Effects Of Organic Matter And Attapulgite Application On The Physicochemical Properties Of Cd-contaminated Soil

With the acceleration of China's industrialization and vigorously development of agricultural intensification, the soil heavy metal pollution is increasingly serious in our country, especially the Cd content in the soil generally increased. This situation brings the growing adverse impact on economic development and agricultural cultivation, and the excessive Cd harm to the human body through the food chain. So the Cd contaminated soil treatment is imminent, and the physicochemical traits of the soil not only affects the soil fertility also affects the treatment effect of Cd contaminated soil by affecting the existing form of Cd. This study took organic matter and attapulgite as amendment to stabilize the Cd contaminated soil, focused on the changes of Cd contaminated soil physicochemical traits such as pH, electrical conductivity?EC?, NH₄⁺-N contents and NO₃^--N content. The results showed that:?1?pH value of the contaminated soil significantly reduced under the organic addition,the more organic matter, the smaller the pH. Organic fertilizer added increased the EC value of different concentrations of Cd contaminated soil, and with the increase of the added amount, the greater increase in the EC values. NH₄⁺-N content with stabilization time emerged slowly rising first and then decreased during organic fertilizer stabilized different concentrations Cd contaminated soil process. At the same stabilized time,organic fertilizer can significantly improve the NH₄⁺-N content in Cd contaminated soil, the greater the amount of organic manure, the higher the NH₄⁺-N content. NO₃^--N content of different concentrations of Cd contaminated soil over stabilization time substantially showed a trend as decline fist then gradual upward. Overall, at the same stabilization time, different Cd concentrations contaminated soil NO₃^--N content increased significantly after organic fertilizer addition stabilized, and the NO₃^--N content increased with the amount of organic fertilizer increased.pH and EC of organic matter added Cd polluted soil was negatively correlated. The correlation between pH and NO₃^--N and NH₄⁺-N content was not significant. EC values and NO₃^--N content was positively correlated. The correlation between NH₄⁺-N content and NO₃^--N content was not significant, but the correlation coefficient is substantially negative.?2?Different concentrations of Cd contaminated soil added with attapulgite pH value over the stabilization time at first increased, then decreased and then increased. At the same stabilized time, different concentrations of Cd contaminated soil added attapulgite treated group pH value was significantly lower than the control group, the greater the amount of attapulgite, the lower the pH. Different concentrations of Cd contaminated soil added with attapulgite at 12 day had highest EC, then began to decline. Various concentrations of Cd contaminated soil attapulgite treated group EC was higher than control group. NH₄⁺-N content with stabilization time showed a trend as rise after the first drop then fell again in attapulgiteadding different concentrations of Cd contaminated soil, each treatment group NH₄⁺-N content appeared obvious downward trend in the period stabilization?3-6 days?. Overall, after48 days stabilized treatment, NH₄⁺-N content decreased compared with the first three days in contaminated soil. At the same stabilized time, different concentrations of Cd contaminated soil treatment groups NH₄⁺-N content was substantially lower than the CK control group.NO₃^--N content in attapulgite adding different concentrations of Cd contaminated soil with stabilization time showed a trend as drop after the first rise then up again. At the same stabilized time, NO₃^--N content of different concentrations of Cd contaminated soil attapulgite added each treatment group was substantially higher than CK in the control group.pH and EC of attapulgite added Cd polluted soil was negatively correlated. The correlation between pH and NO₃^--N and NH₄⁺-N content was not significant. EC values and NO₃^--N content was positively correlated. The correlation between NH₄⁺-N content and NO₃^--N content was not significant, but the correlation coefficient is substantially negative.?3?Corn germination rate, plant height of maize, corn shoot dry weight on Cd contaminated soil added with organic matter decreased with the increase of pH, but the corn root length increased. With the increase of EC, the corn plant height increased, but the correlation between other corn growth indicators and EC value was not significant.germination rate and shoot dry weight increased with NH₄⁺-N content increased, there is no significant correlation between corn root dry weight and NH₄⁺-N content. With the increase of NO₃^--N content, maize emergence rate increased but corn root length decreased. pH of Cd pollution soil added with Attapulgite between corn root length and corn plant height had significant correlation, the correlation between corn plant germination rate, shoot dry weight,root length and pH was not significant. Corn plant germination rate, shoot dry weight and plant height was significantly correlated with EC value, the root dry weight was positively correlated with the EC value, the correlation between root length and EC is not significant.With the NH₄⁺-N content increased, above ground dry weight increased but root dry weight decreased, and there is no significant correlation between germination rate, root length, corn plant height and NH₄⁺-N content.?4?Cd contaminated soil added attapulgite and organic matter, Cd accumulation in maize plants increased with the increase of pH. There was not significant correlation between the EC and the corn plant Cd enrichment. Correlation between NH₄⁺-N content of contaminated soil and Cd accumulation was significantly negative.NO₃^--N content was not significant correlated with maize plant Cd enrichment, but known from the regression equation, Cd amount of corn plants accumulation reduced with the NO₃^--N content increased.