Crop rotation refers to the sequencing of crops over time on a field or planting bed. It is not unique to organic systems; it is practiced by many conventional farmers as well. Organic systems are unique in that crop rotation is specifically required in the USDA organic regulations.
Farmers are required to implement a crop rotation that maintains or builds soil organic matter, works to control pests, manages and conserves nutrients, and protects against erosion. Producers of perennial crops that aren’t rotated may utilize other practices, such as cover crops, to maintain soil health.
Crop Rotation in Perennial Crops
For producers of organic perennial crops, the requirement for crop rotation can be confusing. Section 205.205, the crop rotation practice standard, is meant to ensure that the farmer implements practices that will maintain soil organic matter, control pests, conserve nutrients, and protect the soil against erosion. For growers of annual crops, those practices typically include crop rotation, but other practices can be substituted if rotation is not practical. Some perennials will be part of a long-term crop rotation, which may last a few years or even decades.
Asparagus, for example, is a perennial that can be productive for 15 years or more. When a field is taken out of asparagus production, it is typically planted with another crop to reduce the incidence of soilborne disease. That practice is considered a long crop rotation. Several other perennials, such as strawberries, Echinacea, and lavender, are not required to have a cover crop because they are typically part of a long crop rotation.
Other types of perennials—those that will not be part of a crop rotation—may require additional practices to ensure soil conservation and biodiversity in the cropping system. This is important with large perennials, such as trees, that have large drive rows between the crop rows. For example, organic farmers must have a cover crop (often grass) between the rows of trees in an orchard. Crops that are required to have a cover crop between crop rows include caneberries, grapevines, blueberries, tree fruits, and nut trees.
Some perennial crops, such as alfalfa, develop a canopy that covers the ground and prevents soil erosion. Such crops are not required to be rotated to other crops.
Biodiversity
Organic production is a system that “respond[s] to site-specific conditions by integrating … practices that …. conserve biodiversity.” The regulations also mention that perennial cropping systems must introduce biological diversity in lieu of crop rotation.
Although farmers are encouraged to have diverse systems, there are no specific requirements, standards, or monitoring practices. Nonetheless, many organic farmers actively manage their farms to increase biodiversity, due to its many benefits.