For a complete inventory of agricultural production today and so a conservative estimate or benchmark for future production, I turn to the thorough inventory of agricultural production published by the FAO and tabulated in Table A-1 in Appendix A. I convert the diverse products into common currencies, calories, and protein. I summarize the calories and protein in five classes (exemplified): (1) crops generally eaten by people (wheat); (2) coarse or feed grains (corn); (3) other crops not commonly eaten or fed (rubber); (4) animal products (meat); (5) products consumed by draft animals (calories eaten by horses).
Although people do not eat the products in the third class, their caloric and protein contents surely provide a conservative estimate of the nutriments that replacement crops might produce on the same land. A change to a food crop on the same land would grow at least the same calories and protein as would the coffee or rubber, without taking land from Nature.
Calculations for the fifth class differ from those for the preceding classes. Instead of estimating the composition of draft animals, I estimate their consumption. It will surprise a Westerner that 139 million water buffaloes and 20 million camels work as draft animals, which consume much.
In 1910, the horses and mules of American farms and cities consumed feed grown on 36 million ha, an area 44% as great as that producing products for domestic use. The grain surplus of the 1930s has been attributed to the replacement of the animals with tractors and trucks (Hassebrook and Hegyes, 1989[HH89]; U.S. Department of Agriculture, 1962,[USDa] 537). Because U.S. farmers now draw plows with tractors burning diesel fuel and gasoline instead of with animals burning oats and hay and because others drive trucks and autos rather than wagons and buggies, millions of hectares today are spared for Nature. Likewise, future people may replace some of the millions of draft animals still used in other places. Then the feed that such animals would have eaten can become food to share with future people, lessening the demand for cropland and sparing more for Nature.
Figure 5.3.1. World agricultural production of calories and protein and consumption by draft animals. Calories or protein in each class are averages/day for each of ten billion people (Food and Agriculture Organization of the United Nations, 1992). (See Table A-1 in Appendix A of this report.)[FotUN]
Figure 5.3.1 translates the trillions of calories and thousands of tons of protein in the inventory tabulated in Table A-1 in Appendix A into comprehensible daily amounts for ten billion people. The figure also summarizes the diverse products into the five classes already described. The pairs of bars, the left for calories and the right for protein, show that the relative contributions of calories and protein are about the same in each class-except in the protein-rich animal products.
The first bar shows food crops like wheat and potatoes would supply about 1,800 cal and feed crops like maize and soybeans another 1,000 to each of the ten billion. Other agricultural products like coffee and rubber are neither food nor feed but could be replaced by different crops; the figure represents the food for ten billion this replacement might add by the calories and protein of the present other products.
The bar for animal products stands shorter than the bar for the feed crops that animals eat. The animal products contain about one-fifth the calories and one-half the protein of feed crops. The ratios of one-fifth and one-half exceed those for conversion of feed into, say, beef because animals graze as well as eat feed grains. The grazing animals add to the meat supply without subtracting from the grain. Further, animal products include both fish that feed in the ocean and poultry that convert feed to meat and eggs efficiently.
Surprisingly perhaps, the world's draft animals consume more than half as much nutriment as in the animal products eaten by people.
How can these categories be added? Obviously cropland produces the 2,856 cal of food, feed, and other crops. But what of the animal products? Because the animals eat more than feed crops, agriculture, if not cropland, must also be credited with some part of the animal calories. In the figure, the calories in products plus feed for draft animals are about half those in feed crops, whereas even efficient broilers only transform about one-fifth the calories they eat into meat. Also fish do not appear in the figure. I have adjusted for the calories in animal products, fish, and the diets of draft animals-roughly-by adding the 265 cal draft animals eat to the 2,856 in crops, bringing the total for the ten billion people to 3,122 cal.
The sum of 3,122 cal/day for ten billion exceeds recommended daily allowances, and it exceeds the 2,921 Japanese eat today. The same accounting adds to an ample 103 g protein/day for ten billion. This accounting of today's farming makes sustaining ten billion while sparing land for Nature conceivable.