Ground View
by Glen
Andresen |
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A friend recently asked why I didn’t rotate my crops. I replied that I do rotate most of my crops, but there are some very specific reasons why I don’t always practice crop rotation.
What is crop rotation? It is an organic gardening practice that, if practiced consistently, can sustain high crop yields and negate the need for high fertilizer and pesticide inputs.
The concept of crop rotation is pretty straightforward and makes perfect sense: Don’t put the same crop — or even a crop from the same family — in the same spot year after year. Usually we try to be on a 3-, 4- or 5-year rotation schedule, meaning we try to put other crops or family of crops in a certain bed before we return to the original crop. The longer the cycle, the better. For example, the first year we plant tomatoes in a bed. This means that in the second year we don’t plant tomatoes there – or potatoes, peppers or eggplant, all of which are in the tomato family. So the second year we might plant broccoli. The third year we plant beets and carrots, and for the fourth and final year we choose peas and beans. Most gardening books can tell you which vegetables belong to which families.
Why rotate your crops?
One reason for rotation has to do with soil fertility. Different vegetables use different amounts of certain nutrients from the soil. By rotating which crops are in your beds, you can help manage your soil fertility. In addition, I’m SURE you are adding compost every year, right?
Some crops — like tomatoes, squash, peppers and broccoli — use a lot of nutrients. You may want to follow some of these “high feeder” crops with the “low feeders,” such as onions, potatoes, beets and carrots. There are even crops that enrich the soil with nitrogen, and these “high giver” veggies include peas and beans. In other words, different crops take different amounts from the soil.
Crop rotation also helps you manage pests and disease, which can overwinter and then attack the same crop year after year. By planting a different crop, you break the cycle. Because most pests and diseases are specific to a certain plant or plant family, if that plant isn’t there then the pest or disease most likely will perish. You can’t find any pesticide that is easier, cheaper or more effective than choosing simply to put in a different crop!
Rotating your crops can also improve your soil quality. Some plants are shallow rooted and some are long rooted. By mixing up what is planted in your beds on a three- to five-year cycle, you can help improve and manage how water and air move through your soil.
Lastly, crop rotation can help you identify weeds quickly. For example, some weeds may look like the crop you are trying to grow. Can you tell the difference between a seedling Queen Anne’s lace and a seedling carrot? I can’t. But if I rotate in a completely different looking crop, like squash, that Queen Anne’s lace sticks out like a sore thumb and can be summarily dispatched!
Even with all these excellent reasons to rotate my crops, I don’t always do it. One reason is because there is no substitute for direct sunlight. For example, I would rather take the chance of my tomatoes getting blight (a fungal disease that overwinters on the soil) than grow them where they would get just marginal direct sunshine.
Another and more distressing reason I don’t rotate some crops is because some of my beds have those rascally symphylans, which will stunt the growth of certain vegetables. Year after year I continue to plant my symphylan-prone crops (onions and carrots) in the same beds because they happen to be symphylan free.
There you have it: Four reasons to rotate your crops every year, and two not to. Take your pick, experiment, and as always, be prepared to change your gardening practices if need be.
Class alert!
I will again be teaching “First-time Beekeeping for the Organic City Gardener” at several locations in North and Northeast Portland in March and April. Please write to me at the e-mail address below for information on my beekeeping classes.
Glen Andresen hosts “The Dirtbag,” aired every second Monday at 10:30 a.m. on KBOO 90.7 FM. He tends his bees on a three-quarter acre organic garden at a retreat in Eagle Creek. He also coordinates Metro’s Natural Gardening Program. Comments and questions may be sent to glen@pacifier.com or c/o The Portland Alliance.
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