Effects Of Tobacco Planting Years On Soil Aggregate Stability And Its Relationship With Organic Carbon Fractions

Aiming at the problem of soil degradation caused by long-term tobacco planting.This paper selects the typical Sichuan tobacco planting area Liangshan,Panzhihua different years of tobacco planting soil as the research object,through sampling and analysis,studies the changing characteristics of soil aggregates and soil organic carbon(total organic carbon,active organic carbon,particulate organic carbon,microbial biomass carbon,water-soluble organic carbon and Organic Mineralization the relationship between the changes of the contents of carbon),and provide scientific basis for the conservation and sustainable utilization of tobacco soil.The main results are as follows:1.with the extension of tobacco life,dry sieve,wet sieve large aggregate disintegration increased,the stability of agglomerates decreased.Compared with the non-tobacco-growing soil,the stability of the agglomerans was decreased after 3,5 and 8 years,and the MWD values decreased by 34%and 35%after 5 years and 8 years The stability of paddy soil agglomerates reached a peak at 3 years after planting tobacco,which was 50%higher than that of non-tobacco soil,and decreased significantly after 5 and 8 years.The results showed that the MWD values of red soil,purple soil and paddy soil decreased by 31%,9%and 17%,respectively.The water stability of purple soil aggregates decreased,and the MWD values decreased by 63.7%compared with that of non-tobacco plants after 5 years of tobacco planting.The water stability of aggregates in paddy soil and red soil decreased significantly in 5 years,The MWD of paddy soil aggregates decreased by 52.1%and the MWD of red soil aggregates decreased by 67.7%,and all of them were stable in 5-8 years.The water-stable aggregates had significant disintegration in 5 years.2.The total organic carbon content of each agglomerates decreased significantly after long-term tobacco planting,and the total organic carbon>5mm and<0.25mm aggregates decreased significantly.The total organic carbon content of aggregates in purple soil decreased by 45.1%and 17.5%,respectively,and the total organic carbon content of soil aggregates decreased by 19.1%and 21.7%respectively.The total organic carbon content of aggregates in purple soil and paddy soil was significantly lower than that in purple soil and paddy soil.The total organic carbon content of purple soil and paddy soil aggregates was higher than that of>5mm and<0.25mm,and>5mm And<0.25mm particle size decreased most significantly.3.The content of organic carbon components in the original soil and the particle size of the increase in the number of years with the decline in the trend.The change trend of active organic carbon content of soil aggregates with the increase of age is similar to that of aggregates,that is,with the increase of the number of active organic carbon in 5 years,the loss of active organic carbon is aggregated water The reason for the decline in stability.The organic carbon of each component is interrelated and is relatively enriched in the agglomerates.With the increase of the number of tobacco growing days,the proportion of soil organic carbon component is lower than that of total organic carbon.The purple soil aggregates,The total organic carbon content decreased by 14.4%and 4.8%respectively,and the content of organic carbon was reduced by 19.4%and 5.8%respectively.The total organic carbon content decreased by 45.8%and 17.5%respectively after 8 years of tobacco planting,That is,in the process of large loss of total organic carbon,active organic carbon and other more active carbon components are more retained,but the original cement particles and the formation of aggregates of the more stable organic carbon loss is more long-term plant The effect of smoke on the water stability of soil aggregates is not easy to repair.4.The results showed that the soil organic carbon content was an important factor atffecting the water stability of the aggregates,and its content was positively correlated with the water stability of the aggregates.In the relationship between the water stability and the total organic carbon content of soil aggregates,Soil and purple soil on the performance of more intense,the correlation coefficient r are greater than 0.900.In short,flue-cured tobacco should not be continuous,especially long-term tobacco(tobacco life of more than 5 years)caused by decreased soil organic carbon content,soil aggregate damage significantly,the stability of the aggregates decreased significantly in the purple soil and paddy soil,Or rest can alleviate the consumption of organic carbon,slow down the stability of the water stability of aggregates,conducive to tobacco conservation soil conservation.