2004 Methane and Nitrous Oxide Emissions from Manure Management in South Africa.

Mokhele Moeletsi,Mphethe Tongwane

doi:10.3390/ani5020193

Abstract

Simple SummaryLivestock manure management is one of the main sources of greenhouse gas (GHG) emissions in South Africa producing mainly methane and nitrous oxide. The emissions from this sub-category are dependent on how manure is stored. Liquid-stored manure predominantly produces methane while dry-based manure enhances mainly production of nitrous oxide. Intergovernmental Panel on Climate Change (IPCC) guidelines were utilized at different tier levels in estimating GHG emissions from manure management. The results show that methane emissions are relatively higher than nitrous oxide emissions with 3104 Gg and 2272 Gg respectively in carbon dioxide global warming equivalent.Manure management in livestock makes a significant contribution towards greenhouse gas emissions in the Agriculture; Forestry and Other Land Use category in South Africa. Methane and nitrous oxide emissions are prevalent in contrasting manure management systems; promoting anaerobic and aerobic conditions respectively. In this paper; both Tier 1 and modified Tier 2 approaches of the IPCC guidelines are utilized to estimate the emissions from South African livestock manure management. Activity data (animal population, animal weights, manure management systems, etc.) were sourced from various resources for estimation of both emissions factors and emissions of methane and nitrous oxide. The results show relatively high methane emissions factors from manure management for mature female dairy cattle (40.98 kg/year/animal), sows (25.23 kg/year/animal) and boars (25.23 kg/year/animal). Hence, contributions for pig farming and dairy cattle are the highest at 54.50 Gg and 32.01 Gg respectively, with total emissions of 134.97 Gg (3104 Gg CO2 Equivalent). Total nitrous oxide emissions are estimated at 7.10 Gg (2272 Gg CO2 Equivalent) and the three main contributors are commercial beef cattle; poultry and small-scale beef farming at 1.80 Gg; 1.72 Gg and 1.69 Gg respectively. Mitigation options from manure management must be taken with care due to divergent conducive requirements of methane and nitrous oxide emissions requirements.

Highlights

Accurate quantification of national greenhouse gas (GHG) emissions is required to provide a sound basis of government policies and mitigation potential opportunities
GHG emissions for manure management are considered as a key source category that needs to be estimated in South Africa [2]
Livestock manure in South Africa is mostly left in the pasture, range or paddocks or managed as drylot and the CH4 conversion factor in these systems is low (1.5%)

Summary

Introduction

Accurate quantification of national greenhouse gas (GHG) emissions is required to provide a sound basis of government policies and mitigation potential opportunities. Reliable information can help in the identification of proper responses in line with food security and economic development in the country [1]. GHG emissions for manure management are considered as a key source category that needs to be estimated in South Africa [2]. Manure management includes storage and treatment of manure, before using it as fertilizer or burning as fuel. Methane (CH4 ) and nitrous oxide (N2 O) are produced during different storage and treatment stages of manure. The term ‘manure’ includes both dung and urine produced by livestock [3]

Methods

Results

Conclusion