Influence of land-use management on CO2 emissions from a silt loam soil in New Zealand

Effects of land-use management on agricultural sustainability and greenhouse gas emissions are major issues for researchers, regional councils and farmers in New Zealand. This study was undertaken to investigate the environmental impact of land-use management on field-CO2 emissions in Ohakea silt loam soil (Typic andoaqualf) that had been converted from permanent pasture to forage cropping for 2 years. The treatments were plow tillage (PT) and no-tillage (NT), with summer fodder maize (Zea mays L.) double-cropped in rotation with winter oat (Avena sativa L.); permanent pasture (PP) was used as control. Field-CO2 emissions measured every 3-4 weeks during 12 months, were significantly highest in the PP. Overall, results indicate that reduction in tillage had only a minor effect on field-CO2 emission throughout the crop growth period, During one year CO2 emissions ranged from 55-132 kg C ha(-1) per day in the PP treatment. 43-91 kg C ha(-1) per day in the NT treatment and 36-81 kg C ha(-1) per day in the PT treatment. Daily field-CO2 emissions measured within a few days after cultivation were significantly highest in the PP treatment and were in the order of PP > NT > PT. Conversion of PP to NT cropping had no effect on surface organic C levels, but conversion to cropping with tillage markedly reduced C levels. (C) 2000 Elsevier Science B.V. All rights reserved.