Editing Crop rotation (section)

=== Three-field systems ===

{{main|Three-field system}}

From the 9th century to the 11th century, farmers in Europe transitioned from a two-field system to a [[three-field system]]. This system persisted until the 20th century. Available land was divided into three sections. One section was planted in the autumn with [[rye]] or winter [[wheat]], followed by spring [[oat]]s or [[barley]]; the second section grew crops such as one of the [[legume]]s, namely peas, lentils, or beans; and the third field was left fallow. The three fields were rotated in this manner so that every three years, one of the fields would rest and lie fallow. Under the two-field system, only half the land was planted in any year. Under the new three-field rotation system, two thirds of the land was planted, potentially yielding a larger harvest. But the additional crops had a more significant effect than mere quantitative productivity. Since the spring crops were mostly legumes, which [[Nitrogen fixation|fix nitrogen]] needed for plants to make [[protein]]s, they increased the overall nutrition of the people of Europe.<ref name="Lienhard 2023">{{cite web |last=Lienhard |first=John |title=No. 26: Three-Field Crop Rotation |publisher=[[University of Houston]] |url=https://www.uh.edu/engines/epi26.htm |series=The Engines of Our Ingenuity |date=2023 |access-date=31 December 2023}}</ref>