Historically, the two-field system served as the foundation of agricultural organization throughout Europe and the Middle East. Arable ground was separated into two fields or groups of fields; one was planted with wheat, barley, or rye, while the other was left fallow until the next planting season in order to regain its fertility. This system provided farmers with a continuous supply of food, even during times of drought or other disasters that might destroy most of their crops.
In modern farming, residual moisture from previous seasons remains important for growing many crops. If all available soil moisture were used up by plants, they would not be able to replenish it through rain or irrigation. Some crops, like soybeans, can grow even when soils are very dry. But most crops need some amount of water to grow successfully. That is why farmers usually plan their fields so that excess moisture does not cause problems for neighboring crops or lose farm land completely.
The two-field system helped farmers achieve this goal. A field could be kept moist by watering it regularly or covering it with a plastic sheet if necessary. And since crops needed different amounts of water, each field had areas that varied in depth of growth. This allowed farmers to take advantage of natural rainfall patterns by planting deep where it was needed most and shallower elsewhere. In addition, the separation of crops that require different amounts of care has been shown to improve their quality. Barley, for example, grows faster than wheat and needs more frequent attention from farmers.
During the Middle Ages, the three-field system supplanted the two-field system in Europe. In the old two-field method, one field was utilized for crop planting while another of similar size was left fallow. During the next year, the usage of the two fields was rotated. The idea behind this method was that no single plot of land was used for farming for an extended period of time, which allowed other areas to recover from previous crops and be prepared for future use.
In the three-field system, all available farmland is used each year for wheat or some other crop. When one field is harvested, it is left fallow until the next spring. After several years of this practice, the farmer will have cycled through all three fields and be ready to start again. This rotation allows room for new plants to grow without destroying existing crops.
There are several terms used to describe the different ways farmers organize their operations. One way to classify farms is by how they handle crop selection. You can find more information about these methods in our article on crop selection strategies.
Another way to classify farms is by whether they utilize hired labor or do it all themselves. On farms where human labor is used, there may be a large tractor driver or group of gardeners who work for pay.
Medieval farmers used the three-field crop rotation method, with spring and fall sowings. In one field, wheat or rye was planted, while in the other, oats, barley, peas, lentils, or broad beans were sown. Crops are alternated each year to leave one field fallow. This system is still used in parts of Europe and Asia today.
In addition to providing food, farmers needed to think about how they could make their crops grow better and yield more fruit. They learned that certain plants like wheat, rye, or corn respond well to being grown in a soil with a lot of organic matter in it. So farmers started adding manure and other types of compost to their fields, which helped them get more nutrients out of what little soil there was by growing nutrient-rich crops.
They also learned that planting different kinds of crops together helps prevent disease. Wheat, for example, needs a lot of nitrogen, so farmers would plant legumes (such as peas or beans) and collect their dried seeds to use as fertilizer for the next season's wheat crop.
Finally, they learned that crops need water to survive. Farmers provided water for their crops by either drilling wells or by using irrigation. They learned that some crops do better with more water and others with less, so they varied the amount of water they gave each field based on what grew best where.