Study On Variation Characteristics And Influencing Factors Of Soil Aggregates In Plastic Shed System During Different Planting Years

The plastic shed system has become one of the important vegetable production methods in my country.In the process of facility cultivation,a large amount of organic fertilizer is generally used to increase crop yield.Although the application of organic fertilizer can increase the content of soil organic matter and increase the quality and quantity of soil aggregate structure,a large amount of organic fertilizer will also bring in a lot of dispersed ions,such as exchangeable Na⁺,which has a certain destructive effect on the aggregates.Therefore,it is necessary to explore the influence of different organic fertilizers on the aggregates and their stability.This research uses Zhuangtouyingzi Village,Wujianfang Town,Beipiao City,Chaoyang City,Liaoning Province for 2 years,4-5 years,10-12 years,19-21 years,28-30 years,34-36 years and more than 40 years.The 0-20cm cultivated layer soil of the facility greenhouse is the research object.The size distribution of soil aggregates,aggregate stability,total soil organic carbon,particulate organic carbon,easily oxidizable organic carbon,microbial biomass carbon,soluble organic carbon and salt The composition of base ions,and the influence of the organic carbon and base ions of each component on the stability of the aggregates are analyzed.The results show that:（1）The soil cation exchange capacity（CEC）of different planting age facilities gradually increased with the increase of planting age and reached a maximum of 25.73 cmol·kg^-1at28-30 years,and then stabilized,exchangeable K⁺,exchangeable Ca²⁺and exchange Sexual Mg²⁺gradually increased with the increase of planting years and reached a significant level at28-30 years and then stabilized.With the increase of planting years,exchangeable Na⁺accumulated year by year,reaching 4.48 cmol·kg^-1at>40 years.（2）The total organic carbon（TOC）content in the soil of different planting years increased gradually with the increase of planting years,and reached a maximum of 35.87g·kg^-1at 28-30 years,and the content of soluble organic carbon（DOC）gradually increased with the increase of planting years And at 28-30,the highest is 282.92 mg·kg^-1,the content of particulate organic carbon（POC）gradually increases with the increase of planting years,and the highest at 28-30 is 36.63 g·kg^-1,easy to oxidize organic The carbon（ROC）content gradually increased with the increase of planting years,and reached the highest at 23.82mg·g^-1at 28-30.Microbial biomass carbon（MBC）did not show obvious regularity.（3）The stability of soil aggregates in facilities with different planting years showed an increasing trend year by year.The average weight diameter reached the highest level of1.51mm when the planting years were 28-30 years,and then stabilized at around 1.32mm;in the soil>0.25.The number of agglomerates of mm increased with the increase of planting years,and reached 77.09%at 28-30 years,and the number of agglomerates of<0.25 mm decreased with the increase of planting years,and reached a minimum at 28-30 years.22.91%,then the distribution of soil aggregates tends to stabilize.（4）The planting period is 2～>40 years.The soil cation exchange capacity（CEC）of the facility has a very significant positive correlation with aggregate stability;particulate organic carbon,total organic carbon have a very significant positive correlation with aggregate stability,easily oxidized organic carbon,Soluble organic carbon has a significant positive correlation with aggregate stability,while microbial biomass carbon does not show a correlation with aggregate stability.In the facility soil where the planting period was 30 years ago,the stability of soil aggregates was mainly affected by soil organic carbon and CEC with the increase of the fertilization period.After 30 years,the average weight diameter did not change much,and did not decrease due to the increase in Na⁺.This may be due to the large amount of accumulated organic matter having sufficient buffer capacity and the soil structure remained relatively stable.