AFTER 10,000 YEARS

In all the discussions about oil, gasoline, coal and nuclear power, there tends to be one kind of energy that is often overlooked: the food we eat, which supplies the energy for muscle power and thought.

But for all the combines, fertilizers and other means of high-yield agriculture, the basic method of food production has not substantially changed for the last 10,000 years. Science has-not yet discovered the cow's secret of turning grass into milk, nor even the secret of a plant's chlorophyl, which uses solar energy to turn carbon dioxide and water into edible carbohydrates.

Half a million square miles of agricultural land in the US provides only 1% of the energy consumed by its inhabitants. And much energy is needed to produce it that way: 80 gallons of gasoline for an acre of corn, for example.

But after 10,000 years, there is a change in the offing. Not a very big one, but one that may bypass the use of land in protein production. Instead of feeding fertilizers to the soil, say scientists of British Petroleum and other companies in a rapidly growing industry, feed petroleum fractions to animals directly. Only the animals are not cows, they are microbes and bacteria that turn petroleum products into high protein edible yeasts edible for cattle, that is.

This type of protein has now been tested on various animals and found both safe and nutritious, a unit of weight containing up to 66% of the protein in standard protein feed such as fishmeal, and more amino acids to boot. Industrial plants producing such proteins biologically are expected to spring up soon next to petroleum refineries. Scientists are also working on petroleum derived food supplements for human consumption.

Not very appetizing? But the active ingredient in the yeast for our daily bread is made up of bacteria. And microbes have been at work all along in getting nitrogen from the air into the soil, which is made even more fertile by petroleum-derived fertilizers. Unless it is cultivated by an organic gardener, who prefers to get the nitrates and phosphates into the soil by urinating on it. Is that more appetizing?