The Azimuth Project
Agriculture (changes)

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Agriculture is responsible for substantial greenhouse gas emissions. The following provides some details about the UK:

Agricultural food production is responsible for just under 10% of total UK GHG emissions – about 63.4 MtCO2e in 2010 (DECC, 2012). Figure 3.25 shows a breakdown of all emissions associated with agriculture.Currently in the UK, about 31% of GHG emissions relating to the agricultural sector come from methane (CH4). Nitrous oxide (N2O) emissions,however, are the largest source of GHG emissions from UK agriculture (42%). Both methane and nitrous oxide are much more powerful GHGs than carbon dioxide (CO2) (ibid.). The proportion of non-CO2 emissions in agriculture is unusually high when compared to other sectors. And they can beharder to reduce, as they originate mainly from biological rather than technological sources, plus pressure is on the food system to keep producing high yields (larger amounts of food on smaller amounts of land).

(p84, Zero carbon Britain 2030)

Agriculture and diet are of course closely linked.

World

Summing the statistics giving at the Worldbank the agrarable land in the world is around 2000 m^2 per person.

Germany

According to Atsuko Wakamiya in the magazine Oekologie &Landbau Nr. 159, Ausgabe 3/2011: Wie viel Fläche braucht ein Mensch um sich zu ernähren? (in german) the current average food consumption of a German needs around 2500 m2 if one uses organic farming practices. Germans however consume a lot of meat. A projection given in the same article suggests that a diet with less meat may make a smaller use of arable land possible. In the article the corresponding land area is projected at 1081 m^2. The article gives unfortunately no overview on the land use for a strictly vegetarian diet, i.e. it is not clear wether this land use would be smaller, since the protein supply of a human, who is on average more involved in brain work than in physical work may eventually be higher, but eventually here only certain types of proteins (or eventually also other nutrients) are important, important. Moreover substitutions like certain tea’s might be area consuming etc. (this is only a speculation sofar…get some physicians here to comment on).

The initiative http://www.2000m2.eu/ tries to initiate europe-wide hands-on experiences to test how much crops can be grown on 2000 m^2 of arable land (while observing nutritional requirements) and how the corresponding food is perceived by test persons. A first prototype field which is projected to be tested in 2015 is currently located at the Havelmathen close to Berlin.

United Kingdom

The following nutrition data from http://ndb.nal.usda.gov/ndb/foods. All figure are per 100g.

FoodEnergyProteinFat
Potatoes105kcal2.44g0.10g
Oats389kcal16.89g6.90g
Canola884kcal0.00g100.00g

Notes. The potatoes are microwaved, cooked in skin, flesh and skin, without salt. Potato protein is high quality. Oat protein is also high quality. Canola is rapeseed oil.

It was harder to get info for yields. The figure for oats may be misleading: it is not clear exactly what is being weighed.

So

  • 100m2 of potatoes yields 0.01*42000/365 = 1.15 kg/day
  • 150m2 of oats yields 0.015*3500/365 = 0.144 kg/day
  • 250m2 of rapeseed yields 0.025*1280/365 = 0.087 kg/day

providing

  • Energy 11.5*105 + 1.44*389 + 0.87*884 = 2540 kcal/day
  • Protein 11.5*2.44 + 1.44*16.89 + 0.87*0 = 52 g/day
  • Fat 11.5*0.10 + 1.44*6.90 + 0.87*100 = 98 g/day

from 500m2. These are a little above the recommended daily allowances. Obviously some vitamins and minerals are missing, but it seems surprising that porridge and chips is such a good basis.