Abstract: In order to examine the effects of tillage regime on soil respiration in a farmland,authors measured the soil respiration rates under no tillage and tillage treatments by using a portable soil CO2 fluxes measurement system in a winter wheat-soybean farmland from March to October in 2010 Soil temperature and moisture at depth of 5cm were also measured during soil respiration measurements.The results indicated that soil respiration rates under the no tillage and tillage treatments developed with similar seasonal variations during both the winter wheat and soybean growth periods. Mean soil respiration rates for the no tillage and tillage treatments were 2.50±0.14 and 2.40±0.29μmol〖KG-*6〗·〖KG-*6〗m-2〖KG-*6〗·〖KG-*6〗s-1 during the winter wheat growth season,respectively,while they were 2.82±0.28 and 3.50±0.29μmol〖KG-*6〗·〖KG-*6〗m-2〖KG-*6〗·〖KG-*6〗s-1 during the soybean growth season,respectively.Mean soil respiration rates were not significantly different between no tillage and tillage treatments in the winter wheat growth season,while it was significantly different (P<0.05) between the two treatments in the soybean growth season.For the soybean growth season,the most obvious significant difference in soil respiration rates could be found during the stages of flowering (late July to mid August). Further investigations indicated that soil respiration could be well simulated by an empirical model in which the effects of both soil temperature and moisture on soil respiration were considered.This model explained 25.3% and 44.0% variances in soil respiration rate under no tillage (R2=0.253,P<0.05) and tillage treatments (R2=0.440,P<0.01),respectively.Based on the results,on the one hand,the effects of plowing regimes on soil respiration were contingent on specific cropping systems.No tillage,in comparison with tillage,significantly reduced soil respiration in the soybean plots,but had no significant effects on soil respiration in the winter wheat plots.On the other hand,the effects of both soil temperature and moisture on soil respiration under the tillage regime were more obvious than those under the no tillage regime.

Key words: No tillage, Tillage, Soil respiration, Soil temperature, Soil moisture