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Organic Agriculture Centre of Canada
The Canada Organic Standard requires organic matter be generated on farm before off-farm nutrient sources can be used. We were curious about the impact of this standard on Canadian organic vegetable producers. A handful of vegetable producers from coast to coast were interviewed about their green manure use, as green manures are one way to satisfy this standard.
All veggie producers interviewed use green manures extensively. They selected different crops depending on their needs:
In BC, a mixed vegetable farmer uses four annual green manure crops in succession on ten percent of his land annually. Fall planted rye is disked in mid May, followed by inoculated field peas which are tilled in when they reach 30 inches and are in flower. Oats, barley or buckwheat is seeded and disked when flowering, towards the end of August, and then the same field is seeded back to fall rye for the winter. Vegetable crops are planted the following spring. Pigs are pastured on a portion of the green manured area.
A Quebec vegetable farmer seeds red clover or alfalfa each year on a third of his land and these are grown for two years before tilling in. On the balance of the land with heavier soils he seeds either oat/pea, or oat/vetch combinations in late summer when there is no chance of any seed set. Both combinations winter kill. He uses oat/pea in fields scheduled for early spring vegetable crops and oats/vetch in areas where he is planning later spring plantings. This allows sufficient time for the greater biomass produced by the oat/vetch combination to breakdown. On sandy fields instead of an oat/legume combo he prefers to use rye to build up organic matter. Green manure crops are always seeded after the cash crop is tilled in to reduce the chance of any weed development. One worker focuses exclusively on the seeding and management of green manures.
For nematode control, an Ontario garlic farmer uses mustard as a green manure crop. He mows it twice, and then tills it in. If weeds are the problem he uses buckwheat instead of mustard. He seeds fall rye after either green manure and then garlic is planted the next fall. The third year other veggies are planted. In the fourth year, he goes back to garlic. When he uses clover as a green manure, he throws in some corn seed to generate long lasting biomass.
Challenges and Tips:
© 2012, Organic Agriculture Centre of Canada (OACC)