兽用抗生素磺胺二甲嘧啶对稻田NH_3挥发的影响

Effects of the Veterinary Antibiotic Sulfamethazine on Ammonia Volatilization from a Paddy Field Treated with Conventional Synthetic Fertilizer and Manure

为了研究兽用抗生素对稻田NH_3挥发的影响,本文采用稻田原位观测试验,分别对比分析了磺胺二甲嘧啶土壤高残留(常规施肥模式,基肥复合肥,追肥尿素)及随有机肥源(基肥猪粪,追肥尿素)进入土壤,对稻田NH_3挥发的影响.试验共设5个处理:对照无肥料无兽用抗生素处理(CK);基肥为复合肥,无兽用抗生素(CF)及添加磺胺二甲嘧啶处理(CF+SD);基肥为猪粪,无兽用抗生素(CM)及添加磺胺二甲嘧啶处理(CM+SD).结果表明,无论基肥是复合肥还是猪粪,磺胺二甲嘧啶均未改变稻田NH_3挥发的季节性排放规律,但均极显著促进了水稻追肥期的NH_3挥发(P<0.01).整个观测期NH_3挥发损失率CF+SD处理和CM+SD处理分别是CF和CM处理的1.65和2.78倍,说明磺胺二甲嘧啶对猪粪为基肥的稻田NH_3挥发促进效应更为明显.磺胺二甲嘧啶显著促进了土壤脲酶活性(P<0.05),而NH_3挥发速率同脲酶活性及土壤氨氮呈显著正相关(P<0.05),表明磺胺二甲嘧啶改变了土壤脲酶活性及无机氮含量,进而改变了土壤NH_3挥发.如何控制兽用抗生素的滥用以及随粪源大量进入农田导致的环境生态风险是我国目前亟需解决的问题.

Veterinary antibiotics have been widely detected in croplands due to the application of animal excrements as fertilizer.However,their effects on ammonia（ NH3） volatilization remain unclear. A field experiment was conducted to evaluate the effect of sulfamethazine on NH3 volatilization from a paddy field when conventional synthetic fertilizer or manure was applied as basal fertilizer.Five different treatments were conducted in this study： without application of fertilizers and antibiotics（ CK）,compound fertilizer used as basal fertilizer with and without the addition of sulfamethazine（ CF ＋ SD and CF respectively）,and pig manure used as base fertilizer with and without the addition of sulfamethazine（ CM ＋ SD and CM respectively）. Urea was used for topdressing in the CF,CF＋ SD,CM,and CM ＋ SD treatments. The results showed that regardless of the fertilizer type applied,sulfamethazine did not affect the seasonal pattern of NH3 volatilization. However,it promoted the NH3 volatilization rate in the topdressing stage significantly（ P〈0. 01）. During the observation period,the proportions of applied N lost as NH3-N in the CF ＋ SD and CM ＋ SD treatments were 1. 65 and 2. 78 times higher than those in the CF and CM treatments,respectively. The promoting effect of sulfamethazine was more obvious in the pig manure treatment than in the compound fertilizer treatment. Sulfamethazine significantly increased the soil urease activity（ P〈0. 05）. Furthermore,the NH3 volatilization rate was positively correlated with urease activity and soil ammonia nitrogen content（ P〈0. 05）. This indicates that sulfamethazine can increase the NH3 volatilization rate by changing the soil urease activity and inorganic nitrogen content. Controlling the misuse of veterinary antibiotics and environmental and ecological risks posed by the antibiotic residues in farmland excrements are urgent problems in China that need to be solved.