Agriculture, yield, and food supply (quantity and quality).

In 2010, agriculture covered 4.9 billion ha (with 3.64 billion ha of pastureland and 0.46 billion ha of cereal cropped land). 9 classes of land quality have been defined, with classes 1 to 6 covering but 45% of total agricultural land area. Classes 7-9 are poor marginal land, unsuitable for agriculture. Productivity in major cereal yield varies by a factor 6 between class 1 and class 6 land types [1].
Average global crop yields increased by 20% between 1985 and 2005, as compared to 56% between 1965 and 1985, indicating that yields are now rising less quickly than before.
Agricultural intensification has been responsible for most of the yield increases of the past 50 years : world’s irrigated cropland area roughly doubled, while global fertilizer use increased by 500% (over 800% for nitrogen alone), increased energy use, and widespread pollution and water degradation [2].

Global production in major crops amounting above 100 million tons per year (2007 data, [3-4]) is given below :

• maize – 791.7 (average yield, 5 tons/ha)
• rice – 659.5 (average yield, 4,2 tons/ha)
• wheat – 605.9 (average yield, 2,8 tons/ha)
• potatoes – 309.3
• soybean – 220.5
• cassava – 214.5
• oil palm – 192.6
• barley – 133.4
• tomatoes – 129.9
• bananas - 119.8
• oranges, clementines, lemons - 104.3
  For comparison,
• world algal biomass yield – 15

World global cereal production in 2011 is forecasted to reach 2,307 million tons, 3% higher than in 2010, but slightly lower that in 2007 (2351 million tons). Predicted demands make production need estimates of 3200 and 4000 million tons for 2025 and 2050, respectively [5].
World cereal trade is forecasted to register an increase in 2011/12 with a sharp jump in wheat trade offsetting a decline in coarse grains, while rice is likely to remain unchanged [6].

Food security / insecurity :

“a situation that exists when all people, at all times, have physical, social and economic access to sufficient, safe and nutritious food that meets their dietary needs and food preferences for an active and healthy life” (World food summit 1996). It rests on 3 pillars : food availability, access and utilization [7]. It is measured in daily calories per person.

Food supply quantity, in kg/capita/year. Figures for kg/capita/year are reached at by multiplying grams/capita/day by 365 and dividing by 1000.

Food supply in kilocalories/capita/day.

Protein and fat supply quantities are in grams/capita/day [3].
.

2007 data Food supply quantity

• (kg/capita/year) Food supply
• (kcal/capita/day) Protein & fat supply
  (g/capita/day)
• World vegetables 119.53 79 4
• World cereals
  (excluding beer) 146.70 1290 32
• World oilcrops 6.91 53 2.6
• World alcoholic beverages 37.33 70 0.36
• Total - our calculation 310 1492 39

Feed conversion :

In animal husbandry, feed conversion ratio (FCR), feed conversion rate, or feed conversion efficiency (FCE), is a measure of an animal’s efficiency in converting feed mass into increased body mass.
The ratio of the kg of feed needed to produce one kg of life weight (body mass). Examples are : Milk 0.7, Carp 1.5, Egg 3.8, Chicken 2.3, Pork 5.8, Beef 12.7. Only part of the life weight is edible [8-9].