Effects Of Biochars On Atrazine Adsorption In Soil And Succession Crops

Atrazine is one of the most widely used herbicides in China.It has been used for a long time and remains in the soil.Therefore,it is of great significance to reduce the amount of atrazine in the soil,repair the soil contaminated by atrazine and reduce the phytotoxicity of the crops.In this paper,atrazine in soil was used as research object,and different types of agricultural waste such as corn stover and peanut shell were used to make biochars.The effects of different biochars on the adsorption of atrazine and the growth of sensitive crops in soil were discussed.The main research contents are as follows:1.The residue analysis method of atrazine on soil and CaCl₂ aq was established by liquid phase-mass spectrometry using QuEChERS pretreatment.The linear relationship was good in the range of 0.001-5.0 mg/L?R²>0.99?.At the three added concentration levels,the recoveries of the two matrices were between 80.9%and 115.4%and the relative standard deviation was between 1.5% and 3.5%,which met the requirements of residue analysis.2.The adsorption capacity of biochar on atrazine in soil was studied by adding different types of biochars to the soil and using batch balance method.The adsorption capacity was:biochar made from corn stover>biochar made from bamboo>biochar made from chestnut>biochar made from peanut shell.This was the result of the combined effects of various physical and chemical properties of biochar.Moreover,biochar made from bamboo reached equilibrium at 12 h and the adsorption rate reached almost 100%.It might be related to its clear pore structure.The other three biochars reached equilibrium at 24 h and the adsorption rates were higher than the soil.The adsorption isotherm of atrazine in black soil by biochar was more suitable for the Freundlich model.3.The pot experiments were conducted to study the effects of biochar on the growth and development of sensitive succession crops?soybean,rape and cabbage?after atrazine application by simulating the concentration of atrazine in the field soil and adding different kinds and contents of biochars to the soil before aftercrops planting.The results showed that biochars suitable for the growth of these three kinds of sensitive crops were different,2%biochar made from bamboo could stabilize the emergence rate and fresh weight of soybean,promote the growth of soybean stem base,effectively adsorb atrazine,improve the growth and development of soybean,significantly reduce the occurrence of soybean phytotoxicity;2%biochar made from chestnut could promote the rapid growth of rape leaves and reduce the absorption of atrazine in the soil by leaves;2%biochar made from corn stover could improve the disease resistance of cabbage seedlings to a certain extent and delay the occurrence of disease.Biochars adsorbed atrazine in the soil for reducing the absorption of atrazine by sensitive crops,and 2%of the biochar content was better for the growth of sensitive succession crops.Comparing the effects of adding biochars on the growth and development of three sensitive succession crops,the effect of adding 2%biochar made from bambo to soybeans was the best.Adding biochars to the soil could not only reduce the phytotoxicity of crops and ensure food safety,but also reduce the residual phytotoxicity in the soil,promote the sustainable development of farmland and ensure the safety of the soil environment.