Effects Of Different Tillage Methods On The Emission Of Methane And Nitrous Oxide From The Rice-wheat Rotation Cropland Of Polder

Study of Chaohu lowland polder rice-wheat rotation soil CH₄ and N₂O emissions has an important role in filling Agricultural CH₄ and N₂O emissions related research in southern China.In the lowlands of Chaohu polder area of rice wheat rotation field as the research object,study the effects of different tillage on farmland CH₄ and N₂O emissions.Four treatments were set up in this experiment,which were conventional tillage（CG）,optimized fertilization（CY）,optimized fertilization + no tillage（CB）and optimized fertilization + straw incorporation（CJ）,and each treatment was treated with random 3 repetitions.The results obtained are as follows:1.The rising trend of air temperature in Chaohu region in the last 60 years is obvious,which is consistent with the global warming in a certain extent.In Chaohu area from 1965 to 2014,the temperature is rising,and the linear tendency rate of temperature is about 0.25℃/10 a.In the 60 year,the temperature decadal change is relatively large,and the positive and negative value of the distance is more concentrated.In the past 1990 s,the average value is negative,which is positive in 1990 s.In Chaohu area from 1965 to 2014,the annual precipitation showed an increasing trend,but the trend was not significant,and the linear tendency rate was about 36.7mm/10 a.Extreme precipitation over the 60 years has disturbed the overall trend of the change in precipitation over the 60 years.2.Diurnal variation of soil CH₄ emission flux in paddy soil was obvious,mainly showed "single peak",the largest peak appeared in 14:00 16:00 in the afternoon.Single rice cropping paddy CH₄ daily emission flux and the emission flux at 10 o’clock in the morning is closest,and the sampling time is reasonable before and after 10 am.Diurnal variation of N₂O emission flux showed "four peaks",the maximum value appeared at 20 pm,the two peak appeared at 12 noon and 0 pm,and the emission peak of N₂O emission peak appeared at 16 pm.3.In the whole growth period of rice,four paddies CH₄ emission flux trends are basically the same,presented as "three peaks",the emission peaks were roughly in the early rice tillering stage,booting flowering stage early,early rice grain filling stage.Early seedling transplanting is a lower stage CH₄ emission flux,CH₄ flux emission decreased continuously during the maturation stage and filling stage of rice.The emission maxima of the four treatments appeared at the 19 days after transplantation.Continuous overcast and rainy weather brought about by precipitation and cooling,contributed to the CH₄ emissions two trough.The temperature greatly affects the emission of CH₄ in paddy fields,especially the low temperature slows down the rate of CH₄ emission from paddy fields.Seasonal variation of N₂O emission fluxes in paddy fields showed "three peaks",which appeared on the twentieth day after transplantation,and then there were two smaller peaks.In the early days of the baking field,the soil air pressure was reduced to make a large amount of N₂O emissions.4.During the growth period of winter wheat,the CH₄ emission flux was negative,and the wheat field on the atmospheric CH₄ showed absorption sink,but there was a big difference in the emission fluxes at different stages.Optimal fertilization + No Tillage Treatment of soil properties is more stable,good soil permeability,is conducive to enhance the activity of CH₄ bacteria.The optimized fertilization and straw returning treatment increased the anaerobic condition and the soil nutrient condition,which affected the CH₄ absorption rate.Crop of greenhouse gas emissions to N₂O dominated,the N₂O emission flux presented five distinct peaks,the first,the third and fifth were related to fertilization,and found the third and fifth N₂O emission peak is not after fertilization immediately,but after 2 3 days after the precipitation.