What is the total tonnage of the world' s primary production
involved in agriculture ? Since no one has responded to this question, I
have attempted to estimate a value.
Plant harvest for use as food/feed (million MT) FAO 1991
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cereals 1890
root crops 570
pulses 60
citrus 77
sugar 111
coffee,cocoa
& tea 11
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TOTAL 2719 million MT
Recognizing that forages were not included in this list, I attempted to
convert the FAO total meat and milk tonnages into forage values using the
following ratios:
1 MT meat = 10MT forage (These are my own rough estimates)
1 MTmilk = 1 MT forage
total meat = 180.9 million MT
total milk = 513 million MT
Thus total forage production = 2300 million MT
New food/feed total = 5019 million MT
The FAO total aquatic harvest (plant&animal) for 1991 was 97 million MT
Not knowing how to differentiate between the plant and animal components, I
am going to arbitrarily multiply this value by 5+ to establish a total of
500 million MT of aquatic plant production.
New food/feed total = 5500 million MT
Non food agricultural plant harvest (million MT)
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wood 3700
fiber 23
tobbaco 8
rubber 5
veg. oils 210
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TOTAL 3946
Thus the TOTAL AGRICULTURAL HARVEST for 1991 = 9500 million MT
What would the dry matter tonnage be ?
How much unharvested residue was produced ?
So back to the original question, how much primary production is involved in
agriculture ?
A few random facts I came across in looking up this info...
Total U.S. annual corn harvest = 7-8 billion bushels
400 million bushels converted to ethanol (1991) i.e. 5 % of total
5 billion lbs of U.S. corn starch used for non-food purposes (1991)
According to "An intro to Ag. Geography" by Grigg (1984)
90% of U.S. farm production is used for food purposes
93% of total farm land produces food
15% of total energy used by man comes from biomass (1991)
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Total primary production on earth = 164,000 million MT dry matter/year*
What portion of this can be sustainably manipulated by man ?
How should we budget our utilization of the earth's primary production ?
* R. H. Whittaker, 1970