Study On Soil Physical And Chemical Characteristics And Heavy Metal Pollution Risk Of Vineyards In Different Regions Of Hunan Province

Soil physical and chemical properties and heavy metals are the key factors affecting grape growth and fruit quality.In this study,vineyards in four main grape producing areas in Hunan Province were selected.Through zoning field sampling and indoor analysis,the transformation mode,planting years,grape varieties and yield of vineyards were investigated,and the soil physical characteristics,contents of large,medium and trace elements and heavy metals and their spatial difference were analyzed.Combined with the technical regulations for the second national soil survey The degree of soil nutrient abundance and deficiency was evaluated,and the main factors affecting grape yield were identified.The main results are as follows:1.Physical and chemical properties of vineyard soil in Hunan ProvinceThe soil p H value of the four regions in Hunan ranges from 5.27 to 6.35.The p H value of the soil in the northern Hunan region is the highest,reaching 6.35,and the lowest in the western region.The soil p H value of the dry-land conversion vineyard is the highest in central Hunan and the lowest in northern Hunan.Vineyard soil 0.25～2 mm aggregates are the highest in central Hunan and the lowest in western Hunan;the conversion of paddy fields to vineyards is higher than that in dry land;the aggregates of soil >0.25 mm in central Hunan are the highest and are relatively stable;except for the dry land in southern Hunan Outside the vineyard,the bulk density of other areas is less than 1.50 g/cm3,which is conducive to the growth of grape roots.The soil volume of the conversion of paddy fields to vineyards in northern and central Hunan is greater than that of dry land conversion,while the opposite is true in the southern and western parts of Hunan.The saturated water content and water holding capacity of soil field total soil porosity and aeration porosity of the dry land converted to vineyards are higher than that of the paddy field converted to vineyards.The soil organic matter content of dry land converted to vineyards in western Hunan is the highest,reaching 28.09 g/kg;the soil organic matter content of dry land converted to vineyards in the same area is higher than that of paddy field converted to vineyards,and the soil organic matter content of the four regions is at an appropriate level.2.Distribution characteristics of soil nitrogen,phosphorus and potassium in vineyards in different regions of Hunan ProvinceThe soil total nitrogen content of paddy field transformed vineyards in Western and central Hunan is generally higher than that of dry land transformed vineyards,while in northern and southern Hunan,the total nitrogen content in Western Hunan is 1.66 g / kg,and the content in Northern Hunan is the lowest,which is 0.95 g / kg.The soil total nitrogen content in the four regions is at an appropriate level except that the dry land transformed vineyards in central Hunan are low;The content of dry land vineyard soil alkali hydrolyzable nitrogen.The content of total phosphorus in the soil of paddy field to vineyard is generally higher than that of dry land to vineyard,and the content of paddy field to vineyard in Northern Hunan is the highest,up to 0.87 g / kg.On the contrary,the content of dry land to vineyard in southern Hunan is the lowest;The content of soil available phosphorus.The content of soil available phosphorus in Northern Hunan is the highest,up to 41.92 mg / kg.The content of soil available phosphorus in be increased appropriately,while Western Hunan.while it is the opposite in southern and Western Hunan;The content of soil available potassium in dry land vineyard is by and large of higher level than paddy field vineyard,and the content in dry land to vineyard in Western Hunan is the highest,up to 773.75 mg/kg.3.Distribution characteristics of medium and trace elements in vineyard soil in different regions of Hunan ProvinceAmong the medium and trace elements,the coefficient of variation of calcium is relatively large,which are 1.17 and 1.37 respectively,and the difference of other trace elements is relatively small.The concentration of calcium is the highest in Northern Hunan,followed by central Hunan,with Ca 0-20 cm > Ca 20-40 cm.In Western Hunan,the content of calcium in deep soil was significantly higher than that in surface soil.The spatial difference of zinc in different regions is small,and they are higher than the background value,but the average value of zinc in 20-40 cm plough layer is 78,which is significantly lower than the background value.The iron content in different regions is lower than the local background value of Hunan Province,and the order is: Western Hunan > Northern Hunan >Central Hunan > Southern Hunan,and the soil iron content in 0-20 cm plough layer is higher than that in 20-40 cm plough layer.Magnesium has little spatial difference in different regions,and is lower than the background value.4.Heavy metal pollution risk of vineyard soil in different regions of Hunan ProvinceThe order of soil pollution degree of vineyard plough layer in different regions of Hunan Province is: Southern Hunan > Central Hunan > Western Hunan > Northern Hunan.In the 0-20 cm plough layer,the degree of the pollution in southern Hunan is relatively high while the degree in Western and central Hunan is comparatively medium,and that in Northern Hunan is low;The pollution degree of 20-40 cm plough layer is lower than that of0-20 cm plough layer.Cadmium(CD),mercury(Hg)and arsenic(as)are the main polluting heavy metal elements in grape planting parks in different regions of Hunan Province,of which cadmium pollution contributes the most,with a contribution rate of 35%-51%.The content of heavy metal mercury(Hg)is only high in Western and southern Hunan,which makes a huge contribution to the heavy metal pollution of local vineyards,with a contribution rate of 57%,and there is a great difference in the content of 0-20 cm and 20-40 cm topsoil soil.