The two non-CO
2 greenhouse gases (GHGs) nitrous oxide (N
2O) and methane (CH
4) comprise 54.8% of total New Zealand emissions. Nitrous oxide is mainly generated from mineral N originating from animal dung and urine, applied fertiliser N, biologically fixed N
2, and mineralisation of soil organic N. Even though about 96% of the anthropogenic CH
4 emitted in New Zealand is from ruminant animals (methanogenesis), methane uptake by aerobic soils (methanotrophy) can significantly contribute to the removal of CH
4 from the atmpsphere, as the global estimates confirm. Both the net uptake of CH
4 by soils and N
2O emissions from soils are strongly influenced by changes in land use and land management. Quantitative information on the fluxes of these two non-CO
2 GHGs is required for a range of land-use and land-management ecosystems to determine their contribution to the national emissions inventory, and for assessing the potential of mitigation options. Here we report soil N
2O fluxes and CH
4 uptake for a range of land-use and land-management systems collated from published and unpublished New Zealand studies. Nitrous oxide emissions are highest in dairy-grazed pastures (10–12 kg N
2O–N ha
?1 year
? 1), intermediate in sheep-grazed pastures, (4–6 kg N
2O–N ha
?1 year
?1), and lowest in forest, shrubland and ungrazed pasture soils (1–2 kg N
2O–N ha
?1 year
?1). N deposited in the form of animal urine and dung, and N applied as fertiliser, are the principal sources of N
2O production. Generally, N
2O emissions from grazed pasture soils are high when the soil water-filled pore-space is above field capacity, and net CH
4 uptake is low or absent. Although nitrification inhibitors have shown some promise in reducing N
2O emissions from grazed pasture systems, their efficacy as an integral part of farm management has yet to be tested. Methane uptake was highest for a New Zealand Beech forest soil (10–11 kg CH
4 ha
?1 year
?1), intermediate in some pine forest soils (4–6 kg CH
4 ha
?1 year
?1), and lowest in most pasture (<1 kg CH
4 ha
?1 year
?1) and cropped soils (1.5 kg CH
4 ha
?1 year
?1). Afforestation /reforestation of pastures results in increases in soil CH
4 uptake, largely as a result of increases in soil aeration status and changes in the population and activities of methanotrophs. Soil CH
4 uptake is also seasonally dependent, being about two to three times higher in a dry summer and autumn than in a wet winter. There are no practical ways yet available to reduce CH
4 emissions from agricultural systems. The mitigation options to reduce gaseous emissions are discussed and future research needs identified.
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