The Effect Of No-tillage And Nitrogen Regulation On CH₄Emissions From Rice Fields

CH4is important greenhouse gases, rice fields is one of the important CH4emission source. How to reduce greenhouse gas emission have become today’s problems that need to be resolved. No tillage protective technology in our country is becoming more and more popular and it affects CH4on paddy significantly. The study through field experiment, system research CH4emission from rice field under the conditions of tillage and no-tillage two cultivation modes, three kinds of nitrogen (N0, N1, N2) and two nitrogen application methods (F1, F2), in order to provide a scientific basis for greenhouse gas emission reduction from paddy field. The main results are as follows:1. The effects of no-tillage and nitrogen regulation on CH4emissions from, rice fieldsPaddy field CH4emission differences diurnal under conventional tillage and no-tillage two cultivation modes. Paddy field CH4emission flux peak appears later, trough period appears earlier, the daily variation amplitude smaller under no-tillage method. In each growing period of rice, the CH4emissions of each treatment generally appear bimodal pattern, with a peak in the tillering stage and booting heading. CH4emission from rice fields are mainly concentrated in rice tillering stage (before shooting stage), accounting for the whole growth duration of rice emissions75.12%.The effect of CH4emission in rice different growth period on different soil tillage methods is significantly different. Before rice jointing, the CH4emission flux from no-tillage paddy field was significantly reduced by29.73%than conventional tillage. After rice jointing, the CH4emission flux from no-tillage rice fields slightly increased35.14%than conventional tillage rice fields. The no-tillage reduces the CH4emissions16.96%totally than conventional tillage throughout the rice growing period. The effect of CH4emissions on tillage are also affected by nitrogen application ways. Under the condition of F1, no-tillage can remarkably decrease the CH4emission. Under the condition of F2, no-tillage can increase CH4emission at a certain extent.Nitrogen fertilizer extremely significantly promote the CH4emission from rice fields. CH4emission increase with nitrogen levels increased, but the increasing strength decrease relatively. Under no-tillage condition the intensity of nitrogen promoting CH4emission is stronger than under conventional tillage.In different tillage methods, nitrogen application methods affect CH4emissions varily. Under no-tillage condition, heavy based fertilizer is beneficial to reduce CH4emissions from rice fields, but under conventional tillage condition, heavy panicle fertilizer is helpful to reduce the emission of CH4from paddy field.The interaction effect of tillage and nitrogen application methods reached extremely significant level. The collocation of no-tillage and basal fertilizer is the best that can reduce the emission of CH4significantly from paddy field. Based on the above, the collocation of no-tillage, low nitrogen and spike fertilizer is the most that can reduce CH4emission from paddy field.2The correlation of soil redox properties and CH4emission from rice field with no-tillage and nitrogen regulation.CH4emission flux and soil reducing amount of material, active reducing substances aggregates are extremely positively correlated, correlation coefficients are0.9778*,0.8612**, but significantly negatively correlated with Fe2+content and correlation coefficient is-0.5955*.3The correlation of soil microbial biomass, soil respiration and CH4emission from rice field with no-tillage and nitrogen regulation.Microbial biomass C content, microbial biomass N content, soil respiration and soil CH4emission flux are positively related, with the correlation coefficient are0.7071**,0.7675**,0.5376*. The microbial biomass and CH4emission flux reach extremely significant correlation.4The correlation of soil nutrient factors and CH4emission from rice field with no-tillage and nitrogen regulation. The effect of experimental treatment of the three factors on the soil organic matter, total N, pH and alkaline hydrolysis nitrogen do not reach significant level. But these factors can promote the paddy soil CH4emission. And that with CH4emission flux are extremely positively related.5The effect of no-tillage and nitrogen regulation on rice yieldThe yield of conventional tillage average increased by1.61%than no-tillage that not reaching significant level. Increasing nitrogen rate significantly increased the yield. Under no-tillage condition, F1production increased by4.11%than F2. Under conventional tillage condition, F1increase production by8.26%than F2. The interaction effect of tillage and nitrogen reached extremely significant level. And the combination of conventional tillage, high nitrogen and heaver basal fertilizer can significantly improve the yield of rice.