Crop rotation as Part of an Organic Gardening Routine
The devastation of the Dust Bowl or the Irish Potato Famine can both be linked to one crucial farming mistake: monoculture. Monoculture in farming is the growing of a single crop on the same piece of land season after season. Crop Rotation involves changing the type of plant grown on a particular piece of land from year to year or season to season. Crop Rotation has many benefits for the soil, the crops and the population as a whole.
You may be familiar with the images of nutrient-leeched soil blowing across the country and driving families from their homes. You may have read about the Potato Famine, a case of monocultural disaster in which a single variety of potatoes was allowed to grow for too long in one place and did not have resistance to the potatoe blight. It turns out that these disasters could have been prevented with a little simple ancient wisdom.
Not Rotating Crops Weakens the Soil
One crop will tend to pull a particular set of nutrients from the soil, depending upon its particular needs. Think of a bowl of trail mix sitting on your dining room table. Your children only eat the peanuts and raisins out of the bowl. They find the cashews and sunflower seeds disgusting. But then a houseguest comes along and finishes off the cashews and sunflower seeds. Better yet, they bring a dish of peanuts and raisins and your kids can go on munching away! Without this houseguest, your trail mix would remain stale and your children unhappy.
What Cover Crops Are and Why You Need Them
While some plants give to the soil, others take away. Cover crops are often soil-building crops. In other words, they are crops that are grown specifically to be worked back in to the soil at the end of the season. These plants provide needed nutrients to the soil and protect it from the sun, weeds, and provide food for beneficial insects.
Example of a Cover Crop
An example of a cover crop is rye. If you grow all of your tomato plants in one spot every spring, what do you do with this land during the winter? It is important to have a soil-building crop grown here in-between tomato crops. Rye will protect the soil from erosion with its roots, suffocate weeds, shade the soil from the sun and, eventually, become a rich food for your tomato plants to feast on.
Cover Crops Protect Your Garden from Disease and Pests
Another benefit of crop rotation is the prevention of disease and pest infestation. Year after year of the same crop allows certain pests and diseases to become comfortable in your garden. Pests that desire a specific crop will make a home in your garden if it remains un-changed. The rotation of crops will confuse pests and keep their population small.
Diseases that target certain plant species can also be avoided with crop rotation. Some crops even assist in killing these pathogens. Diseases will not be allowed to grow and flourish in the soil of an ever-rotating crop. Just as rotating the furniture in your living room helps to prevent dust and mildew, so does plant rotation serve as a ‘spring cleaning’ for your garden.
Basics of Crop Rotation
There are two very important categories of plants that should always be paired and rotated for each other. These are plants that need nitrogen and plants that assist in nitrogen fixation, or ‘nitrogen fixing plants’. Nitrogen fixing plants have bacteria that grow on their roots. These bacteria fix atmospheric nitrogen and ammonia found in the soil to the soil in a form that can be easily absorbed by neighboring plants.
Legumes are an example of a nitrogen fixing plant. These should be rotated with your vegetable crop in order to keep a proper amount of nitrogen in your soil. Crops most often paired by farmers are rice and cotton, and soybeans and maize. These crop pairings are essential for the continuing health of the soil.
In addition to being just plain good for your plants and the soil, you will find that crop rotation saves you money and trouble. By planting soil-building cover crops and nitrogen fixing crops you will save money on fertilizers: rye seeds are very cheap. By preventing the infestation of insects, weeds and diseases with cover crops and general rotation you are saving time, money and stress over pest-ridden crops.
Rotating Crops is a Time Tested Gardening Practice
Crop rotation is practical for a number of reasons and is far from being a new idea. Farmers in Ancient Rome, Africa and Egypt were found to have rotated their crops. In the England of the Middle Ages farmers used a three-year crop rotation of rye the first year, oats or barley the next year and nothing the third year.
Crop rotation has been taught by the proponents of the green revolution and is a key today to permaculture practices. George Washington Carver pushed for crop rotation in the United States and organic farmers around the world recognize its importance in preserving the health of the land and the people.
A natural crop rotation is occurring all around us, inside and outside of our gardens all of the time. A good organic farmer recognizes that nature knows best, and follows her guidance in her own garden.
The Irish Potato Famine could have been prevented had crop rotation been employed to divert the spread and growth the pathogenic fungus that caused the demise of the staple food of the living poor in Ireland. Furthermore, had the potatoes been planted in a polyculture, the spread of the fungus would have been further curtailed due to the fact that the vector of the fungus would be interrupted by plantings of soil building and nitrogen fixing plants.
