Effects Of Combined Application Of Cow Manure And Straw On Cadmium Transformation In Brown Soil And Uptake By Baby Bokchoi

Inefficient burning and random dumping of a lot of straw and cow manure will cause waste of resources and environmental pollution.A pot experiment was conducted to study the effect of cow manure combined with corn straw on cadmium transformation in brown soil and uptake by baby bokchoi.The soil pH,organic matter content and cation exchange capacity were measured to reveal the mechanisms of cadmium transformation.Cadmium distribution in subcellular and chemical forms of cadmium in baby bokchoiwere measured to study the effect of combined application of cow manure with straw on cadmium uptake and translocation in baby bokchoi.Chlorophyll content,malondialdehyde content and the activity of antioxidant enzymes in baby bokchoi were also measured to analyze the inhibition effect of combined application of cow manure with straw on cadmium toxicity.To provide theoretical basis for remediation of heavy metal Cd contaminated soil.The results are as follows:(1)Compared with no cow manure and straw addition,the contents of the exchangeable fraction of cadmium decreased 4.14% for the combined application of carbon ratio of straw to cow manure being 1:2,respectively,while the organic bound form cadmium and residual cadmium increased 8.21%,respectively.(2)Compared with no straw and cow manure addition,the cadmium contents in root cell organelle decreased 2.17%、2.39% and 1.30%,respectively for the combined application of carbon ratio of straw to cow manure being 1:1,1:2 and 1:4.Compared with straw addition,ethanol extractable form of cadmium reduced 9.78%,16.44% and 13.48%,respectively for the combined application of carbon ratio of straw to cow manure being 1:1,1:2,and 1:4.While compared with manure addition,the values decreased 6.95%,13.61% and 10.65%,respectively.(3)Compared with no cow manure and straw addition,the activity of peroxidase and superoxide dismutase in root cell organelle of the baby bokchoi increased 94.64% and 11.41%,respectively,for the combined application of carbon ratio of straw to cow manure being 1:2.Compared with no cow manure and straw addition,the malondialdehyde content in root cell organelle of the baby bokchoi decreased 49.25%,and the malondialdehyde content and the activity of catalase aboveground of baby bokchoi decreased 42.05% and 48.65%,respectively,for the combined application of carbon ratio of straw to cow manure being 1:2.The chlorophyll content of baby bokchoi leaves increased 42.53%,and the fresh weight in baby bokchoi was increased.Thus,carbon ratio of the straw to cow manure being 1:2 should be considered a suitable soil amendment for cadmium.