| In order to explore the impact of topsoil structure on promoting agricultural production and soil sustainable development,the composition of soil aggregates under different conditions was simulated to explore the mechanism of aggregates on improving soil fertility,improving the structure of rhizosphere microbial community in tobacco planting soil and improving the quality of flue-cured tobacco.The soil culture experiment was carried out in the Yunyuan experimental base of Hunan Agricultural University in 2021.Yunyan 87 was used as the test material,and four treatments with different aggregate composition were set up.After studying the effects of different aggregate composition on soil chemical properties,microorganisms and flue-cured tobacco quality,the following main results were obtained:(1)In terms of soil chemical properties,changing the composition of soil aggregates can improve the soil pH,among which the simulated powder ridge deep tillage aggregate has the best soil lifting effect,which can improve the trouble of soil acidification with advantage;The simulated powder ridge aggregate soil can increase visibly the contents of soil organic matter(SOM),total potassium,available potassium and nitrate nitrogen in the early stage of transplanting,and can significantly increase the contents of soil total nitrogen and ammonium nitrogen in the whole growth period.It has no obvious effect on soil total phosphorus and available phosphorus.(2)In terms of rhizosphere microorganisms,the simulated powder ridge deep tillage aggregate soil microbial community diversity is the highest,the total number of species is the highest,the microbial abundance is the highest,and the species distribution uniformity of microbial community is the highest.There are obvious differences in the structure of rhizosphere soil microbial community among different aggregate composition.There are species differences in soil microbial communities with different aggregate composition,and there are significant differences in the promotion and inhibition of bacterial populations with different aggregate composition.The microbial ecological network structure of simulated powder ridge deep tillage aggregate soil is more complex and closely connected.(3)In the growth and development of flue-cured tobacco,the simulated powder ridge deep tillage aggregate soil was significantly higher than the conventional tillage soil in all growth stages after transplanting;It can significantly increase the dry and fresh weight of tobacco leaves;It can smarkedly promote the root volume of flue-cured tobacco,make it better absorb nutrients from the soil and promote the growth and development of tobacco plants;The proportion in deeper plough layer is significantly increased,which can help plants obtain more sufficient nutrients.(4)In terms of the quality of flue-cured tobacco leaves,the flue-cured tobacco leaves treated with simulated powder ridge deep ploughing aggregates have a significant improvement effect in physical indexes;Among the chemical indexes,it increased visibly total sugar,reducing sugar,total nitrogen and total potassium,remarkably cut down nicotine and raised the inter character of tobacco leaves. |
