Monday, November 5, 2007
99-3
Contribation of Fungi Activity for N2O Emission in No-Tillage with Cover Crop Field.
Winter cover crops would be a effective tool to enhance the potential of soil carbon sequestration in the soil, however, N2O emission may offset that positive potential due the decomposition of cover crop residues. It is also expected that soil microbial population and activities affect the residue decomposition process and greenhouse gas emission from soil. However, limited information is available regarding the effects of cover cropping and tillage system on soil microbial population and N2O emission. This study was conducted on a Humic Allophane soil to evaluate the effects of tillage systems (plow, rotary and no-till treatment), and cover crop species (hairy vetch , rye and fallow) and fertilizer N level (0 and 100 kg N ha-1) on soil microbial populations in a two years field experiment. Soil bacterial and fungal populations were analyzed at the two weeks after the seeding of upland rice and two days before the harvest in the number of microorganisms. Cover crop species and tillage systems were strongly affected soil bacterial populations in the soil from 0 to 10 cm depth in May, the bacteria population showed significant difference between cover crop treatments in no-tillage and rotary tillage treatment, but no significant effect in plow treatment. No-tillage with cover crop treatment showed significantly high soil fungal biomass, comparing with the tillage system. Further, no-tillage with cover crop system showed significant high denitrifying bacterial populations. With respect to the field N2O emission in the no-tillage system, rye and hairy vetch showed higher N2O emission than in fallow, furthermore it was approximately two times higher in 100 kg N ha-1 than in 0 kg N ha-1.
These factors can potentially affect the availability of plant nutrients and organic matter transformations, all of which are important in the development of sustainable agricultural system.
Presentation