Crop rotation can bring great benefits to your yields, plant health and soil health, whether you’re a market gardener, homesteader or backyard grower. Crop rotation is the principle of avoiding repeating a crop with either the same crop or one in the same botanical family in successional plantings. For example, broccoli, cauliflower, cabbage and kale are all in the Brassica family, so you’d avoid planting one of these straight after another. It also involves rotating crops according to their nutrient needs, whether they are a fruit, leaf, legume or root crop.
Why Should We Rotate Crops?
The practice of rotating crops ensures variety; a cornerstone for a diverse biological system. By varying the crops going into the same place each year, you’ll help avoid pest and disease problems. This is because it disrupts the life cycle of many organisms, especially soil-borne diseases, which might otherwise be able to thrive on a continuous planting of the same crop. Some of these plant diseases can be difficult to get rid of once present, however crop rotation and avoiding the reintroduction of the affected crop for at least four years after is a good way to break the cycle.
Crop rotation also helps the garden to continue producing without detrimental effects and depletion of the soil. By looking at the different nutrient needs of plants, we can rotate in a way that provides all plants with what they need without having to constantly add compost or fertilisers. Planting crops of diverse root depths will penetrate the soil and improve its structure, as will adding organic matter. Rotating crops also helps to encourage habitat and biodiversity.
Crop Rotation Framework
Just as the benefits of crop rotation are many and diverse, so too are the considerations and the ways in which it can be done. Rotation plans can be as short and simple as a twocycle rotation (e.g. legumes and non-legumes), or as long as eight or ten-year cycles.
A common framework for crop rotation is a four-bed (or four-year) rotation focused on plant type. These are usually in the following categories and order:
• Legumes, e.g. beans, peas, green manures. These are good at building nitrogen in the soil and providing organic matter.
• Fruit, e.g. tomatoes, capsicum, cucumber. As heavy feeders, fruiting plants benefit from the nitrogen left behind by the legumes, building strong leafy plants early in the season.
• Leaf, e.g., spinach, cabbage, lettuce. These still do best with plenty of nitrogen in the soil and benefit from the legume nitrogen, although levels are likely to be lower.
• Root, e.g. beetroot, carrot, potato. With low nutrient demands, these are great to follow on after the others.
The cycle then starts again with another legume crop. The simplest way of incorporating this system at home is to use four beds or growing spaces. In year one you’ll have your legumes in bed one, fruit in bed two, leaf in bed three and roots in bed four. Then for each successional planting you’ll want to ensure it cycles in the rotation, so that your fruit then moves into bed one following the legumes from year one, the leaf into bed two to follow the fruit, the roots in bed three to follow the leaf, and you’ll plant legumes into bed four to follow on from roots.
Also consider the botanical families in rotations. These groups for example would include:
• Leguminosae/fabaceae, e.g. peas and beans
• Asteraceae, e.g. lettuce, Jerusalem artichoke, endive
• Brassicaceae, e.g. cabbage, kale, broccoli, turnip, kohlrabi, radish, rocket
• Apiaceae, e.g. parsnip, carrot, parsley, fennel, coriander
• Solanaceae, e.g. tomato, potato, capsicum, eggplant
• Cucurbitaceae, e.g. cucumber, pumpkin, zucchini, watermelon
• Chenopodiaceae, e.g. spinach, beetroot, chard
• Amaryllidaceae, e.g. onion, leek, shallot
Rotating purely by botanical family can get a little trickier due to their soil fertility needs and working that into a cycle, however the upshot is that it tends to offer more protection against diseases.
You may have a bed with lettuces (a leaf), so in the following rotation you’d look to plant a root crop. In this instance you’d avoid planting Jerusalem artichokes because they are the same family. Instead you might look to choose something like carrots or beetroot. Likewise, a bed that holds your tomatoes for a season would ideally not be the same bed you’d plant potatoes into when it comes time for a root crop, given they’re of the same botanical family.
Adding these considerations in develops an extra but worthwhile layer of complexity to your planning. Researching beneficial preceding and following crops is a good thing to do for this part of the planning.
Likewise, having knowledge of both the plant type and botanical families will help you in starting to group different plants together in your home patch. Using a crop rotation plan doesn’t mean a bed of just one crop to be followed by another. You might plant out a ‘fruit’ bed with tomatoes, capsicums and eggplant – all solanaceae. Then follow that bed with ‘leaf’ crops of the same botanical family, like cabbage, rocket and kale.
Doing A Crop Rotation Plan
When it comes to crop rotations and the methodology, as you’ve probably figured by now, there is not just one clear-cut way to do it. It can feel like a giant puzzle, working around the complexities of a plant’s botanical family, harvest type, nutritional needs and a crop’s time to maturity. Personal choice on what to grow will also come into play, and throughout the season unexpected crop failures, seasonal changes affecting maturing times and other unexpected factors may also impact your well-thought-out plan.
Ideally as you work out your rotation plan, you’ll consider as many of the above parameters as possible. However, you may also choose to make your plan as simple or as developed as you like. The best starting point is to map out on a large piece of paper your growing areas. On smaller pieces of paper, mark out the crops you’d like to grow and move them around until you find a rotation that follows the principles outlined.
The more you practise this process and begin to gather knowledge on various beneficial and detrimental relationships between different plants (via experience, other growers or research), the more you’ll find different rules and principles to be guided by in making your planning decisions.
Putting It Into Practice
One of the great things about using crop rotations is beginning to create a system in your garden where you are using plants to not only make the most of the soil, but to feed it too.
In your crop planning it can pay to note where you might like to add compost before a new crop succession. Consider which crops have preceded the new crop and whether the new crop is a heavy feeder that might benefit from a boost of compost, or a crop that would do fine in more depleted soil. Between each crop, we remove the preceding crop manually in whichever way will cause the least disturbance to the soil. This sometimes means chopping it in and other times means pulling, along with any weeds.
Depending on the crop going in, we will then use a broadfork to aerate the soil and help with soil structure. Plants with deeper roots benefit from some deeper tillage, so it’s great to use the broadfork prior to planting. if you don’t have a broadfork, you could use a garden fork, digging the tines into the soil and pulling them back a little to introduce some aeration without turning the soil over. Then use a rake to gently till the surface and prepare it for planting, also adding compost at this stage when needed.
Keeping Things In Order
Doing a crop plan on paper is one thing, following it by the book is another! It can sometimes be a tricky thing getting it right. It comes down to practice in anticipating when a crop will end so that you are able to plan for the right time to get the next one in, particularly if it’s a crop you also want to prepare your own seedlings for in advance.
Your rotations don’t need to happen all at once, as the purpose is to be able to create beneficial successions within each bed (or plot, or pot). If one of your beds is ready for the following crop but another bed isn’t, simply plant your crops in each bed as they’re ready.
It is a practice of ongoing tweaking and refining your plan, as the season, the weather and the plants do their thing too. Ultimately though crop rotation is a fantastic tool to begin using in your garden if you’d like to see an improvement in resilience and yields.
• The New Organic Grower by Eliot Coleman (Chelsea Green Publishing 1995)
• The New Organic Gardener by Tim Marshall (ABC Books 2011)
• The Market Gardener by Jean Martin Fortier (New Society Publishers 2014)
• NOFA Guides Set: Crop Rotation and Cover Cropping by Seth Kroeck (Chelsea Green Publishing 2011)
Emma is co-founder and general manager of Pocket City Farms, an organisation which recently opened their first urban farm in Sydney.