ghg-inventory-1990-2013

5.3.1). In comparison, the combined N 2 O emissions from organic fertilisers (spreading of
animal manure) and pasture, range and paddock manure (deposited directly by grazing
livestock) reported under the Agricultural soils category totalled 8,453.4 kt CO 2 -e in 2013
(15.5 per cent of emissions from the Agriculture sector).
Table 5.3.1
Manure
management subcategory
Trends and relative contribution of methane and nitrous oxide emissions under the
Manure management category between 1990 and 2013
Emissions
(kt CO 2 -e) Change from 1990
Share of Manure
management
category
Share of total
Agriculture
sector
Difference
2013 1990 2013
1990 2013 % (kt CO 2 -e) 1990 (%) (%) (%) (%)
Methane 685.5 1,129.6 64.8 444.1 92.8 92.7 2.0 2.9
Nitrous oxide 53.5 89.4 67.1 35.9 7.2 7.3 0.2 0.2
For the major livestock categories in New Zealand, only dairy cows have their excreta
stored in anaerobic lagoon waste systems (table 5.3.2). This stored excreta represents a
small proportion (5 per cent) of the total dairy effluent produced (Ledgard and Brier,
2004). The remaining 95 per cent of excreta from dairy cattle is deposited directly onto
pasture. This relates to the proportion of time dairy cattle spend on pasture compared with
the time they spend in the milking shed. Non-dairy cattle, sheep and deer graze outdoors
all year and deposit all of their faecal material (dung and urine) directly onto pastures
(table 5.3.2).
For the minor livestock species: goats, horses, mules and asses, and alpacas are assumed
to graze outdoors all year and deposit all of their manure directly onto pastures. Estimates
of the proportions of different waste management systems for swine and poultry broilers
in the manure management systems in New Zealand have been provided by Hill (2012)
and Fick et al (2011) respectively (table 5.3.2).
Nitrous oxide emissions from the spreading of animal manure and from manure deposited
directly to pasture by grazing livestock are reported under the Agricultural soils category
(under sections: Organic nitrogen fertilisers and Urine and dung deposited by grazing
animals respectively).
New Zealand’s Greenhouse Gas Inventory 1990–2013 149