Simulation of greenhouse gas emissions and mitigations by Brazilian beef cattle feedlot manure management using Manure-DNDC mathematic model

Abstract

Brazil holds the largest commercial herd as well as being the major beef producer. This production is characterized by grazing systems, which currently derives about 90% of slaughtered animals. The remaining 10% are finished in feedlots. Different types of beef production (extensive and intensive) result in different magnitudes of GHG emissions, which are usually linked to quality of diet offered, which, on animal basis, changes GHG emissions pattern through enteric fermentation and manure. The better quality diet offered in feedlots leads to reduction of methane (CH4) emissions, via enteric fermentation, but in the other hand increases CH4 and nitrous oxide (N2O) emissions via manure with levels dependent on the management. For being parameters of sustainable production, manure management and their respectively GHG emissions, which have not been evaluated in Brazilian feedlots, need to be further analyzed and explored. The use of mathematical modeling can be used to estimate these emissions, not only for allowing the integration of biogeochemical data obtained at field, but also enable the evaluation of the impact of different manure management practices. The objective of this project is to estimate the emissions and mitigation potential of GEE by different manure management systems carried by beef cattle feedlots in Brazil, using the mathematical model Manure-DNDC. With data from field collection will be simulated the carbon and nitrogen dynamics contained in manure at feedlot pens, several treatment forms (heaps, composting and anaerobic digestion), and manure application in field (digested and nitrification inhibitors addicted) and their effects in the soil. In addition to publishing scientific articles, the results of this project might support national GHG emission reporting and provide subsidies for the establishment of better manure management in beef cattle feedlots in Brazil, aiming to reduce these emissions. (AU)