Greenhouse Gases Emission In Maize-soybean Relay Strip Intercropping System

In recent years,with the prominence of global greenhouse effect,the agricultural ecosystem,as the important source and sink of N2 O,CH4 and CO2 in the atmosphere,has an important impact on global climate change,making intensive agricultural production and food security facing great challenges.How to improve the output of farmland ecosystem food through cultivation management measures,and seek sustainable green emission reduction technology to slow the global greenhouse effect has become a hot issue in the global climate change research.In this study,a field location test was carried out to monitor the emission of CO2,CH4 and N2 O greenhouse gases from the typical maize soybean strip cropping system in the hilly region of Southwest China,and to analyze the time variation of soil greenhouse gas emission from the corn soybean strip cropping system.The effects of different fertilizer types on greenhouse gas emissions were analyzed,and the carbon change of farmland ecosystem was analyzed.The results are following:1.The change rule of the total of CO2 emissions in the growing season: under different planting patterns,monocropping maize andmonocroppingsoybean were significantly higher than intercropping maize and intercroppingsoybean;under different fertilization treatments,NPKM>NPKS>NPK,under different planting patterns and different fertilization treatments,monocroppingmaize and monocroppingsoybean were treated with NPK and NPKM treatment.NPKS treatment increased 7.31%,15.82% and 9.25% respectively compared with intercropping maize and intercropping soybean.The changes of absorption and emission of CH4 in growing season soil: under different fertilization treatments,NPK and NPKM were treated as absorbing sink and NPKS treatment was the emission source.Under the interaction of different planting patterns and different fertilization treatments,the total amount of CH4 absorbed by single cropped maize and single cropped soybean under NPK treatment and NPKM treatment was more than that of intercroping.However,the total amount of soil CH4 emission in the growing season of single cropped maize and single cropped soybean under NPKS treatment increased by 41.45%.The change rule of the total of N2 O emission in the growing season: under different planting patterns,monocroppingmaize and monocroppingsoybean were significantly higher than intercropping maize and intercropping soybean;under different fertilization treatments,NPKM>NPKS>NPK,different planting patterns and different fertilization treatments,monocropping maize and monocroppingsoybean were treated with NPK,NPKM treatment and NPKS treatment increased 16.84%,11.68% and 19.03% respectively compared with intercropping maize and intercropping soybean.2.Maize aboveground biomass and yield: different planting patterns,intercropping pattern is higher than monocroppingmode;different fertilization treatment,NPKM treatment is higher than NPK,NPKS treatment;different planting mode under different fertilization treatment,the intercropping is higher than monocroppingmode.Soybeanaboveground biomass and yield,different planting patterns and different fertilization treatments had not shown significant difference in 2016 year.The biomass of soybean in 2017 year monocroppingsoybean was higher than that of intercropping soybean,and the yield of intercropping soybean was higher than that ofmonocropping soybean.The variation of carbon content in maize and soybean plants,under the interaction of different planting patterns and different fertilization treatments: Maize NPK treatment,NPKM treatment and NPKS treatment were significantly higher than that of monocroppingmaize 16.73%,10.72% and 18.63%,and NPK treatment,NPKM treatment and NPKS treatment were 6.67%,2.69% and 12.91% lower than monocropping soybean respectively.Crop biomass not only affects crop yield,but also determines the carbon sequestration effect of crops.For the change rule of soil carbon content,different planting patterns and different fertilization treatments: SOC content,monocroppingmaize,monocropping soybean in NPK treatment,NPKM treatment and NPKS treatment,there is no significant difference between maize,soybean monocroppingand intercropping;for DOC,ROC,HWOC,monocroppingmaize and monocroppingsoybean at NPK The treatments of NPKM,NPKS and maize were significantly lower than those of intercropping maize and intercropping soybean.The results showed that NPK,NPKM and NPKS treatment could not only increase soil organic carbon,but also improve the carbon content of crop plants.3.The greenhouse gases intensity(GHGI)to evaluate the greenhouse gas emissions per unit output is a comprehensive greenhouse effect evaluation index which combines the global warming potential(GWP)and crop yield.For GHGI,under the interaction of different planting patterns and different fertilization treatments,monocropping corn and monocropping soybean increased by 31.88%,226.42%,3.74% of intercropping maize and soybean under NPK,NPKM and NPKS treatment.For GWP,Under the interaction of different planting patterns and different fertilization treatments,monocropping maize and soybean increased by 38.99%,20.80%,185.40% in intercropping maize andsoybean under NPK,NPKMand NPKS treatment.It shows that NPK treatment,NPKM treatment and NPKS treatment can not only reduce GHGI but also reduce GWP,which is an ideal emission reduction measure.The above study results are showed,intercropping system compare with the monocroppingsystem,the carbon content and soil organic carbon content of the crop could be improved.At the same time,it can also reduce the warming potential of greenhouse gases and improve the material production capacity of farmland ecosystems,which is an ideal measure for carbon fixation and emission reduction and cultivation.