"Leguminosa Forrageira" in the EMBRAPA agricultural research database
| Livestock Research for Rural Development 33 (5) 2021 | LRRD Search | LRRD Misssion | Guide for preparation of papers | LRRD Newsletter | Citation of this paper |
Sustainable animal production alternatives are necessary to change the current productive paradigms. Sustainable intensification of animal production systems could be achieved through silvopastoral systems (SPS). Despite the fact that Brazil has always been at the forefront of agricultural development in Latin America, silvopastoral system areas seem to expand more modestly. Thus, the objective of this review is to describe the history of alternative forage crops in Brazil and to understand the factors that limit the adoption of SPS.
Key words: forage shrubs, limited adoption, ruminant production, sustainable intensification
Sustainable animal production alternatives are necessary to change the current productive paradigms. Foods of animal origin have a greater production intensity and emission intensity than their vegetable equivalents. This is particularly evident for foods of ruminant source (Poore and Nemecek 2018). In addition to the difference between products of animal and plant origin, there could also be a difference within the same product; the so-called, emission intensity gap (FAO 2021), which separates the production systems with the lowest and highest emissions per unit of product. This gap represents several opportunities for mitigation options which could actively reduce the emissions of the sector by 30% (Gerber et al 2013). Consequently, sustainable productive intensification has been described as one of the most promising strategies to increase the efficiency of livestock systems and reduce their environmental impacts without threatening food security or altering cultural patterns (Herrero et al 2016).
Silvopastoral systems and the use of legumes and/or shrubs forages to complement grazing feeding systems are considered as a sustainable alternative for productive intensification. They allow to increase the amount of biomass per unit of area and provide other ecosystem and biological services (Murgueitio et al 2011). They are also recognized by the FAO as sustainable alternatives to reduce the environmental impact of animal production (FAO 2020). However, despite the fact that Brazil has always been at the forefront of agricultural development in Latin America, silvopastoral systems seem to expand modestly. Currently, as a result of the commitments made during COP21 (MAPA 2017) Brazil has been strongly promoting strategies for sustainable livestock production with emphasis on integrated livestock systems. But despite the growing interest and decades of research, just over 5% of the Brazilian grazing area are covered by silvopastoral systems. Thus, the objective of this review is to describe the history of alternative forage crops in Brazil and to understand the factors that limit SPS adoption.
Historically, cattle livestock systems in Brazil were based almost exclusively on the extensive exploitation of land with native or naturalized gramineous species (Kluthcouski et al 2013, Serrão & Simão Neto 1975). Regarding the native species present on the Brazilian territory; until the beginning of the 60s, beef cattle in the Amazon region was based almost entirely on extensive exploitation, producing cattle and buffalo, mainly aimed at meeting regional demands (Serrão 1984; Townsed et al 2012). The native pastures in the Brazilian Amazon can be grouped into three main ecosystems: well drained savannas, poorly drained savannahs and floodplain alluvial soils and their characteristics are discussed in more detail by Townsed et al (2012). There is a great diversity of grasses, legumes and shrubs in these ecosystems, such as species belonging to the genera Axonopus, Andropogon, Panicum, Paspalum, Desmodium, Cyperus and others.
In the Brazilian northeast, the Caatinga vegetation is an important native forages resource and has been exploited mainly for sheep and goat production. This biome is mostly composed by non-forage plants such as shrubs and small trees, usually thorny and deciduous, which lose their leaves in the early dry season; and annual plants, like cacti, bromeliads, herbaceous grasses and dicotyledons (Pereira-Filho et al 2013; Santos et al 2008).
In the Pantanal biome, the basic vegetation formations are arboreal, grassy-woody (savannas), grassy and aquatic, distributed in a mosaic fashion among the landscape units of the region (Santos et al 2002). Axonopus, Mesosetum, Panicum, Reimarochloa, Andropogon, Paspalum, Oryza, Hymenachne and Leersia are the most prominent genera. Legumes, on the other hand, have little quantitative expression, Desmodium species being the most frequent according to Pott (1982), Pott, Catto & De Brum (1989) and Rocha et al (2020).
In the Brazilian south, natural grazing fields belong to the Pampa biome and are recognized for containing a rich biodiversity, with a vegetation cover composed predominantly of grasses and herbaceous plants (occasionally small shrubs and trees are found) (Carvalho & Batello 2009; Gonçalves 1999). Mazzocato (2009) highlights Paspalum notatum, Paspalum dilatatum, Paspalum nicorae, Paspalum pumilum and Bromus auleticus as native species with forage potential in this biome. Carvalho & Batello (2009) also highlights other genera of grasses such as Axonopus, Andropogon, Panicum, Setaria, Digitaria, Schizachyrium and Stipa, as well as legume genera such as Adesmia, Vicia, Lathyrus, Trifolium, Medicago, Desmodium, Rhynchosia, Aeschynomene, Arachis and Vigna.
Overall, extensive areas of native pasture have always had a great relevance to Brazilian livestock activity. However, despite their services as forage resource and their environmental and social benefits, the areas with presence of natural pastures have been altered during many decades for diverse uses (pasture, forestry, crops etc.). The accidental or intentional introduction of exotic fodder is an old reality in Brazilian livestock and even before the popularization of cultivated pastures, there was already the presence of exotic grasses that were naturalized in Brazilian fields.
According to D’Antonio & Vitousek (1992), Kluthcouski (2013), Rocha (1988) and Souza (2001), among the naturalized grasses that predominated until the 1940s were gordura grass (Melinis minutiflora P. Beauv.), colonião grass (Panicum maximum Jacq.), jaraguá grass (Hiparrhenia rufa (Nees) Stapf.), angola grass (Brachiaria mutica (Forsk.) Stapf) and kikuyu grass (Pennisetum clandestinum Hochst.). These pastures, with origins on the African continent, are believed to have been brought during the 18th century, on ships for the transportation of goods or where the forage was used as a bed for slaves (Parsons 1972, Rocha 1988, Souza 2001). It is believed that these grasses gained space due to their effective competition against the native vegetation, occupying large areas where human intervention was little, or due to their high resilience after planned burns. D’Antonio & Vitousek (1992) mentioned the fire tolerance and increased occurrence of Hyparrhenia rufa and Melinis minutiflora after anthropic interventions with fire.
Despite the predominance of African grasses in the pastures, at the time, there was still no organized trade of seeds; and sowing in the felled and burned areas was carried out vegetatively by planting stems. The greatest change in the establishment of pastures would occur after the 1970s with the intensification of direct seed trade between livestock properties (Rocha 1988).
According to Souza (2001), the availability of tropical forage’s seeds in Brazil followed three distinct phases. The first, comprised by the period before the 70s, where the pastures were occupied by the grasses described above. Although, with very low physical and physiological qualities and as already mentioned, vegetative reproduction by means of seedlings still predominated.
The second phase was characterized by the commercial importation of large quantities of seeds from Australia in the early 1970s. Resources for these imports came from government programs of credits and technical assistance for livestock; such as those implemented by SUDAM (Superintendência do Desenvolvimento da Amazônia), CONDEPE (Conselho Nacional de Desenvolvimento da Pecuária) and CATI (Coordenadoria de Assistência Técnica Integral) (Souza 2001). Through these initiatives, new forages were introduced and implanted; such as Brachiaria decumbens (cv. IPEAN and cv. Australian), B. humidicola, B. ruziziensis and U. brizantha, as well as several cultivars of Panicum maximum, Setaria sphacelate; forage legumes such as Stylosanthes guianensis; several perennial soybean cultivars (Neonotonia wightii) and Leucaena leucocephala (Kluthcouski 2013, Rocha 1988, Souza 2001). Those seeds with a good cultural value promoted the popularization of pasture formation practices, encouraging a large number of producers to use cultivated areas for the exclusive purpose of seed production (Rocha 1988, Souza 2001). Yet, this had little impact on local livestock production and Souza (2001) argued that it was probably due to inadequate management practices, poor adaptation and poor soil fertility.
Serrão & Simão Neto (1975) mentioned the opening of programs focused on the development of forages at the Instituto de Pesquisa Agropecuária do Norte, the Instituto de Pesquisa Agropecuária da Amazônia Ocidental and at the Instituto de Pesquisa Agropecuária do Oeste by the end of 70s. Additionally, the germplasm bank of forage plants of the Centro de Pesquisa Agropecuária do Trópico Semiárido was created in 1977 (Silva 1979; Silva et al 1984). In this way, the third phase is marked by the consolidation of the seed market, with the launching of cultivars studied by Brazilian research centers, such as EMBRAPA ( Empresa Brasileira de Pesquisa Agropecuaria) and international institutes such as CIAT (Centro International of Tropical Agriculture) or the IBPGR (International Board for Plant Genetic Resources) (Rocha 1988; Souza 2001). Among the studied forages, different species of Brachiaria spp and cultivars of Panicum maximum stand out, which, by 2005, were estimated to comprise more than 50 million hectares planted in Brazil in the case of Brachiaria spp and 12 million in the case of Panicum maximum (Macedo 2005).
In Brazil, 90% of livestock production is carried out in grazing systems (Anualpec 2013 apud Oliveira Silva et al 2017). Parente et al (2017) using satellite images, estimated that there are 175 million hectares of pasture in Brazil, of which, according to the Instituto Brasileiro de Geografía e Estatística (IBGE 2017b), approximately 12 million are in degraded conditions. Some authors have reported values between 15 and 25 million (Boddey et al 2004; Oliveira Silva et al 2017; Fernandes et al 2018); and others had shown higher estimates, such as Dias-Filho (2011) who stated that at least half of Brazilian pastures were in some state of degradation or Pereira et al (2018), which estimates that in the Cerrado biome alone were 18 million hectares of degraded pastures.
In most of the Brazilian territory, where livestock production is extensive, there is a seasonality in forage production that is determined by periods of rain and drought (Teixeira et al 2011). This seasonality impacts the quality and quantity of the forage; 80 and 20% of biomass production per year, respectively. During the rainy season, between November and April approximately, the high temperatures and the long photoperiod increase the production (Araujo et al 2018). However, the low temperatures and reduced volume of rain, during the dry season, between March and October, reduces the quality and quantity of the forage (Araujo et al 2018; Santos et al 2004; Teixeira et al 2011). Moreover, the unpredictable nature of climate change exaggerates the impact of the weather and makes it difficult to carry out adequate feed planning for livestock throughout the year, thus, the stocking rate achieved during the dry season cannot be reached during the rainy season (Santos et al 2004). As a result, the grasslands become degraded by overgrazing, which leads to a consequent reduction in the stocking rate (Boddey et al 2004); which was estimated on average between 0.85 to 0.97 AU / ha (Arantes et al 2018; Latawiec et al 2014; Strassburg et al 2014).
Strassburg et al (2014) mentioned pasture degradation as one of the main causes of low pasture productivity and Boddey et al (2004) concluded that high stocking rates and lack of maintenance fertilization lead to degradation of pastures. Strassburg et al (2014) estimated that Brazil was ceasing to produce around 70% of its productive potential and that with the implementation of better pastures species, the introduction of mixed systems (livestock and crops) and improvements in livestock productivity, it would be possible to fulfill the demand for food in a scenario where there would be no needs to expand the livestock frontier towards the forests, as discussed by Soares Filho et al (2011) and Strassburg et al (2014).
The integration of herbaceous, shrub forage species and trees into pastures is another alternative to mitigate the effects of seasonality and improve the efficiency of land use in livestock production (Gerber et al 2013). This type of integrations are also called silvopastoral systems (SPS) and have been defined as agroforestry arrangements where forage plants, such as pastures and leguminous herbs, are combined with shrubs and trees for animal feed and complementary uses (Murgueitio et al 2011). For Murgueitio et al (2011), some of the most common silvopastoral systems around the world are: scattered trees in paddocks, managed plant succession, live fences, windbreaks, forage tree banks, cut-and-carry systems, tree plantations with grazing cattle, pastures between tree alleys and intensive silvopastoral systems (ISPS).
In Brazil, during the 1960s, various authors had already reported the benefits of legume forages in the soil and their ability to regenerate degraded areas through nitrogen fixation (Döbereiner et al 1966; Miyasaka et al 1966; Neme 1966; Scaranari & Inforzato 1952; Williams 1967). From the 1970s and on, as a result of the success of the use of legumes in countries such as Australia, in Brazil, the possibilities of its use in association with grasses began to be explored to improve the nitrogen content in the soil and increase the productivity of the pastures (Serrão & Falesi 1977). Centrosema, Styolsanthes, Pueraria, Cajanus, Desmodium, Calopogonium, Neotonia, Macroptilium, Arachis and Leucaena were some of the most researched legume species (Costa et al 1979, Valentim et al 2008). Valentim et al (2008) reported that during the 1970s and 1980s most of the research including legumes were focused on forage production, establishment methods in associated pastures, nutritional requirements and quality of the produced forage. Later, due to the presence of the international germplasm evaluation network, the investigations were focused on the comparison of different genotypes and their behavior in different environments.
After a diversification in the subjects and species studied during the 1990s, at the end of that decade; Arachis, Pueraria, Styolosanthes, Cajanus and Leucaena were the most studied species due to their resistance to grazing and palatability (Valle et al 2009; Valentim et al 2008).
Dias-Filho & Andrade (2006) reported, based on the experiences of field technicians, that the estimated use of legumes in association with pastures in the states of Acre, Amazonas, Rondônia and Roraima, represented, 45, 10, 10 and 2% of the area with pastures, respectively. Similarly, Valentim & Andrade (2005b, 2005a), reported the success of the implementation of Arachis pintoi in the state of Acre, with about 65.000 hectares associated with U brizantha and the presence of 480.000 hectares (30% of total pastures) of Pueraria phaseloides planted in the pastures and also claiming degraded area. These authors explained that the availability of adequate technology, the need for solutions to the mortality problems of Urochloa cv marandú due to intolerance to humid soils and susceptibility to insect attack (Eri et al 2020) and the environmental restrictions for pasture expansion to the forest, were the main factors that contributed to its success. In addition, the long-term research focused on the producer, the easier access to the seed market and the environmental and economic benefits of its implementation had been mentioned as relevant factors.
Despite the above, in proportion to the total area of pasture in Brazil, the presence of legumes represented less than 1%, based on the data of Parente et al (2017) and Valentim & Andrade, (2005b, 2005a). It is difficult to estimate with certainty the current proportion of mixed pastures in the Brazilian territory, since to the knowledge of the authors, there are no recent surveys; suggesting that the adoption of grass systems with shrubs and/or legumes is still restricted and isolated (Andrade et al 2004; Miles & Lascano 1997; Shelton et al 2005).
Regarding the forestry component of silvopastoral systems, Brazil has also a long research trajectory evaluating the potential of different species to be used in the SPS (Andrade, Salman, Bentes-Gama et al 2012 andrade, Assis, Oliveira et al 2013 and Franke & Furtado 2001). The EMBRAPA (2019) has even developed a methodology for selection of trees on SPS with focus on native species. According to the latest census by the IBGE (2017a), in Brazil there are 13.8 million hectares of agroforestry systems, that is, the area cultivated with forestry species also used for agriculture and animal grazing. According to the IBGE (2017d) there are in Brazil, 105008 livestock farms with some kind of forestry production, that represents 444914 hectares of land with forestry species planted. Of those, Eucaliptus genera make the 90% (404800) of the tree species and the rest in descending order are Pinus ellioti (18886 ha), Acacia mearnsii (5.771 ha), Tectona grandis (2570 ha), Prosopis juliflora (1940 ha), Swietenia macrophylla (1047 ha), Araucaria angustifolia (994 ha), Mimosa caesalpiniifolia (424 ha), Bambusa tuldoides (188 ha), Hadroanthus/Tabebuia (161 ha), Acacia Mangium (43 ha) and Mimosa scabrella (34 ha). 5057 hectares are also listed as occupied by “other species”.
Several authors have also researched the use of native tree species on silvopastoral systems. Among the more prominent ones mentioned are, Guazuma ulmifolia, Peltophorum dubium, Croton floribundus, Jacaranda decurrens, Hymenaea courbaril, Genipa americana, Copaifera spp, Zeyheria tuberculosa, Schinus terebinthifolius, Gliricidia sepium, Erythrina verna, Acromacia aculeata, Dipteryx alata and Schizolobium amazonicum (Dias, Souto & Franco 2007; Franke & Furtado 2001; Lima, Malavasi, Ecco et al 2013; Melotto, Nicodemo, Bocchese et al 2009; Nicodemo, Porfirio-da-Silva, Santos et al 2010; Simões, Carvalho, Evaristo et al 2016; Viana, Maurício, Matta-Machado et al 2002). These species have gained recognition due to its high survivability, rapid growth rate, natural occurrence, ability to fixate nitrogen (of some of them), wood production and rusticity; and have also been highlighted due to its biodiversity, frugal, feed, commercial, medicinal and ornamental benefits (Simões et al 2016).
Nonetheless in the same way as the presence of leguminous species is lackluster, according to the numbers given by IBGE (2017d) the area used for agroforestry in animal production is minimal, less than 0.25% of the pasture area. This number could be even lower if we take into account that this area includes not only ruminant farms but also other farms were the main productive activity is animal production.
The persistence of legumes in grass pastures has always been a drawback, which perhaps partly explains the incipiency of their adoption. In mixed pastures, herbaceous legumes (C3) ended up being overwhelmed by grass (C4), which hindered their survival (Canto and Italiano 1978, Paciullo et al 2014, Serrão & Simão Neto 1971). For these reasons, Valentim et al (2008), argued that one of the major difficulties for the adoption of systems with legumes was, historically, the lack of studies focused on specific strategies for grazing management in mixed forages (C3 × C4); and that it was only in the middle of 1990s that this began to be considered as a priority in research. By this time, Brachiaria spp was already beginning to take center stage as one of the most promising forages and it was one of the main research topics (Fig. 1.)
Regarding the success of Brachiaria and Urochloa and the low adoption of legumes and other shrubs, Miles (2001) explained that African grasses, with C4 photosynthetic pathway, evolved alongside large ruminants and developed tolerance to intense grazing and other biological advantages with respect to the legumes with C3 pathway. Based on this, he stated that tropical shrubby forages that could withstand intense grazing and function as efficient foragers haven’t been discovered yet and if they indeed existed producers would have found them, as it happened in temperate regions with alfalfa (Medicago sativa) and white clover (Trifolium repens); where these species were already being used by producers when pasture research was just beginning (Miles 2001). Other authors have also written about the biological peculiarities that make forage grasses less susceptible to grazing damage than forage legumes; its less exposed meristems in the steam, its greater photosynthetic efficiency and deeper root systems are some of the mentioned arguments in favor of grasses (Fontaneli & dos Santos 2012, Paulino et al 2008).
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| Figure 1. Number of results per decade for the search terms
"Brachiaria", "Leguminosa" and "Leguminosa Forrageira" in the EMBRAPA agricultural research database |
However, the growing interest in the forage legume species and the success cases with the use of creeping forages such as Stylosanthes, Arachis and shrubs such as Cratylia, Guazuma, Leucaena and Tithonia in countries such as Colombia, Mexico, Cuba, Panamá and Australia (Calle et al 2013, Valle et al 2009, Mohammed et al 2016, Murgueitio et al 2011, Ruiz et al 2019, Shelton et al 2005), suggest that the argument of Miles (2001) is not the only thesis that explains the low adoption of silvopastoral systems.
Miles &Lascano (1997) stated that producers in Latin America did not appreciate the benefits of legumes and Andrade et al (2004) commented that this was a significant obstacle to even the most outstanding cultivar of any species. From a practical point of view, the establishment and maintenance of silvopastoral systems (high biological complexity), implies for users to change methods or introduce new technological practices, which represents a disadvantage compared to the simplicity and familiarity of traditionally establishing pastures, that is perhaps another factor in favor of the great dissemination of African pastures and the little adoption of silvopastoral systems. Shelton et al (2005) commented that simpler innovations were more easily established than more complex ones and they reported the case of the easy adoption of Stylosanthes in Thailand and Australia, compared to the newer Leucaena systems. Added to this, the presence of anti-nutritional factors in some cultivars of Leucaena and the susceptibility to anthracnosis of Stylosanthes (Jerba et al 2004, Neto & Velloso 1986), promoted a negative image (Miles & Lascano 1997) and a reduced inclusion for cattle feeding in the case of Leucaena (Costa et al 2001, Ramos et al 1997).
Despite the introduction of less toxic and pest resistant cultivars and practices to prevent fatal poisonings (Andrade et al 2004, Dalzell et al 2006) alternative forage crops have been considered more as a complement to the pasture and not as an essential part, which makes them dispensable without greater risk for the survival of the system.
The establishment and management of silvopastoral systems requires particular technical practices that guarantee their success. Practices that are normally focused on the survival of the herbaceous or shrub. Andrade et al (2006) studying management strategies for forage peanut (Arachis pintoi) and P. maximum, found that despite having a higher amount of grass biomass with a sward height of between 66 to 82 cm, the grazing height that guaranteed the survival of the legume was between 51 to 65 cm. Maraschin &Mott (1989) found that legumes, unlike grasses, required long periods of rest to recover and stay in the pasture; and Zapata et al (2019) mentioned that in Colombia, resting times of less than 42 days for systems associated with L. leucocephala compromised their survival.
More intensive arrangements, such as iSPS, require even more careful handling. iSPS, agroforestry arrangements where trees and highly productive pastures are combined with fodder shrubs in high densities (> 10,000 plants / ha) for direct grazing (Murgueitio et al 2011) are one of the most productive examples of silvopastoral systems, present in countries such as Colombia, México, Cuba, Panamá and Australia, but also one of the most complex ones. Calle et al (2012) and Calle et al (2013) described that for the correct functioning of an iSPS it was necessary a permanent supply of mineral salt and quality water in mobile troughs, living fences planted in the periphery and in the internal divisions of paddocks, fences or electrical tape to concentrate grazing in small strips and management practices in agreement with animal welfare. Due to the intensive component of the arrangement, grazing management in iSPS borrows the high stocking rates and short occupation periods of the holistic grazing of Savory (1988) and Voisin, (1988) and the long rest periods of intensive rotational grazing. These three conditions, according to Calle et al (2013), were essential for the correct functioning of the system and Aguirre et al (2016) agreed that these conditions increased the amount of biomass and shrub protein offered to animals, which provided better productive performance, when compared to traditional systems (Mahecha et al 2012).
However, despite the great performance of animals in this type of arrangement, as has been reported in Colombia (Enciso et al 2019, Liliana Mahecha et al 2008, Rivera et al 2015, Zapata Cadavid et al 2019) México (Estrada et al 2017, González 2013, Mahecha et al 2012, Mohammed et al 2016, Ramírez-Avilés et al 2019), Cuba (Alonso et al 2016, Reinoso and Simon 2000, Ruiz et al 2019) and Australia (Dalzell et al 2006) it is possible that the demands on its establishment and management make its adoption limited. The high costs of establishment (fences, seeds, drinkers, electric fence, labor, fertilizers) and the limited access to technologies and adequate technical assistance have already been described as some of the factors that contribute to the reduced success in the adoption of alternative systems (González 2013, Mahecha 2003, Radrizzani et al 2019, Ramírez-Avilés et al 2019, Zapata Cadavid et al 2019). The former is particularly important if we consider the large extension of agricultural properties in Brazil (48% of farms are larger than 10 ha) (IBGE 2017b) as an extra limitation to the establishment and management of more complex systems (Souza Filho et al 1999).
In contrast to the above, despite the complexity in its management (Sandro 2018), in Brazil, exists also the so-called integrated systems, such as the Integração Lavoura Pecuária (ILP) or the Integração Lavoura Pecuaria Floresta (ILPF) in which, in the same area, crops (corn, soybeans, sorghum), pasture, ruminants and timber trees (mainly eucalyptus) are produced consecutively. Of these systems, according to EMBRAPA, in 2006 there were already 11.5 million hectares established (Pereira 2019). 80% of that area are ILP; adaptations of old practices that were commonly used by producers in order to take advantage of some crops such as rice, corn or cotton during pasture formation (Machado et al 2011). In addition to this familiarity, the establishment of these systems was accompanied by large federal incentives such as the Agricultura de Baixo Carbono program (MAPA 2012) or the most recent certifications in Carbon Neutral Meat (MAPA 2020). This is a great example that, despite having considerably different management, government support and prior technical knowledge play an important role in the dissemination of alternative systems (Shelton et al 2005). Nonetheless, the area of integrated systems in Brazil represents little more than 6% of the area occupied by pastures.
Another argument against the complexity of the practices being a barrier in the adoption of SPS, is the case of agroecology and organic production practices that have being employed by a share of Brazilian agriculture producers for a long time. According to the Brazilian ministry of agriculture livestock and supply, there are around 17000 certified organic producers on Brazil and in the last 7 years, the number has increased by 3 fold (MAPA 2019). This probably has to do with the fact that since the 1970s Brazil has a strong agroecological movement (PNAPO 2012) that has promoted multiple laws in benefit of agroecological production (Costa et al 2017). According to the 2017 agricultural census, of the 2.75 million agricultural farms in Brazil where organic practices could be implemented for food production, only 64000 use organic production practices; of these, 17000 are organic livestock production, 36000 organic vegetable production and 10000 are establishment who uses organic practices for the production of both livestock and vegetable commodities (IBGE 2017c). This suggest that Brazilian producers have in fact the ability to deal with complex systems such as the agroecological or organic production, nonetheless these practices are only present on about the 2.4% of the total amount of farms where organic production could be relevant.
In contrast to silvopastoral systems, extensive grass monoculture systems are simple, familiar, easy to establish and require little labor. The low establishment and management costs allow inefficient grazing systems to be able to satisfy economic needs, compromising, however, the long-term sustainability of the system.
Silva & Carrero (2017), researchers from the Instituto de Conservação e Desenvolvimento Sustentável da Amazônia (IDESAM), established Tithonia diversifolia in dairy herds in Apuí, Amazonas state (Brazil) with a certain degree of success and diffusion throughout the municipality. However, they state that despite the fact that producers recognized the potential of the shrub as a complement to the productive system, in the region, the prices of milk and the necessary work did not compensate the costs of establishment and the producers considered, as a more viable option, expand their pastures towards the forest (M. Alcântara, personal communication, August 13, 2020). A practice that, despite being illegal, was still common among livestock farmers (Barona et al 2010; Carvalho et al 2019).
In Brazil, the cases where there was massive adoption of silvopastoral systems have been product of situations in which the producers encountered adverse conditions that forced them to make changes in their pastures, such as the case of pests attack in Urochloa brizantha cv Marandú (Eri et al 2020, Valentim & Andrade 2005b), environmental restrictions or product of government incentives, as in the case of integrated systems promoted by EMBRAPA (Pereira 2019). This last case also applies to countries such as Mexico and Colombia where, as a result of the involvement of various institutions, silvopastoral systems were established in large areas (Murgueitio et al 2013).
This contrasts with the Australian case, where the systems with Leucaena gained popularity due to their productive benefits, facilitated by the availability of technology and resources for the producers (Dalzell et al 2006, Shelton et al 2005). This suggests that in Latin America the adoption of associated systems and, more generally, productive intensification, benefits not only from specialized technical assistance, but also from state incentives and policies aimed at reducing deforestation and the environmental impact of livestock production (Picoli et al 2020, Stabile et al 2020).
Aguillar and Cabreira (2016) have mentioned how Brazil has had a relationship with monocultural agriculture since the XVI century, with the implantation of the extensive sugarcane plantations in the sesmarias (large areas of land donated by Portugal during the colonization process in Brazil) using slaves as the main working force. Those authors have also mentioned that the monoculture in large properties and the slave labor defined the agrarian structure of Brazil and that those factors, continued to be present under imperial times and during the XIX century, citing the large coffee plantations as an example. Monoculture in large extensions of land persists to this day, suggesting that those practices are deeply rooted on the history of the Brazilian agrarian development. Later during the Green Revolution in the 60s, the monoculture productive model was disseminated over the country, encouraged by American institutions promoting the maximization of the productivity through the use of external resources like seeds, fertilizers, machinery and pesticides (Alves & Tedesco 2016). This model synchronized very well with the Brazilian agrarian practices, as was designed to deal specifically with the necessities of monoculture (Aguillar & Cabreira 2016; Alves 2013) overlooking mixed crop systems.
Alves (2013) mentioned how the American foundations promoted the entry of the green revolution model through the investment in the Brazilian research and academic institutions, which molded the regional agriculture and prepared professionals to deal with this agricultural model. This could explain why, to this day, other complex agricultural models have been overlooked, as professionals were not suited to deal with them.
Borsari & Vidrine (2005) evaluated American (Louisiana and Texas) and European (France and Italy) undergraduate curricula with the objective of characterize the presence of sustainable production principles on the agrarian academic courses. The authors mentioned how in Italy the formation of professionals in agricultural sciences was more focused on satisfying the commercial needs of the industry rather than on the student’s specialization; and how in France, sustainability topics were included only when the student was involved in post graduate studies and not during the undergraduate program. Those authors identified how concepts such as “integrated production systems”, “alternative agriculture” and “plant succession” were difficult to grasp by European students and concepts such as “reductionism”, “holism” and “eutrophication” were difficult to understand by the U.S students. Borsari & Vidrine (2005) argue that the reason for such peculiarities was explained by a curriculum that was more focused on agribusiness than sustainability, prioritizing economic factors, thus, overlooking sustainability as an essential topic in the preparation of the new generation of agriculture professionals.
In a similar study, Scare et al (2016) evaluated the attitude towards sustainable agriculture in a research about 288 agronomy students from Brazilian universities. The authors reported that the participants were able to identify the importance of sustainable agriculture practices, understood the concept, its relationship with the environment and the social and economic viability of those practices. Conversely, Jacob et al (2016), in a study about the inclusion of agroecology concepts on agronomy programs in universities on the state of São Paulo, found that agroecology was approached mainly as an optional course and that from the 778 analyzed courses only 49 of them mentioned agroecology or sustainability on its name. In a similar manner analyzing the current curriculums from the 10 most important agronomy and animal science programs in Brazil (USNEWS n.d.) , we found that, in average, those programs dedicate 1.94% of their required course load on courses with ‘agroeco’ or ‘sustent’ on its name. Of that percentage only 0.6% represented mandatory courses and the rest were optional ones. The minimum course load required for getting a degree on the analyzed universities was in average 3735.5 ± 516.7 hours. It is important to note that, it is highly probable that sustainability or agroecology topics are included or discussed on courses without mentioning this on its title or that activities not listed under the curriculum, discussed these matters.
Therefore, it is clear that although Brazil has a long history of introducing alternative practices and forage crops to pastures, it is only recently that, probably, as a result of the environmental commitments assumed by the country, silvopastoral practices seem to be gaining strength, represented mainly by the accomplishments of the integrated crop livestock systems. The growing demand for sustainable livestock alternatives by society and institutions (e.g. university and research centers) has stimulated the introduction of academic courses, related to the sustainability and management of biologically complex systems, to agricultural science programs; courses that previously did not exist and perhaps could have added to the factors that limited the adoption of alternative production systems.
Regardless of the enormous research efforts made in Brazil, represented by farmers and institutions, the implementation of silvopastoral systems is still incipient taking into account the productive potential of the country (land availability and favorable weather) and the large area of degraded pastures that still exist. The difficulties in its establishment, its sensibility to grazing and the lack of research and education on the management of biologically complex systems are some of the possible causes.
Compared to monoculture systems, the costs, technical support for implementation and management of SPS are higher, however, the long-term positive effects demonstrate their viability not only economically but also environmentally. Regarding the latter, the payment for environmental services could be one strategy that can compensate farmers for the adoption of SPS and also work as an incentive for others to implement. It could be argued that the neutral carbon initiative is an example of the country starting to research about this kind of strategies.
Government and institutional support are key elements to scale up the adoption of SPS which is also linked to the implementation of long terms policies. Research focused at the farm level is extremely necessary, as well as the study of implementation and management strategies that are accessible and easy to adopt.
The global demands for sustainable animal production systems are relatively recent and it is possible that due to this, current productive and educational paradigms are gradually starting to change. However, for the Brazilian reality it seems that is still necessary to develop tools for easy adoption accompanied by public policies.
The authors wish to thank CAPES and CNPQ foment agencies. Also thank Dr. Newton Lucena Costa from EMBRAPA Roraima and Melquesedek Alcântara and Gabriel Carrero from the IDESAM in Apuí, Amazonas for their valuable insights.
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