Maximizing Yields in the Tropical Moist Forest Biome

Home , Hydrocarbon plant, Tropical desert

Chapter XII The Gene Revolution: Maximizing Yields in the Tropical Moist Forest Biome

James A. Duke U.S. Department of Agriculture

Beltsville, MD 20705 Contents

Page Abstract ...... 227 Introduction ...... 227 Economic Botany Laboratory ...,...... 229 The Quest for Tolerant Germplasm ...... 230 Intercropping ...... 230 Legumes. ., ...... 231 Azolla as Fertilizer. , ...... ,....., ...... 232 Heat or Meat...... 233 Wood ...... 233 Sewage ...... 234 Oil Seeds ...... 235 Allelopathy ...... 236 Drug Crops ...... 236 Essential Oil ...... 237 Fiber Crops ...... 237 Gums, Resins, and Balsams ...... 237 Rubber ...... 238 Wax Crops. ., ...... ,..., ...... 238 Weeds ...... 239 Tropical Moist Forest Biomass ...... 239 References, . . . ., ...... ,, ,...., ...... ,, ...... 242 Appendix A–Magic Mountain: 2000 AD ...... ,. 243 List of Tables Table No. Page l. Estimates of Net Primary Production in Tropical Forests...... , ...... 240 2. Tropical Root Crops, .....,, ,, .,..,, ., . . . , , , ..., , , , ., ...... 240 3, Tropical Vegetables ...... 240 4. Tropical Spices, ...... 241 5. Net Primary Productivity . . .+.,...... ,+...... 241 Chapter XII The Gene Revolution: Maximizing Yields in the Tropical Moist Forest Biome

It is the skills of plant geneticists, rather than record after another in crop yields in , . . both large amounts of artificial additives such as temperate and tropical zones (Norman Meyers, pesticides and fertilizers, that have led to one The Sinking Art, 1980).

Should there be a Gene Revolution, based on clude small-scale biomass- and alcohol-fueled low-input multiuse extensive agroecosystems, and solar plant-extraction equipment, as well to supplant the Green Revolution, based on as fermentation and distilling apparatus, de- high input intensive agriculture? Genes best signed to run on some of the products of the adapted to the marginal environments found agroecosystem. In summary, the Gene Revo- in the humid tropics should be pooled, com- lution should be directed toward a multitiered, bined, and recombined to produce moderate- multiuse, polygenic, low-input agroecosystem, yielding, well-adapted, multipurpose species. fueled and fertilized from within. The Gene These gene combinations and recombination Revolution should pull together the five major should be tested, not for their yields in mono- ingredients important in marginal environ- cultural situations, but in well-planned, multi- ments: 1) tolerant germplasm, 2) multiple and tiered intercropped agroecosystems. intercropping scenarios, 3) organic gardening (recycling animal and plant residues), 4) bio- The search for appropriate genes can be logical control of pests (including allelopathy), scientifically directed by a computerized cat- and 5) whole plant fractionation and utilization alog of the varieties, cultivars, and species of for such integrated agroecosystems. Such sys- potentially economic native and introduced tems should be developed from existing farms, species. Technologies that would be part of not from the forests. such a multiple-use agroecosystem would in-

INTRODUCTION

... Plant germplasm can be selected and su- long periods without a high level of inputs. But perior cultivars developed on the basis of their such inputs are rarely affordable to develop- adaptation to problem soils. Although we have ing tropical countries. If these countries can- moved slowly to capitalize on this information, not afford the inputs required for high-level it offers great promise in reducing energy in- production of conventional food crops, per- puts and improving the reliability of crop haps they should aim instead for a moderate yields in both developed and developing countries (A. A. Hanson, 1976). production of nonconventional crops with moderate inputs. The Green Revolution, which The highly weathered soils of the humid trop- called for maximum inputs, has pretty well run ics will rarely support conventional crops for its course, maximizing productivity where high

227 228 inputs are possible. It is time for the Gene Rev- for biomass and chemurgic crops, not food olution, to tailor existing plant types to max- crops. imize output with minimal input. The genes exist in nature, but they are disappearing fast. It In this talk, I will try to respond to the cen- is up to the Gene Revolutionists to get the genes tral issue: the highly weathered soils of the hot, together in the most meaningful manner, to wet tropics. These soils are rich in aluminum, maximize productivity under various low in- silica, and iron, and poor in the common plant put scenarios. nutrients. What could USDA’s Economic Botany Laboratory (EBL) do to improve “bio- With the end of the cheap energy era, devel- logical productivity of such soils without using oped and developing countries must reassess much or any chemical fertilizer?” That is the their imports and exports, their agricultural in- charge put to me by the Office of Technology puts and outputs, and their needs, often with Assessment. Let’s analyze that a bit before pro- a view toward substituting botanochemical ceeding. Is it rare that we can improve natu- fibers, fuels, and pharmaceuticals for those ral biological productivity? Nature does a good derived from petrochemicals. job maximizing biological productivity under Energy-hungry developing countries should nature’s constraints. If I compared produc- closely watch developments at the Northern tivity, I would only be comparing usable with Regional Research Laboratory in Peoria, Il- total productivity. And if we are talking about linois. If the botanochemical approach is prac- the maximum Usability Concept, then we are tical today or tomorrow in an energy-rich coun- not talking conventional agriculture at all. try like the United States, then it will be all the more practical in the energy-poor countries of Before laying out my plans for any country, the humid tropics because: I would analyze their import tables, especially the energy columns. Then I would plan a 1. Natural (and agricultural) productivity per multitiered agroecosystem that would max- unit area is higher in tropical than tem- imize benefits to the countries, import-export perate zones, other things being equal. situation, seeking the best genes to maximize Hence, there should be much more bio- output for a modicum of inputs, under the mass for a total-utilization scheme. The ecological conditions prevailing. Geneticists Gene Revolutionist is charged with find- could maximize the yields while American ing the best genes and combining them in technology could maximize the extraction of the best plants for maximizing output in useful products from the total yield. the marginal low-input farm scenario. 2. The diversity of useful species on which Humid tropics has been variously defined. to draw for our total-utilization concept is Most of my examples relate to what is called perhaps 10 times as high in the Tropics as the Tropical Moist Forest (TMF), where annual in the temperate zone. Hence, the array of biotemperatures are greater than 24° C and an- combinations for the recommended inter- nual rainfall is between 2,000 and 4,000 mm. cropping approach is staggeringly com- I have spent years in the Tropical Moist Forests plex. The multitiered, intercropping agro- of Latin America, and am still awed by the ecosystem being studied seems to be one diversity of economic products endemic to the of the most highly productive terrestrial area. There are even more exogenous eco- agroecosystems, competing with the highly nomic species from similar ecological zones productive aquatic ecosystems of the Trop- outside Latin America. Unlike others in this ics. Yields of either of these systems can workshop, I do not stress using native species, be improved vastly by the addition of ame- but I share the belief that we should not intro- liorated sewage sludge or other natural fer- duce exotics that are ill-adapted to an area. tilizers in lieu of artificial fertilizer inputs. EBL’s computer system helps find the right However, sewage sludge is recommended germplasm for a given tropical ecosystem. 229

Drawing on these tropical gene pools, the 3. Presence (acid soils) of free Mn, also toxic. Gene Revolutionist has perhaps more than 75 4. Fixation of phosphate percent of the world’s species to consider, per- 5. Deficiency of molybdenum, especially for haps 250,000 species. Each is a unique chemi- legumes. cal factory, manufacturing biomass that we 6. Fe and Mn toxicity shown by paddy rice. may need to draw upon as a source of energy. Such soils are said to occupy more than a bil- As the preface of the National Research Coun- lion hectares, more than 8 percent of the cil’s book, Conversion of Tropical Moist world’s soil. Forests, begins: “The tropical moist forest biome is biologically the richest, and least well There are those who say that conversion of known portion of the earth’s surface.” TMF to agriculture will lead only to the so- called “red desert. ” Ewel (8) says, however: Unfortunately, much of TMF is underlain by femalsols (strongly weathered soils of tropical The red desert view of mature tropical eco- regions, consisting mainly of kaolinite, quartz, system destruction is incorrect. Nature abhors and hydrated oxides, and having a low base ex- a vacuum, so sites laid bare by human activ- change capacity). Dudal (6) summarizes the ity are quickly covered by some kind of com- mineral stress phenomena in such soils: munity, although not usually the original one. We must face the fact that successional com- 1. Deficiency in bases (Ca, Mg, K) and in- munities are going to be the dominant tropi- capability to retain bases applied as fer- cal ecosystems of the future. tilizers or amendments. 2. Presence (pH < 5.2) of exchangeable Al, toxic to many species and active in bind- ing phosphates.

ECONOMIC BOTANY LABORATORY

I am still awed by the diversity of the Tropi- With careful expansion, such a data base cal Moist Forest. Working at the Economic could catalog information on ecology, utility, Botany Laboratory, I have begun to try to and yields of all economic plants, and guide organize the information pertinent to the Trop- the Gene Revolutionists in their search for the ical Moist Forest. There is already so much in- right genes or germplasm. Details of some strat- formation that we depend on computers to egies that should be employed in the quest of assimilate the information. We are primarily tolerant germplasm are explored in Duke (7). concerned with the medicinal plants of the Ecological data on more than 500 species suit- world, especially those with anticancer activ- able for exploitation in the Tropical Moist For- ity. secondly, we are concerned with catalog- est are tabulated. I will not relate all those data ing agronomic, ecological, geographical, and here, but will present a few examples. utilitarian information on economic plants of any description. From his studies alone, We know the conventional yield figures for Schultes (23) compiled a list of more than 1,300 only a fraction of tropical crops. Biomass or species employed by natives of the northwest residue figures are even rarer, although such Amazon as medicines, poisons, or narcotics. numbers are necessary for systems analysis of Our computer files already contain entries on the yield potential of a multiuse agroecosystern. more than 4,000 folk medicinal species, some According to Westlake (29), conversion factors of which double as food plants, fiber plants, range from 1.3 to 4.0 for estimating aerial dye plants, etc. We have yield data on some of biomass from conventional yield units. I called these, under various ecological regimes in the all the experts I could find, in vain, in my Tropical Moist Forest. search for the biomass figures for the temperate 230 lentil. Who would I call for such figures on the did not make a commitment to preserve their myriads of tropical products? The numbers do current forests, and concentrate on increasing not exist. “The accuracy of productivity meas- the productivity of current croplands. urements is the lowest for tropical areas. The Why should the remaining forests not be con- key to future refinement of our understanding verted into agroecosystems? If they are lost, the global productivity capacity lies, therefore, thousands of undescribed species will disap- in the study of tropical primary productivity” pear forever before they have been named. (16). If biomass is a viable competitor in the Thousands of others will disappear with no energy field, it is time pertinent numbers were studies of their economic potential. It is diffi- generated by baseline research program. cult to put a price on their heads. One in ten If I were Secretary of State, determining species studied shows anticancer activity; but what strings were tied to AID funds overseas, only about 15 of the first 30,000 species stud- I would see to it that funds went to carefully ied in our anticancer program are of sufficient distributed research plots in developing coun- interest to have reached preclinical testing. tries. These plots would be funded to generate Only one of those has resulted in thousands of the numbers needed to support Maximum Uti- remissions in cancer. This superstar, Catharan- lization Concepts. How much biomass can we thus roseus, the Madagascar periwinkle, is a grow and harvest under various scenarios? pantropical ornamental and folk medicine in Which scenario gives us the greatest net usable Tropical Moist and Dry Forests. There are returns? I would fund no studies that did not probably nine more superstars awaiting discov- give biomass yields related to climatic and ery (if they do not fall victim to the tropical edaphic data, and I would fund no country that axe). Can we afford to extinguish them?

THE QUEST FOR TOLERANT GERMPLASM

Elsewhere, I have advocated and outlined is cheaper to increase yields by finding a measures for seeking out the genes we need for cultivar that will tolerate the acidity, and its marginal environments in the Tropics (7). complications, than to increase the yields by Other research backs this idea: importing 6 tons of lime per acre. This is just the first step in the Gene Revolution. Incor- The correction of Al and Mn toxicities by liming is not always economically feasible, porating the appropriate genetically tailored especially Al toxicity in strongly acid subsoils. species, varieties, races, and cultivars in a However, plant species and varieties with spe- multitiered, multiple cropping system requires cies differ widely in their tolerance to both even further genetic selection, manipulation, factors, and some of these differences are and experimentation. genetically controlled (10,25). It is such differences we hope to capitalize on in the EBL Quest for Tolerant Germplasm. It

INTERCROPPING

Work on multitiered agroecosystems is pro- trees, are common. Thousands of combinations ceeding most rapidly in Asia, but temperate are possible in a tropical three-tiered system. systems are familiar to us all. Two-tiered sys- In one, pineapple was planted as the ground tems, with hay, legume, or cereal crops alter- crop, cocoa as the first story, and pepper as the nating or intercropped with rows of fruit or nut second story. Total harvestable crops and 231 residues from such systems usually exceed sig- small forest-enclosed plots probably attains nificantly the expected crops of the individual mycorrhizal homeostasis. Mycorrhizae seem species, had they been planted in monoculture. to minimize the expense to the host of seeking- Advocating agroecosystems that simulate the out minerals. Cultivation of annual crops may natural ecosystem it replaces Hart (12) says: lead to increased prominence of nonmycor- The replacement of weeds by analogous rhizal species and grasses in weed communi- crops and an increase in crop diversity will ties. Soil sterilization can eliminate mycor- usually reduce the amount of energy used by rhizal fungi, and fungicides used against weeds and pests. pathogens may adversely affect mycorrhizal fungi as well. Monoculture of crops that are Those systems of tropical forestry and agri- probably nonmycorrhizal, such as grain ama- culture that have been successfully employed ranths and chenopods, might markedly lower for the longest periods are those that favor the mycorrhizal fungus populations and jeopard- maintenance of large mycorrhizal fungus pop- ize subsequent mycotrophic crops (14). ulation. Traditional shifting agriculture in

LEGUMES

Even the nitrogen fixed by legumes is not The amount of N fixed by legumes varies of free. Under conventional farming, there is a course, but some of our economic legumes play price to pay for the nitrogen contribution of a larger role than making beans and fixing ni- the legume. In an unpublished paper, I pulled, trogen. According to Nigmator, et al. (1978), at random, biomass yields for pure stands of the cultivation of the legume licorice (Glycyr- C-4 grasses, C-3 grasses, and legumes. Though rhiza glabra) showed a marked ameliorative ef- relatively higher in nitrogen and protein, the fect on saline soil in Uzbekistan, Russia. The legumes yielded only half as much total bio- licorice, in pure stands, did not form a com- mass as the C-3 grasses, which in turn yielded plete soil cover during the first 1 to 2 years, but only about half as much total biomass as the this was achieved by sowing it in mixture with C-4 grasses. These are the biological costs (1) sudan grass, cowpea, and lablab. The mixture for nitrogen fixation and (2) excessive photo- decreased the evaporation and the rise of salts respiration. Although no one seems to have ac- to the upper soil layers. Haines, et al. (11), re- cepted my simple 1:2:4 ratio, I believe it. So ported that undersowing sycamore (Platanus called super-yield targets in the United States occidentals) with clovers and vetch in a dis- are 100 bushels of soybeans; the target for corn cultivated, z-year-old plantation suppressed is 400 bushels. weed growth to the point where height and vol- ume increments of the young trees were in- Appropriate combinations of legumes and creased significantly. grasses seem to give the best yields for forage or hay, and probably for maximum utilizable According to Felker (9): biomass under renewable situations where water is not the limiting factor. The C-4 grass Leguminous trees have a unique advantage might give highest yields for a while, but it over annual legumes in dealing with the in- seems doubtful that such yields would be sus- hibitory effect of drought stress on nitrogen tainable without the help of added N, be it from fixation because the deep-rooted leguminous trees may reach moisture, and thus relieve the legume, crop residues, manure (green or plant of water stress for a longer time in the brown), or sewage sludge. For high-quality leaf year than is possible with annuals. protein, the legume seems indispensable for most scenarios (without the sewage increment) An illustration of the ability of leguminous whether the protein is for animal food, human trees in semiarid climates to increase soil fer- food, or chemurgic use. tility more than annual legumes can be found 232 in West Africa, where yields of peanuts are in- with nitrogen fixation in blackberries. Becking creased if grown beneath Acacia albida trees. (z) assayed nitrogenase activity by acetylene reduction in detached Rubus ellipticus root The work on “teaching the grasses to fix ni- nodules. It was similar to that in several non- trogen” goes on, but does not generate as many legume N2 fixing nodules. The endophyte was headlines as in the past. Nitrogen-fixation is an actinomycete. being reported in more and more nonlegumes. Just this month, I noted an abstract dealing

AZOLLA AS FERTILIZER

While legumes are one source of fertilizer for that the advocates are willing to foot the bill our multitiered agroforestry units, tropical should these wonders become the major weed azollas might be another. Azolla, an aquatic of the 21st century. fern, is a source of nitrogen. Clark (5), review- I mention Azolla first because it is being ing Azolla use in China, notes that Azolla championed as a free fertilizer, one producing “seed” are started in nurseries, then the seed 150 MT of biomass, while increasing the yield ferns are introduced directly into rice paddies. of rice by I% times. These are the “facts” In some areas, two rows of rice are planted hailed by the advocates. Azolla pinnata can with the Azolla growing in larger rows on ei- double its biomass in 3 to 5 days, maybe 5 to ther side of the double rice rows. Yields of 15 10 days in the field. Some claim that Azolla will MT/ha of rice and 150 MT of Azolla have been suppress other weeds in rice, if not the rice reported for this simultaneous cultivation itself. Other reports indicate the Azolla can ei- method. Rice grown with conventional fer- ther prevent mosquitoes from laying their eggs tilizers averages only 10 MT/ha (5). No men- of their larvae from surfacing. Some say it re- tion is made of fish biomass harvested from leases nitrogen while alive, others only after such ecosystems. Could they also harvest 15 death. Vietnam reports 1 MT/ha N fixed per MT/ha catfish as have been reported from well- year; China 0.7 to 1.8 MT N (13). aerated Louisiana fishponds (21)? Grass carp (Ctenopharyngodon idella) and Tilapia mossam- But there is a weed potential lurking there. bica are said to relish azolla, which has also Weeds cost the United States about $16 billion been fed to cattle, chickens, ducks, and even in 1979. Would Azolla introduce increase has been suggested for human consumption. yields or would it clutter up more ponds than Typically, yields of grass carp are 10 times it helps. Responsible weed scientists as loudly higher in the Tropics (l,500 kg/ha) than in the and justly proclaim their fears as responsible temperate zone (164 kg/ha). forward-lookers champion this “free” fertilizer. There is no cut and dry answer. Unfortunately, we do not know that Clark’s On the negative side of the Azolla equation: 150 MT of Azolla is dry weight or wet weight; if dry weight, we have our fertilizer factory pro- ● In Japan, there have been complaints ducing biomass equivalent to some of the high- about Azolla covering the rice seedlings. est reported, while increasing the yields of the ● In the Philippines, Azolla is called a weed rice crop, almost incredible. Here let me point in rice. out serious conflicts facing USDA officials: ● In New Jersey, it has clogged up water there are potent advocates and opponents of channels to boat traffic. the introduction of many of the biomass ● In South Africa, farmers claim it killed wonders of the world (Acacia, Azolla, Leu- fish, prevented cattle from drinking the caena, Prosopis, etc.) and the opponents hope water, and clogged pipes. 233

MEAT OR MEAT

The Tropics may not face the heat or meat ing high fiber and/or vegetarian diets. In one, decision that temperate countries will face if 20 male subjects, none vegetarian or particu- there are no energy breakthroughs soon. Ac- larly sympathetic with vegetarianism, were fed cording to some estimates, more than 90 per- soy protein in lieu of meat protein. None suf- cent of U.S. cereals and legumes are destined fered from the soy as opposed to meat. On the for animal food. If Americans went vegetarian contrary, there were no significant changes in tomorrow, and quit exporting grain, more than the health of the subjects, at least by the stand- 95 percent of our agricultural biomass could ards investigated. From 40 to 50 percent of the go into ethanol production here. Some of us human subjects preferred each soy analog to would rather be warm and do without meat, its meat counterpart. than be cold and eat meat regularly; others Thanks to coal, America need not face the would say an emphatic “no.” According to heat or meat crisis immediately. Thanks to the Meyers (19), much TMF biomass goes into temperature of the humid tropics, the TMF cheap hamburger for the United States. Would might not face that choice either. But they it be better converted to fuel for the people of might need to decide whether their biomass the TMF? residues go into animal production or fuels for I have been a human guinea pig on three their machinery. human nutrition studies at USDA, all involv-

WOOD

Even today in the United States, wood is said MT/ha; SWF, 6 MT/ha; SDFA, 5 MT/ha; and to provide more energy than hydroelectric or Tropical Montane Rain Forest, 1 MT/ha. nuclear power. Wood is a valuable byproduct I do not advocate replacement of wood as a of the multitiered agroecosystem, and the Gene source of energy for cooking and heat in the Revolutionist should remember that in tailor- TMF. I do advocate the production of cheap ing species for TMF. wood-burning devices for distribution to the The growth rate of tropical weed trees char- poor. Most of the timbers of the Tropics go up acteristic of the humid lowlands are quite in smoke, much of it wasted. With energy- remarkable. I have measured naturally regen- conserving wood stoves, there would be more erated Trema micrantha in Costa Rica’s OSA biomass available for the production and dis- Peninsula, which were 9 m tall at one year, tillation of alcohol and other uses. and more than 30 m tall at 8 years. It is these fast-growing, low-density trees which will Liquid fuels for use in cars, trucks, and constitute the wood resource of the future as vehicles should be produced by all but the mature tropical forests are felled and regen- smallest farms in cheap mass-produced stills erate (8). provided by the technologically well-off, Ewel’s figures for 13-month-old regrowth in various life zones are TWF, 12 MT/ha; TDF, 10 234

SEWAGE

There is justifiable concern that maximum more building on the floodplains should be use will strip the soils of organic matter. If we permitted. These most fertile lands are being only use the above-ground biomass, we leave gobbled-up by suburban creep, here and the below-ground biomass. According to Van elsewhere. Dyne, et al. (28): I decry the cancellation of plans to barge Below-ground production is more than sludge to Haiti, because I believe sewage sludge twice above-ground in annual grasslands, but could play a big role in the greening of Haiti standing crops of biomass below-ground or the Sonoran or Negev deserts for that mat- maybe five to ten times as much as above- ter. We could concomitantly alleviate the short- -ground standing crops. age of water and organic matter in the desert, The humid tropics do not lack water like the with its low real-estate values, while alleviating arid tropics, but they do need organic fer- the waste disposal problem in the cities, with tilizers, especially if continuously harvested. their high real-estate values. Here I take the opportunity to introduce into Water-borne sludge could prove a boon to the the tropical scenario an idea that I think should humid tropics. If sewage sludge can double be exploited in the United States: piping yields in the humid tropics, the reverse pipe- sewage sludge out of the cities of the world and line could be shipping ethanol out, still leav- into energy farm areas. The pipeline routes ing a positive balance in organic matter in the could parallel proposed coal-slurry lines, nat- humid tropics. Once the pipelines were estab- ural gaslines, or petroleum pipelines. Oil shale lished, the sludge could be a free input, dou- mines, strip mines, any type of old mine site bling outputs. Hence, I see this untried concept could be partially or totally reclaimed or im- as one way to double the productivity of the proved with sludge-planted areas. The highest humid tropics, or treble the productivity of the biomass yield reports I find are from The arid tropics, with a free input. The excess wealth of India, where such yields as 160 MT/ yields could be devoted to production of al- ha for Pennisetum purpureum are reported for cohol, for internal or external energy use. fields irrigated with sewage. Westlake (29) reports unusually high yields even in the tem- Such an area might appropriately be called perate zone. With sewage irrigation and inter- an energy sump, and would not be an attrac- cropping, he reported DM yields of mixed tive place to live, but the products of the energy alfalfa-orchardgrass at 26 to 39 MT/ha, at least sump could make jobs there, and a higher five times greater than the expected yield of standard of living elsewhere. alfalfa alone, without sewage irrigation. This Here, as much as anywhere, the talents of the compares with 40 MT for Phragmites australis, Gene Revolutionists will be called into play. which Westlake describes as the most produc- The genes for maximizing productivity in the tive temperate community. energy sump will be very different from those City planners should adopt the Design With for maximizing productivity in the unaltered Nature Concept, building above the productive humid tropics. Planting, cultivating, weeding, alluvial plains, clearly the most productive and harvesting technologies, even the recom- lands in any biome, with nothing but natural mended varieties, if not species, will be dif- inputs. Alluvial plains and energy sumps ferent for the two scenarios. should occupy the fertile lowlands, while no 235

OIL SEEDS

Back in April 1977, I suggested that palm oil colorless oil very similar in composition to might someday be competitive with petroleum. coconut oil. The seed cake remaining, con- Today, foreign palm oil in New York is still taining 27 percent protein, is an excellent ani- higher than domestic petroleum at the pump, mal feed. I read this as a ton of biomass per but at the rate the gap has closed since my pa- year, more than 100 pounds of which is oil. I don’t know that these figures are more or per. Palm oil will be as cheap as petroleum by less reliable than those with which Calvin the year 2000. derived 50 barrels of diesel per acre. Conser- Oil palm is one of many species with vari- vatively, it would take four of these produc- eties tolerant of the allic soils of the humid trop- tive palms to produce one barrel of oil per year, or 200 trees to produce 50 barrels, From ics. Oil palm is currently growing in countries my experience in Latin America, I would pin that show deficits in both edible oils and my 50 barrels/acre hope on the palm before energy. It has already been shown that simply I would Calvin’s Diesel Tree. Calvin figured growing legumes between the oils palms can at least 100 trees per acre, but his trees were increase oil yields by 2 MT/ha/yr (3) or the 1 m in diameter. I don’t know any palms that equivalent of 6 barrels of oil per hectare, simply big. Thin canopied palms would permit inter- by the selection of proper legume for intercrop- cropping of food crops, which I speculate ping. These legumes (Centrosema pubescens, would be impossible in the shade of “diesel Pueraria phaseoloides), in addition to increas- trees.” ing our energy budget, at little or no cost fol- Note that with our hypothetical Orbignya, lowing planting, can provide food, conven- with no genetic research, we are getting 50 bar- tional or unconventional. I am sure, based on rels of palm oil per acre, with a residue of 1,900 temperate figures, that more protein per hec- pounds per tree. We have assumed a tree pro- tare will be produced if the whole aerial bio- ducing 2,000 pounds of fruit, 100 pounds of mass of the legume is harvested, thrown into which is oil (3,300 pounds are reported, with our energy vat, the leaf protein extracted for an oil yield in excess of 200 pounds oil per tree). human consumption, the carbohydrates for Assume 300 to 350 pounds per barrel of oil. We ethanol production, the residues for return to can further assume after the extraction of our the soil. 100 pounds of oil, we have 1,900 pounds of We have spoken only of the oil yields of the biomass in the pot, 900 pounds of which might, oil palm, There is still a lot of unused biomass, conservatively, be water. Of the remaining which could go, depending on the outcomes 1,000 pounds, perhaps there is another 100 of our systems analysis, into ethanol produc- pounds of protein, per tree, and 900 pounds tion, internal or external combustion devices of carbohydrates, etc., 400 pounds of which and/or soil amendments. might give us another barrel of ethanol per hectare. So, hypothetically we have 100 pounds of Not all, but most palms, survive or thrive in protein and 2 barrels of ethanol as byproduct the humid tropics. Like the oil palm, they are from our 1 barrel of palm oil. multiple-use plants, prime candidates for the The technology needed for this oil palm upper or intermediate stories in the multitiered scenario: agroecosystem for the humid tropics. Could we not multiply the yields of these unstudied 1. oil extraction (available for oil palm); palms by 10 as we have done with the Hevea 2. carbohydrate fermentation and distilla- rubber plant. Let’s look briefly at one mention; and tioned by Amazonian expert R. E. Shultes (23): 3. protein purification and sanitation, for human or animal production. Orbignya martiana: One palm may produce a ton of nuts a year, 198 pounds of which is There are palms for the arid tropics, for the kernel . . . with up to 72 percent of an almost humid tropics, for brackish swamps, for fresh- 236 water swamp situations, and for our sewage handled in the U.S. market. Residues could be sump, all potentially intercroppable with other used for alcohol or methane generation, or as food/energy/chemurgic crops. But the Gene a soil amendment. Revolutionist has not started to tailor these spe- Some prices quoted in the Chemical Market- cies to specific environments and to increase ing Reporter for various tropical oilseeds dur- their yields. And we have not even talked about ing 1979 are avocado ($ S. IS/lb), castor oil the waxes, steroids, leaf-proteins, and ethanol that could be produced by the leaves. Some ($0.40/lb), coconut ($0.57/lb), corn ($0.50/lb), cottonseed ($0.18/lb), oiticica ($0.60/lb), palm palms will disappear before we have studied their potential. ($0.33/ lb), palm kernel ($0.42 /lb), and soybean ($0.48/lb). The newly generated market for jo- Production of conventional palm oil (from joba “oil” has a cult of followers, but this so- Elaeis) was expected to total 4.3 million MT called oil is a liquid wax, unique to the jojoba in 1979-80, compared to 3.9 million MT in among plants. Soy oil, peanut oil, and sun- 1978-79 [1). Whether or not these are viewed flower oil have been used as diesel substitutes. as petroleum alternatives, many oilseeds are

ALLELOPATHY

Allelopathy has not yet been developed to be Euphorbia esula reduces the frequency of an alternative to herbicides. But if different quackgrass and ragweed, but also reduces the chemurgic species are selectively herbicidal, growth of tomato seedlings. Dry leaves of the as one gathers from reading the allelopathic medicinal species, Parthenium hysterophorus, literature, then all these herbicidal activities inhibit growth and modulation in legumes, should be cataloged. Residues of the allelo- branching in tomato and plant height in ragi pathic species might then be returned to the (Eleusine coracana) and reduce the yield of intercropped agroecosystem where its her- bean, tomato, and ragi. On the other hand, the bicidal effects will do the most good and least leaves stimulate the growth of Pennisetum harm. One can even suggest how coumarin- americanum (15). Such data are being gener- containing residues (Melilotus, Trigonella, etc.) ated rapidly, but there seems to be no com- can be used to stimulate rooting in the soft- puterized catalog to enable us to evaluate and wood cuttings used for propagation in our trop- use these data effectively in planning multiuse ical agroecosystem (17). Steenhagen and Zim- agroecosystems. dahl (26) show that the hydrocarbon-producing

DRUG CROPS

The Economic Botany Laboratory specializes harvested in the humid tropics. Many of these in medicinal plants. We have found that there are million dollar items that could be extracted are often huge residues of biomass following on-site as income producers, leaving behind 99 drug extraction. It takes 11/2 MT of dry stem percent of the biomass for food and/or fuel pro- and bark of Maytenus to yield a gram of duction. Some drugs might be byproducts from maytansine, one of the anticancer superstars conventional foods, e.g., caffeine from coffee of the last decade. and tea, theophylline from tea, steroids from legumes, rutin from buckwheats. The steroids Bruceine, cassia, caffeine, cocaine, helio- once derived from tropical dioscoreas (“bar- tropic, ipecac, papain, pilocarpine, quinine, basco”) are now largely derived as byproducts quinidine, reserpine, rutin, steroids, and the- of legumes and agaves. ophylline: these are a few drugs that can be 237

ESSENTIAL OIL

The United States imports nearly 10,000 MT ● Forbs: cardamon, citronella, ginger, lem- of essential oils at close to $100 million per ongrass, palmarosa, patchouli, vetiver. year. This probably represents the distillation The trees might be considered as alternating of about one million MT of biomass, 99 per- trees or strata with other trees, like palms, in cent of which could have been funnelled into the upper strata of our multitiered agroecosys- food and fuel production as byproducts. By no tem. The forbs might be considered for the means all of these essential oils are humid trop- ground layer. Our Gene Revolutionists should ical species, but I list a few that are from the already be looking for tolerance to shade and humid tropics: root competition in our lower tier, and toler- ● Trees: bay, bergamot, camphor, cassia, ance to root competition in candidates for the cinnamon, clove, copaiba, grapefruit, upper tier. guaiac, lemon, lime, linaloe, nutmeg, petit- grain, ylang-ylang

FIBER CROPS

On the last day of October 1980, an official steriods, waxes, leaf protein and alcohol, even called from the Strategic Materials Department tequila, could be produced. Many natural fibers to ask where in our 50 States we could grow can be produced in the humid tropics, among several strategic materials. Among them were them abaca, baobob, coir, cotton, ensete, hemp, two tropical fibers, abaca and sisal, the former henequen, jute, kenaf, remaie, roselle, sisal, adapted more to the humid tropics, the latter snakeplant, sunn hemp, etc. As the cost of pe- more to the arid tropics. With sisal, fiber yields trochemicals rise, some economists predict a are only 3 percent of the leaves. From the re- return to natural fibers instead of synthetics. maining 97 percent biomass, I am certain that

Some chemicals in this group approach the langsdorfii. According to Dr. Calvin, (4) 11/2 classical petrochemical or “neoclassical” inch holes drilled halfway through large trees botanochemicals. Swedish and Finnish firms about 2 feet above the ground yield about 20 are reported to have developed an efficient liters of “diesel” (mostly 2 or 3 main C-15 ses- turpentine car engine that runs on turpentine quiterpenes and 30 or 40 minor C-15 sesquiter- produced from the oleoresin of scotch pine. penes) in two hours. The holes are bunged and High road mileage is claimed for turpentine retapped again in about 6 months, and said to (20). Presumably, yields of tropical pines may yield another 20 liters of diesel, or 40 liters of be higher than the temperate pines. The Gene diesel per year per tree. This is exactly the same Revolutionist would be charged with increas- yield reported in Grieve’s Modern Herbal, ing both the nut (pinyon) and turpentine for 1931. Dr. Calvin, perhaps optimistically, cal- specified intercropping stratagems under spec- culates that we can get 25 barrels of diesel per ified ecological conditions. acre per year on a sustainable basis from the copaiba tree (18). Unfortunately, the tree seems Copaiba oil, traded at over $2.00 per kilo, to be intolerant of frost. I will be getting resin may or may not be the same as the oil from from an equally productive timber species of Melvin Calvin’s tropical “diesel tree” Copaifera Copaifera during my next trip to Panama. 238

Gum arabic, guar, karaya, locust, myrrh, ported with a value of $608,346. More than 23 olibanum, and tragacanth are among some of million pounds of guar gum were imported in the vegetable gums now traded. With problems that same month. Acacia, Tamarinds, and in Iran, a major producer of tragacanth, prices Sterculia are major tropical sources of gums of tragacanth have risen considerably. In April that can provide renewable harvests in inter- 1979, 56,900 pounds of tragacanth- were im- cropping- strategies.

RUBBER

The first Hevea plantation set out in the Far by 1995, The Department of Energy has East yielded about 450 pounds dry rubber per granted Calvin $250,000 to continue his re- acre, while currently available clones yield search. Marvin Bagby, head of the Agriculture about 3,000 lbs/acre (<10 barrels). New chem- Departments hydrocarbon-plant research ical treatments applicable during tapping can project, thinks that gopherweed is the leader increase the figure to 6,000 lbs an improvement among 45 hydrocarbon-bearing plants that have commercial promise (l). of 13.3 times. These yields are available while leaving the biomass intact. Other options might Other species of Euphorbiaceae are better be to grow whole plants for rubber extraction adapted to and more productive in TMF than between our upper story palms in the humid the headliners Calvin promoted. The latex of tropics. The Petroleum Plant from which milkweeds could more appropriately be fun- Calvin once projected 50 barrels per acre could nelled into rubber production. Be it spurge or be grown in the humid tropics as well as the milkweed as hydrocarbon sources, the whole arid tropics. Detractors from Calvin say yields plant would be thrown into the extraction vat, would be closer to two barrels than 50 barrels with waxes, drugs, rubber, leaf-protein and from the “Petroleum Plant.” ethanol as feasible byproducts, all grown between our upper-story palm trees. Whether Calvin’s plant has received other headlines Calvin gets 2, 10, 25, or 50 barrels/acre of pe- under the name of gopherweed (Euphorbia troleum or rubber from the “petroleum plant,” lathyris): gopherweed,” or “diesel plants,” I maintain Melvin Calvin, Nobel Laureate in Chem- that the ethanol potential from the residues has istry, believes that the U.S. could produce more energy content than what he obtains. more than 2 million barrels a day of gopheroil

WAX CROPS

Waxes tend to be more frequently derived protein or energy stock. One second-growth from arid land plants than humid tropical spe- “weed,” Calathea lutea, of the humid tropics, cies. But if the wax can be taken as byproduct, could serve as source for food, wax, and bio- like ethanol, following extraction of edible leaf mass, as could members of the banana family. protein, humid tropical waxes might become The Calathea is easily propagated with as many export money-makers. In the Chemical Mar- as 30,000 plants per hectare, yielding up to 70 keting Report, one finds such waxes as the pounds of wax per acre (23). I project that temperate bayberry wax ($3.00/kg), the arid would leave at least 29,700 pounds dry weight lands candelilla wax ($3.()()/kg), and the sub- of biomass in the vat for leaf protein and tropical carnauba wax ($4.00/kg). Yields rarely ethanol production. This leaves the under- exceed 1 percent of the plant, leaving 99 per- ground roots untapped. Aerial biomass yields cent of the biomass as waste, or better as leaf- of 18 MT/ha might complement the edible- 239 rooted Calthea allouia (12 MT root/ha). Here other tropical plants, now all but unexploited, we must remember that increases in the below- can yield food, fiber, fuel, and residue for the ground yields will usually be compensated for energy farm of the humid tropics. by losses in above-ground yields. Calathea and

Neither the Weed Science Society of Amer- mistic outputs. Research should provide these ica (WSSA) nor the oil companies have loudly numbers. advocated the use of biomass as an energy A more pessimistic note comes from Shell’s alternative in the past. I find it interesting that “Ecolibrium” 9(4):1980: there were five items in the October 1980 Newsletter of the WSSA hinting at plants as According to the Gold Kist plant officials, a source of energy. Not necessarily believing a good peanut crop can reap 142 gallons an the figures myself, I summarize the estimates acre. And, unlike alcohol from grain, you from that WSSA newsletter: don’t have to distill peanuts to get oil, you just squeeze them. The peanut oil costs about ● Euphorbia: 50-125 bbls/ha, $3.00 a gallon. ● Salsola: Arizona grant to make fuel from The 142 gallons an acre is equivalent to less the Russian thistle, a serious weed. than 10 barrels per hectare. ● Asclepias: Improved variety of milkweed could be source of biomass for synthetic This shows the wide disparity in figures used fuels and chemical feedstocks and a source by optimists and pessimists. Scientific research of fat, protein, oil and fiber. Lab estimate should rectify this disparity. of 60 bbls/ha crude oil. It seems doubtful that the herbicide indus- ● Parthenium: Guayule provides a latex that try would encourage hand harvesting of weeds can be used for fuel, petrochemicals, and rubbers. and their conversion into alcohol and/or protein. I advocate just that in TMF countries with ● Simmondsia: Speculation holds that mature jojobas might produce the equiv- unemployed hungry people. Almost all studies show that hand weeding, though using human alent of 50 bbls/ha. labor, results in better yields than herbicide It might be added that these optimistic esti- controls. In some cultivated communities, mates are based on marginal weed species in weeds constitute 8 to 27 percent of the shoot areas of marginal inputs. But these are gross biomass. This 25 percent might represent 2.5 energy outputs. Whether it would take 100 to MT on a tropical hectare, which could be 250 bbls/ha input to obtain the 50 to 125 bbls/ha harvested and converted to fuel, at the same output is speculative. No one has analyzed the time increasing the yield of the crops the weeds energy inputs required to obtain these opti- were competing with.

TROPICAL MOIST FOREST BIOMASS

Do energy farms produce more biomass than be extremely high, metabolism erases the the pristine moist forest produces? Those who profit, leaving no net biomass increase. Do speak of highly productive TMF mention great agroecosystems produce more total biomass quantities of biomass. The climax forest is in than native forest ecosystems? I cannot say equilibrium, metabolizing as much as it syn- categorically. The optimist figures on arid land thesizes, so that although gross production may weeds yielding 50 to 125 barrels of oil per hec- 240 tare; the pessimist peanut prospectus lies at less Table 2.—Tropical Root Crops (yields in MT/ha) than 10 barrels per hectare. And we see esti- Arrowroot...... 37 mates of up to 150 MT dry weight from some Canna...... 85 tropical grasses under sewage irrigation. These Cassava ...... 56 figures suggest to net that agroforestry is more GalIan , ...... 120 Ginger ...... 30 productive of biomass than the climax forest. Groundnut (bambarra) ...... 4 Estimates of the net primary production of Leren ...... 12 tropical forests (table 1) presented by UNESCO Lotus ...... 5 Peanut ...... 5 (27) range from 9 to 32. Sweet Potato ...... 36 Taro ...... 128 For comparison, I list in tables 2 through 4 Turmeric ...... 35 some examples of yields of tropical crops that Yambean ...... 90 can be grown in the lands occupied by the Yautia ...... 32 forests mentioned in table 1. These data, gathered from a variety of sources, do not con- sistently represent maximums, minimums, or means, nor are such data available. Hence, these numbers cannot be compared. Today the biomass data bank at the Eco- nomic Botany Laboratory has close to a thou- Table 3.—Tropical Vegetables (yields in MT/ha) sand entries in it. EBL is probably the best Banana ...... 18 MT equipped lab in the USDA to compare biomass Cantaloupe ...... 14 MT Eggplant ...... 24 MT potential of different monocultural, polycultural, Garlic...... 10 MT and natural ecosystems. Consequently, I have Okra ...... 23MT brought my computer to this workshop so you Onion ...... 29MT Pepper ...... 14MT can check it out on the spot. Incidentally, EBL Pigeonpea ...... 13MT is probably the best equipped lab in the USDA Plantain ...... 45MT to give you the ecological amplitudes, nutri- Pumpkin ...... 23MT Squash ...... 23MT tional analyses, and folk-medicinal attributes Tomato ...... 22MT of the little known economic plants of TMF, Tomatillo ...... 36MT some of which now extant, may soon be Yardlona bean ...... 10 MT extinct. Watermelon ...... 20MT

Table 1 .—Estimates of Net Primary Production (MT/ha/yr) in Tropical Forests (UNESCO,1978)

Forest type Location Net production Equatorial Yangambi, Zaire 32 Equatorial Khao Chong, Thailand 29 Secondary forest 40 years old Kade, Chana 24 Lowland dipterocarp Pasoh, Malaysia 22 Bamboo in monsoon forest Burma 20a Subequatorial (Banco plateau) Ivory Coast 17 Bamboo in rain forest Burma 16a Dry deciduous Varanasi India 16 Lower montane El Verde, Puerto Rico 16 Subequatorial (Yapo plateau) Ivory Coast 15 Seasonal rain Anguededou, coastal 13 Ivory Coast Mangrove Puerto Rico 9 aEstlrnate does not include roots. 241

Table 4.—Tropical Spices Table 5 presents estimates of standing phytomass and net primary productivity for some Trees: Allspice ...... Pimenta dioica of the various vegetation types that might be Bayrum tree . . . Pimenta racemosa expected in a tropical country. I believe, but Camphor ...... Cinnamomum camphora cannot prove, that intensively- managed agro- Cassia ...... Cinnamonmum aromaticum Cinnamon . . . . . Cinnamomum verum ecosystems used in places formerly occupied Mace ...... Myristica fragrans by these forest types could produce two to five Herbs and vines: times as much (except for the alluvial swamp Lemon grass: Cymbopogon citratus 95 MT WM forests). I do not advocate replacement of for- Patchouli ...... Pogostemon cablin 36 MT WM Pepper, black . . Piper nigrum 6 MT (fr) est with agroecosystem, but better management Vanilla ...... Vanilla fragrans 1 MT (sol) of existing agroecosystems. Vetiver ...... Vetiveria zizaniodes 2.5 MT (rt)

Table 5.—Net Primary Productivity

Republic of Panama Republic of Panama Phytomass NPP Phytomass NPP MT/ha MT/ha MT/ha MT/ha Tropical: 240 18 Subtropical: 133 14 Humid tropics: 440 29 Humid subtropical: 366 25 Bright Ferrallitic Evergreen . . . . . 650 27 Bright ferrallitic Evergreen . . . . . 450 20 Swamp Forest ...... 500 25 Rendaina Evergreen ...... 380 16 Bogs ...... 300 150 Prairie ...... 30 13 Monsoon Forest (Savanna) Red . 200 16 Swamp Forest ...... 400 22 Monsoon (Dark Soil) ...... 80 15 Meadow Bog ...... 200 130 Alluvial Forests ...... 250 70 Gallery Forest ...... 250 40 Mangrove ...... 130 10 Submontane Forest ...... 410 18 Submontane Evergreen ...... 700 35 14 Submontane Monsoon ...... 450 29 Semiarid subtropics: 99 Xerophytic Forests ...... 170 16 Semiarid tropics: 107 14 Shrub-steppe (Gray-Brown soil) . 35 10 Xerophytic Forest (Ferrallitic) . . . 250 17 Shrub-steppe (Soloneta) ...... 20 6 Grass Shrub Savanna Shrub-steppe (Chernoaenoid) . . . 25 8 (Redbrown) ...... 40 12 Psammophyte on sand...... 20 5 Grass Shrub Savanna (Black) . . . 30 11 Halophytes on Glanchak ...... 1.5 0.5 Grass Shrub Savanna Gallery Forest ...... 250 40 (Solonets) ...... 20 7 Submontane Forest ...... 120 13 Swamp Savanna ...... 60 14 Submontane Shrub-steppe . . . . . 99 14 Alluvial Gallery ...... 200 60 7 Sub montane Xerophytic Arid Subtropics: 14 Forest ...... 200 15 Steppe desert (Serozem) ...... 12 10 Sub montane Savanna ...... 40 12 Desert (sub-desert soil) ...... 2 1 Psammonphytes on sand ...... 3 0.1 Arid tropics: 7 2 Desert on takyrs ...... 1 0.5 Savanna (red-brown soils) ...... 15 4 Halophyte on solonchak ...... 1 0.2 Alluvial Gallery ...... 150 40 Gallery Forest ...... 200 90 Tropical Desert ...... 1.5 1 Submontane Desert (Serozem) . . 15 12 Psammonphyte on sand ...... 1.0 0.1 Submontane Desert (Desert Desert (Coalessed soil) ...... 1.0 0.2 soil) ...... 3 1 Halophytes (solanchaks) ...... 1.0 0.1 Submontane Desert ...... 7.0 2.0 SOURCE Rodln and Brazil in Lieth. 1978 .

242

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