Agriculture Reference
In-Depth Information
crop of acorns about one year in three, whereas further south in Europe they 'abound in
most years, and pigs (and occasionally men) may depend on them.' 10 According to Oliver
Rackham, that was why pannage, the grazing of pigs in woodlands, was never as wide-
spread in Britain as it was on the continent. 11
Whitefield pins his hopes on breeding new varieties that will fare better in the British
Isles, and this is not unreasonable. Colin Tudge reports that 'breeders at Oxford University
are now seeking to create varieties [of walnuts] that really can tolerate our decreasingly
harsh, but increasingly fickle climate.' 12 But the most promising experiments in nut cul-
tivation in the UK are being carried out by Martin Crawford of the Agroforestry Research
Trust on land at Dartington in south Devon. Crawford has reported yields from his top vari-
eties of trees equivalent to three tonnes of walnuts per hectare, or 1.35 tonnes of edible
kernels. This is less than two thirds the weight of soybeans that can be obtained from a
hectare, but with a 60 per cent fat content this quantity would yield more oil than a hectare
of soybeans, though less protein. The yield for hulled hazelnuts (after Crawford succeeded
in controlling squirrels through the use of live traps) was about 1.1 tonnes. 13 The timber
yield is negligible because these are low bushy trees, but productivity can be enhanced by
feeding animals on the grass growing between the rows.
These yields, if they can be replicated on a wide scale, suggest that there could be a vi-
able role for walnuts and hazelnuts grown in the South of England as a source of strong
tasting oil and as an alternative for meat. 1.35 tonnes of walnuts probably has a higher nu-
tritional value than the 1.6 tonnes of pork you could get by feeding a hectare of high yield-
ing grain to pigs at a conversion ratio of 5:1. And this high pork yield cannot be achieved
by organic cultivation, whereas Crawford's system is organic, with 30 per cent of the crop-
ping area put over to fertility building plants, which can be grazed by animals.
The results for chestnuts are less convincing. Crawford gets the equivalent of five tonnes
of chestnuts per hectare off his best varieties, which is a respectable yield compared to the
international figures given above. The nutritional value of chestnuts is too low for them to
provide a satisfactory substitute for meat, but with roughly twice as many calories as pota-
toes, and about the same protein content, chestnuts can serve as a staple. However, five
tonnes per hectare is only one fifth the average UK yield for organic potatoes, which means
that a hectare of potatoes produces over twice as much energy as chestnuts, and five times
as much protein. Similarly a four tonnes per hectare yield of organic wheat would produce
over 1.5 times as many calories and more than four times as much protein as chestnuts. 14
My own reaction to the proposal to develop chestnuts as a staple is coloured by what I
witnessed when for a few months I lived in the remnants of what must be the most northerly
agricultural economy founded upon a tree-sourced staple in Western Europe. The moun-
tains around the southern French town of St Pons (and a number of other areas in France,
Spain and Italy) hosted, until the early 20th century, an agricultural economy whose main
 
 
 
 
 
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