Remediate Effects On Acid Soil And Aluminum Toxicity In Plant By Using Mineral Conditioners

Under the action of some factors such as acid deposition and excessive application of chemical fertilizer,the area and degree of acidification of soils in China continue to increase,and the consequent loss of salt ions and the problem of aluminum(Al)poisoning restrict the development of food safety and agricultural sustainable.In this context,the study investigated the improvement effect of three Al-containing mineral on acid soil,which was the brick red soil from Xuwen County,Guangdong Province.The mineral conditioners consist of a mixture of calcined product include potassium feldspar,dolomite and limestone powder which is rich in available Ca,Mg,K and other nutrients.In this study,the stability of Al in the conditioners and its effect on the improvement of acid soil were studied by soil incubation and simulated acid rain soaking experiment.At the same time,the mitigation effect of conditioners on plant Al toxicity was studied by pot experiment.The results show that this kind of mineral conditioners does not cause superposition effect on soil aluminum toxicity due to the high stability of Al in conditioners.Moreover the application of conditioners can not only effectively neutralize soil acidity and reduce the content of soil toxic Al and active Al,but also can supply the soil mineral elements to promote the plant growth and the absorbing nutrients function and reduce the Al content in plants to keep the food safety.Specific conclusions are as follows:(1)The contents of Al2O3% in three kinds of mineral conditioners were 4.32%,6.42% and 8.51%,and the content of effective of CaO%,MgO%,K2O% and SiO2% were 30.10-37.25%,0.75-2.38%,1.36-5.70% and 17.39%-20.94%,respectively.All of them can improve the pH of soil.The same level of three conditioners caused the same raise of pH.The soil pH was stabilized after 5 days of conditioners application,and it rose from 4.98 to 5.04-5.42 when the dosage was incrasesed from 0.5 to 2 g/kg.(2)The three kinds of conditioners on the contents of exchangeable aluminum(Ex-Al)and organic-bound aluminum(Or-Al)has the same effect.,which decreased with the increase of soil pH(P <0.01).The adsorbed hydroxyl aluminum(Hy-Al)may be affected by the conversion of aluminum in exchangeable aluminum(Ex-Al)and the conditioning agent,and its content increases slightly with the dosage and aluminum content in the conditioners.However,toxic Al(the sum of Ex-Al and Hy-Al)and active Al(the sum of Ex-Al,Hy-Al and Or-Al)decreased by 5.44-9.57% and 5.62-13.26%,respectively.Morever,the application of the conditioners improves the soil Ca,Mg,K and other mineral elements.Their entire contents are related to the active ingredient content of the conditioner.(3)The migration of Ca,Mg,K and other nutrient salt ions in the original soil was great under the simulated acid rain.After the application of conditioner,Ca migration increased,but it still less than the exchangeable Ca content which was supplemented by conditioners.The amount of dissolved Al decreased with the increasing of the conditioner application dosage.Under acid rain at pH 5.60,4.80 and 3.50,the total amount of dissolved Al in soil without the conditioners was 6.08 mg/kg,7.43 mg/kg and 19.05 mg/kg,respectively.After the application of conditioners,the amount of dissolved Al was reduced by varying degrees.The removal rate of dissolved Al at the dosage of 2g/kg was the most significant,and the reduction rate was 72.90-82.41%.(4)After applying 0.5-2g/kg mineral conditioner,the contents of aluminum in the roots and shoots decreased by 24.61-29.68% and 39.52-46.99%,respectively.The growth environment of Lettuce was improved,andthe active of superoxide dismutase,peroxidase,catalase and malondialdehyde contents decreased.The uptake of Ca,Mg and K by Lettuce were increased,and the plant height and aboveground biomass of Lettuce increased by 17.01-23.05% and 26.79-54.67%,respectively.