Determination And Evaluation Of Available Phosp Horus In Tobacco Planting Soil In Hunan

Phosphorus is an essential nutrient element for plants.The bioavailability of phosphorus in soil depends on the content and form of phosphorus.Available phosphorus as a basic indicator reflecting the level of soil phosphorus supply has been widely concerned for a long time.There are many studies and reports on the effectiveness of soil phosphorus,but there are relatively few studies on the effectiveness of phosphorus in tobacco-growing soil.Therefore,based on the distribution characteristics of soil available phosphorus in the second tobacco planting soil survey in Hunan Province,this study selected and collected 11 tobacco planting soils in Hunan’s main tobacco-producing areas according to their soil types and available phosphorus content.A representative soil sample,without the application of phosphorus fertilizer,conducted a pot experiment of continuous soil phosphorus depletion of three crops of tobacco planted for 2 years,and different methods were used to analyze and determine the content of available phosphorus in the initial soil and the soil at the time of each tobacco crop harvest,and its correlation with the amount of tobacco phosphorus uptake and growth and development was analyzed in order to explore a method suitable for determining available phosphorus in tobacco-growing soils in Hunan,and to evaluate the effectiveness of phosphorus in tobacco-growing soils.The main research results are as follows:(1)The traditional Olsen method,double acid method,M 3 method,Bray-1 method,Bray-2 method,hydrochloric acid method,sodium hydroxide method,water extraction method and other 8 methods were used to determine the content of available phosphorus in tobacco planting soil.The content of available phosphorus in the tobacco-planted soil measured by different methods(acidic,neutral,and alkaline extractants)varies greatly,and the effectiveness of phosphorus differs significantly.This is related to the strength of the soil phosphorus extracted by different extractants.It is also related to the different forms of phosphorus-containing compounds in tobacco-growing soils.The content of soil available phosphorus measured by sodium hydroxide method is obviously higher than other methods,and the content of soil available phosphorus measured by M 3 method is the lowest.The regularity and reproducibility of soil available phosphorus content measured by sodium hydroxide method,hydrochloric acid method and water extraction method are poor,so they are not suitable for determining available phosphorus in tobacco planting soil.The soil available phosphorus measured by Olsen method,double acid method,Bray-1 method,M 3method and Bray-2 method has moderate value and good regularity.(2)On the basis of Olsen method,double acid method,M 3 method,Bray-1 met hod and Bray-2 method,the measurement method of soil available phosphorus was im proved by adjusting the concentration and acidity(alkali)degree of the extractant to g et 9 kinds of soil available phosphorus determination methods.The improved soil avai lable phosphorus determination method was used to compare and determine the availab le phosphorus in tobacco-growing soil.The results showed that Olsen to 1 method ha d the best regularity for determining available phosphorus in tobacco-growing soil.Olse n method,Olsen to 2 method and M 3 method followed;M 3 to 1 method and doub le acid to 1 Method has poor regularity;M 3 to 2 method,double acid method,doub le acid to 2 method,Bray-1 method,Bray-2 method,Bray to 1 method,Bray to 2 m ethod.And Bray to 3 method have worse regularity.(3)Correlation analysis of the available phosphorus content of tobacco planting soil by different methods with the phosphorus uptake of tobacco,the dry matter quality of tobacco plants and the growth and the development of tobacco plants(plant height,effective leaf number,maximum leaf area)was made,and according to the changes of available phosphorus in tobacco planting soil,the effect of tobacco growth and development was verified.The results show that the overall performance of different methods is Olsen to 1 method> Olsen method> Olsen to 2 method> M 3 method> M 3 to 1 method.The Olsen to 1 method has the best correlation between the available phosphorus content in tobacco planting soil and the phosphorus uptake of tobacco.At the same time,the correlation with the tobacco dry matter quality,plant height,effective leaf number and maximum leaf area is good,which shows that Olsen to 1 method is more suitable for the determination and evaluation of the available phosphorus in tobacco planting soil in Hunan.The Olsen method and the Olsen to 2 method has a good correlation between the available phosphorus content in tobacco planting soil and the phosphorus uptake of tobacco,as well as the correlation with the dry matter quality,plant height of tobacco,effective leaf number and maximum leaf area is also good.M 3 method and M 3 to 1 method have a poor correlation between the available phosphorus content in tobacco planting soil and the phosphorus uptake of tobacco,at the same time,the correlation with the dry matter quality,plant height,effective leaf number and maximum leaf area is also poor.Therefore,Olsen method 1 is more suitable for the determination and evaluation of available phosphorus in tobacco-growing soils in Hunan.