Effects Of Different Soil Improvement Measures On Net Greenhouse Effect Of Tobacco Fields In Central Henan

This study relies on localization experiments to explore the effects of different soil improvement measures on greenhouse gas emissions and comprehensive net greenhouse effect in central Henan tobacco fields.A randomized block experiment was used in this study,and a total of 5 treatments were set: no fertilization(NF),only NPK(NPK),NPK+planting and turning over ryegrass(NPKG),NPK+wheat straw also field(NPKS)and NPK+application of tobacco straw biochar(NPKB).The decomposing characteristics of the upper part of the rye grassland,the root system and the wheat straw were studied by the buried bag method.Taking China Tobacco 100 as the test variety,the greenhouse gas emissions of the flue-cured tobacco-soil ecosystem were determined annually by the static closed obscura method.The net carbon budget and carbon sequestration effect of the ecosystem were evaluated,and the CO2 emissions caused by chemical inputs and agricultural operations in the tobacco production process were recorded.comprehensive evaluation.The main conclusions are as follows:(1)The decomposing rates of the upper part,roots and straws of rye grassland were basically the same,showing that the decomposing rate was fast in 0-30 d,and the decomposing rate slowed down and gradually stabilized after 105 d.The decomposition rate of the upper part of the rye grass was faster than that of the root,and the cumulative decomposition rate showed that the upper part of the rye grass > straw > the root of the rye grass.The nutrient release rate was potassium>nitrogen>carbon>phosphorus,and the potassium element in the upper part,root and straw of rye grassland was basically released within 105 d.(2)NPKG,NPKS and NPKB treatments can significantly increase the yield of tobacco leaves.The yield of tobacco leaves treated with organic materials in 2020 is1.22,1.37,and 1.13 times that of NPK treatment,respectively.The yield of tobacco leaves treated with organic materials in 2021 is 1.50,1.22,1.14 times of NPK treatment.(3)NPKG,NPKS and NPKB treatments could increase the contents of soil soluble organic carbon,nitrate nitrogen,microbial biomass carbon and microbial biomass nitrogen,among which NPKG treatment increased the most.(4)In different periods of flue-cured tobacco,NPKB treatment significantly increased soil pore water content(WFPS)compared with NPK treatment,and the WFPS of NPKB treatment increased significantly by 16.06% in 2021.(5)NPKG,NPKS and NPKB treatments can all increase carbon dioxide(CO2)emissions from soil ecosystems of flue-cured tobacco in different periods.NPKG and NPKS treatments significantly increase the total CO2 emissions in 2021 compared with NPK treatments,increasing by 42.98% and 54.03%,respectively.(6)Compared with the NPK treatment,the NPKG and NPKS treatments increased the total nitrous oxide(N2O)emissions in 2021 by 9.63% and 8.43%,respectively,while the NPKB treatment significantly reduced the soil N2 O emissions by 9.63%.During the growth and fallow periods of tobacco,N2 O emissions were mainly affected by WFPS and soil nitrate nitrogen content,both of which had positive effects on N2 O emissions.Structural equation modeling showed that the main related genes affecting N2 O emissions were amo A-AOA,nir S and nir K genes.(7)Tobacco fields in central Henan appear to be absorbing sinks for methane(CH4).In 2021,the total CH4 uptake by NPKG,NPKS and NPKB treatment decreased by3.22%,6.43% and 11.70%,respectively.During the growth period,CH4 uptake by different treatments was negatively correlated with WFPS and soil nitrate nitrogen content,and positively correlated with soil temperature;the main factor affecting CH4 uptake in fallow period was soil temperature,and the two were positively correlated.Structural equation modeling showed that pmo A gene could promote the absorption of CH4.(8)NPKG,NPKS and NPKB treatments can increase the content of soil organic carbon,and NPKB treatment has the best carbon sequestration effect.NPKG,NPKS and NPKB treatments can effectively reduce the comprehensive net greenhouse effect(net GWP)and greenhouse gas intensity(GHGI).Among them,the net GWP and GHGI of NPKB treatment decreased the most,with net GWP decreased by 76.22% and GHGI decreased by 79.52%.In summary,the addition of organic materials can improve tobacco yield,increase soil carbon sequestration capacity,and reduce the overall net greenhouse effect and greenhouse gas emission intensity.Among them,the application of tobacco straw biochar treatment had the best effect on carbon sequestration and emission reduction in the tobacco field ecosystem in central Henan.