/ha): barley - 17.2, rapeseed - 25.4, and Italian [annual] ryegrass - 14.8. Rapeseed was superior in retaining nitrogen that might otherwise be leached as nitrate.

N Contribution

In an experiment on rotational cash crops ("break crops") for wheat farmers, fertilizer N requirements were increased by 10 kg/ha following winter oat; decreased by 30 kg/ha following winter rape, winter peas, spring faba beans, or cultivated fallow; and decreased by 40 kg/ha following spring peas (McEwen et al., 1989).

Effects on Water

Effects on Soil

Hoffland et al., (1989) grew rape, Brassica napus cv 'Jetneuf,' in agar plates and nutrient solution with and without phosphorus. Bromocresol purple was included as a pH indicator. Acidification, caused by exudation of citric and malic acids, occurred along a restricted zone about 1.5 cm in length, just behind root tips. Conditions were alkaline along the remainder of the root systems. Concentrations of citric and malic acids were generally lower for plants grown with sufficient phosphorus. Further work will be needed to test whether the acidification observed leads to solubilization of rock phosphate. Potassium, calcium, and nitrate were taken up about twice as rapidly by plants with sufficient phosphate than by plants grown in a phosphorus-deficient medium.

Pest Effects, Insects

Bugg and Ellis (1990) observed that flowers of canola attracted adults of the following species of hoverflies (Syrphidae): Allograpta obliqua (Say), Sphaerophoria spp., Syrphus spp., and Toxomerus spp. Larvae of all of these species are predators on aphids.

Pest Effects, Diseases

Winter oat, winter rape, winter peas, and spring faba beans as break crops greatly reduced the incidence of take-all of wheat (Gaeumannomyces graminis) (McEwen et al., 1989).

Canola/rape is susceptible to Sclerotinia sclerotiorum and could possibly act as an inoculum source of this pathogen (Steve Koike, pers. comm.).

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