生物质炭添加对重金属污染稻田土壤理化性状及微生物量的影响

Effects of Biochar Addtion on Physicochemical Properties and Microbial Biomass of the Red Paddy Soil Polluted by Heavy Metals

分析了生物质炭添加对红壤性水稻土理化性状、重金属含量及微生物生物量的影响。通过田间小区长期定位试验,一次性施入不同量生物质炭(0,10,20,30,40t/hm2),于2017年9月采集各处理表层土样(0—15cm),研究土壤理化性状、重金属含量及微生物生物量的变化。结果表明:生物质炭添加对土壤理化性状、重金属含量及微生物生物量均有显著影响。与对照相比,供试土壤的pH、EC和有机质含量随生物质炭添加量的增加而增大,增幅分别为5.11%~18.43%,37.62%~104.31%和1.72%~22.41%,而有效磷和铵态氮含量随生物质炭添加量的增加呈先增大后减小趋势,分别在生物质炭添加量为10t/hm2和30t/hm2时达到最大值。随生物质炭添加量的增加,土壤有效态Cd和有效态Pb含量均呈降低趋势,而土壤有效态As含量呈先增加后减少的趋势,三者均在生物质炭添加量为40t/hm2时达到最小值。土壤微生物生物量碳、氮和微生物商随生物质炭添加量的增加均呈先升高后降低的趋势,均在生物质炭添加量为20t/hm2时达到最大值。相关分析表明,生物质炭添加量分别与土壤有效态Cd和Pb含量之间呈极显著负相关(P<0.01);通径分析表明,生物质炭主要是通过直接作用影响土壤有效态Cd含量,而土壤pH、EC、有机质、微生物生物量碳、氮和有效磷主要是通过间接作用影响土壤有效态Cd含量。因此,添加适量生物质炭不仅可以改善土壤重金属污染现状和土壤理化性状,提高土壤养分含量,还可以改良土壤生物学性质,增加土壤微生物量。研究结果可为提高稻田土壤肥力和改善土壤重金属污染状况提供科学依据。

The objective of this long-term positioning experiment was to study the effects of biochar addition on soil physicochemical properties,heavy metal concentrations and microbial biomass in the red paddy soil polluted by heavy metals.Biochar was added once at rates of 0,10,20,30,and 40 t/hm2,and the topsoil samples（0—15 cm）were collected in September 2017.The results showed that biochar addition had signification effects on soil physicochemical properties,heavy metal concentrations and microbial biomass.Soil pH,electrical conductivity（EC）and soil organic matter（SOM）were observed significantly increased under biochar addition as compared to the control,ranging from 5.11% to 18.43%,37.62% to 104.31%,and1.72%to 22.41%,respectively.However,the available phosphorus and ammonium nitrogen content were firstly increased and then decreased with the biochar addition rate increment,and the highest available phosphorus and ammonium nitrogen content were in the 10 t/hm2 and 30 t/hm2 treatments,respectively.As for the changes of heavy metals,the available content of Cd and Pb decreased with the biochar addition rate increment,whereas the available content of As increased firstly,and then decreased with biochar amendment rate increased,and the highest content of As was in the 40 t/hm2 treatment.Soil microbial biomass carbon,nitrogen and microbial quotient firstly increased and then decreased with the addition rate of biochar increment,they maximum value of them were all in the 20 t/hm2 treatments.Correlation analysis showedthat the biochar addition was significant negative correlated with the available content of Cd and Pb（P〈0.01）.The path analysis indicated that the available content of Cd in soil was mainly affected by biochar addition through the direct impact,whereas the soil pH,EC,SOM,microbial biomass carbon,nitrogen,and available phosphorus content could mainly affected the available Cd content by indirect impact.In conclusion,biochar addition can not only improve status of soil heavy metal pollution and soil physicochemical properties,but also improve the soil biological properties.This study can provide a scientific basis and support for improving the soil fertility and remediating the heavy metal contamination.