城市污泥与园林废弃物堆肥混合添加对土壤改良的影响

摘要

以北京市城市污泥与园林废弃物为研究对象,采用盆栽方法,将污泥与园林废弃物堆肥按不同体积配比(1:0, 1:3,1:1和0:1)混合后作为改良基质,设置不同施加量(无混合物、25%混合物、50%混合物、75%混合物、100%混合物),比较其对种植高羊茅(Festuca arundinace)后盆栽土壤的改良作用以及对植物的影响.结果表明,污泥与园林废弃物堆肥1:1混合后土壤 pH 相比对照有明显降低(P<0.05),加入改良基质后与对照相比电导率均有提高,但4个月后电导率降低至正常范围(0.5~1.5 ms?cm—1);加入改良基质后土壤有机质、全氮、全磷含量显著提高(P<0.05),而且土壤速效磷成倍增加.本盆栽试验所用土壤重金属Cr、Pb含量较高,加入改良基质并种植高羊茅后4种重金属浓度均降低;重金属向高羊茅体内的迁移能力以Pb最强,Zn、Cr次之,Cu最弱;高羊茅的发芽与重金属 Cr含量关系密切,而其生长则主要与土壤中氮的含量相关紧密.本研究表明,高羊茅作为常见草坪草,对重金属有强烈的吸附作用,可以用来改良被污染的土地;污泥与园林废弃物堆肥混合之后,虽然对重金属的总量无明显影响,但可能改变重金属的形态,更有利于被植物和微生物吸收并降解.%To study the effects of sewage sludge and garden waste composts on soil amelioration and plant growth,pot experiments were carried out based on sewage sludge and garden waste in Beijing.The experiment consisted of four types of mixture of the two composts as modified substrate (volume ratios 1:0,1:3,1:1, and 0:1),at five concentration levels [0 (soil as control),25%,50%,75%,and 100% compost mixture]. The results showed that the pH value of the 1:1 mixture increased significantly compared to that of the con-trol.Soil electrical conductivity increased at the beginning of the modified substrate addition,and then dropped to the normal range after four months.Meanwhile,additions also significantly increased the organic matter,to-tal nitrogen,and total phosphorus.Soil available phosphorus was greatly increased,indicating enhanced soil phosphorus activity.Although the soil used in the pot experiment had relatively high amount of heavy metals, adding modified substrate could reduce their concentrations.After planting Festuca arundinacea,concentra-tions of heavy metals decreased significantly.For the four heavy metals studied,Pb had the strongest migration to plants,followed by Zn and Cr,while Cu was the weakest.Germinations of tall fescue were closely related to Cr,and the growth was related to the nitrogen content of the soil.In summary,tall fescue,as a common lawn grass,has a strong adsorption of heavy metals,and thus can be used to amend contaminated land.Although mixing sludge compost with garden waste does not reduce the total amount of heavy metals,it may affect the form of heavy metals,and promote their absorption and degradation by plants and microorganisms in soils.