▼翻訳は下 232 SECRETS OF THE SOIL engine wear. Cars in the Indianapolis 500 use 40 to 75 percent alcohol in their engines， and the world's speedboat record was made with 100 per-cent alcohol fuel. That the petrochemical companies， now faced with imminent deple-tion of their oil reserves， may be looking to control the source of biomass is evident from the manipulation of farmers into debt and expropriation by foreclosure. A straw in the windy politics of the nation's capital was seized by Vice-President George Bush as he girded himself to carry the chemical banner into the presidential race of 1988. In Chemical Market-ing Reporter of August 10， 1987， he was quoted as touting ethanol and methanol as a step toward "energy independence， less smog in cities， and more American jobs." Already in 1983 Duke was commissioned by the Northern Agricul-tural Energy Center of the USDA in Peoria， Illinois， to prepare an un-biased comparison of two hundred of the more promising renewable energy species of plants. Included， along with such common energy grasses as sugar cane and the all-too-familiar oilseed， the peanut， were more exotic specimens such as the "petroleum plant，" euphorbia， and the "gopher" plant， whose milk， according to Nobel Laureate Melvin Calvin， can produce fifty barrels of oil per acre per year; and diesel trees like the huge copaifera， which bleeds like a rubber tree to give fifty barrels of diesel per acre per year; and the kerosene tree， sindora， another large tropical tree， which is bled for its resin; and petroleum nuts like pitto-sporum， a fast-growing tropical legume tree grown for firewood to bum for electricity; and the fast-growing fuel-wood species like leucaena， the Philippine tree from whose fruit kerosene is readily derived. In Hawaii， says Duke， it is economically feasible to produce electricity from leucaena. In the Philippines Pittosporum resineferum bushes could satisfy the kerosene needs of every Philippine family. Four percent of Panama planted to leucaena could satisfy Panama's energy require-ments. And Duke points out that all of U.S. petroleum requirements could be satisfied with the hydrocarbons derived from planting acreage the size of Arizona with the "petroleum" plant， euphorbia， commonly known as "spurge，" a shrubby plant with a bitter milky juice that survives in arid areas. Then there is the family of oil palms， considered the third among.the plant families important to man after legumes and grasses. They produce quantities of oil， and can grow very well on marginal， or even desertified， land. According to the Office of Technological Assessment (1984)， about two billion hectares of tropical lands are in various stages of degradation， a wasted potential asset. Technologically improving such degraded lands
with sewage sludge and planting energy trees would offer an organic solution that would lead to higher productivity of energy sources while temporarily but vitally tying up CO2. Tropical countries， especially humid countries， with few or no fossil fuels， bankrupt by high energy costs and hungry for energy alternatives， must， says Duke， look to what natural resources they have at hand. For the Third World， he suggests a variety of palm ，oils that could make many of those countries self-sufficient in fuel. Much degraded land requires expensive irrigation and desalinization， but the nypa， a palm of southeast Asian mangrove swamps， grows even where it is inundated once or twice a day with saline tides. The nypa can give two to three times as much alcohol per hectare as sugar cane; and the Philippines alone have 400，000 hectares suitable for nypa production. Upgrading the OTA's two billion degraded hectares to give twenty-five barrels of oil per hectare per year， could， said Duke， reading from one of his serious papers， facetiously entitled "Reading Palms into the Future，" produce the required fuel to run the world. "OPEC，" he added with a smile， "might become an acronym for Oil Palm Exporting Coun-tries. Oil palm trees， representing a standing biomass of about ten to one hundred metric tons per hectare， would meanwhile tie up a lot of CO2 in previously unproductive land that tied up very little." The babassu tree (Orbignya barbosiana Burnet) is reported by OTA to yield more than a ton of fruit per year. During World War II liquid fuels were derived from the babassu; they burned easily and cleanly in diesel engines. Residues were converted to coke and charcoal. In Brazil nearly 100，000 people are employed on 15 million swampy hectares described as "probably the largest vegetable oil industry in the world." It is wholly dependent on wild plants， developed from an indigenous cottage indus-try， capable of further expansion. Of the fruit， 10 percent is kernel， 50 percent of which is oil， indicating a yield of about forty kilograms of oil per tree， or a barrel for every four trees. Ironically， Brazil， a leader in developing alcohol from energy crops， producing a billion gallons of alcohol a year， mostly from sugar cane， is obliged to import diesel fuel. Yet it is admirably suited to producing diesel from palms that have twice the energy content of sugar cane， and are casier to grow. Duke is convinced that the oil palm (Elaeis guineensis) can outyield other varieties， such as those in the Aleurites and Sapium genera to produce ten to sixty barrels of oil per hectare per year， renewable yearly. Transesterified palm oil is an excellent substitute for diesel fuel， with a r lower polluting effect.* • A chemical term for converting an organic ester into another ester of that same acid.
Clement and Mora Urpi (1984) suggest that Bactris gasipaes may yield four times as much fruit as the date palm， or 11 to 30 metric tons per hectare， with up to 55 possible. Its oil yield might be as high as that of oil palms， with a more nutritious residue. They speak of a yield of from 35 to 105 barrels of oil per hectare per year， renewable. Malaysia， presently at the forefront of palm-oil production， has twenty-four-hour pipelines relaying palm oil from the interior to the coast. To supply the whole world's requirements in fuel oil would take two billion hectares of palm oil. But if it were possible to double the yield through biotechnology such as developed by Steiner， Carlson， and oth-ers， that acreage could be halved. By OTA figures there are 4.8 billion hectares of land in the tropics， of which only 1.8 are in forest， leaving 3 billion to develop for energy plantations. To increase their potential， Duke suggests screening clone tissue cultures for increased tolerances to aluminum， cold， drought， salt， and salt-water irrigation. Opting for a green world instead of a greenhouse， Duke points out that anywhere on the planet we can increase the rate of photosynthesis to sop up CO2 to make simple and complex sugars we can decrease the magnitude of the greenhouse effect， a solution simpler， cheaper， and more practical than some of the farfetched and expensive suggestions of worried climatologists. A hectare of leucaena can fix 25 metric tons of CO2 per year， or 2，500 metric tons per square kilometer， up to maturity when the trees slow down almost to a stop. Balick and Gershoff (1981) mention another palm species also found in Latin American swamplands， and in upland forests: Jessenia baua. It is a rich source of both food and oil， and could tie up plenty of CO2 in marginal swampy land. It should take only a million square kilometers or 100 million hectares of leucaena to soak up the 2.5 billion tons of CO2 we put into the air each year. And if all the leucaena was harvested to give energy (instead of our burning fossil fuel) the effect would be doubled. CO2 could be stopped in its tracks. But Duke warns that palms are presently an endangered species， their fragile family disappearing about as fast as the energy resources they could help replace. He urges concerted effort to analyze all palms for their economic potential， while they are still around. "Then there's conservation. A good half of the energy this nation uses—more fuel than is consumed by two-thirds of the world's popula-tion—could be saved through conservation， which alone could decrease the U.S. contribution to the greenhouse effect by 50 percent， denting the world total by one-third." Each North American consumes about 2，900 gallons of fuel oil equiv-alent per year，. or nearly 70 barrels per capita， 17 percent of which goes for producing food， whereas the world mean is only about 11 barrels.
Americans use much more energy to produce， process， retail， and pre-pare food than there is energy in the food produced. And each year the average American consumes about as much wood in the form of paper as people in the Third World use to cook their food. It takes as much as 300 gallons of oil per acre to cultivate land in America. Ninety percent of all grains， including corn， grown in the U.S. goes to livestock to provide the animal protein that Americans crave， or have been maneuvered into craving. A meat-centered dish is the most resource-expensive of all diets. An American steer eats twenty-one pounds of plant protein to produce only one pound of protein in steak. A stunning twenty-five thousand calories of energy are expended for every thousand calories of beef protein produced， which only goes to putrefaction in the human gut. If America were to take the presently unpalatable step of going vegetarian， says Duke， all that grain could be saved for energy production， resolving the energy crisis and greatly im-proving the health and energy of humans. As John Robbins points out， 1.3 billion human beings could be fed on the grain and soybeans eaten by U.S. livestock. And if the U.S. population were to reduce its intake of meat by a mere 10 percent， they could adequately feed the 60 million people who starve to death in a year worldwide. Energy conservation， says Duke， does not require the curtailment of vital services; it merely requires the curtailment of waste. Often a dollar invested in energy conservation makes more net energy available than a dollar invested in developing new energy resources. Thirty to 50 percent of the operating energy in most existing buildings could be conserved， and 50 to 80 percent could be saved in new buildings. Duke makes several encouraging suggestions for improving the coun-try's future， many already popular with organic gardeners: planting gar-dens on rooftops; developing two- and three-tiered forest ecosystems in lieu of monocultured orchards; developing desirable vines to climb over houses during summer to function as natural air-conditioners， conserv-ing energy and cutting down on CO2; filling every window with culinary herbs or ornamental plants. But， like Hamaker， his prime suggestion is to keep planting trees; he suggests the addition of fast-growing species to the existing slow-growing ones. At the present rate， an acre of trees disappears from the United States every five seconds. A firewood farm that generates fifty metric tons per hectare per year instead of twenty-five will tie up twice as much CO2. Fallen firewood in the forest， harvested and burned instead of fossil fuel， frees up more space for green plants. And Duke recommends using living fence posts as practiced throughout Latin America—instead of energy-consuming instal-electric fences. Richard Saint Barbe Baker， the English forester who pioneered the movement to save California's redwoods， and whose bioethic philosophy led to the planting of an estimated 26 billion trees around the world， proclaimed that man's existence depends as much on trees as it does on plants， and that trees are as essential to agriculture as to breathing. The minimum for safety， he insisted， is tree cover encompassing a third of the total land area of the planet， a ratio we have imperiled to the point that we are losing an acre of rain forest every second. Saint Barbe， as he was familiarly called， discovered that in an agri-cultural area if he devoted 22 percent of the surface continuously to trees he could double the crop output of the contiguous cleared area.
Trees create microclimates in which crops flourish; they reduce the speed of wind， lift the water table， feed an increased population of worms. A single eucalyptus tree， forty-five feet tall， will transpire over eighty gallons of water a day， and a willow can transpire five thousand. Only .2.8 percent of the world's land is fertile enough to grow wheat indefinitely without the assistance of trees. In England， one field that has raised wheat continuously for a hundred years is surrounded by oaks whose roots go deep， tapping minerals to feed its leaves. When the leaves have served their function， they fall to earth and rot. Surfacing worms carry down their residue overnight to replenish the soil with essential trace elements. And yet， for decades， the trend has been to fell trees and plant pasture， which rapidly erodes， further imperiling life， as nature's long-term wisdom is sacrificed to man's short-term gain. Saint Barbe and others have cajoled thousands of men and women into planting millions of trees， and have pleaded that millions more can， and must be， planted. One of the adherents of his world-wide "Men of the Trees" movement， Charles Peaty， after a lifetime spent creating， managing， and harvesting forests in Europe， decided to do something about reforesting man-made wastes of western Australia， which less than a century ago were covered with hardwood forests of timber and shrubs that each year sprang into a blaze of colored flowers across the entire countryside. When farmers cleared this land， a thin layer of topsoil was swept away in a single generation by cyclonic winds and downpouring rain. The fertilizer-laden runoff accumulated in creeks and rivers to turn them into salt bogs， while the trees that had flourished along their banks turned into matchwood. To create new tree stands and shelter belts Peaty in vented a special method of planting trees in desert country， with mini• ma!， even no， watering. Over the past six years he has planted on treeleit farm acreage millions of specimens of false mahogany， Bald Island mars lock， blue mallet， flat-topped yate， wandoo， cypress， two kinds of acacia， eleven varieties of eucalyptus and casuarina trees， one of the world's