城市污泥堆肥与氮肥配施对稻田CH4和N2O排放及水稻重金属含量的影响

Effects of Composted Sludge Combination with Urea on Greenhouse Gases Emissions from Paddy Soil and Heavy Metals Accumulation in Plant

随着城市污泥量的日益增大,污泥农用备受关注。本研究通过田间原位试验,以水稻为研究对象,观测氮肥与污泥堆肥以不同比例(1︰0、0.75︰0.25、0.5︰0.5、0︰1)配合施用对稻田CH4和N2O排放以及植物重金属累积的影响。结果表明:随着污泥堆肥施用比例的增加,稻田CH4排放呈线性增加(P<0.05,r=0.967)。与施全量氮肥处理相比,施全量污泥堆肥处理显著增加CH4排放118%(P<0.05),而配施处理的CH4排放仅增加30%~34%(P>0.05)。与CH4相反,稻田N2O排放随着污泥堆肥施用比例的增加而逐渐减少,与施全量氮肥处理相比,施全量污泥堆肥处理减少N2O排放39%(P<0.05),配施处理N2O排放减少29%~38%(P<0.05)。施全量污泥堆肥处理的温室气体排放强度(GHGI)与施全量氮肥处理相当,而配施处理的GHGI比施用全量污泥堆肥处理减少18%~24%(P<0.05)。各处理水稻产量无显著差异(P>0.05),各处理稻米中重金属含量均在国家食品安全标准限值范围内。与施全量氮肥处理相比,施全量污泥堆肥处理稻米中Zn、Cr、Cu含量分别增加42%(P<0.05)、103%(P>0.05)和12%(P>0.05),而配施处理稻米中的Zn、Cr、Cu含量分别增加19%~27%(P<0.05)、14%~33%(P>0.05)和4%~7%(P>0.05);Ni在稻米中未检出;施全量污泥堆肥处理与配施处理稻米中的Cd含量相当,相对于施全量氮肥处理均增加了33%(P>0.05)。但各处理上述重金属含量均未超过食品安全标准。综合以上研究结果,污泥堆肥与氮肥配施可作为稻田污泥堆肥推荐施用方式,但需要监测土壤重金属积累动态。

With the increasing of municipal sludge,applying sludge in agriculture has been of great concern.A field experiment was conducted to investigate the effects of applying urea,composted sludge and its combination with urea on the methane and nitrous oxide emissions from paddy soils and heavy metals accumulation in soil and plant.Five treatments,i.e.,no fertilization(CK),urea(U),urea and composted sludge(U+O)with a ratio of 7.5︰2.5(U7.5O2.5),5︰5(U5O5),and total composted sludge(O)were installed,and the N application rate in treatments U,U+O,and O was the same(N,240 kg/hm2).As the amount of sludge compost increased,the emission of CH4 increased linearly(P<0.05,r=0.967).Compared with treatment U,treatment O increased CH4 emission by 118%(P<0.05)and treatments U+O increased CH4 emission by 30%–34%(P>0.05).In contrast to the CH4,N2O emission reduced with the increasing composted sludge.Compared with treatment U,treatment O decreased N2O emission by 39%(P<0.05),treatment U+O decreased by 29%–38%(P<0.05).Treatments U and O had the same Greenhouse Gas Intensity(GHGI).Compared with treatment O,treatment U+O decreased GHGI by 18%–24%(P<0.05).The rice yield was no significant difference among the treatments.Compared with treatment U,treatment O increased Zn by 42%(P<0.05),Cr by 103%(P>0.05),Cu by 12%(P>0.05)in seed,treatment U+O increased Zn by 19%–27%(P<0.05),Cr by 14%–33%(P>0.05),Cu by 4%–7%(P>0.05)in seed,Ni was not detected in seed.Compared with treatment U,treatments U+O and O increased Cd by 33%(P>0.05).The heavy metal content in seed did not exceed the national standards.The combination of sludge compost and nitrogen fertilizer can be used as the recommended method for sludge compost in paddy field.But the soil heavy metal accumulation needs to be monitored.