Effects Of Quicklime Amounts On Acidic Soil And Pre-Growth Of Tobacco

Reasons such as increased acid deposition and large-scale application of nitrogen fertilizer have led to increasingly serious soil acidification,and soil acidification will lead to the decline of soil fertility,the reduction of soil safety and so on.Which in turn endangers crop growth and agricultural product safety.Wannan tobacco area is one of the main tobacco producing areas in my country,but in recent years,the impact of soil acidification has severely restricted the improvement of tobacco quality and yield.In order to reduce the acidity of the soil,improve the safety of the soil environment and agricultural product,and promote the healthy growth of tobacco,this study selected the typical acidified tobacco field soil in Wannan tobacco area,and used quicklime as an amendment to acidify the soil.Mix different amounts of quicklime with soil through indoor cultivation test,study the changes of soil physicochemical properties and enzyme activities under different amounts of quicklime,as well as the change trend in a certain time,and analyze the response of microorganisms to quicklime in different time periods.Set high and low amounts of quicklime through pot experiment to study its effect on the early stage of tobacco growth.The improvement effect of quicklime in the acid soil of southern Anhui tobacco area is preliminarily explained.The main conclusions are as follows:1.Cultivation test shows the soil p H and cation exchange capacity increase with the increase of quicklime amount in a certain range.The p H gradually decreases during the cultivation process,the cation exchange capacity gradually increased in the early stage of culture,and then stabilized.Quicklime effectively reduces the exchangeable acidity of the soil.When the amount of quicklime is 4.5 g·kg^-1,the exchangeable acidity of the soil is reduced to zero,but the treatments of quicklime amount with 0.75 and2.5 g·kg^-1 have an upward trend during the cultivation period.In the early stage of cultivation,quicklime has the effect of reducing soil available P,while the available P content of quicklime amount is 4.5 g·kg^-1 exceeds that of the control group after 70 days of cultivation.The content of available K all decreases after the addition of quicklime.In a certain range,the NH₄⁺-N decreases with the increase of quicklime amount,and gradually decreased during the cultivation period.In contrast,the NO₃^--N increased with the increase of quicklime amount,and gradually increased during the cultivation period.The soil urease activity treated with quicklime is significantly higher than the control group,and only when the amount of quicklime is 0.75 g·kg^-1,the soil?-glucosidase activity is effectively increased during the entire cultivation period.2.Select the soil cultivated to 20 days and 50 days to analyze the microbial diversity.Studies shows that when adding quicklime for 50 days,0.75 g·kg^-1 quicklime significantly increased the bacterial diversity.When the quicklime amount is 4.5 g·kg^-1,the bacterial and fungal diversity significantly decreased.After culturing to 50 days,the abundance of genus-level bacterial Gaielales,Rhodanobacter,Terrabacter,Streptomyces,etc.and the genus-level fungal Mortierella,Talaromyces,Penicillium,Trichoderma,etc.changed significantly between treatments.Correlation analysis results showed that the main environmental factors affecting the distribution of fungal and bacterial communities are p H,K,P,?-glucosidase.3.The pot experiment shows that compared with the treatment without adding quicklime,0.75 g·kg^-1of quicklime significantly increased the plant height,aboveground and underground biomass of the tobacco,and had no significant effect on the root growth of tobacco.4.5 g·kg^-1 of quicklime inhibited the plant height,stem girth and growth of tobacco root system.Meanwhile,the content of chlorophyll a and carotenoids in the treatment with quicklime increased significantly.When the quicklime amount is 0.75g·kg^-1,the net photosynthetic rate and transpiration rate of tobacco increased significantly.Under the treatment of 0.75 g·kg^-1 of quicklime,the activities of superoxide dismutase and peroxidase of tobacco were significantly increased,and the content of malondialdehyde was significantly reduced.