threefield

The three-field system, also known as a three-field rotation, was an agricultural method used in medieval and early modern Europe to manage arable land. It divided a farm’s cultivated land into three large fields, with each field serving a different purpose in turn. Typically, one field carried winter crops such as wheat or rye, a second supported spring crops like barley or oats and sometimes legumes such as peas or beans, and the third was left fallow to restore soil fertility. Each year the roles shifted so that every field rotated through the three functions over a three-year cycle.

Historically, the system emerged in early medieval Europe and became widespread during the High Middle Ages, transforming agricultural practice across many regions. By keeping a portion of land fallow, farmers allowed soil nutrients to recover and reduced the risk of total crop failure. The inclusion of leguminous crops in some rotations helped fix atmospheric nitrogen, improving soil fertility. Fallow land often served as pasture or was used to produce fodder, supporting livestock and contributing to a broader farming economy. The system also enabled a greater area to be under cultivation compared with earlier two-field arrangements, supporting population growth in medieval Europe.

In many areas, the three-field system was gradually supplanted by the four-field rotation in the later medieval and early modern periods, which added a root crop and more pasture to improve soil health and sustain livestock through winter. The transition varied by region and depended on changes in technology, economy, and agriculture.