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The objectives of this experiment were to study the effects of a plastic mulched-ridges and unmulched furrows(PMRF) cropping system on soil respiration.The experiment field was planted to winter wheat.Soil CO2 emission was determined with an SR1LP chamber(Qubit Inc.,Canada) between October 2010 and June 2011.The data suggested that soil CO2 emission in the plastic film mulched-ridge(RM) was greater than that in an unmulched,smooth field(FC).Furthermore,CO2 emission rates from the plastic film-mulched ridges were greater than those from the unmulched furrows(FU).The mean soil CO2 fluxes were(1.14±0.20) μmol CO2 · m-2 · s-1 from the unmulched,smooth field,(2.06±0.44) μmol CO2 · m-2 · s-1 from the plastic film-mulched ridge,and(0.75±0.11) μmol CO2 · m-2 · s-1 from the unmulched furrow.There were significant seasonal variations in soil respiration.Soil respiration was lowest during the winter when the wheat was in the seedling stage and highest during the summer when the wheat was mature.Diurnal CO2 emissions from plastic film-mulched ridges,unmulched furrows,and unmulched,smooth fields followed similar patterns during the winter and early spring.Specifically,CO2 emissions increased during the morning,reached a peak around noon,and then decreased in the afternoon.In contrast,there were differences in diurnal CO2 emissions among the treatments after jointing stage.There was a double peak in soil CO2 emission from plastic film-mulched ridges.However,CO2 emissions from unmulched furrows and unmulched,smooth fields remained steady throughout the day.Soil respiration was significantly correlated with soil temperature at the 5 cm depth.Soil respiration increased as the soil temperature increased from 10 to 24—31 ℃.Soil respiration decreased at soil temperatures 31 ℃.The effect of soil temperature on soil CO2 emission was best described by a quadratic function,whereas the interactive effects of soil temperature(T) and soil moisture(W) on soil CO2 emission were best described by the following equation: f(R)=a(bT2+cT)(1+dln(2W)/T)+e.The soil respiration in winter wheat field was changed with the plastic mulched-ridges and unmulched furrows practice. |
