| With the rapid development of the society,the development of industrial and agricultural production is progressing increasingly.However,because of the irrational discharge of industrial and agricultural waste,the environment issue has become more and more serious.Among them,the heavy metal cadmium（Cd）pollution is becoming increasingly serious,which has threatened human health.Therefore,under the condition of not changing the status quo of farmland soil utilization,to reduce the bio-availability of Cd in farmland soil by means of applying an improver or passivator is of great significance to ensure the safe production of food in China.In this paper,the effects of combined application of cow manure and lime on soil Cd morphology are studied by soil culture test.In this trial,the concentration of exogenous Cd is 10 mg·kg-1;The manure is applied at 7.5 g·kg-1and 15 g·kg-1respectively;The amount of lime applied is 1,2,3,4 and 5 g·kg-1respectively.Through the determination of soil p H,organic matter and Cd occurrence form,the mechanism of reducing soil Cd availability by combining cow manure with lime application is discussed,and the suitable soil improver is selected by measuring effective Cd content.Then,the effect of leaf selenium（Se）fertilizer on Cd absorption of brassica chinensis is studied by pot experiment.The concentrations of Se spraying are 0,1,2,4 and 8 mg·L-1,respectively.By measuring the biomass,Cd content,malondialdehyde content,antioxidant enzyme activity and glutathione content of brassica chinensis,the mechanism of Se reducing Cd toxicity of brassica chinensis is discussed in order to provide theoretical basis for the restoration of Cd contaminated soil and the safe planting of agriculture products.The main conclusions are as follows,（1）Compared with no amendment,the addition of cow manure and lime significantly increases the p H of the soil.Among them,7.5g·kg-1or 15g·kg-1cow manure with 4g·kg-1or 5g·kg-1lime shows the greatest increase in soil p H,which increases by 1.52、1.56、1.54 and 1.58 units respectively,and there is no significant difference among the four.The content of soil organic matter is increased by adding cow manure and lime.Among them,the organic matter content of 15g·kg-1treated with 1g·kg-1、2g·kg-1and 3g·kg-1lime increases the most,by 11.9%、11.5%and 11.0%respectively,and there is no significant difference among the three.（2）Compared with no amendment,the addition of cow manure and lime reduces the content of weak acid soluble Cd in soil,and promotes the conversion of weak acid soluble Cd to reducible,oxidizable and residual Cd.Among them,7.5g·kg-1cow manure with 5g·kg-1lime reduces the content of weak acid soluble soil Cd by 38.5%,the content of residual soil Cd increases by 338.5%,the content of available Cd reduces by 37.9%.From the perspective of economic cost,7.5 g·kg-1cow manure and 5 g·kg-1lime are used as soil modifiers in the pot experiment.（3）The absorption of Cd from brassica chinensis could be effectively inhibited by applying leaf surface Se fertilizer with cow manure and lime.Compared with the soil without leaf Se fertilizer,the soil contaminated by 0.47 mg·kg-1and 3 mg·kg-1Cd with 4 mg·L-1Se fertilizer has the best effect,the biomass of Chinese cabbage increases by 25.8%and 99.3%,respectively,and the Cd content decreases by 12.9%and 78.7%,respectively.Spraying 8 mg·L-1Se fertilizer on soil contaminated by 6 mg·kg-1Cd has the best effect,which increases the biomass of brassica chinensis by 222.6%and reduces the Cd content by 81.4%.（4）Compared with soil contaminated with 0.47 mg·kg-1and 3 mg·kg-1Cd,spraying 4 mg·L-1Se fertilizer makes the largest reduction in MDA content of brassica chinensis,which is 29.9%and 60.6%respectively.In the soil contaminated by 6 mg·kg-1Cd,spraying 8 mg·L-1Se fertilizer reduces MDA content of brassica chinensis by 71.9%at most.Foliar Se application significantly increased the antioxidant enzyme activities and GSH content of brassica chinensis in different Cd contaminated soils. |
PDF Full Text Request