Effects Of Different Livestock/Poultry Manure Biochar On Fertility And Pollution Characteristic Of Red Soil

The Red soil in southern China has always been characterized by"acid,sticky and thin",which has seriously hindered the productivity of soil.At the same time,the development of animal husbandry has also brought about the problem of fecal pollution,affecting the sustainable development of agricultural production in China.In this paper,livestock/poultry manure biochar was used as an acid red soil amendment to study the differences of physical and chemical characteristics of red soil between different types of livestock/poultry manure biochar,and to explore the effects of different livestock/poultry manure biochar application rates on fertility and pollution of red soil,so as to provide methodological basis for livestock/poultry manure biochar to improve red soil.According to the ratio of 5%and 15%,four kinds of livestock and poultry manure were applied to the tested red soil respectively.The soil was cultivated under simulated natural conditions for 1 year.Then the pakchoi was grown in the soil,and soil fertility index and environmental pollution index were detected.The results showed that the aeration,temperature,pH value,electrical conductivity,organic matter,total nutrients of N,P,K and available nutrients of phosphorus and potassium in red soil increased,while the humidity and alkali-hydrolyzed nitrogen decreased after the application of livestock/poultry manure biochar.In terms of environmental pollution,due to the low bioavailability of heavy metals in livestock feed,the application of livestock/poultry manure biochar will increase the content of heavy metals in soil,and even exceed the standard.The results are as follows:15%PB treatments exceed the standard of copper,15%CAB,5%GB,15%GB,15%CHB treatments exceed the standard of Cd,15%CAB,5%GB,15%GB,5%PB,15%PB,5%CHB treatments exceed the standard of As,but adding livestock manure/carbon.The content of Cu in Chinese cabbage treated with 5%PB was the highest and 15%GB was the lowest.The other treatments were significantly lower than CK.In the five leaching events treated with livestock/poultry manure biochar,the DOC leaching amount of leaching solution treated with 15%CAB,15%GB,15%PB and 15%CHB increased by 3.54 mg,1.94 mg,2.72 mg and 1.84 mg,respectively,compared with CK treatment,and was significantly higher than that treated with 5%livestock/poultry manure biochar;the leaching amount of nitrogen,phosphorus and potassium in 5%livestock and poultry manure biochar treatment was consistent with the control level,and the treatment added with livestock/poultry manure biochar decreased.Heavy metal leaching reduced the accumulation of heavy metals in Chinese cabbage.In the treatment of 5%livestock/poultry manure biochar,the order of improving soil fertility by different livestock/poultry manure biochar was cattle manure biochar,sheep manure biochar>pig manure biochar>chicken manure biochar,and the order of improving soil fertility by 15%livestock/poultry manure biochar was chicken manure biochar>pig manure biochar,sheep manure biochar>cattle manure biochar.The application of livestock/poultry manure/carbon significantly increased the biomass of Chinese cabbage,of which 5%treatment was better than 15%treatment.The conclusions of this study are as follows:(1)Adding livestock/poultry manure biochar can increase the content of heavy metals in soil to some extent,but the forms of heavy metals in soil are mainly residual and insoluble oxidized.(2)The nutrient and heavy metal leaching of livestock/poultry manure biochar soil with 5%ratio was less,which indicated that it had the effect of slow-release nutrient and passivation of heavy metals,while the effect of 15%ratio was worse.(3)Applying 5%livestock/poultry manure biochar improved soil physical and chemical properties,increased soil fertility and effectiveness,promoted crop growth,and improved soil quality.The 15%application rate would inhibit the growth of crops.(4)Generally speaking,the application ratio of livestock/poultry manure biochar should be reduced in agricultural production to achieve better results.Cattle manure biochar should be preferentially selected as soil improvement material among the four kinds of livestock/poultry manure biochar.