Crop rotation means different things to different people, and there are various schools of though on the best way of achieving a good rotation system.
The main emphasis is on the fact that if you grow your produce in the same position each year, eventually the soil will build up diseases that affect your crops. Because these diseases can be plant specific or plant family specific, by rotating the position you use to plant you can eradicate the build up of such diseases.
The basic principle is, if you plant potatoes in a bed one year, the following year, plant something else in its place and put the potatoes elsewhere.
Methods of crop Rotation
This is the area of most confusion, how do you decide what to rotate and when. There are many schools of thought and we will try to describe some of the main ones.
Family Crop Rotation
This method is the traditional way of rotating crops and it works based on grouping plant families together and rotating them all at the same time.
The benefits being that some members of the same plant family attract the same diseases, so by moving them altogether you are doing the most thorough job of eradicating the build up.
The Royal Horticultural Society in the UK gives the following crop rotation system.
Year one: b1 legumes, b2 onions, b3 potato family, b4 umbellifers, b5 brassicas
Year two: b1 onions, b2 potato family, b3 umbellifers, b4 brassicas, b5 legumes
Year three: b1 potato family, b2 umbellifers, b3 brassicas, b4 legumes, b5 onions
Year four: b1 umbellifers, b2 brassicas, legumes, onions, potato family
Year two: b1 onions, b2 potato family, b3 umbellifers, b4 brassicas, b5 legumes
Year three: b1 potato family, b2 umbellifers, b3 brassicas, b4 legumes, b5 onions
Year four: b1 umbellifers, b2 brassicas, legumes, onions, potato family
Year five: Start again
b1 = bed 1
b2 = bed 2 etc
An additional advantage of this method is the plant groups require slightly different soil preperation so you can encorporate a soil improvement programme with your crop rotation one.
Seasonal Crop Rotation
Another method of crop rotation is to rotate based on the maturaty date of the plant, for example if you have 2 to 3 vegetables that will all be ready to harvest at the same time, then you rotate them together. This way you clear the bed at the same time allowing you to prepare it for the next season.
The idea of this method is that most people who grow for themselves do not build up diseases and pest because they are growing small amounts of produce.
At the end of the day when it comes to crop rotation its important to choose the right method for you and the conditions you will be growing in.