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Medicago sativa L.
Fabaceae
Alfalfa, Lucerne
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Uses
- Folk Medicine
- Chemistry
- Toxicity
- Description
- Germplasm
- Distribution
- Ecology
- Cultivation
- Harvesting
- Yields and Economics
- Energy
- Biotic Factors
- Chemical Analysis of Biomass Fuels
- References
Alfalfa or lucerne is a highly valued legume forage, extensively cultivated in
warm temperate and cool subtropical regions. It has been heralded as having
the highest feeding value of all commonly grown hay crops, producing more
protein per ha than any other crop for livestock. In some areas it is used in
combination with corn for silage. In parts of China and Russia tender alfalfa
leaves serve as a vegetable. It is used to reduce water runoff and soil
erosion. It is an excellent pasture for hogs, cattle, and sheep, often in
mixtures with smooth bromegrass, orchardgrass or timothy. Supplemental feeding
of grain to dairy cows, sheep and fattening cattle reduces bloating and
balances the high protein level of the alfalfa pastures with energy and extends
the usefulness of the pasture. Alfalfa meal is presently made into pellets and
used in mixed feeds for cattle, poultry and other animals. Alfalfa may be
grown as a cover crop and often increases yield of succeeding crops, as
potatoes, rice, cucumber, lettuce, tomatoes (increased by 10 MT/ha), corn,
apples, and oranges. It is valued for bee pasturage. Extracts produce
antibacterial activity against gram-positive bacteria. Powdered alfalfa is
used as a diluent to adjust strength of digitalis powder, and the root has been
used as an adulterant of Belladonna root. Seeds yield 8.511% of a drying oil
suitable for making paints and varnish. Seed screenings are ground and used to
a limited extent in feeds for ruminants. The seeds also contain a yellow dye.
Alfalfa fiber has been used in manufacturing paper.
Seeds contain the alkaloids stachydrine and 1-homostachydrine, and are
considered emmenagogue and lactigenic. They are used as a cooling poultice for
boils in India. To increase weight, a cupful of 1:16 alfalfa: water infusion
has been recommended. Though containing saponins, alfalfa is sold in many
"health food" stores. It is considered antiscorbutic, aperient, diuretic,
ecbolic, estrogenic, stimulant, and tonic, and said to aid peptic ulcers, as
well as urinary and bowel problems. In Colombia, the mucilaginous fruits are
used for "tos".
Tender shoots of alfalfa are reported to contain per 100 g 52 calories, 82.7%
moisture, 6 g protein, 0.4 g fat, 9.5 g total carbohydrate, 3.1 g fiber, 1.4 g
ash, 12 mg Ca, 51 mg P, 5.4 mg Fe, 3410 IU Vit A, 0.13 mg thiamine, 0.14 mg
riboflavin, 0.5 mg niacin, and 162 mg ascorbic acid. Green forage of
Medicago sativa is reported to contain per 100 g, 80.0% moisture, 5.2 g
protein, 0.9 g fat, 3.5 g fiber, and 2.4 g ash. Silages of alfalfa contain per
100 g, 69.5% moisture, 5.7 g protein, 1.0 g fat, 8.8 g fiber, and 2.4 ash.
Alfalfa whole meal and leaf meal are reported to contain per 100 g, 66 and 77
calories, 7.5 and 8.0% moisture, 16.0 and 20.4 g protein, 2.5 and 2.6 g fat,
27.3 and 17.1 g fiber, 9.1 and 11.5 g ash, respectively.The "betaine fraction"
of alfalfa contains 0.785% stachydrine, 0.063% choline, 0.0069 trimethylamine,
and 0.0052% betaine. The following purines have been identified: adenine,
guanine, xanthine, and hypoxanthine; the pyrimidine, isocytosine; and the
ribosides adenosine, guanosine, inosine, and cytidine. These factors stimulate
the growth of Bacillus subtilis. Three abundant compounds in alfalfa
juice are adenine (0.17%), adenosine (0.25%), and guanosine (0.36%). Nitrate
concentrations greater than 0.2% can harm livestock. Prebud alfalfa in spring
growth has 0.18% nitrate gradually decreasing to 0.12% at green pod stage.
Prebud alfalfa in summer growth has 0.32% nitrate, gradually decreasing to
0.17% at green pod stage. Heavy N fertilization may increase nitrates to 1.0%.
One study (4th Annual Alfalfa Symposium) cites 5.1 g arginine/16 g N; 3.1 g
cystine and methionine, 1.5 g histidine, 4.6 g isoleucine, 7.2 g leucine, 5.6 g
lysine, 4.6 g phenylalanine, 4.1 g threonine, 1.5 g tryptophane, and 4.6 g
valine for alfalfa hay. Another study (C.S.I.R., 19481976) gives 3.5
arginine, 1.5 histidine, 4.2 lysine, 1.5 tryptophan, 4.1 phenylalanine, 1.3
methionine, 5.0 threonine, 7.9 leucine, 4.3 isoleucine, and 4.9 valine. One
report gives total crude lipids as 5.2% of total dry weight, with 11% fatty
acids, 10% digalactolipids, 16% monogalactolipids, 8% phospholipids, 44%
neutral lipids, and 12% others. In the chloroplasts, linoleic, linolenic, and
palmitic acids are the predominant acids, while stearic and oleic are low. The
triglyceride fraction of alfalfa meal contains 16.9% linoleic acid, 32.2%
linolenic acid, 31.0% oleic acid, and 19.9% saturated fatty acids. The
phospholipid fraction (0.24% dry alfalfa meal) contained 35.2% linolenic acid,
36.8% oleic acid, 14.7% linoleic acid, and 13.3% saturated acids. Good alfalfa
hay contains 138 to 198 mg chorine/100 g hay. Alfalfa meal contains 21 mg
A-spinasterol/100 g. Five xanthophylls comprise 99% of the xanthophyll
fraction of fresh alfalfa viz 40% lutein, 34% violaxanthin, 19% neoxanthin, 4%
cryptoxanthin, and 2% zeaxanthin. Volatiles identified from alfalfa include
acetone, butanone, propanal, pentanal, 2-methylpropanal, and 3-methylbutanal.
Australian herbage samples contain 0.3 and 0.4% glucose, 0.3 and 0.3% fructose,
2.5 and 2.7% sucrose, and 0.6 and 0.6% oligosaccharides at early and later
flowering stages. Tannin concentrations between 2.7 and 2.8% have been
reported. Several coumestans occur in alfalfa, 4'-0-methylcoumestrol,
3'-methoxycoumestrol, lucernol, medicagol, sativol, trifoliol, and 11,
12-dimethoxy-7-hydroxycoumestan. Mineral constituents present include (av.
values, dry basis): calcium (CaO) 2.80, phosphorus (P2O5) 0.74, potassium (K2O)
4.11, sodium (Na2O) 0.35, and magnesium (MgO) 0.44%: trace elements; barium,
chromium, cobalt, copper, iron, lead, manganese, molybdenum, nickel, silver,
strontium, tin, titanium, vanadium, and zinc. Alfalfa is a valuable source of
vitamins A and E; it contains: b-carotene 6.24, thiamine 0.15, riboflavin
0.46, niacin 1.81, and a-tocopherol, 15.23 mg/100 g; panthothenic acid,
biotin, folic acid, choline, inositol, Pyridoxine, vitamin B12, and vitamin K
are also present. Fresh lucerne is rich in vitamin C (1.78 mg/g) but it loses
80% on drying. A flavone, tricin, which inhibits the movements of smooth
muscle has also been isolated. Lucerne is reported to contain citric, malic,
oxalic, and malonic acids; succinic, fumaric, shikimic, and quinic acids are
present in minor quantities. Enzymes reported in alfalfa are amylase, emulsin,
coagulase, peroxidase, erepsin, lipase, invertase, and pectinase. Among the
miscellaneous constituents present in lucerne are: saponins (0.52% or more),
an alkaloid 1-stachydrine (0.14%) which also occurs in seeds, and two ketones,
myristone (C27H54O), and alfalfone (C21H42O). Hay contains the following
vitamins (av. values): vitamin A, 3013 IU; thiamine, 0.29 mg; riboflavin, 1.37
mg; niacin, 3.84 mg; pantothenic acid, 1.78 mg; biotin, 0.018 mg; vitamin D,
199.5 IU; and vitamin E (as a-tocopherol) 2.60 mg/100 g. Lucerne and mixtures
of lucerne and grass make good silage. When alfalfa alone is used,
fermentation is enhanced by the addition of molasses. A good silage is
obtained by ensuing wilted cuttings. Cattle and sheep fed on alfalfa as the
sole source of forage occasionally suffer from bloat or tympanitis. The cause
of bloat has not been clearly defined but it may be prevented by feeding corn
or sorghum silage along with alfalfa hay or using mixed alfalfa-grass pasture.
Forage cut at flowering time and dried in the field rarely causes bloating.
Several methods have been developed for processing concentrates and beverages
for human consumption; they involve the removal of odor and taste
characteristic of alfalfa and also the fiber. A fiber-free concentrate is
prepared by steeping tender leaves in cold water, followed by grinding in a
blender, extraction with water, concentration and drying under vacuum. The
product so obtained (yield, 13%) contains: protein 44.2, fiber 0.86, ether
extr. 3.55, N-free extr. 30.69, ash 13.2, calcium 1.90, and phosphorus 0.52%,
carotene 110.1 mg, ascorbic acid 51.6 mg, and thiamine 1.15 mg/100 g. Alfalfa
honey gave the following average values: water 16.56, invert sugar 76.90,
sucrose 4.42, dextrin 0.34, protein 0.11, acid (as formic) 0.08, and ash 0.07%.
Alfalfa seeds contained: moisture 11.7, protein 33.2, fat 10.6, N-free extr.
32.0, fiber 8.1, and mineral matter 4.4%.
The genus Medicago has been reported to contain the following chemicals,
relative toxicities of which are tabulated in Duke's "Phytotoxin Tables" (Duke,
1981b): choline, citric acid, hydrocyanic acid, limonene, malic acid, malonic
acid, oxalic acid, pantothenic acid, pectin, quinic acid, saponin, shikimic
acid, tannin, trigonelline, and tryptophane. Four isoflavones are reported in
alfalfa (daidzein, formononetin, genistein, and biochanin A) and they, like
coumestrol, produce an estrogen-like response, perhaps contributing to
reproductive disturbances of cattle on high-estrogen forage. Seeds are
reported to contain trypsin inhibitors. Some people are allergic to the dust
generated when milling alfalfa.
Perennial herb; stems erect or sometimes decumbent, 0.31 m long, 525 or more
per crown, much-branched, 4-angled, glabrous or the upper part hairy; rhizome
stout, penetrating the soil as much as 79 m; stipules united 1/3 to 1/2
length, free portion triangular-lanceolate, tapering, basally entire or with
12 teeth, glabrous or sparingly appressed-hairy; leaves pinnately
trifoliolate; leaflets obovate-oblong, ovate or linear, tapering to base,
crenate above middle mostly retuse and mucronate, 1045 mm long, 310 mm broad,
glabrous or appressed hairy, paler green beneath; racemes oval or rounded,
12.5 cm long, 12 cm broad, axillary, 540-flowered; peduncle slender, firm,
always exceeding the subtending leaf, glabrous or appressed-hairy; calyx
tubular, with linear-subulate teeth longer then tube; corolla yellow or blue to
purple or violet, 615 mm long; bracteoles whitish, linear-subulate, mostly
equaling the pedicel; pod slightly pubescent or glabrous, 39 mm in diameter,
with 23 spirals, prominently reticulate-veined; seeds 6 or 8 per pod, yellow,
castaneous or brown, ovoid, irregularly cordate or reniform. Fl. MayJuly
(US); fr. late summer to fall.
Demand for better adapted, disease- and insect-resistant cvs has prompted
extensive alfalfa breeding programs. Medicago sativa easily hybridizes
with Medicago falcata (which is sometimes treated as a subspecies of
M. sativa). Most newer cvs are synthetics, i.e., they contain a set of
selected clones or seed lines produced and maintained under conditions
specified by the originator. Promising plants are vegetatively propagated to
obtain clonal lines and then the polycross progenies are tested to determine
the combining ability of each clone. Of about 50 named cvs grown in the US,
about 13 make up 74% of alfalfa acreage. 'Vernal' and 'Ranger' account for
about 52%. Other cvs include: 'Buffalo', 'Hairy Peruvian' (7250 ha in 1969),
'Indian' (2450 ha), 'Cayuga', 'Cody', 'Cossack' (100,000 ha), 'Du Puits',
'Grimm' (180,000 ha), 'Ladak' (425,000 ha), 'Lahontan', 'Moapa' (resistant to
spotted alfalfa aphid), 'African' (5000 ha), 'Narragansett', and 'Sonora'.
'Buffalo' is a bacterial-wilt-resistant selection from 'Kansas Common'.
'Cayuga' and 'Ranger' are also wilt resistant. 'Cody' and 'Zia' are resistant
to spotted alfalfa aphid. 'Lahontan' and 'Washoe' are resistant to stem
nematodes. There are many new cvs especially selected for specific areas,
resistances and other agronomic purposes. Each cv is adapted to a limited area
or to a specific set of climatic conditions. Assigned to the Central Asia,
Near East, and Mediterranean Centers of Diversity, alfalfa or cvs thereof is
reported to exhibit tolerance to aluminum, anthracnose, bacteria, disease,
drought, fungus, hydrogen fluoride, high pH, heat, insects, low pH, mine,
mycobacteria, nematode, salt, slope, smog, SO2, virus, weeds, waterlog, and
wilt. (2n = 16, 32, 64).
Native to southwest Asia as indicated by occurrence of wild type in the
Caucasus and in mountainous regions of Afghanistan, Iran, and adjacent regions.
The cultivated forms probably arose in western Persia and then spread, to
become widely cultivated, often a "weed" throughout Asia, Europe, and
America.
Alfalfa shows considerable variation in form and adaptation to environment.
Form of plant varies from erect to decumbent from southern subtropical areas to
northern temperate regions and from lower to higher elevations. Length of
vegetation period decreases from south to north and from lower to higher
elevations. Many strains are adapted to different climatic plains as in hilly
regions, up to an altitude of about 2400 m (to 4000 in Boliva); can withstand
high temperatures of 3941°C as well as rather low temperatures, the degree
of adaptibility varying with different strains. Thrives particularly well in
semi-arid regions under irrigation. Some clones that are self-sterile at low
temperatures may be partially self-fertile at high temperatures. Annual
rainfall of 56 dm is optimum (in the temperature zone), but crop will survive
less. Soil moisture can be reduced to 35% of the water holding capacity of a
soil before affecting photosynthesis. In areas of high rainfall of 10 dm or
more, alfalfa does not grow well as a perennial. Grows on a variety of soils,
but thrives on rich, friable, well-drained loamy soil with loose topsoil
supplied with lime; does not tolerate waterlogging and fails to grow on acid
soils. Alfalfa may be a bit more tolerant of frost and salt than wheat.
Salinities of 3 mmhos reduce yields by 10%, 5 mmhos by 25%, and 8 mmhos by 50%.
Deep penetrating roots make alfalfa quite drought resistant. Alfalfa is
reported to range from Boreal Moist to Boreal Wet through Tropical Desert
(irrigated or alluvial situations) to Dry Forest Life Zones, annual
precipitation ranging from 0.9 to 27.2 (214 cases = 10.3 dm), annual
temperature ranging from 4.3 to 28.5°C (213 cases = 17.7°C), and
pH ranging from 4.3 to 8.7 (136 cases = 6.5). One source (Agr. Gaz NSW 1972)
suggests that a pH of 67 is optimum, another (Parodi, 1964) suggests that 78
is optimum.
For cultivation of alfalfa, land should be well-plowed. Farm manure could be
applied six weeks before planting, with additional manurings as top dressing
after every third cutting. Crop is propagated by seed. As seeds have hard
coat, they should be scarified or soaked in water before sowing. Fresh seeds
do not germinate as well as those 23 years old. Seed should be inoculated
with the proper strain of inoculum. Crop may be sown pure or in mixture with
grasses or other legumes. Seeds sown broadcast or drilled in rows or on ridges
5572 cm apart. Sowing on ridges as facilitates weed control. When broadcast,
seed rate is 1220 kg/ha, when sown on ridges, 1012 kg/ha. Crop may be grown
with or without irrigation. In some areas, frequent irrigation is necessary
until seedlings become established. When crop is well established, a single
irrigation is sufficient. Crop requires frequent hosing or cultivation to
control weeds and stir the soil. Especially in the seedling stage, weed
competition for light, nutrients, and water reduces alfalfa yields. Weed
competition is reduced by use of clean seed, selection of planting dates,
clipping weeds, and use of companion crops, but herbicide use is increasing in
the US. Alfalfa is sensitive to some herbicides. Results are good with farm
manure and any fertilizer containing phosphates, such as bone meal, fish meal,
basic slag, rock phosphate or superphosphate (ca 250 kg/ha annually or 500 kg
in alternate years). Alfalfa is often used in rotation with other crops e.g.
wheat, oats or flax. Liming to pH 7 is often recommended. Generally alfalfa
and alfalfa/grass mixtures with at least 1/3 alfalfa do not respond markedly to
N, but respond well to P and K. Many soils lack adequate K for high yields.
Apparently deficiencies of S and Mg are becoming more common. Addition of
micronutrients, especially B may be necessary locally.
Alfalfa hay is harvested when the first flowers have opened. One cutting a
year may be made at the prebloom stage without seriously damaging the stand and
subsequent production. Number of cuttings per year varies from one in drier
northern areas to nine or more under irrigation in southern areas; 34 cuttings
in central areas are normal (US). For high quality hay, leaves must be
retained since at early bloom stage leaves constitute about half of plant
weight. All processes from field to storage (mowing, conditioning, windrowing,
baling, bale handling, etc.) are mechanized in the US. Seed production, is
most efficient under irrigation, but rainfed seed is produced. Row spacings of
60110 cm are superior to closer plantings. In dense stands; nectar
production, insect visitation and, subsequently, seed production often are
depressed. Nearly all seed is directly combined. Use of spray defoliants has
facilitated harvesting. Proper adjustment of combine is very important to
avoid injury to seed. Alfalfa tolerates rotational grazing but weakens rapidly
under continuous grazing. 'Ladak' is superior on rangelands, and creeping or
decumbent alfalfas are better adapted for dryland conditions.
Forage yields are 575 MT/ha per year (with 812 cuttings per year). Seed
yields are 186280 kg/ha annually. Alfalfa is estimated to fix 83594 kg
N/ha/yr (Miller, 1976). About 10 years ago, this most valuable of common hay
crops had an estimated hectarage of 33 million, the US, USSR, and Argentina
producing 70% of world production, France, Italy, Canada, and Australia
producing another 20%. Alfalfa accounts for about 60% of total US hay
production.
In UK, the best options for annual energy plantation crops would probably
involve the use of grasses, lucerne, clover, or forage cereals. With total
cultivation and harvesting costs at $700/ha/yr and fresh weight yield of 70
MT/ha/yr, the DM yield would be 15.75 MT/ha/yr and the output of gross energy
275 GJ/ha/yr. ($2.55 per GJ gross energy before transportation and storage and
a minimum biogas cost of $8.75/GJ.) (Palz and Chartier, 1980). Shortly after
the US energy crisis of 1973, Jim and Peggy Duke (1975) offered one simplistic
scenario: What if, instead of making auto fuel from the fossilized remains of
plants (oil and coal), we made it from fresh plant tissue? High-quality,
low-pollution fuel is as available from fresh plants as gasoline is from oil.
We contend that by growing plants with conversion to fuel in mind, America
could become self-sufficient in energy, utilize some of its organic wastes to
build soils, and achieve many other benefits. Assume we have 62.5 million
acres of unused and marginal land available for energy farming. Now let us
develop a concept we inherited from the American Indiansthe intercropping of
a legume like alfalfa with a cereal like corn, adding some organic matter like
sewage sludge. Alfalfa, like most legumes, takes nitrogen from the atmosphere
and puts it in the soilnearly 200 pounds per acre. It would take nearly a
barrel of oil to manufacture that much inorganic nitrogen fertilizer. Alfalfa
grows well in the cool months, producing enough vegetation to yield the energy
equivalent of 2 to 7 barrels of oil per acre. Basing estimates on average
alfalfa hay yields, participants at the Fourth Annual Alfalfa Symposium
concluded that we could get nearly a ton of leaf protein per acre from alfalfa.
This would mean 55 million tons of protein from 62.5 million acresabout 10
times what Americans need in their diet. Residues remaining after protein
extraction would yield the equivalent of 250 million barrels of oil in
residues. This alone could cut gasoline imports significantly. If we
fertilized with sewage sludge, our 62.5 million acres of alfalfa could probably
meet President Ford's target import reduction of one million barrels a day, but
also provide protein for the US with plenty for export. Duke (1981a) reports
DM yields of 037 MT/ha/yr (24 in Bolivia, 11 in Czechoslovakia, 1011 in
Cyprus, 11 in Egypt, 7 in France, 69 in Germany, 811 in Hungary, 321 in
Italy, 024 in New Zealand, 1013 in Romania, 29 in Turkistan, 737 in USA,
221 in USSR, and 812 in Yugoslavia.
Nearly all alfalfas require the flowers to be tripped for pollination to take
place; this amounts to release of the sexual column from the keel of the
flower. Many types of bees can serve as trippers, e.g. the alfalfa leaf-cutter
bee (Megachile rotundata), alkali bee (Nomia melandri), honeybees
(Apis mellifera), and bumblebees. In North America, alfalfa-pollinating
genera, listed with the number of effective species, are as follows: Apis (1),
Bombus (7), Xylocopa (1), Anthophora (1), Tetralonia (1), Osmia (2), Megachile
(10), Hoplitis (1), Nomia (1), Agapostemon (2), Halictus (3), Evylaeus (1),
Lasioglossum (1), Andrena (2), Calliopsis (1). Over 100 species of fungi have
been reported to cause diseases on alfalfa. Among the most serious are the
following: Colletotrichum trifolii, (anthracnose), Pseudopeziza
medicaginis, P. jonesii, Leptosphaerulina briosiana, Stemphylium spp.,
Uromyces striatus (rust), Peronospora trifoliorum (downy mildew),
Phoma medicaginis (spring black stem and leafspot), Ascochyta
imperfecta (leafspot), Sclerotinia trifoliorum (stem rot),
Fusarium spp., and Phytophthora megasperma (root rot).
Bacterial wilt, caused by Corynebacterium insidiosum, is one of the most
destructive alfalfa diseases. Virus diseases include: Alfalfa mosaic, Lucerne
mosaic, Yellow-green stripe mosaic, Rugose leaf-curl and Witches broom virus of
lucerne. Parasitic plants attacking alfalfa include: Orobanche lutea,
Cuscuta australis, C. arvensis, C. campestris, C. chinensis, C. epithymum, C.
gronovii, C. indecora, C. pentagona, C. planiflora, C. racemosa, C.
suaveolens, and C. trifolia.. Nematodes attacking alfalfa are
numerous and belong to several genera. Some are found in the roots, while
others are only found in the soil near the roots. Stem-nematodes
(Ditylenchus dipsaci) and root-knot nematodes (Meloidogyne spp.)
cause much damage; the cultivars, 'Lahontan' and 'Washoe' are resistant to stem
nematodes. Among important insect pests of alfalfa are the following: alfalfa
weevil (Hypera postica), to which there are some resistant cultivars;
spotted alfalfa aphid (Therioaphis maculata), and pea aphid
(Acrythosiphon pisum), to both of which there are resistant cultivars;
Potato leafhopper causing alfalfa yellows (Empoasca fabae) and meadow
spittlebug (Philaenus spumarius). Lygus bugs, seed chalcids and alfalfa
weevils are most harmful to seed production. About 10 years ago, this most
valuable of common hay crops had an estimated hectarage of 33 million, the USA,
USSR, and Argentina producing another 20%, alfalfa accounts for ca 60% of total
US hay tonnage.
Analysing 62 kinds of biomass for heating value, Jenkins and Ebeling (1985)
reported a spread of 18.45 to 17.36 MJ/kg, compared to 13.76 for weathered rice
straw to 23.28 MJ/kg for prune pits. On a % DM basis, the seed straw
contained 72.60% volatiles, 7.25% ash, 20.15% fixed carbon, 46.76% C, 5.40% H,
40.72% O, 1.00% N, 0.02% S, 0.03% Cl, and undetermined residue.
- C.S.I.R. (Council of Scientific and Industrial Research). 19481976. The wealth
of India. 11 vols. New Delhi.
- Duke, J.A. 1981a. Handbook of legumes of world economic importance. Plenum
Press. NewYork.
- Duke, J.A. 1981b. The gene revolution. Paper 1. p. 89150. In: Office of
Technology Assessment, Background papers for innovative biological technologies
for lesser developed countries. USGPO. Washington.
- Duke, J.A. and Duke, P. 1975. Organic energy farms: Will they free us? Org.
Gard. (Sept). 135138. Reissued in D. Wallace. Energy we can live with. (Book
Chapter).
- Jenkins, B.M. and Ebeling, J.M. 1985. Thermochemical properties of biomass
fuels. Calif. Agric. 39(5/6):1416.
- Palz, W. and Chartier, P. (eds.). 1980. Energy from biomass in Europe. Applied
Science Publishers Ltd., London.
- Parodi, L. 1964. Encyclopedia Argentina de agricultura y Jardinaria, Acme,
Buenos Aires, 2 vols.
Complete list of references for Duke, Handbook of Energy Crops
Last update Wednesday, January 7, 1998 by aw