Can Permaculture Feed the World?
Published online for the first time, Patrick Whitefield's timely essay that made people wake up to the potential of permaculture food systems. Today we celebrate his pioneering spirit and dedication to permaculture.
Patrick Whitefield was a British permaculture teacher, designer, author, and consulting editor for Permaculture Magazine. He was regarded as one of the leading and pioneering permaculture authorities in Europe.
Can permaculture feed the world? ... Well I would say ‘yes’ to that, wouldn’t I?
But whether I’m right or wrong, one thing’s certain: conventional agriculture certainly can’t feed the world for much longer. It’s based on a one-way flow of non-renewable resources and it falls down both on the input side and the output side.
The output includes soil degradation. In the USA, one of the world’s major food exporters, a third of the topsoil that was there when Europeans arrived has been eroded away, and the loss continues at 17 times the rate of soil formation. Carrying on with present farming methods means trying to feed ever more people on an ever-shrinking amount of fertile soil. It can’t be done.
On the input side, perhaps the most significant flow of non-renewables goes into chemical fertilisers. One of the big three nutrients supplied is phosphorous. Phosphorus is mined from deposits of phosphate rock in certain parts of the world and, just like oil, it’s approaching its peak: quite soon world production will be unable to keep up with demand. Nitrogen is required in even greater amounts than phosphorous and it’s extracted from the air by a process which uses a huge amount of fossil fuel energy. As energy prices have risen during the past decade, farmers have seen fertiliser prices more than double. This is just the beginning.
Organic farmers tackle these problems by crop rotation, which here in Britain usually means alternating a few years of cereals with a few years of mixed grass and clover, which is grazed by cattle and sheep. This reduces erosion, though it doesn’t do away with it, and nitrogen is provided by the clover, which ‘fixes’ it from the atmosphere. The downside is that organic farmers only grow cereals on part of the farm at any one time. The temporary grassland does produce human food in the form of meat and milk but this amounts to much less food per hectare than the cereals. This, more than the lower yield of organic cereals per se, reduces the yield of organic farms compared to conventional ones which don’t practise rotation.
Permaculture goes a step beyond this by growing a mix of clover and cereals in the same field at the same time. This is known as bicropping. It enables a cereal, or some other crop for direct human consumption, to be grown every year. The yield of cereal is potentially little lower than it would be if the clover wasn’t there and there’s a modest yield of clover as animal feed.
The clover is present as a permanent understorey, so there’s never any bare soil and thus erosion is eliminated. The permanent ground cover and lack of ploughing also makes ideal habitat for certain fungi, which, in a symbiotic trade-off for organic food, provide the crop plants with phosphorous. Meanwhile the clover provides the nitrogen right where and when it’s needed. There are also positive effects on weeds, pests, diseases and fuel use.1
One factor which helps the bicrop work is the difference in growth pattern of the two plants. The tall cereal and low clover make two distinct levels of vegetation and this reduces competition between the two. We call this stacking.
The most striking form of stacking is agroforestry, in which tree crops are mixed with herbaceous crops, which can include cereals, vegetables or grassland. A traditional orchard of apple trees and pasture is an example. The difference in height between the two elements means that there’s minimal competition between them. In fact when the trees are still young there’s no loss of yield in the herbaceous layer at all.
The annual cycles of the two components are also different. Take for example the combination of wheat and walnuts. The wheat is sown in the autumn and makes much of its growth then and again in the spring before the walnut trees come into leaf. At the other end of the season the walnuts stay in leaf a good two months after the wheat has turned from green to gold. It’s those green leaves which produce food and they’re present for much more of the year in the mixture than they are where either crop is grown alone.