Soil Element Characteristics And Migration Mechanism Of A Grape Base In Bishan,Chongqing

Bishan District of Chongqing is committed to building a "one hundred thousand mu high-quality fruit base" in the west of Bishan.This study takes a grape base in Bishan District as the research object.Through the way of field collection,investigation and testing of soil,plant(grape)and other samples to get the soil nutrient and heavy metal content data of sample in grape planting areas.Excle 2016,SPSS 19.0,Mapgis and Geochem Studio software were used to count the average value,minimum value,maximum value,coefficient of variation and other parameters of the data,and data analysis and make the geochemical map and evaluation map.Have find out the distribution of beneficial and harmful elements in the soil in the study area.The soil fertility,soil environment and soil quality in the study area were evaluated,and the suggestions for planting extension were put forward.The main research results are as follows:1.The contents of nutrient elements and heavy metals in surface soil of grape base were tested.The results showed that the contents of N and P in soil nutrient elements changed greatly in the study area.The contents of N and P are 940 mg/kg to 658.05 mg/kg,respectively,which was 1.369-2.186 times of the China and Chongqing background values of soil elements.Compared with the background values of Bishan District,the P content was higher than the background values,and it is closely related to the application of more phosphate fertilizer in grape production in the study area.The content of K in the soil of the study area is equal to the background value,which is 0.997-1.093 times of the background value.The variation coefficients of Hg and Zn in heavy metals are larger,reaching 3.83 and 1.96,which are non-uniform distribution.As,Cd,Cu and Ni have a variation coefficient of 0.2 < Cv < 0.5,which is more uniform distribution.The variation coefficients of Pb and Cr are the smallest and are uniform distribution.Compared with the background values,the contents of Cd,Hg and Zn are higher in three different regions.The content of Cd have the biggest difference,which is 1.123-3.590 times higher than the background values.As is lower than the three background values,and the content of other heavy metals is no significant difference compared with the background values of three different regions.2.The results of grape fruit test showed that the content of heavy metals in grape samples was much lower than that in grape samples by comparing the hygienic requirements of grape according to NY/T 428-2000 standard of "Green Food Grape" and GB2762-2017 standard of "Contaminant Limit in Food National Safety Standard Food".The content limit showed that the quality of grapes in Daxing grape base was better and no heavy metals exceeded the standard.3.On the soil profile,the content of As,Pb and Hg decreases obviously with the deepening of the soil depth,and the content of Hg decreases gradually with the deepening of the soil depth,with a small reduction range;the content of Zn decreases first and then increases with the depth increasing,and the content of D layer is the turning point;the average content of Cd element in each layer is potentially fluctuates and decreases with the deepening of the soil depth;the content of Ni in the profile does not change significantly,the average content of each layer is not different;the content of Cr in B and F layers varies greatly;the content of Cu in E layer is obviously higher than that in other layers.Generally speaking,except for Zn,the overall trend of heavy metal content changes in the profile decreases with the deepening of depth.4.The results of soil nutrient geochemical grading and soil environmental quality evaluation in grape base show that the nitrogen content in the study area is mainly in the middle-deficient level,accounting for 85.61% of the area of the evaluation area,and is relatively deficient as a whole;the phosphorus content is mainly in the middle-rich level;the potassium content is mainly in the rich-medium level,accounting for the special area.93.48% of the product is abundant on the whole.The results of nutrient grading showed that the overall level of the study area was above the medium level.Except Cd,Ni and Hg elements,the soil environmental quality of heavy metals in the study area is clean grade,and Cd elements account for about 50% of the slightly polluted area in the study area.The results of soil environmental quality classification show that only 3.1% of the total areas with slight pollution or above are classified.It shows that the soil environmental quality in the study area is generally good.5.In view of the status of soil nutrients in the study area,it is suggested that vineyard farmers can take the following measures:(1)increasing organic fertilizer(especially Bio-bacterial fertilizer)and planting green manure to supplement organic matter to absorb heavy metals,thereby reducing the absorption of heavy metals by grapes.(2)Using biological nitrogen fixation,intercropping leguminous crops to increase soil nitrogen content.(3)Balanced application of phosphorus fertilizer to prevent excessive accumulation and deficiency of available phosphorus.