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The Permacultivator - Journal of Cool Climate Permaculture
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Crop Rotation

Some ideas for the cooler months of the year by David Johnson

It’s great on a cold winter’s day to curl up in front of a fire and bury your nose in a good book or seven, but should your conscience be pricked by some nagging thought of beds to be prepared for the planting of potatoes and onions, or for spring planting - here’s an out! You can stay inside where it is warm and prepare your garden beds by planning your crop rotations. To help you, here is an outline of crop rotation and several suggestions for putting it into practice.

What is crop rotation?

Crop rotation is the cyclic changing of crops grown on a farm paddock or in a garden bed to ensure healthy soil and satisfactory yield are maintained.

The different plants that we grow take out from the soil, and return to it, different nutrients and different amounts of nutrients. By varying the crops we can ensure that each crop gets what it needs in the amounts it needs for best results. For example, carrots planted into newly fertilised soil will produce very leafy plants with small roots. This is avoided if they follow a heavy feeding crop like broccoli.

The damage caused by insect attack is something we accept as an integral part of growing organically, however we can reduce the strength of some particular pests by breaking their cycle of reproduction. We do this by simply not providing them with an ongoing supply of food. Hence insects overwintering in the soil awaken in spring to find that the crop they had been dreaming of all winter is no longer immediately available for their consumption.

Plants are also susceptible to a range of diseases - from bacteria, viruses, moulds and fungi. A succession of crops increases the time between plantings of the same crop and so the soil concentrations of the spores of pathogens that affect that crop cannot build up to problem levels. For example, potatoes resown in the same beds soon build up unacceptable levels of diseases like wilt.

Anne Heazlewood operating in Tasmania, has two offerings. Her simple system is

  1. heavy feeders
  2. legumes
  3. light feeders

She also describes a more involved seven crop rotation

  1. brassicas
  2. greens
  3. legumes
  4. roots
  5. tubers
  6. cucurbits
  7. others

Lawrence Hills has a system based on what you could be eating each month

  1. potatoes
  2. legumes
  3. brassica
  4. roots

+ tomatoes to follow winter cabbage

+ salad crops and pumpkin to use space to advantage.

Jonathan Sturm offers three approaches to rotation.

His simple form is

  1. potato tribe
  2. brassica
  3. peas and beans
  4. everything else

He describes his personal system

  1. peas and beans
  2. onion tribe
  3. brassicas
  4. everything else

He grows these over a three year cycle and his system is adapted as he grows a lot of onions for market.

Also, based on feeding needs of plants, he suggests

  1. peas and beans (with lime)
  2. heavy feeders (leaf, fruiting veg, potatoes)
  3. light feeders (roots, onion family)

Jackie French offers three principles to follow:

  1. don’t follow a crop with the same family
  2. don’t follow one root crop with another
  3. grow a legume in each area each year

Jeffrey Hodges basic principles include:

  1. leaf crops which need high levels of nitrogen should follow legumes which provide same
  2. root crops should be a final crop when soil nitrogen is lowest before fallow
  3. include a period of fallow of at least two months.

His personal rotation based on Brisbane climate is

  1. legumes
  2. leaf crop
  3. fruit or flowers
  4. root crops
  5. fallow
  6. fruit or flowers

So where does that leave us?
In summary there is no hard and fast way of doing your crop rotations. But several themes emerge fairly consistently in the above sources.

1. The basic rotation is

• soil feeder (a legume or green manure or just weeds in fallow)
• heavy to medium feeder (a leafy plant or fruiting plant that has a high nutrient requirement)
• medium to light feeder (a crop that produces best in soil with lower nutrient levels).

2. Avoid planting family members consecutively.

3. Acid soil should be limed before the planting of peas and beans.

4. If fertiliser or compost is to be added in the cycle wait till after the legumes have done their nitrogen fixing. If there is a high level of nitrogen in the soil then the fixation by the bacteria associated with the legumes will be inhibited.

Garden Bed Planning

So now we have decided that we want to do the right thing by the soil and by our crops, but how to achieve it. Next time you are outside getting a load of wood to keep you warm just whip round to the vege patch and sketch the beds that you are using and list what is growing in each. It isn’t too important to make the sketch exact. Back inside you can tidy up or redraw your work area to a suitable scale. This basic "map" can be simply written on, showing each bed’s current planting. As each crop is finished (in future) you put brackets around the name and write in the name of the new crop. Thus you have an ongoing record for each bed. You might choose to add dates of planting and harvesting to help future decisions as well.

References