Rotations

Make them work for you and your soil

For centuries, our arable farming systems were based on the Norfolk four-course rotation which originated in the East of England. Rotations consisted of two cash crops and two crops to feed livestock and would have included legumes for fertility building, and livestock to graze and provide manure directly to the field.

The last sixty years have seen many farms replace the fertility building phase and livestock with artificial fertilisers. While allowing much shorter rotations, this has had unintended consequences for soil organic matter (SOM) levels and soil structure. However, where crop rotations tend to be longer we are seeing higher levels of organic matter. A recent review of studies from all over the world demonstrated that organically managed soils are 21% higher in SOM.

The main components of an organic or agroecological rotation are:

1. Green manures and grass leys 

These normally include a nitrogen fixing crop like clover or Lucerne, and a grass such as Rye or cocksfoot that build carbon through their fibrous roots and bulky tops. Farmers are opting for diverse leys with additional species like chicory and a range of legumes.

2. Cash Crops

Nitrogen demanding cash crops, such as wheat, potatoes or cabbages, are usually grown immediately after the fertility building phase. As a general guide, the amount of N available in the first year will be around 40–60% of the total amount of N in the legume, with much smaller amounts of nitrogen available in following years. In the later years of the rotation, less nutrient demanding crops, such as oats, triticale or carrots are usually grown. 

3. Break crops

Generally, these are non-cereal or grass crops and are important in the arable component of mixed systems, as well as on stockless farms. Break crops can reduce disease and competition from weeds and pests.

4. Cover

Periods of bare ground between cash crops should be kept to a minimum. Green cover captures sunlight which will benefit subsequent crops, and reduces the leaching of valuable nutrients. Bare soils are also vulnerable to weeds and erosion.

5. Intercropping

This is used for a wide variety of reasons, including reducing inputs and combatting weeds. Additional plants can also serve as another crop – it’s worth thinking what the market opportunities may be.

Benefits of extending a rotation

  • Weed control: Cover crops can out-compete or restrict some weeds.
  • Using the whole soil profile: Crops with different rooting depths and rooting structures are important for ensuring the whole soil profile is exploited.
  • Balancing your nutritional requirements: Calculating a nutrient management plan for the rotation will help to ensure the nutrient supply for each crop in the rotation will be adequate. There are many decision support programmes freely available to assist with this.
  • Pest and disease disruption: Diversity in cropping through the rotation is key to reducing the ability of any pest or disease to gain a foothold. Diversity within the field can also be helpful.

Organic Crop Rotation Factsheet

Soil Association

 

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Rob Corlett - Where in the rotation should you apply nutrients

Pollybell Organic Farm

 

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Jepco: Farmers Working Together for Soil Health

Soil Association

Author: Haydn Evans

Head of Farming Cymru

Haydn farms 97 hectares with his wife Janet and son Stuart. The farm is principally Dairy consisting of 100 milking cows supplying milk to Rachel's Dairy in Aberystwyth, where the milk is used for the manufacture of yogurts. The cows are a mixture of traditional breeds being British friesian, dairy shorthorns and Ayrshires. The farm is in rotation principally stubble turnips, wheat, whole top, red/white clover grass ley.

Last year Stuart became head of holding following successful completion of his MSC in organic agriculture. Whilst Haydn now focuses on young stock management. 

In addition to chairing the Soil Association farmers and growers board Haydn also acts as a farmer member of the Agricultural Land Tribunal.

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