Cultivation and production of eucalypts in South America

FAO country estimates for the areas of plantation eucalypts in 1990 show that Brazil had the second largest area after India, 3.6 million ha (). The most recent estimate, also from FAO sources, puts the figure at 3.1 million ha (). Although this massive resource is designed to meet the raw material needs of Brazil’s forest-based industries such as timber, pulp and charcoal, it has, nevertheless, indirectly influenced the development of the eucalyptus oil industry in the country, at least in the early days. Apart from China, Brazil has been the only other significant producer and exporter of Eucalyptus citriodora oil and this aros from the widespread availability of ‘waste’ leaf from Eucalyptus citriodora planted primarily for charcoal production. Charcoal is used for fuelling the furnaces in the iron and steel industries and in the manufacture of cement and Eucalyptus citriodora has played an important role in the Brazilian economy (). In addition to Eucalyptus citriodora oil, oils from Eucalyptus globulus and E. staigeriana are produced in Brazil

Production of eucalyptus oil elsewhere in South America is small compared to that in Brazil and although brief mention is made later in this chapter to Chile, Bolivia, Paraguay and some other countries, the bulk of the discussion concerns methodologies employed in Brazil. Much of what is described will, of course, be applicable elsewhere. Details are given in the form of a case study relating to a company which, until recently, produced Eucalyptus citriodora oil in Minas Gerais state. Supplementary information is provided from other sources concerning this oil and those from Eucalyptus globulus and E. staigeriana produced in Brazil.

Historical review

Introduction of eucalypts to Brazil and end use

Although eucalypts were planted in the Botanical Gardens of Rio de Janeiro as early as 1824, it was Edmundo Navarro de Andrade who established the first eucalypt plantations in the first decade of the twentieth century (). On returning to Brazil from his studies of agronomy in Portugal he brought with him seeds of Eucalyptus globulus for planting. He worked for a railroad company to provide firewood for the steam engines and wood for sleepers and the experimental plots were so successful that they led to over 200 species of Eucalyptus being introduced into Brazil.

From 1909 to 1965, about 470,000 ha of eucalypts were planted, 80 per cent of them in São Paulo state and intended mainly as a substitute for native woods for use as fuelwood. Other energy sources such as good quality coal were not available in Brazil. In 1948, the first eucalypt plantations were established in Minas Gerais to provide wood for charcoal for use by the iron and steel industries. Although Firms spp. were also being introduced, partly in response to depletion of the native Araucaria as a source of high quality timber, the high yields and quicker returns from short-rotation eucalypts saw them become the dominant plantation species. A federal law passed in 1966, and a further one in 1970, gave considerable financial incentives to companies to plant trees, and accelerated this process of reforestation. The consumption of charcoal by the cement, iron and steel industries has continued to increase although this has been tempered by lower prices of imported coal since 1997 and other economic factors which are beginning to make alternative forms of fuel more attractive.

A further impetus to the planting of eucalypts was the increasing use of short fibre pulp for paper making in the 1970s. The favourable conditions for growth in Brazil, the development of appropriate silvicultural techniques and the advantages gained by using cloned planting stock and hybrids led to the massive plantations that now feed Brazil’s pulp mills. Aracruz Celulose SA. alone has 132,000 ha of eucalypt plantations. In the 1980s, coinciding with growing environmental concerns worldwide on the loss of natural forests and other related issues, laws were passed which removed the financial incentives to the forestry sector provided by the earlier legislation. Today, new plantations are mostly established on previously harvested areas rather than on new land.

Brazil’s eucalypt plantations extend from the northern states of Pará and Maranhão to the eastern and southern states of Bahia, Minas Gerais, Espírito Santo, São Paulo, Paraná, Santa Catarina and Rio Grande do Sul. The species grown for pulp are mainly E. grandis, E. urophylla (and hybrids of these) and E. saligna, that is, species containing little or no leaf oil, together with E. dunnii and a few oil-yielding species such as Eucalyptus globulus, E. viminalis and E. tereticornis. Although Eucalyptus citriodora is still the dominant species for charcoal production, there has been some replacement of it by other, faster growing species of eucalypt.

Eucalyptus oil production in Brazil

Production of essential oils from eucalypts in Brazil started during World War II. It began as a result of a collapse in international trading of citronellal-rich oil produced in Java from citronella. At that time there were, in Brazil, some Eucalyptus citriodora and Eucalyptus globulus plantations and these were used by the first local companies to produce essential oils, mainly citronellal-rich oil from Eucalyptus citriodora. São Paulo state was the most important area for essential oil production and in the 1970s Brazil became the biggest producer of Eucalyptus citriodora oil in the world. Later, Minas Gerais, Espírito Santo, Mato Grosso do Sul and Bahia contributed to the increase in Brazilian production of this type of oil (). Eucalyptus citriodora oil is employed in whole form for fragrance purposes but is also used as a source of citronellal. This in turn is used either as an aroma chemical or for conversion to hydroxycitronellal and other compounds used in perfumery. Eucalyptus globulus, one of the first species to be introduced in Brazil, is a source of cineole-rich medicinal oil. However, while Eucalyptus citriodora is widely distributed from the north to the south of the country, Eucalyptus globulus is highly dependent on specific climatic and edaphic conditions. Furthermore, Eucalyptus globulus in Brazil is used mainly as a source of leaf oil whereas Eucalyptus citriodora is grown widely for timber and charcoal production and so forms an abundant, ready-made source of ‘waste’ leaf suitable for distillation. Today, the main eucalyptus oil distilleries in Brazil are located in São Paulo, Minas Gerais, Bahia and Mato Grosso do Sul and use Eucalyptus citriodora leaf as the principal, or sole, raw material.

Of the many hundreds of species of Eucalyptus which exist, fewer than twenty have ever been exploited commercially for oil production (). For a country as large as Brazil, with continental dimensions and a very large edaphic and climatic diversity, it is perhaps not surprising that of the half dozen most important species for oil production worldwide, two are utilised in this way in Brazil, Eucalyptus citriodora and Eucalyptus globulus. A third species, E. staigeriana, is also grown for oil and Brazil is the only such source. Eucalyptus citriodora and Eucalyptus globulus furnish oils in approximately 1—1.5 per cent yield (fresh weight) containing citronellal (65—85 per cent) and 1,8-cineole (around 65 per cent), respectively. E. staigeriana oil, in yields of 1.2—1.5 per cent, contains a more complex mixture of terpenes (see later), but with citral as an important fragrance component.

Today, the production of eucalyptus oil in Brazil is carried out by a small number of medium-to-large companies, together with some smaller ones. The technology used in the distillation of the oil is virtually the same for all of them and the main difference is in the way in which they obtain their raw material. Larger companies have their own eucalypt plantations, established specifically for oil production, while the smaller ones rely on ‘waste’ leaf bought from small landowners or from eucalypt plantations managed for the production of wood (for poles and timber as well as charcoal and firewood). Both large and small companies sometimes enter into joint ventures with those involved in Eucalyptus citriodora-based charcoal production — the leaves collected from harvested areas are sent to the distilleries and a percentage of the profits from the production of oil is paid back for the use of the raw material.

Oil characteristics

The general characteristics of the oils from the commercially important oil-bearing eucalypts have been described elsewhere in this volume but data relevant to South America are presented in Table Yields and characteristics of leaf oils obtained from eucalypts growing in South Americaa:

SpeciesCountryDatabMain constituent (relative abundance, %)Oil yield c (%)
E. camaldulensisArgentinarp-Cymene (31.2)0.4
Chilerp-Cymene (31.4)0.2
E. cinereaArgentinar1,8-Cineole (69.0)0.7 (air-dry)
Brazilr, r1,8-Cineole (76.3, 61.0–62.8)1.4, 4.1–8.2 (dry)
Eucalyptus citriodoraBrazilcCitronellal (75.7)
ChilerCitronellal (85.1)3.0
UruguayrCitronellal (59.2)1.3
Eucalyptus globulus

subsp. globulus

Brazilc1,8-Cineole (73.6)
Chilec1,8-Cineole (60–75)1.2–1.7
r1,8-Cineole (60.3)1.0
Uruguayr1,8-Cineole (64.5)0.8
E. piperitaBrazilrPiperitone (7.5–40.5)0.2–2.1
r1,8-Cineole (47.4)
E. staigerianaBrazilc, cCitral (37.2, 22.1)—, —
BrazilrCitral (10.1–63.0)0.3–2.5
E. viminalisUruguayr1,8-Cineole (43.6)0.4

a The species listed are those where there is commercial production of the oil in South America (not necessarily in the country specified) or where there is, or has been, production elsewhere in the world. Some of the references cited refer to other species, in addition to those indicated here.

b Indicates whether data are research results (r) or relate to commercial production (c).

c Yields are on a fresh weight basis unless otherwise indicated.

E. staigeriana oil, which is used in perfumery in whole form, has, as implied by the variable but relatively low figures for citral shown in Table 10.1, a complex composition. Analysis of one such commercial sample found 26.8 per cent limonene, 10.8 per cent terpinolene, 9.6 per cent neral and 12.5 per cent geranial (i.e. 22.1 per cent citral), 4.7 per cent methyl geranate, 4.6 per cent geranyl acetate and 4.7 per cent geraniol (Coppen unpubl.).

Specifications provided by a leading producer of Eucalyptus globulus, Eucalyptus citriodora and E. staigeriana oils in Brazil are a minimum 70 per cent 1,8-cineole, minimum 70 per cent citronellal and minimum 20 per cent citral, respectively.

Eucalyptus citriodora: a case study of its cultivation and distillation in Brazil

In some regions of São Paulo state, the lower branches of oil-bearing eucalypts are periodically cropped for oil production, leaving the stems standing for further growth and future use for timber. In parts of Minas Gerais and Bahia, the availability of suitable ‘waste’ leaf from eucalypt plantations managed for charcoal production is taken advantage of to produce oil when the tree is felled at the end of the rotation. In both cases eucalyptus oil production is a secondary activity. There are also companies, however, who grow eucalypts specifically for oil and, here, the trees are planted and managed more intensively, with much shorter rotations than the normal ones of around seven years.

The company used as a basis for this case study was founded in 1990 and established itself in the western part of Minas Gerais, where it acquired 2500 ha of land in the savanna region. Five million trees of Eucalyptus citriodora were planted specifically for oil production. The company built a distillery (annual production capacity 360 t oil) and infrastructure such as laboratories, offices and a village for its 250 employees.

Silviculture

Site selection

Eucalyptus citriodora does not present good leaf biomass yield in areas subject to strong winds since they desiccate the leaves and lead to leaf drop. It is very important, therefore, to select sites for its cultivation which are not exposed to winds. The sites should also be located in flat or gently undulating areas to facilitate mechanised silvicultural and harvesting operations. The stands are best kept below 40–50 ha in size and planted with the contours when necessary.

Land preparation

Eucalyptus citriodora is very demanding on soil quality and does not grow well where the pH is lower than 5.5 (such as lateritic soils). It is therefore important to analyse soil samples for each plot before planting and to correct soil acidity where necessary. Nutrients such as phosphorus and potassium, and micronutrients such as boron and zinc, should also be added if required. With the annual harvesting of leaf, and the consequent continued removal of plant biomass from the land, occasional foliar analysis is also desirable in order to monitor and rectify any depletion of nutrients and micronutrients.

In the area considered in this case study there were sandy soils and the first operation consisted of locating contour lines in the field to avoid erosion, mainly during the rainy season. To improve the physical and chemical properties of the soil it was common practice to plant legumes one year before planting the eucalypts. These plants are then incorporated into the soil during land preparation. After demarcation of the stands and the building of roads and fire breaks, 1000 kg of lime and 500 kg of natural phosphate per hectare are applied five months and one month, respectively, before planting the eucalypt seedlings. This is followed by arrowing and ploughing the soil to a depth of 30 cm and furrowing to 60 cm. Finally, the soil is levelled with a lighter arrow and the planting lines in contour are marked with furrows 30 cm deep. Before arrowing and ploughing, leaf cutting ants are controlled using sulfluramid-based pesticides.

Establishment

Before planting the seedlings a final check is made on the absence of leaf cutting ants. The spacing between rows is 2.8 m and the distance between plants in the same row is 0.75 m. A total of 300 kg of NPK (20 : 20 : 20) plus 6 per cent of boron is applied per hectare, distributed along the furrows where the planting holes are located. Planting is carried out during the rainy season as soon as moisture conditions in the soil are satisfactory. At that time, 2g of pesticide are placed in each planting hole to prevent attack by termites. Replanting of seedlings which do not survive is carried out fifteen days after the initial planting to avoid heterogeneity in the size of the trees later on. New applications of fertiliser are made thirty and sixty days after planting using 50 g of NPK (20 : 0 : 20) per seedling. For each 40–50 ha of a new eucalypt plantation it is necessary to have a labourer to tend the site and to prevent attack of the seedlings by leaf cutting ants.

In the region applicable to this case study the planting months are generally November and December, coincident with the rainy season for the western part of Minas Gerais. High temperature and air humidity at this time make it necessary to discontinue harvesting of the leaves, otherwise fermentation of the raw material is promoted and low quality essential oil is produced. Advantage is taken of this ‘down time’ to undertake maintenance of the distillery and to attend to other necessary work in the eucalypt stands.

Maintenance

The most important silvicultural treatment of eucalypt plantations established for essential oil production is weeding. In the study in question this involves dealing mainly with grasses such as Brachiaria brizantha. Initially, control was achieved by applying 4l/ha of Roundup twice a year. This resulted in a relatively low tending cost and a good level of soil conservation. Later on, herbicide application was replaced by renting the forest land to local farmers so that the pastures could be used by their cattle. Rental was paid on the basis of 10 per cent of the dollar value of each 15 kg of living animal per month. Besides controlling the grass and other weeds which might compete with the eucalypts, the cattle provide an additional income for the company. Two heads of cattle are enough to control the weeds and avoid the use of 8l of Roundup per year. The use of cattle to control the weeds, mainly the grasses, was also valuable in reducing the fire risk.

As mentioned earlier, periodic soil and foliar analyses are carried out for individual stands and fertilisers applied when necessary, usually at the beginning of the rainy season. Control of leaf cutting ants is carried out every month of the year.

Rotation

The eucalypt stands are grown under an intensive, coppice system of management, solely for the purpose of oil production, and harvesting takes place once a year in different months. There are therefore always stands at different ages and stages of development. There are no special treatments for the coppices or for the stumps but the objective is to obtain the biggest possible production of leaf biomass. The trees never reach more than 5 m in height before they are cut and so irrigation can be used if necessary. The first harvest is usually taken at around 15–16 months (about March) with subsequent harvests at approximately twelve-month intervals. After eleven or twelve years the original stumps are removed and new seedlings planted.

Silvicultural practice elsewhere in Brazil

Propagation is from seed which is germinated over a period of 2–3 weeks; the seedlings spend a further three months in the nursery before planting out. Propagation by cuttings has not been successful. Eucalyptus globulus is shy to seed in Brazil and most seed for planting purposes is bought from Australia. Seed of Eucalyptus citriodora and E. staigeriana is collected from mature trees within the company’s plantations.

As in the case study, contour planting is practised in order to avoid soil erosion. Spacing is 3.5 m X 0.5 m. Fertiliser application is usually too expensive to carry out but ‘spent’ leaf from the distillery is returned to the fields to provide some replenishment of nutrients (). Undergrowth around the trees is cleared annually.

Harvesting

Initially, the company used to employ manual labour with chain saws to cut the small trees and to remove the branches with the leaves for transportation to the distillery. No stem biomass was utilised in any subsequent stage of the processing and the energy required to produce steam was derived from the residues of distillation. Later, the company adapted a circular saw fitted to a tractor to mechanise the harvesting operation and so reduce labour costs. The potential hazards associated with the use of eight chain saws were also thereby eliminated. With this new equipment the trees are cut leaving a stump 0.8–0.9 m in height. Tests showed that this stump height gave the best results in terms of percentage of subsequent sprouting. About a third of a hectare per hour can be harvested. Each year thereafter the cut is made 2–3 cm above the previous one, resulting in a loss of only 2–3 per cent of the coppicing per year.

Loading of the trucks which take the harvested material to the distillery is also mechanised and approximately 0.6 ha of cut biomass can be loaded per hour. The annual yield of biomass is around 20 t/ha.

Approximately 30 per cent of the harvesting operation involves manual labour to select the branches and leaves to go for distillation. The calorific value of this spent material after distillation – when used to fuel subsequent distillations – is smaller, and there is less of it, than the residue from the small whole trees which result from the mechanised part of the harvesting. These are chipped at the distillery (see below). In both cases, any surplus residue not fed to the boiler is either sold locally or returned to the fields as organic fertiliser.

Elsewhere in Brazil, the harvesting of coppice-managed eucalypts for oil is sometimes carried out more frequently than every twelve months. One company clips the side branches a year after planting and takes the first full harvest at eighteen months. Thereafter, harvesting of branches and foliage is usually carried out three times in two years. In the fourth year most of the stems are cut approximately 60 cm from the ground and allowed to sprout; 10 per cent are left uncut and allowed to grow for timber production. The first harvests from the cut stems are taken after twelve months, with subsequent ones as before. Some trees have been harvested for thirty years or more. Most of the harvesting is carried out manually but mechanical grabbers go between the rows loading the heaped foliage onto tractor-trailers for transport to the distillery.

Distillation

Once the trucks containing the harvested biomass arrive back at the distillery each load is weighed and then fed into a chipper to furnish a mix of chipped eucalypt wood and leaves. The chipper has the capacity to process 20 t/h of biomass. This biomass is then loaded into the stills for distillation. Some loss of moisture from the charge before being put into the stills is beneficial since the oil concentration is thereby increased. However, the biomass should not be exposed to the air for too long since there will be some loss of oil through evaporation and/or enzymic oxidation or decomposition.

The distillery in this case study has eight stills, each with a nominal capacity of 1.5 t of mixed, chipped biomass (stem, branches and leaves) and 1.0 t of biomass comprising whole small branches and leaves. When loading the stills with unchipped material it is essential to pack firmly and uniformly so as to avoid air gaps and subsequent channelling of steam when distillation is in progress. This is usually achieved by the workers who load the stills stepping inside them and stamping the biomass down; at the same time a little steam is trickled through the charge.

Once loaded, detachable, insulated lids are attached to the stills, forming a good, steam-tight seal, and distillation proceeds in the manner described in site. Steam is generated from a separate boiler at 90— 110°C and uses ‘spent’ leaf from previous distillations as fuel. Although multi-tubular condensers are the most efficient, the company in question uses a simple coiled pipe running through a cold water tank to condense the oil/steam vapours. Each distillation takes about 1.25 h to complete and yields about 1.0—1.25 per cent of oil. This represents a yield of approximately 200 kg of oil per hectare of Eucalyptus citriodora.

For each distillation charge, the oil is analysed to check citronellal content. The oil is allowed to stand to cool for 48 h and the fully separated oil is then transferred to separate containers for storage.

Distillation by another Brazilian company utilises 1- or 2-t stills operating in pairs, with one lid and condenser per pair (). In this way, one still can be loaded with leaf while the other, already packed, is being distilled. At the end of this distillation the lid is removed and transferred to the second still, where distillation commences, while the first still is unloaded and repacked with fresh material. Distillation usually takes about one hour for Eucalyptus citriodora and a little longer for Eucalyptus globulus and E. staigeriana. With year-round harvesting and distillation, average oil yields equate to approximately 140 kg/ha for Eucalyptus globulus and 100 kg/ha for Eucalyptus citriodora and E. staigeriana. Spent leaf from the distillation is returned to the fields to act as a slow-acting fertiliser ().

Eucalyptus oil production elsewhere in South America

The most recent estimates of eucalypt plantations () show that Argentina, Peru, Chile and Uruguay all have substantial areas – 245,000 ha or more. According to Brown (2000), Eucalyptus species accounted for 90 per cent of the forest plantation area in Peru in 1995 and 80 per cent of the area in Uruguay. However, none of these countries have ever produced eucalyptus oil on a scale to match Brazil’s. The feasibility of exploiting Eucalyptus globulus for oil production in Peru has been investigated but no significant commercial production is known to have developed as a result. Research on oil-bearing eucalypts has been undertaken in Argentina () and there has been some commercial production of oil.

Chile, Bolivia, Paraguay, Uruguay, Argentina and Colombia have all produced oil at one time or other but no reliable data relating to current production are known. Chile and Bolivia produce cineole-rich oil from Eucalyptus globulus, while Paraguay produces Eucalyptus globulus and Eucalyptus citriodora oils. Chile, Paraguay and Argentina all exported oil in 1999 and/or 2000.

Chile

Although planting of eucalypts on an industrial scale began in Chile in the 1930s it was not until the late 1980s that rates of planting rapidly increased, reflecting the new-found enthusiasm for Eucalyptus as a source of wood for pulp and paper making. By 1992, planting had reached almost 41,000 ha per year and estimates at about that time put the total area under eucalypts at 180,000 ha (). More recent estimates put the figure at 245,000 ha () and it is predicted that there may eventually be 300,000 ha of eucalypt plantations in Chile (). Chilean plantings are almost entirely of Eucalyptus globulus, mostly in the Valparaiso and Bio–Bio Administrative Regions in the centre of the country, although E. camaldulensis and non-oil bearing species such as E. nitens, E. delegatensis and E. regnans are starting to be planted, according to climatic preferences.

Such a massive resource of leaf biomass from a species recognised for its oil quality, Eucalyptus globulus, invites exploitation. Chilean production of eucalyptus oil and purified eucalyptol (1,8-cineole) intended for export began in the 1980s () and new investment was still taking place in 1991 (). Oil containing 60–75 per cent 1,8-cineole is distilled in yields of 1.2–1.7 per cent from ‘waste’ leaf. Yields of such leaf from trees planted for wood production have been estimated at 8–10t/ha, equivalent to approximately 100–150kg/ha of oil (). Other species of eucalyptus have been examined as sources of oil () but their limited plantings have meant that none has ever come close to matching Eucalyptus globulus as a commercial source.

Bolivia

Published accounts of Bolivian oil production are scant but Canadian assistance in the 1980s led to the establishment of farming cooperatives in Cochabamba, whose aims were to produce essential oils from locally grown plants (). Three oils were chosen for production – eucalyptus, mint and lemongrass – and by 1991 ten cooperatives had been formed, each using a 5 t capacity still for distillation. In the case of eucalyptus, the nearby university rectified the crude oil and the final product was then sold to various Bolivian end-users. Although carried out on a relatively small scale, it well illustrates the way in which such an operation, if properly organised, can generate much-needed cash income for rural families.

Research and development

Genetic improvement and the establishment of seed orchards for the production of improved planting stock are vital for the maintenance of a competitive eucalyptus oil industry but more research is needed to quantify the likely gains. Xavier et al. () analysed the genetic variability of forty-two-month old Brazilian-grown Eucalyptus citriodora in terms of oil and citronellal content and found that selection within families provided greater gains than selection among progenies. The need for careful provenance selection is illustrated by the analyses of Argentinean and Chilean E. camaldulensis (De Iglesias et al. 1977, Erazo et al. 1990): both sets of plant material yielded oils richer in p-cymene than 1,8-cineole (). If this species were to be considered as a potential oil-producing species (rich in cineole) then seed from the well-known Petford provenance would be better planted and tested.

The Department of Forestry of the Federal University of Viçosa, through the Society for Forestry Research, has always been committed to this kind of research and several collaborative studies have been undertaken with the company which has been the subject of the case study above. These have included the genetic improvement of Eucalyptus citriodora for oil production and the evaluation of eighteen other eucalypt species and provenances with potential for essential oil production. In addition to the three species that are currently utilised in Brazil, E. camaldulensis has been found to have great potential.

 

Selections from the book: “Eucalyptus. The Genus Eucalyptus”. Edited by John J.W. Coppen. Series: “Medicinal and Aromatic Plants — Industrial Profiles”. 2002.