Effects Of Water And Fertilizer Supply On Soil N₂O Emissions In Maize-wheat Rotation System

N₂O is an important greenhouse gas,N₂ O caused by global warming and ozone damage more and more people have attracted attention..The N₂ O produced by the farmland ecosystem is the main object of the study of agricultural greenhouse gas emissions,which accounts for a large proportion of anthropogenic greenhouse gases and is easily disturbed by human interaction.Therefore,this study uses the static chamber method in the area of maize-wheat farmland under different irrigation and fertilization treatments of soil N₂ O emission flux of in situ observation,the purpose is to reveal the influence of water consumption of farmland ecosystem soil N₂ O emissions,to explore greenhouse gas emission reduction measures,to provide the basis for improving the management of water and fertilizer and the environmental quality and reducing agricultural greenhouse gas.The results are as follows:?1?The soil N₂ O emission in the whole growth period of maize and wheat had obvious seasonal variation.In the maize season,the main peak and the second peak of all treatments appeared in the jointing stage of maize to the male stage and the male to the filling stage,and the lower emission level was in other periods.?2?The change range of N₂ O emission in maize season and wheat season was 0.24-0.80 kg · hm-2,0.19-0.65 kg · hm-2,and the variation range of N₂O-N emission coefficient was 0.08%-0.22 %,0.17%-0.26%;urea loss rate range of 0.16%-0.31%,0.25%-0.33%.?3?The soil N₂ O emissions during the whole growth period of maize and wheat were relevant to the supply levels of irrigation.In high fertilizer F1?N 300 kg·hm-2,P2O5 90 kg·hm-2?and low fertilizer F0.7?N 210 kg·hm-2 P2O5 63 kg·hm-2?,average soil N₂ O emissions flux during the maize whole growth period of high water W1?90 mm?were significantly higher than that of low water W0.7?63 mm??P<0.05?.?4?In medium fertilizer F0.85?N 255 kg·hm-2,P2O5 76.5 kg·hm-2?and low fertilizer conditions,the medium water W0.85 had no significant difference with low water?P>0.05?.In the high fertilizer?N 210 kg·hm-2,P2O5 150 kg·hm-2?,average soil N₂ O emissions flux during the wheat whole growth period of W1?140 mm?and low water W0.7?98 mm?had significant difference?P<0.05?.In medium fertilizer?N 178.5 kg·hm-2 P2O5 127.5 kg·hm-2?,the difference between medium water W0.85?119 mm?and low water is significant?P<0.05?.In the low fertilizer level?N 147 kg·hm-2,P2O5 105 kg·hm-2?,the difference between high water,medium water and low water were not significant.?5?The soil N₂ O emissions during the whole growth period of maize and wheat were relevant to the supply levels of fertilizer.The effect of different fertilizer application rate on the average N₂ O emission flux during the maize and wheat whole growth period was significantly increased with the increase of irrigation level?P<0.05?.In high water conditions,average soil N₂ O emissions flux during the maize whole growth period of high fertilizer was significantly increased 14.82% than low ratio of fertilizer?P<0.05?.?6?In medium water conditions,medium fertilizer significantly increased than the lower?P<0.05?,while the differences between the levels of fertilization were not significant in the low water conditions?P>0.05?.The application of fertilizer will significantly promote soil N₂ O fluxes of the whole growth period of wheat in high water and medium water conditions?P<0.05?.In low water conditions,the average soil N₂ O emission flux was appeared as medium fertilizer> high fertilizer> low fertilizer,the increase of medium fertilizer was larger than high fertilizer.?7?Soil moisture and soil temperature are the main factors affecting soil N₂ O emission.The correlation analysis showed that there was no significant correlation between soil N₂ O emission flux and soil inorganic nitrogen content?nitrate nitrogen and ammonium nitrogen??P> 0.05?,and there was a significant positive correlation with 0-10 cm soil water filling porosity?P <0.05?,and there was no significant correlation with WFPS at 10-20 cm?P> 0.05?.?P <0.05?,and there was significant correlation with 5cm,10 cm,15cm,20 cm and 25 cm soil layers.?8?The effect of irrigation amount on grain yield of maize and wheat at different growth stages will vary depending on the level of fertilization.The yield of maize was higher than that of low water?P <0.05?.Under low fertilizer level,the ratio of high water to low water was significantly increased?P <0.05?.There was no significant difference between medium and low water?P> 0.05?.Low water level,high water> medium water> low water?P> 0.05?.The effect of irrigation on the grain yield of wheat season has the same result.?9?The effect of fertilizer application on maize-wheat crop yield was changed due to changes in irrigation level.Maize and wheat showed consistent changes: high water and low water,high fertilizers were significantly higher than low fertilizers?P <0.05?.However,there was no significant difference in the yield of wheat and low-fat and low-yield?P> 0.05?.Under the condition of middle water,the medium fertilizer was significantly higher than that of low fertilizer.Under low water condition,there was no significant difference between medium and low fertilizer.Under the condition of low water,high fertilizer,medium fat and low fertilizer were significantly higher than those without fertilization,but the difference between fertilization was not obvious.The effect of irrigation,fertilization and water and fertilizer interaction on maize and wheat yield was significant?P <0.05?when the supply and quantity of water and fertilizer were 15% and 30%.?10?The effect of nitrogen and phosphorus fertilizers on the yield of wheat and maize showed the same rule: the difference of nitrogen application was significantly increased without nitrogen application?P <0.01?,and the difference was significant?P <0.01?The difference between the two groups was significant?P <0.05?.?P <0.05?.There was no significant difference in the yield of Crops under nitrogen application?P> 0.05?.The results showed that there was no significant difference?P> 0.05?.The effects of nitrogen fertilizer,phosphorus fertilizer and nitrogen and phosphorus on crop yield were significant?P <0.05?...