| The chicken manure-derived biochar can not only fix carbon and nutrients,but also overcome the environmental problems caused by improper treatment of chicken manure,however,because of the high content of Cu and Zn in chicken manure,the risk of heavy metal pollution may exist in the use of this kind of chicken manure-derived biochar.Result of this study was to explore the use of 300? and 600? temperature and ozone oxidation biochars on the physical and chemical properties,after a preliminary probe with thermostatic cultivation into the change of the effectiveness of copper and zinc in soil,and studied the effect of chicken manure-derived biochar added in soil culture and Bok choy pot experiments on copper and zinc form in soil and adsorption by plant in greenhouse,in order to provide scientific basis for scientific and rational use of chicken manure-derived biochar.The results are as follows:(1)With the increase of the preparation temperature,the pH and EC values of the chicken manure-derived biochar were also increased.In addition to the manure in the 600? when preparation into biochar total heavy metal zinc has a large loss.Chicken manure-derived biochar mineral elements and total copper?zinc were got concentrated,but effective state content was reduced significantly.Chicken manure is made into biochar that the ratio of Cu and Zn acid in the form of biochar is obviously reduced,and the ratio of the oxidizable state and the residue state is increased.It is shown that although the chicken manure-derived biochar can be enriched with Cu and Zn,its effectiveness is significantly reduced.(2)Because 600? preparation biochar material loss is bigger,so the low temperature 300? biochar for constant temperature soil culture.The soil pH and EC value can be increased by using chicken manure-derived biochar,after 90 d training,chicken manure-derived biochar plays a certain role in the effective state Cu content in blank soil,increased the content of the effective Zn,however,biochar has no significant effect on the soil effective state of adding deer manure.Under water condition,ozone oxidation chicken manure-derived biochar still retains its fixed effect on copper,but unoxidized biochar has no fixed effect.In addition,after 90 d the increase of the effective state Cu and Zn in the soil with the addition of deer manure soil was higher than the normal conditions.(3)In high-temperature,high-humidity greenhouse,the application of chicken manure-derived biochar in soil increases the content of available phosphorus and instant potassium,moreover,the use of chicken manure-derived biochar could slow down the two nutrient contents of the blank and the addition of deer manure soil.Chicken manure-derived biochar can significantly reduce the content of ammonium nitrogen in blank soil and deer manure soil,increasing the levels of nitrous nitrogen,the nitrate nitrogen content in potted culture was significantly reduced.In addition,chicken manure-derived biochar can reduce the content of water-soluble organic carbon in soil but increase soil organic carbon content.For Cu and Zn in the soil,after culture,the application of biochar can significantly decrease the effective state Cu in the blank and added deer manure soil,the content of Zn was increased relative to contrast,but compared to the early stages of culture,Adding chicken manure-derived biochar added processing can greatly reduce the effective state Zn content with the cultivation.The form shows,the ratio of the acid soluble state to the original Cu can be reduced by using the chicken manure-derived biochar,increase the residue state Cu ratio,the Zn ratio of the oxidation state and the residue state of the biochar was increased.The application of chicken manure-derived biochar can promote the growth of Bok choy,increase the dry weight,reduce the amount of heavy metal Cu and Zn in the root and the root enrichment factor of Cu and Zn,after two potted the addition of chicken manure-derived biochar can also reduce the content of Cu and Zn in the stem and leaf of Bok choy.From what has been discussed above,there is a transient risk of heavy metal contamination after the chicken manure-derived biochar is applied to the soil,moreover,the pollution risk of Zn is greater than Cu.But it can increase the organic carbon content of soil to achieve the effect of carbon fixation.With the extension of culture time,the slow release of nutrients in chicken manure can promote the growth of Bok choy.it can also fix Cu and reduce the release of Zn,thereby reducing plant absorption of Cu and Zn. |
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