Effect Of Liquid Conditioner Applied On The Accumulation Of Nutrient And Cadmium In Rice And Leafy Vegetable On Cadmium-polluted Soil

Cadmium pollution of soil has become an important factor restricting the safe production of agricultural products in China.In this study,two pot-culture experiments in rice（Oryza sativa L.）and flowering cabbage（Brassicacampestris L.）,together with one field experiment in common head cabbage（Brassica oleracea L.var.capitata L.）,were conducted.The liquid conditioner（LC）of soil developed by the Institute of resources and environment,Guangdong Academy of Agricultural Sciences,is used as the material applied on acidic soils to study the effect of the use of the LC in different rate or distributed manner on the yield and the food qualities in the crops,the content and absorbed amount of the main nutrient and Cd,as well as on the target of soil nutrient and soil available Cd level.The principle results obtained were as follows:1.The result in pot-culture and field experiments indicated that the application of LC in different rate or distributed manner could increase Biomass in aerial part of flowering cabbage by 12.00%to 37.00%compared with no LC applied and increase the content of soluble sugar in food part.But on the condition of water management practice in pot-culture experiments on rice which were in water-logging status throughout the growth period,the effect on yield increase was not significant.2.The result in pot-culture and field experiments indicated that the application of LC in different rate or distributed manner could promote the absorbed amount of N,P,K,Ca and Mg in aerial part.But insignificant effect was emerged on the absorbed amount in rice.The K content in straw tend to significant increase with the increase of rate of LC.The application of LC in different distributed manner in rice could to some extent promote the content of K in straw and grain,and the content of Ca,Mg and Si in grain,and that of Si in straw.3.The application of LC in different rate or distributed manner of leafy vegetable could decrease the content of Cd in aerial part,decreased by 25.97%to 32.68%or 3.76%to 34.52%in pot-culture and 12.72%to 34.20%in field experiment compared with no LC applied.The absorbed amount of Cd was decreased by 5.13%to 20.42%or 5.21%to24.71%in pot-culture of flowering cabbage.LC applied in different rate or distributed manner in rice could decrease the content of Cd in leaves,stems and grains or the absorbed amount of Cd in aerial part,and showed the tendency to increase the proportion of Cd in stems and decrease that of Cd in grains.The content of Cd in coarse rice tend to decrease in the experiment of different distributed manner.4.The application of LC in different rate or distributed manner could decrease the level of available Cd（extracted by Ca Cl₂）by 2.53%to 44.69%or 4.28%to 28.13%in flowering cabbage,and 2.23%to 10.55%or 0.05%to 27.31%in rice.The soil p H value in harvest stage in pot-culture tend to increase compared with no LC applied.The increment of soil p H were 0.06 to 0.44 unit or 0.02 to 0.30 unit in flowering cabbage,and0.06 to 0.11unit or 0.01 to 0.20 unit in rice.In field experiment,the p H was increased by0.15 to 0.54 unit,and the level of available Cd decreased by 21.18%to 57.03%compared with no LC applied.5.The application of LC in different rate had the effect to increase the level of alkali-hydrolyze N,available K and available Si in the soil in harvest stage and the tendency to increase the EC value and the level of available P.The LC applied in different distributed manner could promote to some extent the level of alkali-hydrolyze N,available P and available K of soil in harvest stage of rice,and that of alkali-hydrolyze N,available P,available K,exchangeable Mg and available Si of flowering cabbage.6.Synthesized the effect of LC applied on every target,the suitable rate of LC applied in pot-culture was 8ml/kg,with the distributed ratio among the transplant,the middle stage and the later stage be one-third evenly.The rate of LC applied from the field experiment on common head cabbage was recommended as 60 L/666.7m².