Legume Proportion of Grass-Legume Mixtures Affects Greenhouse Gas Emissions from Animals Grazing Pasture

Project Overview

Project Type: Graduate Student
Funds awarded in 2015: $11,000.00
Projected End Date: 08/31/2017
Grant Recipient: University of Florida
Region: Southern
State: Florida
Graduate Student:
Major Professor:
Dr. Lynn Sollenberger
University of Florida
Major Professor:
Dr. Jose Dubeux, Jr.
University of Florida - NFREC

Annual Reports


  • Agronomic: Rhizoma peanut, bahiagrass
  • Animals: bovine


  • Animal Production: feed/forage, grazing management, Greenhouse gas emissions


    We are comparing legume- and grass-based beef production systems in terms of greenhouse gas emissions from animal urine and dung, and potential methane emissions from enteric fermentation. Typically enteric fermentation emissions in legume-based diets are less than those of animals grazing pure grass pastures, however greater nitrogen content in diets containing legumes may increase emissions of some greenhouse gases (such as nitrous oxide) from animal excreta. The first year of field experimentation was completed in October 2015, and laboratory and data analysis are ongoing.

    Project objectives:

    1. To quantify emissions of N2O and CH4 from animal dung and N2O from animal urine for these two pasture types in order to obtain emission factors of N2O separately for each excreta type (urine or dung) and for animals with contrasting diets, and to compare emission factors obtained in this study with others reported for different production systems in the literature and those used by the IPCC model;
    2. To quantify enteric fermentation CH4 emissions from the two pasture types and compare these measurements with those estimated by the IPCC model with parameters currently used for Southeast US in order to assess the prediction capability of the model;
    3. To sum emissions of N2O from dung and urine and CH4 from dung and enteric fermentation of animals grazing the two pasture types and use global warming potential to estimate emissions in CO2e.
    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.