Acclimation, carbon flux, and greenhouse gases emission from Brachiaria brizantha cv. Marandu and Brachiaria Mavuno pastures inoculated with Azospirillum brasilense under a warmed atmosphere under field conditions

Abstract

Anthropogenic climate change is one of the most important challenges that humans will face in the next decades. The increase in the atmospheric temperature associated with changes in climate patterns significantly impact livestock production and ecosystems productivity. However, tropical and subtropical ecosystems were less studied when compared to temperate ecosystems. This knowledge gap creates enormous uncertain on global carbon flux models and decrease our comprehension about possible feedbacks and the complex relations within biomes. In Brazil, livestock sector is very important for GDP and the country is recognized as the biggest meat exporter in the world. This production is made mainly on rainfed natural and managed pastures, but 80% of it are degraded pastures. In order to mitigate the negative impacts of livestock on climate, Brazil created in 2010 the National Plan for Low Carbon Emission in Agriculture (ABC Plan) to develop sustainable production techniques. Within these techniques, bacteria inoculation that are able to fix atmospheric N or induce plant growth has shown to be very efficient in increasing the productivity and C assimilation into biomass, and decreasing the soil emissions of greenhouse gases and improving plant tolerance to drought. Therefore, plant inoculation strategy can amplify or mitigated the effects of elevated temperature on C sink strength of tropical pastures in a future climate change scenario. Until now, the scientific literature lacks substantial studies that evaluate under field conditions the carbon flux dynamic on tropical grasslands. In this research proposal, we will unravel using an integrated perspective, for the first time, how the temperature increase under field conditions will affect the dynamic of C flux and greenhouse gas emissions by soil on Brachiaria brizantha cv. Marandu and Brachiaria híbrida cv. Mavuno pastures with or without the inoculation of strains of Azospirillum brasilense, each season. Analysis will be performed at leaf and ecosystem scale. The results will improve our comprehension about C flux dynamics, greenhouse gases, and grasslands adaptation under a warmer atmosphere and under ABC plan. In addition, results will help us to understand the mitigation potential of tropical pastures and C sink, creating scientific knowledge to decisions makers and indicating the most adequate productivity systems for grasslands. (AU)