To aid effective cultivation, many farmers follow a system of
crop rotation.
Rotation has been practised in Britain for hundreds
of years. The aims of rotation are to keep the land as fertile as
possible by deep manuring and cultivating a root crop using the
humus and nitrogen build-up from grass seeds.
Control of weeds is
assisted by one year planting in the autumn, another in the spring
and so on. This kind of alternate cultivation eradicates many
stubborn weeds that would become a major problem if one crop
were continuously grown. By alternating the types of plants grown,
parasitic organisms are destroyed as their hosts are removed.
Traditionally rotations were planned to spread labour requirements
as effectively as possible throughout the year. An example
of a six-year rotation is:
- wheat
- roots
- cereal
- seeds (grass)
- cereal — a different variety
- potatoes
As grass seeds are expensive and modern plants perform well for
several years, it is becoming common to run the seeds part of the
rotation for two or three years. When this is intended, the seed
mixture comprises several different grasses, clovers and other
seeds. If the seeds are only for one year, then Italian ryegrass is
often used as it is a heavy yielder.
crop rotation