Tropical forage legumes for environmental benefits: An overview

Abstract

Ruminant livestock production in the tropics, particularly when based on pastures, is frequently blamed for being detrimental to the environment, allegedly contributing to: (1) degradation and destruction of ecosystems, including degradation and loss of soil, water and biodiversity; and (2) climate change (global warming). In this paper we argue that, rather than being detrimental, tropical forage legumes can have a positive impact on the environment, mainly due to key attributes that characterize the Leguminosae (Fabaceae) family: (1) symbiotic nitrogen fixation; (2) high nutritive value; (3) deep-reaching tap-root system; (4) wide taxonomic and genetic diversity; and (5) presence of particular secondary metabolites. Although there are also potential negative aspects, such as soil acidification and the risks of introduced legumes becoming invasive weeds, we submit that legumes have potential to contribute significantly to sustainable intensification of livestock production in the tropics, along with the provision of ecosystem services. To further assess, document and realize this potential, research for development needs in a range of areas are indicated.Keywords: Biodiversity, ecosystem services, GHG emissions, land rehabilitation, soil enhancement, symbiotic nitrogen fixation. ResumenLa producción ganadera de rumiantes en el trópico, especialmente cuando es basada en pasturas, frecuentemente es considerada como perjudicial para el medio ambiente, ya que supuestamente contribuye con: (1) la degradación y destrucción de ecosistemas, incluyendo la pérdida de suelo, agua y biodiversidad; y (2) el cambio climático (calentamiento global). En el artículo se exponen argumentos para mostrar que, en lugar de ser perjudiciales, las leguminosas forrajeras tropicales pueden impactar positivamente en el medio ambiente, principalmente debido a sus atributos clave que son característicos de la familia de las Leguminosae (Fabaceae): (1) fijación simbiótica de nitrógeno; (2) alto valor nutritivo; (3) sistema de raíz pivotante profundo; (4) amplia diversidad taxonómica y genética; y (5) presencia de metabolitos secundarios particulares. Aunque se deben reconocer aspectos negativos como la contribución potencial a la acidificación del suelo y el riesgo de convertirse en malezas invasoras, concluimos que las leguminosas forrajeras tienen un potencial significativo para contribuir a la intensificación sostenible de la producción ganadera en el trópico, junto con la prestación de servicios ecosistémicos. Sugerimos una serie de áreas donde se requiere de investigación para evaluar más a fondo, documentar y realizar este potencial.Palabras clave: Biodiversidad, emisiones de GEI, fijación simbiótica de nitrógeno, mejoramiento del suelo, rehabilitación de tierras, servicios ecosistémicos.

Liveweight gain of beef cattle in Brachiaria brizantha pastures and mixtures with Stylosanthes guianensis in the Brazilian savannah

“…For a range of experiments in Queensland, Coates et al (1997) described an advantage of 30–60 kg/head/year for cattle grazing pastures including Verano ( S. hamata ) and/or Seca ( S. scabra ). In the Llanos of Colombia, annual liveweight gain advantage for cattle grazing gamba grass ( Andropogon gayanus ) mixed with S. capitata ranged from 40 to 60 kg/head/year (Schultze‐Kraft et al, 2018), also superior than observed in the current study. This lesser impact of mixed pastures on ADG could be explained by the greater quality (i.e.…”

Grassland Management Affects Delivery of Regulating and Supporting Ecosystem Services

“…The development of legume-based grassland-livestock systems is considered a pillar for more sustainable and competitive ruminant production systems in the future (Lüscher et al, 2014;Schultze-Kraft et al, 2018). There have been relatively few quantitative studies of the impact of legume introduction on SOC accumulation ( Jensen et al, 2012), but the consensus is that forage legumes increase the rate of soil C sequestration (Cong et al, 2014).…”

Disaggregating Landscape‐Scale Nitrogen Attenuation Along Hydrological Flow Paths

“…Our estimates of N attenuation in crop and pasture systems are close to the global average N use efficiency of 47% (Lassaletta et al, ) and agree with estimates for Florida production systems (Prasad & Hochmuth, ). While legumes are often identified as a more sustainable N source (Schultze‐Kraft et al, ), the results from Desormeaux et al () suggest that conventional cultivation of legumes can potentially contribute to net N inputs leached below the root zone. While legumes account for only 2% of N inputs in the springshed and therefore did not contribute significantly to spring N export, this has implications for catchments with higher contributions from agricultural BNF (e.g., Sobota et al, ).…”