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

Abstract

Carbon dioxide (CO2) 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 CO2emitted 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 (CH4). No-tillage cropping of this site therefore contributes much less CH4and CO2to the atmosphere than either grazing or cropping with cultivation. Using 20-year global wanning potentials of 20 and 1 for CH4and CO2respectively, the data showed that ruminants grazing this site would have had more influence on atmospheric warming than cropping with cultivation did. © 1992 Taylor & Francis Group, LLC.