Many modern farms are made up of a number of fields which can be cultivated separately and thus can be used in a crop rotation sequence. Crop rotation has been employed for thousands of years, and has been widely found to increase yield and prevent harmful changes to the soil environment that limit productivity in the long-term.[3] Although the specific mechanisms regulating this effect are not fully understood,[4] it is thought to be related to differential effects on soil chemical, physical, and microbiological properties by different crops.[5] By affecting the soil in different ways, crops in a rotation help to stabilise changes in these properties. Another consideration is that many agricultural pests are species-specific, so having a given species present in a field only some of the time helps prevents populations of its pests from growing.[6]