Brazil is a very young country. It was discovered in 1500 by the Portuguese navigator Pedro Álvares Cabral and was Portuguese until 1822, when it became independent. Abolition of slavery came in the same century, in 1888, and the first Republic was established two years later. The large majority of slaves brought to Brazil came from African ethnic groups including Bantu from Southern Africa (the Congo, Angola and Mozambique), as well as Samba, Moxicongo and Anjico, and ethnic groups from the north-western coast of Africa such as Nago, Jeje, Fanti, Achanti Haussa, Mandinga, Tapa and Fulla, originating from regions from Senegal to Nigeria.

With the Portuguese being the first, there have been many immigrations from Europe, principally in the 19th century (Italy, Spain, Germany, Poland and Ukraine), as well as from Japan, Syria and the Lebanon. From 1875 until 1960, about 5,000,000 Europeans emigrated to Brazil. All these immigrations were added to an indigenous population estimated at 5,000,000 when European colonists first arrived (at present reduced to thousands), which conferred on Brazil a uniquely rich ethnic and cultural diversity.

The census carried out by the Brazilian Institute of Geography and Statistics-IBGE (2000) indicates that the Brazilian population is some 169,590,693 inhabitants, which corresponds to a geometric medium annual growth rate of 1.93 percent. This last census indicates a strong tendency to a changing population age pyramid with an increasing age span. Life expectancy at birth of the total population is 63 years for men and 71 years for women.

Brazil is the fifth most populous country in the world with 2.8% of the world’s population. Despite having less than 11% of the total territory, the South-east region contains 42% of the Brazilian people. On average the population density is not very high (19.92 hab/km²) but it varies strongly between different communities (0.13 to 12,897.8 hab/km²). In the last five decades there has been an enormous reversal in the ratio of rural/urban population. At present, only 18.8% live in the countryside.

In terms of political organization, Brazil is a Federation, composed of a Federal Union, 26 states, 1 Federal District and 5,507 municipalities. The government system is presidential, organised on Federal, State and Municipal levels.

Figure 1. Latin America and Brazil

Brazil is located in the Western Hemisphere, between the meridians 34^o47'30" and 73^o59'32" to west of Greenwich. Located between the parallel of 5^o16'20" of north latitude and 33^o44'42" of south, it is cut to the north by the Equator and, to the south, by the Tropic of Capricorn, therefore, about 90 percent of its territory in the Southern Hemisphere. Part of the American continent, Brazil is the only Portuguese-speaking nation in the Americas (see Figure 1).

Brazil is in the centre-oriental portion of South America and has a border with nine countries: Uruguay, Argentina, Paraguay, Bolivia, Peru, Colombia, Venezuela, Guyana and Suriname, and with the French Department of Guiana; exceptions are Ecuador and Chile (Figure 2).

Figure 2. Location of Brazil and its political divisions

Its dimensions characterize it as a continental country, its territory occupying 1.6% of the surface of the terrestrial globe, with 5.7% of the dry land of the planet and 20.8% of the surface of the American continent, as well as 12.7% of the world's river water (5,190 km³ a year). The Brazilian territorial area is 8,547,403.5 km² and its perimeter embraces 23,086 km, being bounded over 7,367 km, by the Atlantic Ocean, that is to say 31.9% of its borders. It is the third largest country in area and the largest in South America, occupying 66% of the South American territorial area. This area comprises arable land (5%), permanent crops (1%), permanent pastures (22%), forests and woodland (58%) and others (14%) (1993 est.).

Brazil is the tenth-largest economy in the world, with 1999 Gross Domestic Product (GDP) of US$ 557.5 billion produced by well-developed agricultural, mining, manufacturing, and service sectors. Between 1993 and 1998 the GDP increased 80% (US$ 429.7 to US$ 775.5 billions), the same period in which the annual inflation rate dropped from 2,489.1% to 2.4%. The 1999 performance reflects the 1998 global economic crisis. The GDP per capita (purchasing power parity) is US$ 6,150 (1999 est.). The GDP composition by sector in 1997 had been: agriculture: 14%; industry 36% and services 50%.

Brazil has a highly diversified economy with wide variations in levels of development, having the most advanced industrial sectors in Latin America. Industries range from automobiles, steel, and petrochemicals, to computers, aircraft, and consumer durables. The leading manufacturing industries produce textiles, shoes, food products, steel, motor vehicles, ships, and machinery. Most large industry is concentrated in the south and southeast. The northeast is traditionally the poorest part of Brazil, but is now beginning to attract new investment.

Brazil has vast mineral wealth, including iron ore (it is the world's largest producer), quartz, chrome ore, manganese, industrial diamonds, gem stones, gold, nickel, tin, bauxite, uranium, and platinum. Natural resources also include petroleum and hydropower. Most of Brazil's electricity comes from waterpower and it possesses extensive untapped hydroelectric potential, particularly in the Amazon basin.

In addition to coffee, Brazil's exports include iron, concentrated orange juice, soybeans, and footwear. In 1999 exports totalled US$ 48 billion. Crude oil, manufactured goods, and chemical products head the imports (US$ 49.2 billion) leading to a trade balance which has been negative since 1995. Most trade is with the European Union nations, the United States, Argentina, and Japan.

Brazil is a country of contrasts and significant poverty levels contrast with the relatively high GDP; around 32,000,000 people were below the poverty line in 1993. The concentration of wealth is among the highest in the world, with the the 10% richest sharing 47.9% of income, yet the 10% poorest share only 0.8%! Malnutrition affects 5% of children under five, which contributes to an infant mortality rate of 3.6% live births. Unemployment rate averaged 7.6% in 1999.

Brazilian agriculture is well diversified, and the country is largely self-sufficient in food. The sector contributes 14% of the GDP, and all the agricultural chain 27%, employing almost 17,900,000 people. Of these, 67% are male and 14% are under 14 years of age. Brazil produced 80 million tons of grains in 1999, particularly soybean, maize, rice, bean and wheat (Table 1).

Other important crops are sugar cane (330 million tons), citrus fruits (32 million tons) and coffee (30 million bags). Cocoa, tobacco, and banana are also important. Forestry accounts for 4 percent of the GDP.

The largest agricultural exports (in value) in 1998 were coffee, soybeans, soybean cake, orange juice and sugar. Soybean is the major agricultural commodity when all of its products (raw soybean, meal, oil, etc) are added. The total value of agricultural exports in 1998 was US$15.3 billion, while the total value of agricultural imports in 1998 was US$ 6,306.4 million. Wheat and dairy products are the main agricultural imports. Brazilian agribusiness and policies are strongly oriented towards international markets due to the need to achieve a positive commercial balance and because agriculture is one of the main sources of income.

According to the "Confederação Nacional de Agricultura" (CNA, 2001), 85% of farmers are land owners with an average age of 52 years (32% under 45, 11% over 70). Most of them have a low level of schooling, with two thirds having less than 6 years schooling; the younger have more. To illustrate the contrasting characteristics of almost all Brazilian indexes, nearly half of farms (44%) have no access to electricity and 60% have no tractors, but 17% of farmers have computers!

Average farm size is not very informative in so vast a country. Two thirds of the farms in Brazil are under 100 ha. In Southern Brazil the average is 92 ha while in "Centro-Oeste" it is 897 ha. Land concentration has been a trend since the middle of the last century. In 1996, 4,800,000 farms occupied 350,000,000 hectares and of these 80.6% were under 50 ha, but shared only 12.2% of the total agricultural land. On the other hand, 1% of farms were larger than 1,000 hectares, occupying 45.1% of all land used in agriculture.

The distance between farm and the nearest urban centre is 23 km on average, but again there are many contrasts (in "Centro-Oeste" it is 350 km). The tendency to migration is variable, being 33 for each 100 farms in the South compared with 66 for each 100 farms in the Southeast region.

In Southern Brazil, 46% of farmers earn less than US$ 100/year/farm (liquid revenue), the gross revenue being US$ 318/ha (all activities comprised, but this is only US$ 150/ha in "Pernambuco" state, to illustrate the variability). To understand how farmers can survive with such a low income it should be mentioned that 64% of commercial farmers have other, off- farm, sources of revenue.

Government finances only 16% of rural commercial activities. Consequently, 34% of farmers believe that the major limitation to their activity is credit. Only 0.3% believe that technology is a primary limiting factor. This probably reflects the average low level of education. For example, in the most intensive ruminant sector, the dairy cattle sector, only 5% of farmers own milking machines and 5.9% use artificial insemination. Of these farmers, 0.2% percent believe that extension is the major limitation even if only 34% of them received some type of agricultural assistance at least once a year, but 71% intend to increase it. Less than 1% of Brazilian farmers carry out any kind of natural resource protection, despite the great increase in soil conservation by direct drilling, mainly concentrated in Southern Brazil in recent years.

The predominant production system is a simple one based on grazing and relying on native and cultivated pastures, which are grazed at continuous stocking all year round. Forage conservation is only utilized in intensive dairy production systems and some rare feed-lot systems. Of the 164,621,038 cattle, 74.5% are beef cattle and 21.5% dairy cattle. In addition there are 14,399,960 sheep, 1,068,059 buffaloes and 8,622,935 goats, the latter showing a considerable increase recently. To complete the domestic herbivore population (and those requiring forage) there are 5,831,341 horses and 2,572,172 other equidea. While stock numbers have been more or less the same since 1994 (for cattle), the number slaughtered have increased almost two fold. About 31,600,000 head were slaughtered in 1999, with only 3,200,000 receiving any kind of intensification during the production process (conserved forage, supplements, feed-lot, etc.).

It is estimated that 38.0 kg/year of beef are consumed per capita (in the mainly metropolitan regions). To give an idea of its market value, in 1999 the farmer received on average US$ 0.6/kg of liveweight. His product has different destinations; on average 65% of the beef goes to supermarkets, restaurants, hotels and industrial catering, 30% to butcher’s and 5% to special meat shops. In 1993, the beef sector provided 6,834,000 jobs, involving 1,793,324 farm units and occupying 221,982,144 ha. In 1999 it produced 6,500,000 tons of carcass-equivalent. Other meat products include 4,500,000 tons of chicken and 1,600,000 tons of pork.

In 2000 twenty billion litres of milk were produced, which represent a production of 4.9 l/cow/day. Milk consumption per capita is around 246 ml (daily intake recommendation is 400 ml/day) and 75% of national consumption goes to 20% of the population. Dairy products, apart from wheat, are the most important agricultural import, accounting for US$ US$440M in 1999, however from the 1999 importation figure of 2,41 billion litres of milk, this fell to only 0,78 billion litres in 2001. The dairy sector has been deregulated during the last decade and at present 60% of the Brazilian market is controlled by transnational companies. Imports pass to private industry. European milk enters Brazil at half of its actual cost.

Exports of meat totalled some US$ 400,000,000 in 1997: 150,000 Mt of meat, mainly to Europe (50.6%) and USA (37.44%). Exports increased to 541,000 Mt of carcass-equivalent in 1999 worth US$ 762,000,000.

Brazil is totally within the South American Platform, whose basement is of very complex geologic evolution, originating in the Archean period. Brazil had its consolidation completed between the Proterozoic Superior period and the beginning of the Palaeozoic period, with the closing of the Brazilian cycle. The basement of the South American Platform is essentially on metamorphic rocks of amphibolite to granulite facies and granitoids of Archean age, associated with the Proterozoic units that are usually represented by folded strips of green schist facies and sedimentary and volcanic coverings (seldom metamorphosed) and several granitoids. That basement is widely exposed in great shields, separated from each other by fanerozoic coverings, whose limits extend to the neighbouring countries. Prominent are the shields of Guyana, Central Brazil and the Atlantic.

The Guyana shield extends to the north of the basin of "Amazonas". The Brazil-central, or Guaporé shield extends to the interior of Brazil and south of that basin, while the Atlantic shield is exposed in the eastern portion reaching the Atlantic. These shields are exposed in more than 50 percent of the area of Brazil.

On that platform were developed in Brazil, in stable conditions of ortho-platform, starting from Ordovician-Silurian, the sedimentary and volcanic coverings that spatially filled three extensive basins with sineclisis character: "Amazonas", "Paraíba" and "Paraná". Besides those basins, several other smaller basins, including coastal basins and other sedimentary areas, are exposed on the platform.

The relief of Brazil is divided into two great plateau areas and three plain areas as follows:

• Guyana Plateau, embracing the mountainous area and the Amazon North Plateau, in the extreme north of the country, it is an integral part of the shield of Guyana, presenting Precambrian crystalline rocks. This area includes the highest point in Brazil - the "Pico da Neblina", with an altitude of 3,014 m.
• Brazilian plateau, subdivided into Central, "Maranhão-Piauí", North-eastern Brazil, mountains and plateau of the East and Southeast, Southern and "Uruguayan-Riograndense", is formed by quite worn crystalline lands and sedimentary basins. It is located in the central part of the country, and encompasses great areas of the national territory.
• Plains and Amazon low lands, in the North of the country, below the Plateau of Guyana, present three different altimetrical levels - valleys, constituted by lands of recent formation near the margins of the rivers; fluvial terraces, with maximum altitudes of 30 m and periodically flooded; and low-plateaus, formed by lands of Tertiary age.
• Plain of the "Pantanal", in the west of the state of "Mato Grosso" do Sul and Southwest of "Mato Grosso", are formed by lands of Quaternary age. Plains and coastal lowlands, along the coast from "Maranhão" to the south of the country, are formed by lands of the Tertiary and by current lands of the Quaternary.

It should be noted that the Brazilian relief does not present formations of very high mountainous chains and prevailing altitudes are below 500 m, since it was developed on an old geologic base, without recent tectonic movements.

In agronomic terms, it should be noted that the main soils are Ferralsols, which are strongly predominant. Ferralsols are extremely weathered soils, often developed on trans-ported materials of Pleistocene or older age in a humid or very humid tropical climate and covered by a tropical rain forest or semi-deciduous forest. These soils are characterised by the dominance of kaolinite clays and a residual accumulation of iron and aluminium oxides and hydroxides, a stable soil structure, a low silt/clay ratio and a very low content of weatherable minerals. They are deep to very deep and generally show yellowish or reddish colours. Ironstone nodules and iron-pans, inherited from previous land surfaces, are common.

Ferralsols are poor chemically, with a low ion exchange capacity, and nutrient reserves that are easily depleted by agricultural practices, while fixation of phosphorus is a major problem. The content of available aluminium may reach toxic levels (84% have acidity constraints), as may manganese also. On the other hand, the physical characteristics of these soils are quite favourable; because of their high permeability and stable micro-structure they are less prone to erosion. Ferralsols are easy to work but the surface is liable to compaction and crusting if heavy machinery is used to clear forest or if they are overgrazed.

Figure 3. Details of the soil of Brazil
Key to the soil map

The chemical constraints of these soils may be overcome in part by careful fertilization, including both phosphate and lime, but attention must be paid to mode and timing of application. Ferralsols are used to grow a variety of annual and perennial tropical crops, either by sedentary or shifting cultivators. According to the FAO classification there are still Acrisols and Leptosols. In a lesser extent, Lixisols, Plinthosols, Arenosols and others.

According to the Soil Aptitude Chart of Brazil, 35% of the territory is not recommended for agriculture due to low fertility and steep slopes. Salinity is not a significant factor, accounting for 2% of the land surface. 7% of soils are shallow. Only 9% of the surface has no constraints for agricultural use, with little nutrient limitation, good drainage as well as physical soil properties, and sufficient precipitation.

Details of chemical and physical soil limitations in Latin America.

The climate of a given area is conditioned by several factors, among them are: temperature, rains, atmospheric humidity, winds and atmospheric pressure - which, in turn, are conditioned by factors such as altitude, latitude, relief characteristics, vegetation and continentality.

Brazil, due to its continental dimensions, possesses a very wide climatic diversity, influenced by its geographical configuration, its significant coastal extension, its relief and the dynamics of the masses of air on its territory. This last factor assumes great importance, because it acts directly on the temperatures and the pluviometric indices in the different areas of the country.

The air masses, especially those that occur more directly in Brazil, are, according to the Statistical Annual of Brazil (IBGE): the Equatorial air mass, which is divided into Continental Equatorial and Atlantic Equatorial; the Tropical air mass, also divided into Continental Tropical and Atlantic Tropical; and the Polar Atlantic air mass. All these air masses provide the climatic differentiation in Brazil (Figure 4).

Thus climates vary from very humid and hot climates, coming from the Equatorial air masses, as is the case for the great part of the Amazon area; to very strong semi-arid climates, such as those in the hinterlands of north-eastern Brazil.

Figure 4. Climate of Brazil
[Adapted from Atlas Climatólogico do BrasilBrasil (1969) by Homero Bergamaschi (2001)- Personal communication]

The Northern Area and part of the interior of the North-east region experience annual medium temperatures above 25^o C, while in the South of the country and part of the Southeast annual medium temperatures are below 20^o C. Absolute maxima above 40^o C are observed in the interior lowlands of the Northeast Area with little variability during the year, which characterises the hot climate of these regions. In mid-latitudes, temperature variation throughout the year is very important for climate definition in the depressions, valleys and lowlands of the Southeast; in the "Pantanal" and lower areas of the Middle-West; and in the central depressions and in the valley of the river Uruguay, in the Southern Area. Absolute minima, with frequent negative values, are observed in the mountainous summits of the South-east and in a large part of the South, where they are accompanied by frosts and snow. During winter, there is a greater penetration of high-latitude cold air masses, which contributes to the predominance of low temperatures.

Because of its great territorial extension, Brazil presents varied precipitation and temperature regimes. All over the country, a great variety of climates with distinct regional characteristics can be found. In the North of the country, a rainy equatorial climate is found, with practically no dry season. In the Northeast, the rainy season, with low rainfall indexes, is restricted to a few months, characterising a semi-arid climate. The Southeast and West-Central regions are influenced not only by tropical systems but also by mid-latitudes, with a dry season well defined in the winter and a rainy summer season with convective rain. The South of Brazil, due to its latitude, is affected mostly by mid-latitude systems, in which the frontal systems cause most of the rain during the year.

The Northern Region has spatial and seasonal temperature homogeneity, but the same is not observed in terms of rainfall. This region receives the greatest total annual rainfall, especially notable at the coast of the "Amapá" State, at the south of the "Amazonas" river and at the western part of the region, where precipitation exceeds 3,000 mm. In this region, three abundant precipitation centres are identified:

• the first one is in the Northwest of the Amazon, with rainfall above 3,000 mm/year. The existence of this centre is associated with the condensation of humid air brought by easterly winds from the Intertropical Convergence Zone, with high rainfall where the flow rises to the Andes Mountains.
• the second centre is in the central part of Amazon, around 5º S, with precipitation of 2500 mm (year),
• and the third one, in the eastern part of the Amazonian base, close to the city of Belém, with precipitation of 2800 mm/year.

Therefore three rainfall regimes can be identified in the northern region of South America:

• one in the Northwest, where rain is abundant throughout the whole year, reaching a maximum in April-May-June, with more than 3,000 mm/year;
• the second one in a zonally oriented band, extending to the central part of Amazon, where the rainy season takes place in March-April-May;
• and the third one in the Southern part of the Amazonian region where the rainfall peak occurs in January-February-March.

In terms of rainfall, there is considerable climatic variation in the Northeast (NE), ranging from a semi-arid climate interior, with an accumulated precipitation lower than 500 mm/year, to a rainy climate mainly observed on the east coast, with an accumulated annual precipitation above 1,500 mm. The northern part of the region receives between 1000 and 1200 mm/year. Similar to the Northern Region, temperature in most of the NE also has a great seasonal and spatial homogeneity. Only in the south of "Bahia" is there a greater seasonal variability in temperature, in view of the penetration of relatively cold masses in winter.

Different rainfall regimes are identified in the NE. In the north of the region, the main rainy season is from March to May, in the south and Southeast rain occurs mainly during the period from December to February, and in the east the rainy season occurs from May to July. The main rainy season in the NE, including the north and east of the region, which accounts for 60% of the annual rainfall, occurs from April to July and the dry season, for the greatest part of the region, takes place from September to December.

The annual distribution of rain in the south of Brazil is quite uniform. Throughout almost all the territory, the precipitation annual average varies from 1,250 to 2,000 mm. Only a few areas are not within this rainfall range. Above 2,000 mm are the coast of "Paraná", the east of "Santa Catarina" and the area around "São Francisco de Paula", in "Rio Grande do Sul". Values below 1,250 mm are restricted to the southern coast of "Santa Catarina" and to the north of "Paraná". Relief exerts little influence on rainfall distribution in this region. Temperature, in its turn, plays a role in the same sense as precipitation, reinforcing climate uniformly in the south of the country. However, this is the region in Brazil with greater thermal variability throughout the year.

Because of their location, the Southeast and West-Central regions are characterized as regions of transition between low latitude hot climates and mid-latitude temperate mesothermic climates. The south of the Southeast and West-Central regions are affected by the majority of synoptic systems that affect the south of the country, with some differences in the system's intensity and seasonality. The inverted troughs act mainly during winter, causing moderate weather conditions, especially in the States of "Mato Grosso do Sul" and "São Paulo". Upper level cyclonic vortices from the Pacific region organize themselves with intense convection associated to the instability caused by the subtropical jet. Pre-frontal instability lines, generated from the association of large-scale dynamic factors and mesoscale characteristics, are responsible for intense precipitation. In the highland regions, located in the eastern part of the Southeast, minimum temperature extremes are registered during winter, while the highest temperatures are observed in the State of "Mato Grosso", in the Central region of Brazil. In general, precipitation is evenly distributed in these regions, with the accumulated annual average precipitation ranging from 1500 to 2000 mm. Two maximum nuclei are registered in the Central region of Brazil and in the coast of the Southeast Region, whereas in the north of the State of "Minas Gerais" there is a relative shortage of rain throughout the year.

Brazil is known as the world’s richest country in terms of its megadiversity, with its fauna and flora comprising at least 10 - 20% of the world's species described to date (Brazil, Convention on Biological Diversity). The vegetation changes from North to South, expressing the different environmental conditions. The main phytogeographic zones are shown in Figure 5.

Figure 5. Main phytogeographic zones of Brazil

The Amazon Forest occupies the North of Brazil, embracing about 47.1% of the national territory or 4,000,000 km², and could encompass all of the European Union (15) countries. It is the largest forest formation on the planet, and is conditioned by the humid equatorial climate. This is the most well-preserved biome, with about 85% of the Brazilian Amazon still forested. About 15% of the Amazon forest has been destroyed, with the opening up of highways, through mining, colonisation and logging, and the advance of the agricultural frontier.

This area possesses a great variety of vegetation physiognomies, from dense forests to floodplain open mixed forests. Dense forests are represented by forests of the Lowland ("terra firme"), the "várzea" forests which are periodically flooded, and the "igapó" forests, which are permanently flooded as happens in almost the entire central region of the Amazon.

The savannahs and savannah woodlands of "Roraima" are on poor soils in the northern end of the basin of "Rio Branco". The "Campinaranas" or "Caatinga amazônica" are white sand forest, being spread in "stains" along Rio Negro's basin. These last two formations consist of the "Cerrado" type of vegetation, thus being areas of "Cerrado" isolated from the main "Cerrado" ecosystem of the Brazilian central plateau. Mixed forest with palms, semi-deciduous forests, lianes, bamboo forests and tidal zones are also important vegetation types.

This area of uncertain rainfall embraces all the states of the Brazilian Northeast, in addition to the north of "Minas Gerais", occupying about 11% of the national territory (at about 1 million km²). It is a vast semi-arid steppe area comprising thorn scrub ("Caatinga") and dry deciduous forest ("Caatinga alta"), as well as isolated rain forest patches ("brejos") and rocky outcrops ("lajeiros"). Its interior, the "Sertão" of northeastern Brazil, is characterised by the occurrence of the very thin vegetation of the semi-arid "Caatinga". The highest areas or "Agreste", which are subject to less intense droughts, are located closer to the coast. The transition area between "Caatinga" and "Amazônia" is known as Middle-north or "Zona dos Cocais" (Palm zone). Suffering from prolonged droughts, desertification, soil erosion and salinization, the "Caatinga" has lost 50% of its native vegetation. Extensive cattle-ranching, agriculture, resource extraction, and subsistence farming have all had major impacts in this biome. Hunting for food is an important additional factor, especially in the dry season.

The "Cerrado" occupies the area of the Brazilian Central Plateau. The continuous area of the "Cerrado" corresponds to about 22% of the national territory (of about 1,900,000 km²), and there are great patches also in the Amazon and some smaller ones in the "Caatinga" and also in the Atlantic forest. Its climate presents two very different and defined aspects. The season of "águas" and the season of "secas", corresponding to wet and dry seasons, respectively, which are very well defined. The "Cerrado" presents varied physiognomies, from clear areas lacking woody vegetation to "cerradões", which are dense arboreal formations. This area is permeated by dendritic forests and pathways that follow the courses of water, and includes high altitude moorlands.

The "Cerrado" biome, which has suffered from the enormous advance of the agricultural frontier in recent decades, has already lost over 40% of its native vegetation through the expansion of crops, cattle ranching, and dramatic increases in human population. More than 50% of the remaining natural ecosystems have been degraded. Burning, both for the maintenance and creation of cattle pasture and for plantations is a common practice, and results in soil erosion as well as serious loss of biological diversity. Economic activities of some sort are present throughout the majority of the remaining area.

The Atlantic forest, including the semi-caducifolius seasonal forests, was originally the forest of greatest latitudinal extension on the planet, ranging from southern latitudes of 6 to 32 degrees (Joly et al., 1999). The forest once covered about 11% of the national territory, but today its extension is smaller, due to centuries of deforestation. Nowadays the Atlantic forest only has 4% of its original area and only about 8.75% of the original forest cover remains (the area of Atlantic forest in the above map is the original area - nowadays only scarce patches of forest exist).

There is great climatic variability throughout its distribution, going from temperate, super-humid climates in the extreme south, to tropical humid and semi-arid in the northeast. The uneven relief of the coastal zone adds still more variability to this ecosystem, which includes montane, restingas (coastal forests and scrub on sandy soils), mangroves and the "Araucária" forests and grasslands of the Campos zone in the south. In the valleys trees are generally well developed, forming a dense forest. On slopes the forest is less dense, due to frequent fall of trees. It is one of the most important repositories of biodiversity in the country and in the world.

The "Pantanal" is the largest plain subject to regular flooding on the planet, covered by mainly open vegetation, which occupies 1.8% of the national territory. This ecosystem is formed largely by sandy lands, covered with different physiognomies due to the variety of micro-reliefs and flood regimes. Savannah, parkland savannah (campo limpo), evergreen gallery forest, seasonal semideciduous forest and chaco are the main vegetation formations. As a transitional area between "Cerrado" and "Amazônia", the "Pantanal" contains a mosaic of terrestrial ecosystems. Ranching became the main economic activity, with cattle-raising on floodplain native grasslands, realizing that the land is not a swamp in spite of its misleading toponymn.

The Campos zone occurs in the subtropical climate of the extreme south, and represents 2.4% of the plant cover of the country. The open lands of the plains and plateaux "gaúchos" (native of "Rio Grande do Sul") and the "coxilhas", of soft-wavy relief, are colonised by field pioneer species that form a vegetation type of open savannah and steppe. There are areas of seasonal forests and of fields with grassy-woody covering. The predominant physiognomy of these fields is herbaceous, with many species of Poaceae, Asteraceae, Cyperaceae, Fabaceae, Rubiaceae, Apiaceae and Verbenaceae (Ministério do Meio Ambiente, 2000). Average height of the continuous, sometimes dense, coverage is 40 to 60 cm, sometimes 1 m. This zone extends to Uruguay and Argentina, totalling 450,000 km² and feeding about 65 million domestic ruminants. Considering the climatic and soil conditions of this ecosystem, one would expect that it should be covered by subtropical forests and not dominated by herbaceous formations. Probably these extensive grass fields are remnants of the semi-arid climate that had dominated the region during the climate changes of the Quaternary period.

The Brazilian Southern Plateau, at altitudes in excess of 500 m, is the area of distribution of the "pinheiro" (pine tree) do "Paraná", Araucaria angustifolia, that occupies about 2.6% of the national territory. In these forests, representatives of the tropical and temperate flora of Brazil coexist, being dominated, however, by the "pinheiro-do-Paraná". The forests vary in arboreal density and height of the vegetation and can be classified according to the soil aspects, as alluvial, along the rivers, sub-mountainous, which no longer exist, and mountainous, the major one dominating the landscape. The open vegetation of the grassy-woody fields occurs on shallow soils. Because of the high economic value the pine tree forests of "Araucária" they are subject to intense logging pressure.

The coastal ecosystems are generally associated with the Atlantic forest due to its proximity. In the sandy soils of the coastal strips and dunes, sandbanks have developed. They vary in form from low-bushy to arboreal. The "manguezais" (mangrove lands) and the saline fields of fluvial-marine origin have developed on saline soils. In the sandy or muddy plains of the Continental Platform benthic ecosystems occur. In the tidal zone the beaches and rocks, colonised by algae, stand out. The islands and reefs are remarkable geographical features of the landscape.

Brazil is the nation with the richest biodiversity in the world (Brazil, Convention on Biological Diversity). At least 10% of the world's amphibians and mammals (27% of the world's primates) and 17% of all bird species occur in Brazil. In terms of the Brazilian flora, there is 50,000 to 56,000 described species of higher plants, or 22-24% of the world's angiosperm species. By way of comparison, the estimate for North America is 17,000 species, that for Europe 12,500, and 40,000 to 45,000 species are believed to occur in Africa. Not only is the number of species high, but also the level of endemism.

The dimensions and complexity of Brazil's biodiversity, both marine and terrestrial, may mean that it will never be completely described. Officially five great biomes are recognised. The Amazonian biome comprises 40% of the world's tropical forest, being the largest remaining rain forest of the world. "Cerrado" is the largest extent of savannah in a single country. Atlantic forest extends from south to northeast covering an area of 1 million km². This biome at present includes the Campos zone, covering 13,608,000 ha of natural pastures in Southern Brazil with more than 400 grass and 150 legume forage species, which is not officially recognised as a biome. "Caatinga" is a vast semi-arid area of about 1,000,000 km², contrasting with the "Pantanal" and its 140,000 km² of wetlands. Coastal and marine biomes add up to 3,500,000 km² under Brazilian jurisdiction. There are numerous subsystems and ecosystems within these biomes, each with unique characteristics, and the conservation of ecotones between them is vital for the conservation of their biodiversity.

Recently, Brazil has made strong efforts towards the preservation of its biodiversity. Nowadays, 130,550,000 ha, or 15.37% of Brazil’s area have been legally declared as protected areas. Moreover, 200,000 records of plant germplasm are being conserved throughout the country (24% are native species).

The main important cultivated pastures are grasses of African origin, which in general, show great adaptation to the Brazilian climate and soils. Some species have become naturalised, since they were first introduced through slave trading in the eighteenth century. Grass was used as bedding for slaves during the trip to the new country.

Until 1985, government policy provided substantial incentives for expansion of agricultural and cattle-ranching frontiers. Between 1970 and 1985, financial incentives and subsidized credits totalled US$ 700,000,000, mostly involving deforestation for cattle ranching. This changed some regions in a remarkable and quick way, the "Cerrado" being the best example. Up until 1960 the "Cerrado" was exploited extensively, with a few farmers using natural pastures for cow-calf operations and many small farmers cultivating cassava and beans, mainly along river margins for subsistence. This changed drastically with government investments in highways and railways or direct agricultural incentives. Monocultures of cash crops or cultivated grasses spread to 40% of this system, and the population quadrupled. Export products, such as soybean, have increased notably. Commercial, large-scale, mechanised and capital-intensive farming has replaced small farmers, who have decreased by 1,000,000 in the last decade (all regions concerned). Socially, the development of modern agriculture in the "Cerrado" has not improved its already uneven social inequality, and also it has brought ecological costs such as landscape fragmentation, loss of biodiversity, biological invasion, soil erosion, water pollution, changes in burning regimes, land degradation and heavy use of chemicals.

Savannahs are responsible for almost 55% of the country's beef and pioneer cattle ranching; they provide good examples of a production system. Natural vegetation is removed and soil fertility is sometimes improved by fertilizers. All these operations can cost around US$ 600/ha or more. Roads and transport are still constraints in many situations. Alternative ways of land exploitation include partial removal of vegetation, followed by burning, disking and direct seeding of pastures. Depending on financial possibilities and local market needs, first operations can be crop production such as upland rice to reduce land clearance and preparation costs and use the residual "natural fertility" incorporated in the soil.

Farming systems in Brazil may be composed of cow-calf operations, store and finishing, with farmers doing all phases or specialising. Beef and dairy enterprises in tropical pasture-based systems are notoriously of low productivity. The low soil fertility, the over-exploitation of native grasslands, the low genetic potential of the animals and the poor management of soil, pasture and animal components are all arguments used to explain these "low-productivity systems". Productivity indexes for cattle enterprises show a lack of productivity (Table 2)

The long payback time on cattle production systems compared to other agricultural enterprises also restrains technology diffusion and adoption. As a result, the financial policy is focusing investment on crops other than pastures to allow farmers to have their investment back as soon as possible. Recently, the beef cattle sector has experienced great positive changes. There has been a reduction of herd age to slaughter from 4 to 3 years on average in the last ten years. But the birth rate is still 60% and calving interval 21 months.

The average beef production in Brazil is 30 kg/ha/year, which can easily be increased by the adoption of already available "conventional" technologies such as:

• Improvement in pasture management;
• Pasture subdivision;
• Recovery and maintenance of soil fertilization;
• Feed supplementation for critical periods;
• Reproductive control of animals;
• Animal genetic improvement;
• Sanitary control;
• Adjustment of the binomial genotype-environment.

Regarding national markets there are signs of a growing potential for beef consumption in Brazil, even with a per capita consumption of 38 kg/year it is important to stress that at least 50% of the population have limited access to meat due to poverty. In terms of international markets, a vast potential for expansion can be foreseen with great competitiveness due to the possibility of increasing grazing production at substantially lower costs than Europe and USA.

For milk production, while the EU, USA and Argentina have 805, 105 and 22 thousand farms, respectively, involved in dairy production, Brazil has 1.2M farms involved in this activity, with 40% having less than 50 ha, which is basically a family production system (Cordeiro, 2000).

In the late nineteen-eighties a survey indicated that, to collect 46,000 tons of milk (the amount to feed 42% of "São Paulo" city for a month) it was necessary to travel 3,400,000 km monthly (Corsi et al., 2001). This corresponds to a trip 85 times around the Earth monthly, and implies that only 13.5 kg of milk was collected for each km travelled. These data reflected the overall low milk productivity as well as the inefficient milk storage and collection system in the country, obliging the dairy industry to collect milk on daily schedules. Extension support associated with logistical approaches in milk storage and collection reduced the travelled distance by eleven times in "Minas Gerais" State, and nowadays, 1.96 tons of milk are collected in 40,066 km or 49 kg of milk/km travelled. It is possible to conclude that the higher milk yield played a vital role in this process since the number of Brazilian dairy farmers decreased in this period. Farmers assisted by trained professionals demonstrated significant improvements in productivity levels and also reductions in production costs and consequently the system of milk collection experienced significant improvements.

The increase in milk yield was a consequence of new approaches to several components of the systems including improved techniques on animal feeding, reproduction, and health. Attention paid to better data collection and on progress towards better farm management also played an important role in the intensification process. The other side of this search for competitiveness and the "intensification" process is the elimination of farmers who can't attain the proposed scale and those who live in remote areas. About 95% of livestock farmers are land owners. Fewer than 10% of farms hold two thirds of the flock reflecting land concentration described earlier and the scale dependency of this kind of activity (Table 3).

Beef production is developed in farms over 100 ha, which involve 82% of livestock. Milk production, by contrast, has a large number of livestock in farms of less than 50 ha, which contribute 39% of national production.

The present Forest Code demands that natural forests be maintained over 80% of private properties in the Amazon and 20% of private rural properties elsewhere. This agriculture legislation is an important "constraint" to farmers when about 5,500,000 ha of permanent pastures are seeded yearly for pasture renovation, and 80,000 tons of seeds are required per year, 50% being Brachiaria brizantha at present. 100,000 tons of seeds of Avena strigosa are sown annually, mainly in crop rotations by direct drilling, and 8,000 tons of Lolium multiflorum and 15,000 tons of Pennisetum americanum for grazing or crop rotations. Of the total area of pastures, 50% are native pastures, but cultivated pastures increased from 30 million ha in 1970 to 105 million ha in 1995, increasing stocking rate from 0.5 to 0.9 head/ha.

In the nineteen-sixties livestock production systems occupied 150,000 km² of native pastures, composed mainly of grasses, legumes and Cyperaceae in upland areas (cerrados and savana well drained from Amapá and Roraima) and flooded areas ("Ilha de Marajó" and the Amazon river). Since then, up until the nineties, the government encouraged the establishment of cultivated pastures, mainly Panicum maximum, Hyparrhenia rufa, Brachiaria decumbens and Brachiaria humidicola. The process of pasture improvement consisted of clearing and burning the forest followed by seeding manually or by plane. In the last decade it was estimated that 62% of deforestation was due to cattle enterprises, where 25,000,000 ha of cultivated pastures were established. Burning pastures at the beginning of growing season is a common practice. These enterprises are very extensive and beef oriented. Apart from 19,000,000 cattle, the region contains more than a million buffalo.

Amazonian soils are characteristically very acid, with extremely low P levels and low CEC, besides other mineral deficiencies (Peixoto et al., 1986). The high P fixing capacity of those soils contributes to reducing opportunities for pasture development. Guineagrass and Hyparrhenia rufa are more responsive to P than Brachiaria humidicola, and tropical legumes may be more tolerant than the grasses to lower levels of P. Lowland grasslands are inundated periodically; species of Echinochloa, Hymenachne, Oryza, Leersia, Luziola and Paspalum, cover poorer soils over huge areas. The problem of these areas is the absence of adjacent land to graze the animals during the floods, so animals loose weight due to nutritional and health constraints.

The upland grasslands, which represent around 60% of the region, display a similarity in botanical composition, where Andropogon spp., Axonopus spp., Trachypogon spp. and Paspalum spp. set the productivity and forage quality. Also important are the legumes Pueraria spp., Centrosema spp. and Dolichos spp. This ample substrate produces poorer quality forage than the lowland grasslands. Within those grasslands nutrient cycling is the driving force for their sustainability. Burning and the high grazing pressure are critical to attain it.

After clearing sections of the tropical rain forest, pasture development brought significant ecological changes to the environment. Initially there was an increase in soil fertility due to the ashes. The rapid establishment of guinea grass, Brachiaria humidicola and Andropogon gayanus pastures encouraged intensive grazing and within three years signs of degradation were evident. But more leniently grazed pastures could be maintained for more than ten years. The P levels of these soils imposed limitations on pasture productivity, although some regional authors showed five to six fold (up to 25 - 36 tons DM ha ^-1) increases in pasture responsess of the upland areas when fertilized and sown to cultivated species.

The level of phosphorous and its decrease following establishment is the most important factor in pasture degradation; according to local authors an area estimated at around 12,500,000 ha is affected. Spittle-bug and disease are also important in contributing to pasture degradation.

North of the Tropic of Capricorn in Brazil is the scenery and environment commonly perceived by the developed world for the tropics of Latin America (see Maraschin, 2001 and Andrade et al., 1995). Within the savannah grassland, this huge environment known as the "Cerrados" deserves special attention since it occupies from 6^oN to 25^oS, around 201,000,000 ha, where species of Trachypogon, Paspalum, Axonopus, Leptochoryphium, Andropogon, Leersia, Elionorus and Aristida, together with species of Poa, Stipa, Agrostis, Festuca and Bromus, contribute to the herbaceous cover. Between the parallels 10^o and 24^o S (38^o and 58^o W) lie about 70% of the "Cerrados" and 40% of the beef cattle herd of Brazil (55,000,000 head). Zebus, mainly Nelore, predominate and most enterprises are cow-calf operations. This area accounts for 14 percent of national milk production.

The main native grasses in this region are Echinolaena inflexa and others such as Paniceae, species of Aristida, Arthropogon, Axonopus, Paspalum, Schizachyrium, Andropogon, Trachypogon etc.. The legumes are represented by Arachis, Centrosema, Desmodium, Stylosanthes, Macroptilium, Rhynchosia, Aeschynomene and others, which in combination with grasses and other species make up the natural pastures of the region. Strongly supported at the beginning of the nineteen-eighties by government action, cultivated pastures, which accounted for 11,000,000 ha, increased up to 29,000,000 ha in the nineteen-eighties, and the area is nowadays estimated to be around 55,000,000 ha, close to the limit of 60,000,000 ha established for this ecosystem. In the last 25 years the green revolution was initiated and most of the "Cerrados" vegetation has been replaced by agriculture, and after one or two years of growing crops, the land was turned into sown tropical pastures. Stocking rates were increased several fold, from 0.3 to 1.0 head/ha (Macedo, 1997). Brachiaria decumbens is one of the most widespread species, covering almost 40,000,000 ha of the tropical savannah. Panicum and Andropogon are also important. Pasture establishment and/or regeneration being integrated with crops is now well adopted.

Low forage availability and quality in the dry season are the main limiting factors, lengthening the productive cycle in cattle raising. Burning is common. Deferment is sometimes used and constitutes one of the rare technologies employed in the most extensive areas. No more than 1-2% of cultivated pastures are legume-based. For most of the area, there was no technological support to ranchers who stay away from agricultural administration, and livestock were practically raised by nature.

After a few years these pastures were no longer able to support the initial stocking rate and now half of the total pasture area is degraded due to lack of fertilization and mismanagement. They began to degenerate very rapidly soon after the establishment year. This raised the suspicion that land use for farming followed by pasture establishment and the intensive management systems imposed on these environments were not sustainable. It is estimated that 50,000,000 ha are degraded in "Cerrados". Integrating crop and livestock systems is one way to promote pasture rehabilitation.

The eastern portion comprises only 12% of Brazil but is responsible for almost 50% of all milk produced and nearly 22.8% of the total Brazilian herd (36,000,000). Dairy enterprises are predominant (Assis, 1997). This is Brazil’s richest region and the most important agricultural and industrial centre, containing 70% of the population.

Most of the dairy production is based on pastures developed on cleared pasture-land, where Melinis minutiflora predominated on the poorer soils of steep slopes, whose forage mass was of acceptable nutritive value, but had a low carrying capacity. Pennisetum purpureum is another important forage in dairy areas. Pastures based on Hyparrhenia rufa were persistent, but their productivity was also low. On some of the remaining fertile soils, Panicum maximum had thriven and is still the main beef pasture for the region. In the last 20 years the Brachiaria sp. took over and Brachiaria brizantha cv. Marandu is being strongly recommended due to its resistance to spittle-bug disease (Deois flavopicta and Manarva sp.). Digitaria decumbens, Brachiaria decumbens and Brachiaria humidicola are still important locally.

Like the "Cerrados", eastern Brazil makes low usage of fertilizers for introduced pastures that are grazed at high stocking rates, so the high grazing pressure causes a weakening, and these pastures soon degenerate. Pasture degradation is an important limiting factor for farmers. Tropical legumes are scarcely used, and the highly seasonal dry matter production does not balance forage quality with animal needs. There is a feed shortage during the winter dry season (April/September), when supplementation is sometimes used, particularly in dairy systems. Intensive management of highly productive cultivated pastures is the most significant technology, but is still weakly adopted.

The semi-arid region of NE Brazil with a dry season of 8-9 month, and an average rainfall of 400 - 600 mm per year uses mixed livestock and involves the use of the natural resources. These areas have been used in an extractive way since the eighteenth century and the natural vegetation of mostly forage species is being replaced by annual and ephemeral ones. High grazing intensity and periodic droughts are responsible for the desertification started in some areas.

The main genus for the region are Mimosa, Caesalpinia, Dalbergia, Paspalum, Setaria, Cenchrus, Aristida, Elionorus, Zornia, Stylosanthes, Centrosema and others. In the short rainy season the herbaceous vegetation and green leaves of trees compose the forage mass. The Caatinga phytomass annual mean production is around 4.0 t/ha and dicotyledon herbaceous and grasses make up 80% of the ruminant diet, but in the dry period the importance of woody species increases. With the onset of the long dry season the leaves of the trees become dry and fall to the ground and are eaten by livestock. By the middle of the dry season 62% of their diet is composed of dead leaves of woody vegetation and up to 28% is from the standing herbaceous vegetation. Early in the rainy season, green leaves of trees comprise 65% of the diet and the herbaceous vegetation the other 35%. These prolonged droughts have a greater impact on the cattle population (22,000,000) than on goats and sheep (17,000,000), since they are better adapted to adverse conditions.

Due to the importance of trees in the diets of grazing animals, manipulation of the vegetation is very important, and it is a common practice to pollard (cut the old branches of the trees and the top of the trunk) to develop new sprouts and branches from where the goats get most of their feed. Thinning of the stand is also done, and gradually they get trunk heights of less than 0.50 m from the ground, when all leaves are within reach of the animals, increasing the foraging substrate. Under natural conditions of the "Caatinga" vegetation, mixed grazing of cattle, sheep and goats is more productive. By thinning the vegetation, cattle and goats are favoured. But when that canopy is manipulated, and the trunks are cut close to the ground for new branching, cattle alone or cattle and sheep make better use of these natural resources. In areas of higher rainfall the main cultivated grasses are Cenchrus ciliaris, Panicum maximum and Brachiaria spp.

The Pantanal is a huge plain ranging from 16 to 21⁰ S and 55 to 58⁰ W covering 139,111 km² (Allem and Valls, 1987). Its vegetational heterogeneity is known as the "Complex of Pantanal". Most farms are extensive cow-calf operations, with stocking rates as high as 3.6 ha/head. Considering flooded areas this stocking rate can decrease by 50%. The total cattle herd is estimated at around 3,800,000. This conservative stocking rate, obligatory by nature, accounts for ecosystem sustainability. There are no large wild ungulates in the Pantanal, which has been called a sort of "herbivore emptiness" by local authors. Commercial livestock at conservative stocking rates are believed to be positive for local diversity. However this means a very low productivity (18 kg LW/ha/year), which in turn determines farm scale (3.5 percent of farms correspond to 57% of the Pantanal’s area). Natural vegetation is a mosaic depending on soil flood characteristics (level, duration, origin, etc.). Communities are known by the dominant vegetation (Canjiqueiral - Byrsonima intermedia ; Carandazal - Copernicia alba ; Paratudal - Tabebuia caraiba ; Gravatal - Bromelia balansae ; Caronal - Elyonurus muticus and Pirizal - Cyperus giganteus and Scirpus validus). Other important species are: Axonopus purpusii, Paspalum pantanalis, Paspalum plicatulum, Paspalum hydrophilum, Paspalum carinatum, Paspalum lineare, Paspalum repens, Panicum stenodes, Panicum laxum, Leersia hexandra, Aeschynomene fluminensis, Aeschynomene sensitiva, Camptosema paraguariense, Indigofera lespedeziodes and others. Native pastures are predominant (99%), grasses being the most frequent group. Savannah and Cerrado are also important formations. Brachiaria decumbens is one of the most important cultivated pastures and its use can be strategic during flooded periods. Native pastures are used basically in two ways: cows remain all year in the same area where flooding depth is not greater than 1 m, or graze flooded areas during the dry period. Eco-tourism is becoming important in this region, which diversifies the economic activity.

Around 33^o S up to 26^o S, in southern Brazil, the low soil fertility, low soil pH, below critical P levels and shallow soils account for the presence of only a few individuals of different species of legumes such as Adesmia, Vicia, Lathyrus, Trifolium, Medicago, Desmodium, Rhynchosia, Aeschynomene, Arachis and Vigna. The whole of the region enjoys the same thermal effects of the climate, encompassing a wide range of soil types and elevations, and where the moisture is abundant the dominant tall grasses, such as Andropogon, Schizachyrium, Setaria, Bothriochloa, Paspalum, Stipa, Aristida, and Axonopus restrain legume growth. As a consequence, the massive dry matter (DM) production in the long warm season is of low quality (< 60% digestibility), the species diversification and selective grazing throughout the seasons of the year makes that growth accumulate, senesce and lose quality even more in winter and it often has to be burned before the following spring season. This accumulation shades cool season grasses and prevents their growth, causing scarcity of forage and quality feed in winter.

With such marked seasonality in DM production, where spring- and summer are responsible for 60-85% of the forage yield, the short days and low temperatures of winter preclude growth of the C4 plants, so that the subtropical grass species dominate the scenario and produce forage for 210 - 240 days during the warm season. Forage shortage in autumn-winter is the main limiting factor to animal production (Maraschin and Jacques, 1993).

The most important cultivated forages are annual winter grasses like Avena strigosa and Lolium multiflorum (Nabinger et al., 2000), as well as legumes of the genera Trifolium, Lotus, Medicago and others. Tropical pasture species are mainly annuals, such as Pennisetum americanum, and Sorghum spp., but perennials are becoming important (Panicum, Cynodon, Digitaria, Paspalum, other Pennisetum, etc.). To a lesser extent, some perennial winter grasses are cultivated (Festuca, Phalaris, Dactylis, etc.). Cultivated pastures comprise around 7,000,000 ha, while native pastures attain 13,700,000 ha. So native pastures feed most of the 26,200,000 cattle and 6,000,000 sheep. Cattle and sheep are mainly raised in mixed-grazing on the native pasture areas.

Traditional pastoralism predominates in the use of these pastures, and feed is used mostly for maintenance purposes. This region is the second most productive in Brazil in terms of volume of milk. Integrated crop-animal production systems are becoming an interesting option mainly in summer crop areas with soybean, maize or rice.

(also see Maraschin, 2001 for this topic)

Tropical America is the centre of diversity for many important tropical forage legumes, but the evaluations were limited to a few species, marginally adapted to the edaphic conditions prevailing in major livestock areas of the region. Perhaps this is one of the reasons for the low use of forage legumes in Brazilian pastures. Other factors, which certainly contribute, are the critical stocking rate and the lack of fertilization.

In many regions of Brazil there are ample opportunities to use forage legumes, since they are endemic to the area. Tropical legumes are also important in restoring lands degraded by imprudent cropping or grazing. These pastures, although contributing, are often unstable, and the management necessary to maintain an adequate proportion of legume is still little understood. The efforts devoted to selecting grass and legume germplasm adapted to the acid soils found in important ecosystems such as savannahs and humid tropical forests, revealed the S. capitata and S. guyanensis are suitable for the savannahs and the humid tropical rain forest, and Arachis pintoi is compatible with aggressive and stoloniferous grasses and is very persistent under heavy grazing. Pueraria phaseoloides and Stylosanthes capitata which animals select in the dry season, also show potential for the tropical rain forest environment. Development of technologies for local seed production to supply legume based forage systems was important. Evaluations under grazing yielded results from 200 - 400 kg LW ha ^-1 in locations with dry-season stress, and up to 500 - 600 kg LW ha ^-1 in areas with no dry-season stress.

For other marginal areas, in the two storey vegetation of herbaceous plants and Acacia caven, the deciduous foliage of the trees replenished the soil minerals removed by the grazed herbaceous plants. Even with the lush growth of the trees, the herbs under that shading were luxuriant relative to those under full sunlight. The trees got most of the water they need from deeper soil layers, allowing more for the herbaceous vegetation that explores the upper layers of the soil. Lots of similarities are also found in the northeast within the "Caatinga" vegetation.

The spectacular increase in individual animal performance when grazing legume-based cultivated pastures compared with native savannah grassland deserves mention. It is hoped that legumes will contribute with low-cost nitrogen to the associated grass. This characteristic and the tolerance to low fertility and acid soils are always major themes of research and the first objectives pursued. The problem is that Brazilian grazing history with large herbivores is short and these legumes have, in general, very limited adaptations to tolerate heavy grazing, having more specialised escape mechanisms; this deserves more attention by forage breeders.

Grazing at optimum carrying capacity is a compromise between optimising intake and individual animal production with animal production per hectare, since intake decreases when available herbage per animal decreases. When forage availability does not limit animal intake, animals with high yield potential can express their growth to near maximum, without supplementation, thus lowering production costs.

It has long been known that lower grazing pressure, or high herbage allowance, allows very high levels of animal performance from either natural or cultivated tropical pastures. Values range for natural pastures: 0.69 - 1.0 kg an^-1 day^-1 and for cultivated tropical pastures: 1.5 - 1.27 kg an^-1 day^-1. This should encourage grazing management practices that use lighter grazing pressures on native or tropical cultivated pastures, but unfortunately this is not the case in the major commercial situations.

The natural grasslands of southern Brazil are the main feed resource for an equivalent of 15,000,000 AU. The ranching philosophy of pasture utilization, coupled with defined conditions for animal output is in its infancy in the region despite the strong support from research results. Grazing efficiencies greater than 50% occur at daily herbage allowance levels from 13 to 18 kg DM 100 kg LW^-1 day ^-1 with peak efficiencies occurring from 6 to 9 kg DM 100 kg LW^-1 day ^-1. Daily herbage allowance values below 20 kg AU ^-1 day ^-1 allow for 4.4 kg DM per 100 kg LW and restricted the intake of a 454 kg mature cow.

It has also been suggested that deferring grazing to recover or rejuvenate these native pastures and to increase the biomass productivity and the frequency of the desirable species for the site, would be beneficial. Reduction in stocking rate and sowing cultivated species is an alternative. By reducing stocking rate one slows down the rate of degradation but not the trend toward degradation, since the grazing animals will continue to overgraze the preferred species selectively within plant communities. This is an ever present phenomenon, and can be a critical one, where pasture biodiversity is not counterbalanced by different species of grazing animals. On the other hand, the introduction of cultivated species is feasible once there are provisions against the limiting factors that might jeopardise the new pasture, especially fertilization.

The distinct pasture canopies can range from prostrate forms of growth under heavier grazing pressures, to rank vegetation under more lenient management. An accumulation rate up to 16.3 kg DM ha ^-1 day ^-1 through the season for natural pastures maintained at an optimum stocking rate was determined to be at a DMO of 13.5% LW per day, which was equivalent to maintaining the existing DM at a level of 1,400-1,500 kg DM ha ^-1 at any one time. The conversion efficiency of this ecosystem in capturing radiation energy from sunlight to transform it into primary production ranges from 0.20% for high grazing pressures to 0.36% at appropriate ones, which represented an 80% increase in system efficiency. This demonstrates the important improvements that can be made simply by managing this pasture ecosystem at the correct grazing intensity. These values and relationships mean that the productivity of these grasslands can be 100% increased at a cost of harvesting forage by the grazing animal, with no other energy input than thought.

In all environments it is necessary to find the best compromise in combining three factors: plant growth, plant utilisation and animal performance, to reach the maximum efficiency taking into account the production costs.

It is recognised that improved pastures have been shown to greatly increase rates of animal production. For example, very interesting was the assessment concerning Cenchrus ciliaris, introduced into the native pastures of the dry-NE Brazil, promoting a two fold increase in the LWG ha ^-1, but with no changes in the average daily gain per animal (ADG an ^-1).

When dealing with productivity the entire system has to be considered, with both seasonal and annual variations included. There is evidence that an increase in ADG an^-1 under grazing is the best way to reduce animal production costs, showing that animals per hectare express the rate of stocking that allows for the optimum individual animal performance.

The results from central Brazil and the "Cerrados" indicate that persistency of cultivated pastures depends on initial soil fertility and lenient grazing management. Lenient grazing is important, but not enough for pasture sustainability. The decline in soil fertility status is the starting point of pasture degradation. The first symptom observed is the reduction in carrying capacity under equivalent forage allowance; the pasture regrowth does not acquire its previous status after resting; and the reduction in forage mass and quality reduces ADG an^-1. Bare spots become visible in the pasture, weeds invade and some native species return. So, judicious monitoring of carrying capacity would indicate the beginning of the degradation process. When detected early it may cost 100US$ ha^-1 to recover the area, while later detection raises costs to 200US$ ha^-1. Reducing the stocking rate helps to maintain animal performance but does not overcome the trend in pasture degradation.

Another choice that is acquiring importance is the integration of crop and grassland agriculture within a complete system of land use and farm productivity. The annual crops will generate financial resources for improving the soil fertility level, thus reducing the costs of pasture establishment. Consistent results are showing new pastures with increased pasture potential for the region, where fertilized Panicum pastures are producing 740 kg LW ha ^-1 year ^-1, while the Brachiaria sp. reach a ceiling yield at 600 kg LW ha ^-1 year ^-1. These differences come from the higher ADG an ^-1 and higher number of steers carried by the Panicum, compared to Brachiaria pastures. For enterprises adopting low levels of technology, Brachiaria is the option, while for those adopting the existing high level of technology, Panicum pastures are recommended.

New experimental results with Brachiaria cultivars showed different rates of leaf growth for the wet and the dry seasons. Some ecotypes displayed higher leaf DM yield in the dry season while others performed better for the wet season, and were recommended to be tested for animal gains. They have already shown high pasture potential. Hopes rest on the animal potential of those new varieties.

The promotion of grazing based on the green leaf lamina dry matter (GLLDM), contributes to our knowledge and understanding of what happens in the pasture profile, to evaluate pasture dynamics and to watching the shaping up of the silhouette of a steer gaining weight and being finished on pasture under grazing. At low levels of GLLDM the animals graze more frequently, promote tiller density as well as invasion of other plant species, and adversely affect root mass, plant diameter, internode length, tiller weight, rate of accumulation of GLLDM and total GLLDM yield. It seems that heavy grazing does not help the pasture.

With clearly defined levels of pasture GLLDM management being applied to Mott dwarf elephantgrass studies reveal that a sustainable optimum ADG of 1.043 kg an^-1 at a herbage allowance of 10.5% LW day ^-1 of GLLDM yielding 1,188 kg LWG ha ^-1 can finish a slaughter steer within 210 days of grazing, under continuous stocking.

Based on the acquired knowledge in conducting grazing experiments to evaluate herbage allowance and animal and pasture responses, it is suggested that at least 1,500 - 2,000 kg ha^-1 of live green leaf lamina DM of the forage mass is required from which the grazing animals will get their diet.

It is well documented and recognized that the levels of available P in the soils are extremely low. The use of fertilizers to increase DM and quality of native pasture production has taken too long to be accepted by those involved with livestock production; cultivated pastures were fertilized at establishment, but not for maintenance.

In a classical experiment done in southern Brazil, phosphorous was applied broadcast in a natural pasture (160 kg ha^-1), and continuous versus rotational grazing was under evaluation. After 11 years of grazing, there was a 10% increase in livestock production from rotational grazing compared with continuous stocking. However, the outstanding response was to P fertilization, which showed an increase in productivity of around 4.95 kg LWG ha^-1 kg^-1 of applied P. After 11 years the fertilized natural pasture was producing 70% more than the unfertilized natural pasture. No doubt, there was a very lasting and contributing effect of the P application.

To illustrate the possibility of changing botanical composition by fertilizers and altering the quality status of pastures, a trial has shown that Desmodium incanum increases from 3.3% up to 24.4% in a pasture as a result of high phosphorus applications in southern Brazil. With regard to nitrogen, when a natural grass such as Paspalum notatum is fertilized and water doesn’t limit growth, pasture production reaches 12.0 tons DM ha ^-1, and places doubt on the necessity for cultivated pastures. This information has had a considerable impact on the southern research programmes resulting in the promotion of native pasture fertilization at medium levels for pasture sustainability.

Maintenance of soil nutrient status is a key variable in pasture sustainability. There are sharp residual effects of P fertilization on forage DM production of subtropical pasture mixtures, with increased legume contribution as the P levels are increased. However, the P levels in the soil are gradually being reduced due to extraction by plants when there is no P replacement, and after five years phosphorous can be reduced to 1/5 of what it was at the beginning.

Annual fertilization of a mixture of guinea grass, Siratro, Glycine wightii and Stylosanthes guianensis on the other hand, kept that pasture productive for more than ten years. The annual application of 20 kg ha^-1 of P helped in maintaining pasture production while the application of 40 kg ha^-1 of P increased the pasture production by 30%, whereas under no fertilization production dropped at a rate of 15% annually. Panicum spp. were also identified as responsive to fertile soils, where high levels of P were applied, while Stylosanthes capitata, Stylosanthes guianensis and Zornia spp. with Brachiaria humidicola, Hyparrhenia rufa and Andropogon gayanus were identified as species with good performance on soils with low P supply. Researchers thus emphasized the development of a philosophy of pasture productivity to take advantage of fertilizer use and applied knowledge in pasture management all over the country to benefit from the improvement brought about by the fertilizer applications.

In fact, farmers do not frequently adopt fertilizer use. A 1997 survey revealed that only 663,000 tons of NPK fertilizers were annually applied to 90,000,000 ha of introduced pastures in Brazil, i.e. about 7.4 kg of NPK fertilizer/ha of pasture per year. Results from grazing trials conducted in eastern and central Brazil, in the "Cerrados" revealed that fertilization increased yield of cultivated pastures from 150 to 400 kg ha^-1, irrespective of the final animal product. The search for cheap sources of nitrogen is suggested to be of paramount importance to supply pasture ecosystems and obtain livestock production at low cost.

The efficiency of P fertilization is 4.6 kg LW ha^-1 kg^-1 of applied P, while for N fertilization it is 1.6 to 2.0 kg LWG ha^-1 kg^-1 of applied N (reported for tropical pastures in central Brazil). The magnitude of responses is associated with the stocking rate, experiencing sharp declines in LWG ha^-1 as the stocking rate is increased.

Supplements ( see Corsi et al., 2001)

The high herbage accumulation rate in tropical grasses favours stockpiling practices. On the other hand, the use of stockpiling practice limits animal productivity for quantity and quality reasons. Long regrowth periods without grazing (or cutting) are prone to excessive herbage losses and in extreme cases the forage damps-off. It is also well established that long regrowth periods are deleterious to forage quality given the reductions on the potential pasture intake due to the nutritive value of the forage.

To better utilize the standing low quality forage some farmers are feeding protein supplements (0.1% of animal liveweight) containing ionophores to correct nutritional deficiencies in winter (dry and cold). While some nutrients are indeed corrected, results seem to indicate live weight gain is primarily additive rather than the supplement.

Grazing animals can also benefit from feeding supplements during the summer/autumn period. Supplementation at that time of the year aims to improve individual performance as well as the output of animal products per unit area. In dairy enterprises this strategy has been widely used and it seems that a similar average response of 1.4 kg of milk/kg of concentrate supplementation might be expected for lactating cows on temperate and tropical grasses.

For beef cattle better responses to concentrate (and possibly degradable fibre) supplement feeding seem to occur in late summer/autumn compared to the beginning of the grazing season. At this time supplemented animals grazing tropical grasses are expected to show liveweight gains above 1 kg/head/day, though feed conversion is a function of the supplement type. Information regarding the synchronism between carbohydrate and protein fractions in the rumen and, consequently, the substitution of pasture DM for concentrate DM, and the high concentrate prices in tropical regions seem to be the most limiting factors restraining the adoption of supplementation programmes on the best-managed farms.

During the (wet and warm) summer, tropical pastures can support high stocking rates, peaking up to 15 AU/ha. This carrying capacity is much lower during winter, averaging 10 to 40% of summer values. Therefore the intensification of tropical pasture-based systems in summer should consider the use of conserved forages or by-products in winter to guarantee the balance between food supply and demand during the whole year. Options such as silage (maize, sorghum or perennial tropical grasses), hay (perennial tropical grasses), and several by-products (sugarcane, citrus, brewer’s grain, etc.) are available.

Feedlots during the winter are also a possibility to allow high carrying capacities on tropical grass pastures in summer. However, feedlots are economically questionable when practised on a small scale, and with high grain prices and low availability of by-products.

Recently, irrigated tropical pastures have been used to enhance carrying capacity for both beef and dairy enterprises. Production costs have been reported of about US$ 0.9/kg carcass weight in irrigated tropical pastures at the same time as selling prices were US$ 1.36/kg carcass weight. Cost analysis studies indicate that adoption of irrigated tropical pasture depends on production costs in the dry pasture system, overall production costs and selling price and the increase in productivity in the irrigated system.

Below are presented different views from research and extension, which give an idea of future possible scenarios for cattle production systems and their potential in Brazil. The following conclusion were drawn by Corsi et al. (2001):

1. Animal production from tropical pasture-based systems has a high plant and animal productivity potential when soil fertility is adequate (e.g., fertilizers are used) and more than 25,000 kg milk/ha/year and 900 kg liveweight gain/ha/year can be obtained.

2. Technology transfer in these systems is constrained because animals and land are used as a capital reserve and animal products (milk and meat) in these situations are by-products rather than products. Economic policies toward cereal/legumes crops instead of high-cost cattle enterprises also constrain uptake of technology. This frequently makes smallholder livestock farmers unable to adopt the necessary technology to efficiently and intensively manage beef and dairy enterprises. On the other hand, capitalized farmers and companies having already reasonable economic outputs in extensive systems have no interest to adopt more intensive ones.

3. Stockpiling practices and grass-legume mixtures are pasture management options when stocking rates are low, generally up to 1.2 - 2.0 AU/ha/year. Stocking rates above this limit are necessary to efficiently use the high herbage growth rate potential of tropical pastures. Higher stocking rates during the summer should consider the use of rotational grazing and the need to plan winter feeding, e.g. the utilization of conserved forages, feedlots, or irrigated tropical pastures.

4. Tropical grass management (mainly for tussock-forming grasses) seems to have different characteristics compared to temperate pasture management. As herbage accumulation rates in tropical species increase above 100 days, tropical pasture management should be oriented toward forage quality and/or pasture structure.

5. The supplementation of grazing animals in summer/autumn periods in tropical environments can be a valuable tool to increase the individual animal performance and the overall pasture output.

6. The use of fertilizers seems to be a pre-requisite to sustain high pasture productivity. Practices that increase the pasture productivity while maintaining the environment quality should be emphasized.

With regard to pastures, according to Zimmer and Euclides (1997) it is necessary to develop better quality forages, which can provide a better animal performance in favourable growth periods as well as in drought. Special emphasis should be given to increase production in the rainy season when the conditions are better, improving animal performance in this way, where the available tropical pasture at present does not fulfil the genetic potential for animal gain. In dry periods the nutritional needs of some animal categories should be met using alternatives for feed supplementation, since in this period forages do not meet animal needs. It is essential that genetic improvement of forages focus on the search of legumes for animal diet improvement and, particularly, for biological nitrogen fixation. Biological N fixation is important for sustainability and for the reduction of possible environmental damage.

According to the National Agriculture Confederation [see CNA] the main demands from the beef cattle enterprise are:

(e) Behaviour of diseases at farm level and necessity for its effective control: research efforts based on actual data.

Several organizations, mainly public, are involved in agricultural research and development. On a national scale, Federal Universities, EMBRAPA and EMATER are important institutions. At State level, we should consider the efforts of public Universities and/or Research Institutes financed by each state. Private Universities are not consolidated concerning research. Investment in scientific and technological research arising directly from Government or from research foundations can be assumed to amount to some 80 percent of the total.

The main overall research efforts are being made in the following areas: plant and animal breeding with the main focus on productivity and capacity to cope with harsh environments; technologies to rehabilitate degraded areas; grazing management focusing on intensive systems, animal nutrition focusing on feed-lot systems.

Private enterprises have recently made efforts, notably on animal genetics and plant breeding. Some of them do development work and assist farmers as a market strategy.

Some key persons and their research areas are presented (this list is not intended to be exhaustive nor definitive and it should be viewed only as a way to start contacts in the following areas):

Empresa Brasileira de Pesquisa Agropecuária: www.embrapa.br

EMATER : www.emater.tche.br/

Universidade Federal do Rio Grande do Sul: www.ufrgs.br

Universidade Federal de Viçosa: www.ufv.br

Universidade Federal de Lavras: www.ufla.br

Universidade Federal Rural do Rio de Janeiro: www.ufrrj.br

Universidade de Brasília: www.unb.br

Universidade de São Paulo: www.usp.br

Universidade Estadual Paulista: www.unesp.br

Universidade Estadual de Maringá: www.uem.br

Instituto de Zootecnia: www.iz.sp.gov.br

Fundação Estadual de Pesquisa Agropecuária: www.fepagro.rs.gov.br

Sociedade Brasileira de Zootecnia : www.sbz.org.br

Conselho Nacional de Pesquisa e Desenvolvimento Tecnológico. www.cnpq.br

Coordenadoria de Aperfeiçoamento de Pessoal de Nível Superior:www.capes.gov.br

This profile was prepared by Paulo César de Faccio Carvalho. His research area is the plant/animal interface and since October 1997 he has lectured at the Faculdade de Agronomia, Universidade Federal do Rio Grande do Sul, in Porto Alegre - RS, in Southern Brazil. E-mail: paulocfc@vortex.ufrgs.br

To prepare a Country Pasture Resource Profile for such a large and diverse country as Brazil has not been a simple task. The author wishes to thank important contributors and has much appreciated the comments received from various reviewers. Contributions are still welcome. Arrangements are being made for local revision and updating.

[The profile was prepared in April/May 2002 and was edited by S.G. Reynolds and J.M. Suttie in June 2002].