Crop Rotation
In medieval times, farming was usually based on an 'open field' system, each village usually having at least three unfenced areas surrounding the village. These would be divided into strips cultivated by the villagers, often working as 'serfs' to the landowner. Wheat or rye would be grown in one field, barley or oats in the second, and the third would be left uncultivated or fallow. In the days before artificial fertilisers, the livestock would be the source of manure to replenish the nutrients in the soil. However, this rotation only cropped two thirds of the cultivated land, with the crops rotating by one field each year.
When Charles Townshend (1674 -1738) retired from politics in 1730, he devoted his time to agricultural improvements. Although turnips were grown in Britain, Townshend became a keen advocate for including them within a rotational system. He introduced a Flemish system, later developed as the 'Norfolk four-course rotation', and also leading to him acquiring the name of 'Turnip' Townshend. His rotation had clover, wheat, turnips and barley as the four crops grown in rotation, the clover and turnips removing the need for a fallow area. These additional crops also provided fodder for livestock during the winter, an important factor where large flocks of sheep were common. Previously many of the livestock had to be slaughtered because of the lack of winter fodder.
The four plots growing in the display cage represent the crops that would be grown in rotation in the fields included within a Norfolk four-course rotation.
  1. Clover, a legume, has nitrogen fixing nodules on the roots. When ploughed in, the nitrogen becomes available for the next crop.
  2. Wheat, utilising the nitrogen released by breakdown of the clover nodules.
  3. Turnips, lifted and stored as winter fodder, or sheep allowed to feed on the crop and manure the soil.
  4. Barley, utilising the nutrients added by the sheep dung.
Additional information on crop rotation is available as a downloadable 'pdf' file.