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Prosopis tamarugo F. Phil.

Mimosaceae
Tamarugo

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Description
  5. Germplasm
  6. Distribution
  7. Ecology
  8. Cultivation
  9. Harvesting
  10. Yields and Economics
  11. Energy
  12. Biotic Factors
  13. References

Uses

Tree produces abundant fodder, palatable to sheep, cattle and goats. It is said that older stands will support 26 sheep per hectare. The wood, though hard and difficult to work, is used for furniture and firewood. Man-made tamarugo plantations are being introduced in the Tamarugal Pampa which are transforming the absolute desert ecosystem into an agroecosystem. The result, is a noteworthy increase in overall productivity in one of the most inhospitable regions of the world (Habit et al., 1981). The potential value of the tamarugo was noted as early as 1918 when Maldonado, a forest inspector called for a tamarugo forest preserve, considering it most important for the Chilean desert (Burkart, 1976).

Folk Medicine

No data available.

Chemistry

Per 100 g, the fruit is reported to contain 3.34 g H2O, 11.14 g protein, 1.62 g fat, 79.63 g total carbohydrate, 31.45 g fiber, 4.27 g ash, 280 mg Ca, and 1,440 mg P. Leaves were analyzed at 94.7% H2O, 90.53% dry matter, 9.98% total protein, 10.72% crude fiber, 1.9% ether extract, 45.91% N-free extract, 22.02% ash, 2.82% Ca, and 0.91% P (Habit et al, 1981). By contrast Gohl (1981) reports:

As % of dry matter
DM CP CT Ash EE NFE Ca P
Browse, Chile 89.3 10.7 32.1 5.0 2.7 49.5 3.98 0.12
Leaves, Chile 88.5 9.9 15.8 20.3 2.0 52.0 6.21 0.11
Pods, Chile 91.1 11.7 41.5 4.6 1.6 40.6 0.33 0.13
Seeds, Chile 92.5 10.1 38.4 7.5 0.7 43.3 0.36 1.50
Digestibility (%)
Animal CP CF EE NFE ME
Browse Sheep 55.0 25.0 47.0 38.0 1.32
Pods Sheep 55.0 50.0 50.0 74 0 2.18

Felker and Bandurski (1979) report that the embryo and seed coat contain 27% protein.

Table 15. Average composition of various tamarugo components for cattle feed.
Plant component DM (%) CP (%) EE (%) CF (%) NFE (%) Ash (%)
Whole-fruit 94.40 13.30 1.40 34.20 44.80 6.40
Fruit without seed 87.25 13.27 0.95 31.67 44.83 9.28
Seed 90.77 27.30 5.33 10.84 50.45 6.08
Dry leaves without rachis 91.70 13.55 1.69 9.90 52.63 22.23
Dry leaves 91.43 9.04 1.77 22.25 55.41 11.53
Rachis of dry leaves 88.15 11.27 1.78 15.98 50.68 20.29
Green leaves 43.71 35.69 2.97 31.55 1.38 28.41
Dry leaves with rachis 90.53 11.02 1.09 11.84 50.73 24.32
Fruit 96.66 11.52 1.68 32.51 49.86 4.43
(Source: Habit et al., 1981)

Pak et al. (1977) present detailed nutritional analyses with comments also on potential toxicities:

Table 1. Chemical composition (g/100g dry weight) and caloric content (g/100g dry weight), of fruit, seeds and leaves of tamarugo (Prosopis tamarugo)

Ash Crude
protien 		Ether
extract 		Crude
fibre 		Soluble
carbohydrate 		Caloric
content
Ripe fruit 4.57 9.2 1.4 29.9 55.0 408
Green fruit 4.54 12.9 1.3 30.4 50.9 n.d.*
Seed 3.34 27.1 3.7 9.5 55.4 446
Dry leaf 13.95 11.3 1.3 13.4 60.6 351
Green leaf 9.80 15.9 3.3 14.7 56.5 420
* n.d. = not determined.

Table 2. Calcium, phosphorus, magnesium, potassium and sodium concentrations (g/100 g dry weight) and Ca/P, K/Na ratios in tamarugo

Calcium Phosphorus Magnesium Potassium Sodium Ca/P K/Na
Ripe fruit 0.22 0.27 0.10 2.09 0.05 0.8 41.8
Green fruit 0.24 0.26 0.13 2.20 0.08 0.9 27.5
Seed 0.19 0.21 0.26 1.11 0.03 0.9 37.0
Dry leaf 3.55 0.19 0.46 1.62 0.11 18.7 14.7
Green leaf 1.44 0.25 0.39 1.86 0.03 5.8 62.0

Table 3. Iron, copper, molybdenum, zinc, cobalt and manganese (parts/106 dry weight) and Cu/Mo ratio in tamarugo

lron Copper Molybdenum Zinc Cobalt Manganese Cu/Mo
Ripe fruit 90 12 4.5 21 0.06 30 2.7
Green fruit 110 12 n.d.* 27 n.d.* 32 --
Seed 160 20 5.2 72 0.10 51 3.9
Dry leaf 460 17 2.5 24 0.03 369 6.8
Green leaf 230 24 13.4 42 0.12 136 1.8
*n.d. = not determined.

Cyanogenetic glucosides and alkaloids, were not detected in any of the samples, saponins were only found in green fruits and seeds, both in low percentages, 0.007 and 0.010% respectively. The seeds appeared to have simultaneous presence of antitryptic factor (2.3 trypsin inhibited units per milligiam of defatted dry sample) and haemagglutinins (6.0 units per milligram protein) (Pak et al., 1977).

Description

Deciduous open-crowned tree up to 18 m tall, the trunk to 80 cm in diameter; with a dense mat of lateral roots and deep taproot (to 6 m deep on tree 15 m tall). Flowers golden yellow, in long axillary cylindrical spikes. Stipules spiny, 5–38 mm long. Leaves unijugate, the pinnae 3–4 cm long or less, with 10–15 pairs of leaflets; leaflets linear obtuse or acutish, 4–8 mm long. Pod arcuate, turgid, brown or stramineous, 2–8 cm long, 2–3.5 cm in diameter with ca 6–8 seeds embedded in a brownish edible pulp, seeds ovate, 3–4.3 mm long, brown (Burkart, 1976). Calyx 1.5 mm long; corolla 4–5 mm long; ovary villous.

Germplasm

Reported from the South American Center of Diversity, tamarugo, or cvs thereof, is reported to tolerate drought, high pH, salt, and sand. (2n = 28)

Distribution

Native to that part of the Atacama Desert in northern Chile known as Pampa del Tamarugal, an island salt desert about 40 km wide and 300 km long. Also planted in Argentina and recommended for other saline deserts of the world.

Ecology

Found on salty-sandy or clay loam soils, occasionally with a 40-cm salt incrustation. In its native habitat the tree ranges from 1000–1500 m elevation. Ranging from Warm Temperate Desert to Thorn Steppe through Subtropical Desert toSubtropical Thorn Forest Life Zones, tamarugo, or cvs thereof, is reported to tolerate annual precipitation of (0-)3 to 5 dm, annual temperature of 12 to 20°C, and pH of 6.8 to 8.0. The desert ecosystem of the Tamarugal Pampa is highly specific. The climate is the normal desert climate; the most biologically significant factors are: high day-time temperatures, great day-to-night temperature range, almost total lack of rainfall, occasional mist, relatively low humidity and intense sunlight. The soils are composed of deposits of fluvial origin from the cordillera of the Andes, and have a surface salt crust ranging in thickness from 10–60 cm or more. Under certain conditions of atmospheric humidity, tamarugo absorbs water through its leaves, transporting it to the root system and depositing it in the micro-rhizosphere, whence it is reabsorbed along with the soil nutrients. This explains why measurements of mean annual evaporation show much higher rates outside than inside the forest area, where a mere fraction of the water is lost in evaporation. This is also why tamarugo trees are found in areas where the ground water table lies 40 m deep and has no contact with the roots of trees (Habit et al, 1981). According to Burkart (1976) the leaves absorb water through their stomata when the relative humidity of the air >95%. Variations in salinity of groundwater had little or no effect on growth rate but distance from water table. The greater the depth to groundwater the smaller the height growth of the trees, tending to minimize the importance of absorption of water from atmosphere (Felker, 1982).

Cultivation

For rooting cuttings a 34°C air temperature and vermiculite medium is recommended. N fixation in tamarugo may be limited. Since the leaf N content appears to be sensitive to phosphorus levels, there is hope that pod N levels may also be P-sensitive. Pods are generally 10% crude protein 3% short of the 13% crude protein level required for good animal growth. In N-fixing systems, phosphate has tremendous leverage over dry matter production. N:P levels are generally ca 10:1, and N:DM ratios ca 1.5:100. Thus every kg deficient P that is corrected has the opportunity to provide 600 kg DM. Habit et al. (1981) cite the following planting instructions: Use a 2:1 mixture of earth and guano. Plant in unperforated plastic bags, 12 cm in diameter, 30 cm long, filled with this mixture and placed in a carefully-levelled planting bed. Water to saturation. Sow three to five seeds a depth of 1.5 cm. First treat with sulfuric acid for 7 minutes, then wash and let dry in shade. Keep the surface, where the seeds are planted, wet, but do not accumulate water in the bottom of the bags, as this encourages fungus growth. Treat the soil with fungicide before sowing to avoid fungus attack. Once seeds germinate, give more water but at greater intervals, to ensure moisture for the downward-growing roots. Avoid excessive use of water. Keep seedlings in nursery 3 to 5 months, until they are 8 to 10 cm tall. Be sure the roots do not pierce the plastic. Plantation spacings in the Tamarugal Pampa are at 10 x 10 m and 15 x 15 m, taking into consideration the tree's growth and its function as fodder. A pit is dug in the ground and in it a hole is made 20 cm in diameter and 50 cm deep, abundantly manured with guano. Pit depth depends on terrain, usually 80 cm in diameter by 30–70 cm deep, varying according to depth of salt crust which must be penetrated before making the planting hole.. Before planting, water hole to saturate soil as far down as possible. Split the bottom of the plastic bags at planting so roots can pass through. Remove plastic bags with care to avoid breaking the cylinder of earth. There must be enough water to penetrate to the roots and keep them moist. It is most important to avoid excess watering, which shows up at the first stages of the seedlings as a "fall" due to fungi, and later as a yellowing of the leaves. Plants are established when they send out new shoots. When this occurs, watering can be spaced at intervals of 20 days, though care should be taken to ensure that the water penetrates properly. If there is moisture in the subsoil, it is advisable to determine whether the roots have reached it by suspending watering and observing the reaction of the plants.

Harvesting

Sheep and goats feed on fallen leaves and pods (fresh seed produced from October to January). Harvested for firewood as needed, the tree coppices readily.

Yields and Economics

In their tabulation, Felker and Bandurski (1979) list yields of 12 MT/ha leaves and pods. According to Habit et al. (1981), the average yield of fruit per tree is 2.1 kg/m2 of crown projection, even higher with adult trees. With insecticides, single tree yield increased from 105 to 210 kg, translating to 10 MT pods/ha. Felker suggests 5 MT. Aerial application of insecticides was suggested. Chileans estimate cost of aerial application at $15–20(US)/ha and the heptachlor at $24 for the 4 liters required, for a total cost of $35/ha compared to $500/ha for ground application. High quality Prosopis wood retails for $6.00 per board foot ($2,540 per cu m) when cut, planed, and cured. Straight growing trees of algarobo occur in Argentina. One could get straight pieces 4 m long and 40 cm in diameter in 20 years. This wood, after being cut, planed, and dried would be worth at least $300 per tree, or $36,000 per ha (Felker, 1982).

Energy

Felker (1982) estimates that prunings from a tree would be 200 kg (not annually) suggesting 20 MT/ha. These could be converted to chips with a heating value of 18,000 BTU/kg. Felker (1982) suggests that trees should be pruned every 6–10 years, removing the lower branches which may preclude animals from eating the fallen pods. The 200 kg/tree prunings could be chipped and blown into a truck at a cost of ca $10/ton. The chips are estimated to produce energy at the rate of $1.47 per million Btu's, about 1/4 the cost of oil energy. Tractor driven chippers are available at $3,000 to $12,000 (US). If there were no market for chips, or charcoal were not available, a small wood-fired turbine could convert the wood to electricity. Felker notes that Aerospace Corporation of Virginia sells 3000 kilowatt wood fired gas generators for ca $2,250,000 (US). They consume ca 3 MT/hr generating 3,000 KWH at $0.15 KWH. At 15 trees per hour and 100 trees/ha, 1,314 ha would need be pruned every year to fuel the generator. Cross yearly electrical sales would be $4,000,000 (US) (Felker, 1982).

Biotic Factors

Habit et al. (1981) present detailed information on the insect pests of tamarugo, listing Leptotes trigemmatus (purple moth), Tephrinopsis memor (measuring worm), Hemiberlesia rapax, Heteropysylla texana, Aphis sp. (tamarugo louse), cecidomids, Eriophyes tamarugae, Ithome sp. (flower moth), Leptotes trigemmatus, Tephrinopsis memor, Frankliniella rodeos (tamarugo thrips), Crytophlebia carpophagoides (fruit moth), and Scutobruchus gastoi (tamarugo worm). Despite its anemophilous pollenization, insect participation seems important to fructification. The solitary bee Centris mixta is the most important insect pollinator. Imported Apis mellifera served as a good pollinator and honey producer (Habit et al., 1981). In addition to enumerating insect pests and control mechanisms, Habit et al. (1981) enumerate associated animals and plants. Marked increases in pod production were evident following insecticide treatment. Untreated tamarugo showed considerable abortion of young pods, much pod stunting, disfiguration, and insect holes (bruchid emergence holes). Rhizobia capable of nodulating tamarugo are being multiplied at INTEC (Felker, 1982). Hectares of dead tamarugo trees were suspected to be fungal infestations, transmitted through root graftings. Felker et al. (1981) review the pest infestations of their Prosopis plantings with suggestions for their control.

References

Complete list of references for Duke, Handbook of Energy Crops
Last update Thursday, January 8, 1998 by aw