科研之友
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摘要
Mixed responses of soil nitrous oxide (N(2)O) fluxes to reduced tillage/no-till arc widely reported across soil types and regions. In a field experiment on a Danish sandy loam soil we compared N(2)O emissions during winter barley growth following five years of direct drilling (DD), reduced tillage (RI) or conventional tillage (CT). Each of these tillage treatments further varied in respect to whether the resulting plot crop residues were retained (+Res) or removed (-Res). Sampling took place from autumn 2007 to the end of spring 2008. Overall N(2)O emissions were 27 and 26% lower in DD and RT, respectively, relative to N(2)O emissions from CT plots (P < 0.05). We observed that in residue removal scenarios N(2)O emissions were similar for all tillage treatments, but in residue retention scenarios N(2)O emissions were significantly higher in CT than in either DD or RI (P < 0.05). Irrespective of residue management, N(2)O emissions from DD and RT plots never exceeded emissions from CT plots. Retention of residue was estimated to reduce emissions from DD plots by 39% and in RT plots by 9%, but to increase N(2)O emissions from the CT plots by 35%. Relative soil gas diffusivity (Rdiff), soil NO(3)-N, soil temperature, tillage and residue were important driving factors for N(2)O emission (P < 0.05). A multiple linear regression model using Rdiff to represent the water factor explained N(2)O emissions better than a water-filled pore space (WFPS) based model, suggesting a need for review of the current use of WITS in N(2)O prediction models. We conclude that on light textured soils, no-till has the potential for reducing N(2)O emissions when crop residues are returned to the soil.
- 出版日期2010-10
