Crop Rotation

Crop Rotation

January is a good time to think about your crop rotation and what quantities you will be growing.  What was a success last year, what did you have a glut of – and what did no one like? Taking photos throughout the year is a good idea too as it is so easy to forget what everything looked like on a dark January day!

What is Crop Rotation?

Crop rotation is an agricultural practice that involves growing different crops in a specific order over a designated period in the same piece of land. This strategic approach is designed to enhance soil fertility, control pests and diseases, and promote overall sustainable farming practices.

Benefits of Crop Rotation

• Soil Fertility: Different crops have varying nutrient requirements and contributions to the soil. For example, brassicas can be heavy feeders so your soil may become tired if you continue to grow them in one spot. However Legumes are good nitrogen fixers so if you plant these the year before in your rotation they can prepare the soil for the following crop. By rotating crops, growers can prevent nutrient depletion and enhance soil fertility, leading to healthier and more productive farmland.
• Weed control: Crop rotation can also aid in controlling weeds. Crops with different growth habits and nutrient requirements can outcompete and suppress specific weed species, contributing to a more weed-resistant system. For example; some crops, like potatoes and squashes, with dense foliage or large leaves, suppress weeds, thus reducing maintenance and weed problems in following crops.
• Pest and Disease Control: Many pests and diseases are plant family specific. If the same crop is grown year after year damaging populations of spores, eggs and pests can build up. Crop rotation disrupts these cycles, reducing the risk of infestations. Common diseases that can be avoided by a good rotation include clubroot (brassicas), white rot (onion family) and eelworm (potatoes).

Plant Families

Plants are divided into different families depending on the characteristics that they share.

Brassicaceae (Cruciferous or Mustard Family)

• Examples: Broccoli, cabbage, cauliflower, kale, radish, turnip.
• Characteristics: Often characterized by four-petaled flowers and a distinctive mustard-like flavor.

Solanaceae (Nightshade Family):

• Examples: Tomato, potato, aubergine, bell pepper, chili pepper.
• Characteristics: Many members contain alkaloids, which can contribute to a bitter taste.

Fabaceae (Legume or Bean Family):

• Examples: Peas, beans, lentils, peanuts.
• Characteristics: Nitrogen-fixing plants, often with compound leaves.

Cucurbitaceae (Gourd or Squash Family):

• Examples: Cucumber, pumpkin, zucchini, watermelon, cantaloupe.
• Characteristics: Vining plants with tendrils, often with large, fleshy fruits.

Apiaceae/Umbelliferae (Carrot or Parsley Family):

• Examples: Carrot, celery, parsley, dill, fennel.
• Characteristics: Hollow stems, often aromatic, and umbrella-like flower clusters.

Amaranthaceae (Amaranth or Beet Family):

• Examples: Spinach, beets, Swiss chard, quinoa.
• Characteristics: Often rich in nutrients, including iron and calcium.

Alliaceae (Onion or Garlic Family):

• Examples: Onion, garlic, leeks, chives.
• Characteristics: Often aromatic, with pungent flavors.

Asteraceae/Compositae  (Aster or Sunflower Family):

• Examples: Lettuce, chicory, sunflower, artichoke.
• Characteristics: Typically have composite flower heads consisting of many small florets.

How To Plan a Crop Rotation

Make a list of the crops you want to grow for the year and then divide them into family groups.

Most yearly vegetables benefit from a crop rotation plan. However, certain annual crops such as courgettes, pumpkins, squashes, marrows, cucumbers, salads and sweet corn can be grown wherever convenient. Just avoid growing them too often in the same place. 

Crops that benefit from a rotation include; Solanaceae (potato family), Brassicas, Onion Family, Roots and Legumes.

Below is an example of a four year rotation and how crops can be grouped -

1) Solanaceae (Potato family): Potato, tomato, pepper, aubergine.

2) Legumes: Peas, broad beans, french beans, runner beans etc.

3) Brassicas: Brussels sprouts, cabbage, cauliflower, kale, kohlrabi, asian salads, radish, swede and turnips.

4) Roots & Alliums: Onion, beetroot, carrot, celeriac, celery, Florence fennel, parsley, parsnip and all other root crops.

Move each section of the plot a step forward every year so that, for example, brassicas follow legumes, onions and roots follow brassicas, and potatoes follow onions and roots.

Why is this a good rotation?

• Brassicas should be planted after legumes - Sow cabbage, cauliflower, and kale in soil that had previously been used for beans and peas. The legumes fix nitrogen in the soil and the brassicas benefit from the nutrient rich soil created. 
• Roots follow brassicas - Root vegetables don’t like very rich soil, too much nitrogen will result in lush foliage at the price of the plant's edible components. Therefore roots like parsnips, carrots etc should be planted following the brassicas which are a very nutrient dense crop.

Points to remember

• Plan your crop rotation before the growing season starts, and mark out the plots on the ground so you know where to plant each crop.
• It's a good idea to keep records or a map of your rotation so you can remember what was where and when.
• Rotations can be as long as you want.
• Brassicas, onions and potatoes should ideally have four years between crops.
• Green manures can be used to fill up space on beds and also to protect the soil over the winter.
• If you have sufficient space you could include flowers in the rotation for a year.
• Perennial vegetables such as rhubarb, asparagus, globe artichoke do not fit into the rotation as they stay in the same place.
• Aim to always keep the soil covered, either with a crop, a mulch or by planting green manures.