How Crop Rotation Works

Posted by admin on July 28th, 2007 at 08:40pm

Make your organic garden sustainable by using good crop rotation.

“In a word, crop rotation means variety, and variety gives stability to biological systems.” - Eliot Coleman, The New Organic Grower

One of the most shortsighted things that modern agriculture has done to our landscape is the development of the monoculture crop. For thousands of years of agriculture practices among human civilization, small and even moderately large cultures have successfully grown and harvested their own crops for generations using sustainable practices such as crop rotation.

What we mean by sustainable agriculture is a system by which we do not deplete the land of essential nutrients through our growing of crops, a pattern that forces many farmers to supplement the soil with harmful fertilizers. Amending the soil continually in this manner (instead of using good organic soil preparation practices) means that time and resources are wasted when they wouldn’t have to be with proper sustainable agricultural practices that would naturally keep the land productive and fertile for generations. As we will see in our more in-depth discussion of crop rotation below, rotating your crops will lead to better pest management and improved soil conditions and soil structure. Crop rotation is simply a good step towards keeping your own organic vegetable garden indefinitely productive and capable of producing the best crops, year-round.

With any monoculture crop like wine grapes, the same piece of land is used endlessly for years on end with the same crop grown over and over again. This leads to more pest problems, as a permanent source of food for certain insects will make their population increase. In modern agriculture, this will inevitably lead to an increase in harmful pesticides that are put into the environment to try to combat these problems. Monoculture also leads to the depletion of the soil nutrients, as the same crop needs the same elements present in the soil year after year. As we have discussed above, without those nutrients returning to the soil, new elements need to be added each growing season in the form of artificially-produced fertilizers. These fertilizers will be used up with the growing of that crop for one season, and then more money will have to be pumped into obtaining more to make the soil able to handle next year’s crop.

We have lost sight of the basics of agriculture. If we could step back in time to heavily agrarian cultures present in Central America or even in Europe many centuries ago, we would find societies that were entirely dependent on growing their own crops able to do so without our modern techniques of fertilizers and pesticides. How did they do this so successfully? First, they didn’t have the means to transport perishable foods like vegetables over long distances in cool, refrigerated vehicles as we do today. Second, they didn’t need to. Communities were completely self-sufficient instead of being as specialized and divided as our society is today. Back then, squash, corn, and beans were grown on the same piece of land and used the natural, inherent qualities of the crop to give nutrients back to the soil. Today, we are quite accustomed to getting our tomatoes from Canada, our apples from New Zealand, and our potatoes from the Midwest. Modern transportation has made this possible. But the incredible costs associated with transportation makes this a more expensive way to obtain vegetables that simply aren’t as fresh and have the potential to be exposed to dangerous bacteria along the transportation route if they are not contained in the appropriate manner.

Crop Rotation is a system in which you can grow all of your organic vegetables in your own garden and naturally return the nutrients to the soil for each successive year. Basically, it works like this. Since different crops require different nutrients from the soil, growing one in one plot the first year and then moving it to another plot the second year allows it to grow in fresh soil that it hasn’t been depleted during the previous year. The crop taking its place is, in turn, exposed to new nutrients and can grow well in new soil. After the harvest, when the remainder of these plants are tilled into the ground in readiness for your soil preparation for the following season and green manures are allowed to grow as a cover crop, nitrogen and other trace elements from the crops are returned to the earth for use by the next crop to occupy its space. For those with large pieces of land, crop rotation can be even more effective if you use one part of your land for your garden. After growing crops on that piece of land for a few years, allow it to go fallow or grow a cover crop on it for a few years while you relocate your garden to another part of your property. Once the soil has had time to build itself back up, move your garden back to the original spot and repeat the process with your other field.

So, let’s jump right in to our discussion of crop rotation as it will pertain to your own organic garden. By getting into the habit of good crop rotation, you will absolutely see an improvement in your harvest. Let’s take a look at some factors that benefit your crop as a result of a planned and effective crop rotation:

Control of Pests and Disease:
Moving your crops around means that the bugs (both insects and harmful microbes) won’t be able to find a consistent source for what they need to prosper. Change the location of your crops from season to season, and those bugs won’t be able to get comfortable and settle in to your free food supply.

Increase of Elements in the Soil:
The natural processes of the life of a plant include seed, growth, and death. In a world without farmers managing crops, these plants would grow and then die without the intervention of a human removing them from the earth. As the plant dies, it returns to the soil and decomposes. This process releases essential nutrients like nitrogen back into the earth, which will become the food for the next generation of plants. Till your crops back into the ground after harvest and get that cycle going of returning those precious nutrients back into your soil. This will also put other essential elements such as phosphorus and potassium into your gardening plots, and these are absolutely necessary for productive vegetable growth.

Release of Carbon Dioxide:
Plants respire in the opposite manner of humans and animals, creating a beautiful balance of life on this planet. While we breathe oxygen and excrete carbon dioxide, plants do just the opposite. They take in carbon dioxide and excrete oxygen, that elemental gas we all need for our survival. By turning plants back into the ground and tilling the soil, soil microbiology production is increased. This means that you help the ability of the beneficial microbes already present in the soil to grow and produce necessary carbon dioxide by giving them a rich supply of food - the decomposing crop remains from the previous planting.

Improved Soil Structure:
Different crops grow their roots at different depths. Some are shallow-rooted, and others, like carrots or parsnips, are themselves the root and dig very deep into the soil. This allows for soil and the nutrients that it harbors further down to be brought up closer to the surface. Deep rooted plants absorb nutrients further down in the soil, leaving the soil closer to the surface available for the succeeding crop. And nutrients that are brought to the topsoil by deep rooting vegetables are made available to more shallow rooted plants when they decompose.

A few final ideas and suggestions for your crop rotation
Now that we’ve learned about the benefits of crop rotation, the only thing left to do is to try it for yourself. There are no strict rules about which vegetables should go where in your rotation. Just make sure to be rotating your crops around in order to maintain good, nutrient-rich soil so that your organic garden can be as sustainable as can be. You may not even find it necessary to rotate your crops each successive season. Doing it every two or three years may make the best schedule for you. The most important thing about growing your own organic garden is to test ideas for yourself until you come up with what works best for you. Having said that, there are a few rules of thumb that experienced gardeners use when setting up a rotation. They include the following:

Plant carrots after squash or potatoes
Squash and potatoes are what farmers call “cleaning crops” because the way they are grown leads to a natural reduction in weeds. A farmer can easily cultivate weeds on a squash plot before the vines begin to really grow well. Once they do, they keep down any remaining weeds naturally because of the size of vines and leaves. Potatoes are hilled for harvest, a process that turns the soil over and prevents any weed seedlings from taking root. Having grown one or two of these vegetables in a plot, it is all ready for the following season when root vegetables can be grown there. Plants like carrots are notoriously difficult to keep weed free and can have a hard time competing with them. However, if the plot has been made clear of weeds before hand, growing your root vegetables becomes considerably easier.

Plant your tomatoes away from your potatoes
Tomatoes and potatoes are two members of the same family, Solanaceae. Whenever possible, it is best not to grow vegetables that are closely related to one another in the same plot or near one another. It is good practice to plant potatoes in a plot that is the furthest in your rotation away from tomatoes. For instance, if you have 8 plots or beds for vegetables, plant your tomatoes in plot 1 and your potatoes in plot 5. Then, you will have several years of other crops combined with green manures to rebuild the soil and prepare it for the related crop. Read further about how to grow organic tomatoes.

Corn is the best crop to follow cabbage or broccoli
Cabbage and broccoli, two members of the Cruciferae family, take a lot of nutrients out of the soil and can be detrimental to any following crop in the same plot. However, farmers have noticed that corn is the crop least affected by this trend. If you have corn as a part of your crop rotation, you will have the best luck with your other vegetables if you dedicate the plot that will be growing it to cabbages and broccoli the preceding year.

These are some simple suggestions and guidelines that should help you get started with a really effective crop rotation. Again, you will need to find the best way of doing a rotation that ideally suits your own garden. You may find that all of the above ideas will make your vegetables better and better each year. Then again, you may find that other alternatives help you in your particular circumstance. Just keep in mind that organic gardening, while beneficial in many ways to your family and to the environment, should also be fun. Experiment with your own ways of growing plants. You may discover a trend in small farming that hasn’t been explored yet and could be beneficial to other organic growers.

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