稻壳和稻壳生物炭对镉污染土壤肥力及镉有效性的影响

Effects of rice hull and rice hull biochar on soil fertility and cadmium availability in cadmium contaminated soil

在镉(Cd)污染土壤中添加等碳量的稻壳及稻壳生物炭,研究不同材料对Cd污染土壤理化性质、肥力、酶活性及重金属Cd有效态含量的影响。共设置4个处理组,未被Cd污染土壤(CK)、Cd污染土壤(CD)、添加2%生物炭的Cd污染土壤(BO)、添加等碳量的稻壳Cd污染土壤(DK)。试验结果表明,BO和DK组的土壤总有机碳含量较CD组分别提高10.05%和5.02%,DK组的可溶性有机碳含量在第60 d,比CD组高出43.90%,BO组培养第90 d时,比CD组高13.00%;BO组的碱解氮含量对比CD显著降低,DK组的碱解氮含量对比CD组显著升高。不同处理组对酶活性有不同影响,第45 d时,BO和DK组的脲酶活性较CD组显著提高,分别提高10.14%和8.61%;施加稻壳和稻壳生物炭均能显著提高土壤中的蔗糖酶活性,但BO组显著低于DK组。不同处理对土壤理化性质有不同的影响,DK和BO组均显著提升土壤的孔隙度、初始孔隙比和土壤中砂粒、黏粒的比例;土壤重金属有效态试验结果表明,DK组中Cd污染土壤中的酸可提取态Cd的含量显著降低。对比施入稻壳生物炭,施加稻壳能够短期提升土壤肥力;生物炭和稻壳均能提升土壤的孔隙度和比重,使土壤中的黏粒占比上升;稻壳生物炭及稻壳均能缓解Cd对酶活性的抑制作用;相比生物炭而言,稻壳更能显著降低土壤中酸提取态的Cd含量。

The effects of different materials on the physical and chemical properties,fertility,enzyme activity and available content of heavy metal cadmium(Cd)in Cd contaminated soil were studied by adding rice hull and rice hull biochar with equal carbon content to Cd contaminated soil.In this study,four treatment groups were set up,including soil not polluted by Cd(CK),soil polluted by Cd(CD),soil polluted by Cd with 2%biochar(BO),soil polluted by Cd with rice hull with equal carbon content(DK).The results showed that the total orgnic carbon content in the soil of BO and DK groups was 10.05%and 5.02%higher than that of CD group respectively,the dissolved organic carbon content of DK group was 43.90%higher than that of CD group on the 60th day,and the dissolved organic carbon content of BO group was 13.00%higher than that of CD group on the 90th day of culture;The content of alkali-hydrolyzed nitrogen in BO group was significantly lower than that in CD group,while that in DK group was significantly higher than that in CD group.Different treatment groups had different effects on the enzyme activity.On the 45th day,the urease activity of BO and DK groups was significantly higher than that of CD group,increased by 10.14%and 8.61%,respectively;The application of rice hull and rice hull biochar could significantly increase the activity of invertase in soil,but the activity in BO group was significantly lower than that in DK group.Different treatments had different effects on soil physical and chemical properties.DK and BO groups significantly increased the soil porosity,initial void ratio,and the proportion of sand and clay in soil.The experimental results of available forms of heavy metals in soil showed that the content of extractable forms of Cd acid in Cd contaminated soil in DK group decreased significantly.Compared with applying rice hull biochar,application of rice hull could improve soil fertility in a short time;Both biochar and rice hull could increase soil porosity and specific gravity,and increase the proportion of clay in soil;Both rice hull biochar and rice hull could alleviate the inhibition of Cd on enzyme activity;Compared with biochar,rice hull could significantly reduce the acid extracted Cd content in soil.