Agriculture Reference
In-Depth Information
• One hectare of arable feeds 20 people
TABLE D: ORGANIC VEGAN
• 7.3 million hectares arable
• 11.2 million spare hectares
Population 60.6 million. Agricultural land 18.5 million ha. Forestry etc 3.69 million ha.
• One hectare of arable feeds 8 people
Vegan Organic: Reliance on Green Manure
In Tables D and E I have again updated Mellanby's diet to 2005, but this time for or-
ganic husbandry. Both these organic diets, vegan and livestock, take more land than their
chemical counterparts. This is partly because average grain yields obtained by organic ag-
riculture today in Britain are less than 60 per cent of those obtained by chemical farmers;
in fact organic wheat yields today are similar to those of chemical agriculture in 1975.
But lower yields are only half the problem. To obtain yields above a bare minimum of
around 750 kg of grain per hectare, land has to be fed with extra nitrogen. Organic systems
by definition do not use synthetic fertilizer, so nitrogen is either imported from other land
where it is not required, usually in the form of animal manure; or obtained by inserting in-
to the rotation a crop of leguminous plants such as beans, clover or lucerne, which extract
nitrogen from the atmosphere. A dedicated crop of legumes, which is not fed to humans
or animals, but ploughed in to provide fertility, is called a green manure. Green manures
which occupy the ground for a whole season lower the yield from each hectare still further.
