The Courier & Advertiser (Perth and Perthshire Edition)
Let’s goround again
Crop rotation needn’t be a mystery. With a little careful planning you can maximise growth and reduce the risk of disease
As the days get longer and the sun’s warmth begins to feel more noticeable the mind starts wandering to thoughts of starting on another gardening year. By now we have had plenty of time to look at catalogues, visit garden centres and choose what we want to grow for 2017. So with seeds in hand and potatoes chitting let’s take a deep breath and begin to plan where everything is going.
Crop rotation is one of those things that many people have heard of – but still don’t quite understand. Boiled right down, it is the process of growing crops on fresh soil, away from the previous year’s plants which may have been infected by disease, with the aim of avoiding reinfection. The main fungal diseases to watch out for include clubroot on brassicas, white rot on onions and blackleg on potatoes.
There are other factors to take into consideration, however. Some crops, such as pumpkins, are gross feeders so need to move to land that was heavily manured during the winter digging.
Others, such as parsnips, carrots and turnips, prefer fertile soil that had no compost in winter.
Salads also like fertile soil and can grow fast so they are often used as a catch crop or an intercrop.
Different crops like varying degrees of acidity or alkalinity. Potatoes prefer an acidic soil, otherwise scab could be a problem. Brassicas prefer an alkaline soil with a high pH as this reflects their natural environment since many grow wild on chalk soils. This also discourages clubroot disease which can be a real problem.
It may sound complicated but it is really good garden practice.
One idea is to draw a plan of your garden to scale (remember to include paths, sheds and compost heap) to make it easier to work out where crops are to go well in advance of sowing.
My rotation plans show where last year’s potatoes were grown and this is often where I start since this area will have to be limed for the next crop of cabbages, sprouts, swedes, kale and cauliflower. The land that grew these brassicas last year will now be assigned to the gross feeders, such as peas, beans, pumpkins, courgettes and sweet corn. And the area where the gross feeders grew last year will now be set aside for root crops and salads.
On a four-year rotation potatoes can follow the salads and roots but they will require a good feed. For maximum yield the potato patch is composted during winter digging, then at planting time I like to take out a furrow and line the bottom with more compost, into which I
If you have enough salads, any spare land can be sown with a green manure crop in early spring and autumn to help improve the soil fertility
plant my chitted seed potatoes.
If you grow strawberries on the same site and replace these every three years include this area and replant fresh strawberries as part of the rotation. They won’t be affected by clubroot or white rot.
INTERCROPS
Salads are short-term, fast growing crops so are very adaptable to use as an intercrop between other slow growers with wide spaced rows, such as Brussels sprouts or sweetcorn, or even on the sides of your celery trench before earthing up. Lettuce, rocket, radish and baby beet can all be used as an intercrop to get the maximum value from the land.
CATCH CROPS
The same salads can also be used as quick maturing catch crops where less hardy vegetables, such as courgettes, pumpkins and sweetcorn won’t be planted until early summer.
Similarly, catch crops can be used after an early harvest of potatoes, onions or first peas when there is usually time to get in another crop before winter. If you grow winter hardy lettuce, spring onion and rocket they can continue to grow well in to winter, especially while the weather continues to be mild.
If you have enough salads, any spare land can be sown with a green manure crop in early spring and autumn to help improve the soil fertility.