Chapter 7

Crop Rotation on Organic Farms

National Organic Program Standards for Crop Rotation

Organic producers are required under the National Organic Program (NOP) rules to choose crop rotations on the farm whether they grow field crops, vegetables, hay, cover crops, or all of the above. The NOP defines “crop rotation as, the practice of alternating the annual crops grown on a specific field in a planned pattern or sequence in successive crop years so that crops of the same species or family are not grown repeatedly without interruption on the same field. Perennial cropping systems employ means such as alley cropping, intercropping, and hedgerows to introduce biological diversity in lieu of crop rotation.” Long-term three to seven year rotations provide the most benefit, but short-term rotations may also be compliant. While crop rotation is part of the rule and is an integral part of the Organic System Plan (which is considered incomplete without a plan), there is no one right way to create a compliant and successful crop rotation plan. Simply including a fallow period could be a start, but a sustainable rotation will require more diversity over the long run. Organic production systems will have difficulty meeting crop nutrition needs if crops that require high levels of fertility are grown frequently. Heavy feeders (e.g., lettuces, tomatoes, peppers, corn, etc.) produce more when rotated with light feeders (e.g., carrots, turnips, radishes, beets, etc.) and nitrogen-fixing legumes.

National Organic Program Crop Rotation Practice Standard

National Organic Program (NOP) Crop Rotation (§ 205.205) is defined as “alternating annual crops grown on a specific field in a planned pattern or sequence in successive crop years so that crops of the same species or family are not grown repeatedly without interruption on the same field.” NOP § 205.205 states that a producer must implement a crop rotation including but not limited to sod, cover crops, green manure crops, and catch crops that provide the following functions that are applicable to the operation:

Maintain and Improve Organic Matter

To maintain or increase organic matter in the soil, include sod-forming crops such as perennial grasses (rye) and legumes (alfalfa). Due to their extensive root system, sod crops in rotation build soil organic matter whether they are used as green manures or harvested. In addition, include green manure crops to add organic matter and nutrients to the soil.

Provide Pest Management

To suppress insect pests, diseases, and weeds include crops in different families to break up pest and disease cycles. If diseases exist in the field, then planting less susceptible crops should be included in the crop rotation. Following a cool season crop with a warm season crop allows the grower to alternate tillage thereby affecting weed germination.

Manage Deficient or Execess Plant Nutrients

To manage deficient or excess plant nutrients include a green manure crop in the rotation. Alternate nitrogen fixing crops (e.g., legumes such as peas, soybeans, alfalfa, clovers) followed by high nitrogen demanding crops (e.g., corn, winter wheat, vegetables).

Provide Soil Erosion

To prevent soil erosion, include cover crops in the rotation to help provide continuous soil cover. Use a mix of crops and cultural practices that minimizes the amount of time that soil is bare.

Perennial Cropping Systems

Section 205.205 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.

Certifying Agencies

It is up to the certifying agency to determine that the farmer is implementing a sound crop rotation on the land that is farmed. Certifying agencies require proper record keeping of the planned sequence of crops in each identified field. Criteria to judge compliance with the standards are subjective. No technical measurement tools are required to evaluate the effectiveness of a rotation for building organic matter or controlling erosion. The NOP standards do not state how frequently a crop can appear in the rotation. Also, the standards do not state that a farmer must include a cover crop or green manure crops in the rotation. Such practices may not be advisable in certain situations, as in dry years in the Great Plains.

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