Greenhouse gas emissions from pasture and arable crops grown on a Kairanga soil in the Manawatu, North Island, New Zealand

Carbon dioxide (CO 2 ) emissions were determined during the first 3 years of cropping a Kairanga soil out of pasture, with either full cultivation or no‐tillage cereal establishment. The CO 2 emitted during cropping was compared with calculated methane production by ruminants grazing pasture at the site. Cultivation resulted in the loss of about 10 t soil organic carbon (C)/ha over 3 years but there was no change in soil C with no‐tillage cropping. Grazing of pastures at a high but sustainable stocking rate was calculated to produce 205 kg C/ha per year as methane (CH 4 ). No‐tillage cropping of this site therefore contributes much less CH 4 and CO 2 to the atmosphere than either grazing or cropping with cultivation. Using 20‐year global wanning potentials of 20 and 1 for CH 4 and CO 2 respectively, the data showed that ruminants grazing this site would have had more influence on atmospheric warming than cropping with cultivation did.