Effects Of Different Ratios Of Organic To Inorganic Fertilizers On Cd Activity Of Soil Heavy Metals In Carbonate Rock Area

Zunyi is a typical karst topography area.The developed soil basically covers the main types of guizhou karst region,and is also an important agricultural production base in guizhou.Based on this,based on the soil of the region as the research object,by setting the different ratio of organic-inorganic fertilizer,conducted field and pot experiment respectively,to study the whole amount of soil Cd,soil Cd form,as well as the changing of Cd content in plant(pepper),explores the organic-inorganic fertilizer ratio effect on the activity of Cd,the main results are as follows:(1)different treatments will increase the content of Cd in the soil.In the field experiment,50% of urea and 50% of pig manure were increased by the maximum amount of Cd,and the growth rate was 9.93%.In the pot experiment,the total amount of Cd was increased by the maximum,the growth rate was 10.00%.Obviously,the fertilizer production is controlled by the national standard,to effectively limit the harmful heavy metal content,but also in the process of organic fertilizer production cannot to effectively remove harmful heavy metals,and become a source of soil heavy metal pollution.(2)different organic-inorganic fertilizer distribution significantly affects the morphology of soil Cd.In field trials,25% of urea and 75% of cow manure were exchangeable with the highest content of Cd,reaching 0.26 mg/kg.The exchangeable Cd was increased by 49.02% in 25% pig manure and 75% urea.In the pot experiment,the content and the growth rate of the exchangeable Cd content and the growth rate were the highest in 25% urea and 75% cow manure.The values were 0.31 mg/kg and65.56% respectively.(3)organic-inorganic fertilizer application results in the accumulation of Cd in the fruit of pepper.In the field experiment,the Cd content of each pepper fruit wassignificantly increased compared with the Cd content(0.17 mg/kg)in the fruit of the pepper in the blank treatment.The content of Cd content of 25% urea and 75% cow manure was 0.28 mg/kg,which was 62.28% higher than that in the blank.All of these treatments resulted in the content of the fruit Cd of the peppers exceeding the national limit for vegetables(fresh weight 0.05mg/kg,GB2762-2012).The results obtained in the pot experiment were basically consistent with the field test,and all the other treatments were higher than the national standard for vegetable qualification.(4)the content of Cd in pepper fruit(0.91 * *)with pot experiment and field experiment(0.76 * *)of Cd content in soil was significantly correlation,correlation with other forms of soil Cd content have not reached significant level,indicates that the area of Cd content in soil was can be used as the evaluation index of soil Cd biological availability.In conclusion,applying different organic-inorganic fertilizer proportion will be of Cd in soil total quantity,Cd in soil morphology,as well as to the effect on biological availability of pepper,and may produce a threat to human health.In addition,due to application of organic fertilizer to improve soil structure,increase crop production has obvious effect,is widely available,but ignores the potential risk of it as the source of heavy metals,should be worth us to re-examine,and formulate and regulate corresponding organic fertilizer production process and standards.