Impact of sustainable intensification of beef production in tropical areas on climate change mitigation

Abstract

Focused on the awareness of climate change, food shortage risks and the concept of sustainable intensification, the main purpose of this project is to measure the environmental and productive impact of process of cattle ranching intensification and to develop a comprehensive set of indicators for ecologically sustainable intensification of beef cattle. We also aimed to measure emissions factors (EFs) for methane (CH4), nitrous oxide (N2O) and ammonia (NH3) to improve greenhouse gases (GHG) inventories e balance. There are two EFs for N2O, one for fertilizer (EF1) and other for animal excreta (EF3PRP) that are used to being quantified separately. However, in the pastoral system, fertilizer is applied on the excreta therefore; we will measure for the first time these two EFs simultaneously in tropical conditions. The experimental area will consist of 24 ha of Brachiaria brizantha Hochst ex A. Rich Stapf cv. Marandu pasture divided into 12 paddocks of approximately 2 ha each. The Marandu grass pasture was implemented in 2005/2006, with no interference (fertilizations) for at least five years. The experiment will be repeated for two consecutive years. Within each year, the experiment will be divided in two stages: rearing phase (rainy season, from November to March; rainy-dry transition, from April to June), and finishing phase on pasture or in feedlot (dry season, from July to September). The treatments will consist of three cattle ranching intensification (low, intermediate and high) in a completely randomized design with four replicates (paddocks), characterized by stocking rates of approximately 1.5, 3.5 and 5.5 animal unit (AU)/ha; respectively. Pasture evaluation will include herbage mass and forage quality determination. Animal response variables include intake and nutrient digestibility, enteric CH4, N balance, performance, carcass yield, and protein and energy deposition. Environmental impacts to be assessed include N loss through volatilization of NH3 and N2O; CO2 and CH4 from excreta and N fertilization; and CH4 enteric. Finally, GHG balance and carbon footprint will be estimated through the calculation of the emissions of GHG from animals and fertilizer and the emission of fossil CO2 by other activities.