| At present,it is common to use biological manure as a fertilizer for cultivation as more affordable means of fertilization.Due to the high use of high-dose copper and zinc as an additive in livestock and poultry feed,the copper and zinc contents of livestock and poultry excrement are generally higher in large-scale farms.Therefore,livestock and poultry manure as fertilizer for soil fertility may causing heavy metals pollution in farmland soils,affecting the quality of crop products and ultimately affecting human health.Studies have shown that biochar may have different degrees of passivation of copper and zinc in soil,but there are few reports on the effect of adding biochar to copper and zinc in soil environment under the conditions of livestock and poultry manure application.In this paper,the physical and chemical properties of rice husk biomass were measured first.Then,the effects of biochar on the germination and growth of wheat under the condition of copper and zinc pollution were studied by hydroponic experiment.Next,the effect of biochar on the transformation and transformation of heavy metals was explored by the study of the influence of biochar on the migration and transformation of copper and zinc in soil under the pot experiment.This study provides a theoretical basis for the remediation of heavy metal pollution caused by excessive use of livestock and poultry manure during the cultivation of farmland,which provides a theoretical basis for the application of biochar in the remediation of heavy metal contaminated soil.The results of the study are as follows:(1)The physical and chemical properties of biochar showed that the pH was 8.45,the ash content was 64.43%,the specific surface area was 16.33 m2·g-1,the cation exchange capacity was 13.75 cmol·kg-1,Ca2+ and Mg2+ are the main exchangeable salt ions in the rice husk biochar,with a total acidity of 279.38 cmol·kg-1,the highest content of phenolic hydroxyl group,171.88 cmol·kg-1,with the ability to adsorb heavy metal ions,Which can provide active sites for the adsorption of heavy metals.The adsorption effect is good,and it is found by scanning electron microscopy that the stratified structure of the experiments is obvious,the thickness of the layered structure is small and the pore distribution is uniform.(2)The results showed that with the increase of biochar content,the germination rate,germination potential,germination index,vigor index,germination index,germination index,germination index,germination index,germination index,germination index The contents of CAT,SOD and POD in wheat seedlings decreased with the increase of biochar content,which indicated that the addition of biochar could reduce the toxicity of heavy metals to seed germination effect.By comparing the changes of physiological and biochemical indexes of three different kinds of biochar to different heavy metal solution,the effect of biochar on wheat seedling mixed with heavy metal was the most significant.(3)The effect of biochar on the growth of wheat seedling in soil was studied.The results showed that the addition of 5% biochar could reduce the exchangeable content of copper in pig manure and chicken manure,which were 0.67% And 0.76% and 5% of the content of biochar can reduce the exchangeable content of zinc in the soil of pig manure and chicken manure by 1.98% and 3.91%,while increasing the content of other forms of copper and zinc in soil.The length and biomass of aboveground and underground parts of potted wheat were significantly increased after adding biochar,and the promotion rate of root length was 47.65%.At the same time,the content of copper and zinc in the aboveground and underground parts of wheat also decreased significantly.For different feces,pig manure to the environment into the amount of heavy metals is greater than chicken manure,so add pig manure soil planted wheat top and underground heavy metal content is higher than the addition of chicken manure soil. |
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