A simple thing like planting squash where tomatoes grew last year will increase your garden soil fertility and cut down on plant disease and pest problems. It’s called crop rotation and it prevents the depletion of nutrients and interrupts disease and pest cycles so the soil stays healthy and out of healthy soil grows healthy plants.
Potato pathogens give us a good example how crop rotation keeps garden soil healthy. Potatoes are an easy to grow home garden vegetable. In one growing season, the fungi that causes scabby skin patches on potatoes increase rapidly in the soil as do almost invisible nematodes. This year’s spud crop will be harvested virtually unscathed by the fungi and nematodes, but they will remain in the soil, multiplying and awaiting next year’s potato crop (tomatoes and egg plants are at risk too) and will attack with a vengeance and destroy the entire potato crop and there is nothing you can do about. All the damage will be taking place underground and you will be blissfully unaware of it, until you remove the spud from the soil.
Three Year Rule
To stop this from happening and starving off the fungi and nematodes, a completely unrelated garden vegetable needs to be planted where potatoes grew last year. And the year after that something beside spuds should be planted in that location. And this is not just a potato problem, this scenario plays out with all vegetables, just the damaging organisms and pests have different names and shapes.
Follow the three year rule for all garden crops. Rotate crops each year so that the same family of vegetable is not grown in the same place for three years. That gives enough time for soil pathogens to die and the soil be healthy enough to sustain the crop planted.
It’s obvious that growing crops take from the soil, but not so obvious that they also add back to the soil. All crops give back, just some more than others. For example, sweet corn grow deep roots which help break up compacted soil, legumes and nasturtiums add nitrogen to the soil, and broad-leafed greens suppress weed growth and germination.
Crop Rotation Made Easy
During the long winter months when there is nothing to do in the garden, grab a seed catalog, pencil and paper and map out your garden. Plan what will be planted where and write all the information on the paper regarding the vegetable varieties planted. Use this ‘master list’ to plan all subsequent gardens so all crops will be rotated on a three year cycle to keep garden soil healthy.