With a good system of crop rotation, and especially with the addition of any sort of fertilizer you may be able to come up with, it’s possible to grow crops on a plot of land for upwards of 2 - 3 years at a time with good results. Ultimately, though, you must let the land rest if you hope to continue farming there in the long-run. Allowing a plot of land to rest for a period of time is known as letting the field go fallow, and there are several reasons for this. Allowing a field or plot to lie fallow means that you don’t grow anything new on it, don’t harvest anything and don’t graze any animals on the land for at least a year. Sometimes a field will lay fallow for two, three or even four years, but the traditional standard on many farms was to let a field lie fallow once every 2 - 3 years.

This fallow period allows the land to replenish many of its nutrients. The root networks of various grasses or groundcovers (like clover) have a chance to expand and grow, which further strengthens the soil and protects it from erosion.

During the fallow period, there are many beneficial flora and micro-fauna, including cyanobacteria, which live in the soil. These microorganisms continue to be active at the root level, steadily improving the quality of the soil so that when you come back in a year or two, you can begin planting food or cash crops anew.