Effects Of Different Fertilization Models On Greenhouse Gas Emissions And Soil Physical And Chemical Characteristics In Pineapple Field

The main inducing factor of global climate change is the aggravation of greenhouse gas emissions,and the important source of man-made greenhouse gas emissions is agricultural activities.As an important pineapple planting area in South China,the total yield of pineapple in the tropical region reached 1.12 million tons in 2011.However,in order to increase the yield,a large number of chemical fertilizers are used in this area,which results in low fertilizer utilization,increased soil acidification and greenhouse gas emissions,and greatly damages the tropical agricultural ecological environment.Therefore,under the premise of ensuring pineapple yield,people have paid more attention to whether it can reduce greenhouse gas emissions by optimizing fertilization,which will also be of great significance to reduce global warming.Aiming at this scientific problem,five treatments were set up in this study:no fertilization（CK）,conventional fertilization（NPK）,reduced single fertilization（INF）,inorganic fertilizer+organic fertilizer（INF+M）,inorganic fertilizer+organic fertilizer+slow control fertilizer（INF+M+S）.The effects of different fertilization modes on the air emission of pineapple ground temperature chamber were studied,and the soil temperature,soil moisture,nitrate nitrogen,ammonium nitrogen and The correlation between soil enzyme and greenhouse gas emission;the comprehensive evaluation of GWP and GHGI of different fertilization models,and the selection of the most suitable fertilization model for pineapple based on Pineapple yield;this study will provide theoretical and practical basis for the realization of green production and development of low-carbon agriculture in the region.The main results of this study are as follows:1.Three fertilization models,i.e.reduced application of chemical fertilizer（INF）,combined application of inorganic fertilizer+organic fertilizer（INF+M）,combined application of inorganic fertilizer+organic fertilizer+slow control fertilizer（INF+M+S）,can significantly improve the content of soil available potassium,available phosphorus,nitrate nitrogen and ammonium nitrogen,as well as the activities of soil invertase,soil acid phosphatase,soil catalase and soil urease.Among them,compared with NPK,（INF）,（INF+M）and（INF+M+S）significantly increased soil invertase activity by 40.89%,16.01%and 40.00%,acid phosphatase activity by 37.00%,58.00%and 63.00%,catalase activity by 20.00%,70.00%and 110.00%,urease activity by 7.79%,9.09%and 31.17%,respectively.2.Compared with NPK,INF,（INF+M）and（INF+M+S）significantly reduced N₂O emissions by 20.47%,30.20%and 45.40%,CO₂ emissions by 9.12%,74.52%and 39.39%,CH₄ emissions by 86.36%,181.82%and 243.32%,and GWP by 8.99%,47.45%and16 74%;compared with conventional NPK treatment,three kinds of optimized fertilization increased the annual crop yield,among which,organic and inorganic slow control combined application（INF+M+S）treatment significantly increased the annual crop yield by 16.77%compared with conventional NPK treatment;the order of greenhouse gas intensity of each fertilization treatment was:INF+M>INF>NPK>INF+M+S.3.Nitrate nitrogen,3cm soil temperature,7cm soil temperature,ammonium nitrogen,available phosphorus,sucrase,acid phosphatase and catalase are the important factors that affect the greenhouse gas emissions.The results of correlation analysis show that the above factors have a significant positive correlation with N₂O emissions,and the importance of these factors is:ammonium nitrogen>nitrate nitrogen>available potassium>7cm soil temperature>3cm soil temperature>available phosphorus,while N₂O emissions and soil p H4.There was a significant negative correlation between the above factors and the soil CO₂ emissions.The significance of the above factors and the soil CO₂ emissions was:urease>catalase>acid phosphatase>sucrase>nitrate nitrogen.The significance of the soil CO₂ emissions was:3cm soil temperature>7cm soil temperature.The above factors and the soil CH₄ emissions showed a significant positive correlation The order of importance of the effect is:soil water content>7cm,soil temperature>3cm,soil temperature>nitrate nitrogen>ammonium nitrogen,while the order of importance of the significant negative correlation effect of CH₄ emission is:sucrase>catalase>available phosphorus>acid phosphatase.To sum up,the treatment of（INF+M+S）not only has a positive impact on soil fertility,but also has the lowest intensity of greenhouse gas emission,the best effect of emission reduction,the highest yield and the best effect of yield increase,that is,（INF+M+S）treatment is the best mode of fertilization.