Recently, Lamont lost a pepper plant to blight and he reminded me that the Great Potato Famine of Ireland was caused by blight. Then I read an article mentioning monoculture, which is growing a single crop in the same location year after year. (Polyculture is the healthy rotation or mixing plants together, as in companion planting.)
In the case of the Potato Famine, one of the mistakes they made was monoculture. They planted potatoes in the same place season after season, until the soil was depleted of nutrients necessary to keep the plants disease resistant and the potato plants could no longer resist the blight that wiped out the entire food source. Another thing they could have done was polycultural…that is plant blocks of another crop with the potatoes, which would have helped slow the spread of the fungus, particularly if they used plantings of soil building and nitrogen fixing plants.
In the case of the Great Dust Bowl, monoculture created nutrient-deprived soil blowing across the country. One crop will pull specific nutrients out of the soil, and if those nutrients are not replaced or allowed to replenish, disease and pest infestation run rampant. Pests that desire a specific plant for food will make a home in your garden if that plant remains in the same place all the time. The rotation of that crop will confuse pests and help keep their population down. It’s the same thing with diseases that target certain plant species, they just can’t flourish in the soil of an ever-rotating crop.
A good thing to know about crop rotation is that nitrogen fixing plants have bacteria that grow on their roots allowing them to “fix” nitrogen into the soil in a form that can be easily absorbed by neighboring plants. Legumes do this, and rye. Farmers often pair rice and cotton, also soybeans and corn, which makes for healthy soil. Another thing about crop rotation…it’s not a new idea. Ancient Rome and Egypt were found to rotate crops. In England in the Middle Ages they used a 3 year rotation of rye, oats or barley, then allowed the land to be fallow the 3rd year.
Cover crops can be rotated, even in the smaller scale of home gardens to encourage healthy soil. Organic gardeners often plant hairy vetch for a season where they plan to plant tomatoes because hairy vetch is a nitrogen fixer. They just allow it to grow until they are ready to plant their tomatoes, then mow it down and turn it into the soil. Make a note however, that they do not allow it to go to seed before they turn it over. One grower I read about just mowed it down and dug holes in it for the tomato plants. He used it as a mulch.
Rotation is normal for me, but I’m new to cover crops. I did purchase some hairy vetch to grow in one of my beds over the winter to refresh the soil….where I plan to put my tomatoes next year. I kinda feel like it’s important for me to learn good soil practices, since I’m committed to organic gardening.