不同作物秸秆生物炭对水稻镉吸收的影响

Effects of Different Crop Straw Biochars on Cadmium Absorption in Rice

【目的】分析桑树枝秆、木薯秆和甘蔗渣生物炭对水稻镉吸收的影响,为广西镉污染稻田稻米安全生产提供参考依据。【方法】以桑树枝秆、木薯秆和甘蔗渣为原料制备的生物炭开展镉污染水稻土盆栽水稻试验[分别设施用桑树枝秆生物炭1.5%(MB1)、3.0%(MB2)、4.5%(MB3)和木薯秆生物炭1.5%(CB1)、3.0%(CB2)、4.5%(CB3)及甘蔗渣生物炭1.5%(SB1)、3.0%(SB2)、4.5%(SB3)处理,以不施用生物炭为对照(CK)]。于水稻收获后测定分析土壤pH、土壤有效态镉含量及稻秆和稻米镉含量。【结果】施用生物炭处理镉污染盆栽水稻土的pH均有所提高,其中桑树枝秆生物炭处理水稻土的pH显著高于CK、木薯秆生物炭处理(CB3处理除外)和甘蔗渣生物炭处理(P<0.05,下同);土壤有效态镉含量均显著降低,其中桑树枝秆生物炭处理水稻土的有效态镉含量显著低于甘蔗渣生物炭处理,与木薯秆生物炭处理差异不显著(CB3处理除外)(P>0.05);稻米镉含量均低于CK,其中,MB1、MB2和MB3处理的稻米镉含量分别比CK显著降低69.48%、70.54%和74.70%;CB1、CB2和CB3处理的稻米镉含量分别比CK显著降低7.14%、40.54%和41.46%;SB1、SB2和SB3处理稻米镉含量分别比CK显著降低29.57%、31.87%和38.37%。相关性分析结果表明,施用生物炭处理稻米的镉含量与土壤pH呈极显著负相关(P<0.01,下同),与土壤有效态镉和稻秆镉含量呈显著或极显著正相关。【结论】在镉污染稻田土壤中施用桑树枝秆、木薯秆和甘蔗渣生物碳可有效降低水稻稻米对镉的吸收量,其中施用4.5%桑树枝秆生物炭的效果最佳,可最大限度地降低水稻生产的镉污染风险。

【Objective】In order to provide a reference for rice safety production in cadmium polluted rice fields in Guangxi,the effects of mulberry branch,cassava stalk and bagasse biochar on cadmium(Cd)uptake by rice were studied.【Method】Biochar was prepared from three crop straws of mulberry,cassava and sugarcane bagasse for pot experiment of rice in Cd polluted paddy soil[the experiment set:Mulberry branch biochar applied quantity 1.5%(MB1),applied quantity 3.0%(MB2),applied quantity 4.5%(MB3);Cassava stalk biochar applied quantity 1.5%(CB1),applied quantity 3.0%(CB2),applied quantity 4.5%(CB3);Bagasse biochar applied quantity 1.5%(SB1),applied quantity 3.0%(SB2),applied quantity 4.5%(SB3);Applied quantity 0 as control(CK)].The soil pH,soil available cadmium,and the content of cadmium in rice and rice straw were analyzed after rice harvest.【Result】The application of biochar treatment all increased soil pH and the pH of paddy soil treatement with mulberry branch biochar was significantly higher than CK,cassava stalk biochar(except CB3 treatment)and bagasse biochar(P<0.05,the same as below).The content of available cadmium in soil decreased significantly,and the treated with mulberry branch biochar was significantly lower than that of bagasse biochar,but not significantly different from that of cassava stalk biochar(except CB3 treatment)(P>0.05).The content of Cd in rice grain was lower than CK,among which,the content of of Cd in rice could be reduced by 69.48%,70.54%and 74.70%by applying the mulberry branch biochar(MB1,MB2 and MB3)than CK;The content of Cd in rice treated with CB1,CB2 and CB3 was significantly reduction to 7.14%,40.54%and 41.46%than CK respectively;The content of Cd in rice was significantly reduced by 29.57%,31.87%and 38.37%when applying SB1,SB2 and SB3 than CK.The results of correlation analysis showed that,the content of Cd in rice was highly significantly negatively correlated with soil pH(P<0.01,the same as below)and significantly positively correlated with soil available cadmium and highly significantly positively correlated with cad-mium content of rice straw.【Conclusion】Application of biocarbon from mulberry branches,cassava stalks and bagasse could effectively reduce the absorption of Cd in rice,and among them application of 4.5%mulberry branch biochar was the best,which could maximally decrease the risk of Cd pollution in rice production.