Keywords: cover crop, soil inorganic N, carbon sequestration, tillage, CO₂ flux
Cover cropping and no-till farming have been paid attention due to add soil organic matter, conserve soil residual nitrogen during fallow season when the threat of leaching is considerably, and enhance soil organic matter. However, these benefits may vary depending on cover crop species and tillage system. A field level experiment was conducted at the Experimental Farm of Ibaraki University on a Humic Allophane soil (Andisol) in Kanto region, Japan from October 2002 to October 2007 to evaluate the impact of tillage system and cover crop on crop productivity, soil nitrogen and carbon dynamics in field rice production. Fall planted rye was successfully to prevent N leaching, and both of rye and hairy vetch was also effective to enhance the soil carbon content. In addition CO₂ emission was refracted to the cover crop residue amount and their quality. There were little difference of yield response between tillage system and cover crop types until 2005, however, magnitude differences were observed in 2006 and 2007 for rice production. No-till field rice yields were significantly higher than rotary and plow treatments. No-till with cover crop system may have great potential to cope with both sustaining crop yields and enhaince soil carbon pool in Andisoil.