Wartość nawozowa komunalnych osadów ściekowych oraz ich wpływ na właściwości fizyczno-chemiczne i aktywność biologiczną gleby
AbstractDue to a considerable content of organic matter and mineral nutrients, but also relatively small resources of organic compounds in a majority of mineral soils in our climatic zone, environmental management of sewage sludge seems a most desired practice. However, application of this type of waste materials for fertilization also involves a. risk of the environment pollution, since beside fertilizer components, sewage sludge may also contain a number of harmful elements, i.e. heavy metals, PAHs or pathogenic organisms. The investigations aimed at providing information enabling a clarification of a complex effect of sewage sludges on the environment. In a four-year lysimetric experiment with various crop species, investigated was fertilizer value of two sludges originating from municipal sewage treatment plants against the background of equal farmyard manure and mineral fertilizer doses and their influence on changes of physicochemical properties and biological activity of soil caused by the application of this type of materials. Conducted experiments revealed that fertilization with sewage sludges beneficently affected crop yield, significantly increasing it macroelement content in relation to the element quantity in crops cultivated in unfertilized soil. Average nitrogen utilization by plants from the soil fertilized with sewage sludges for four subsequent years was 22%, phosphorus 9.5% and potassium 57%. On the other hand, at a single fertilization of soil with sewage sludge and subsequent application of mineral fertilizers, the indices were as follows: nitrogen 51%, phosphorus 14% and potassium 53%. Sewage sludges applied four times had a more pronounced effect on crop yielding and soil properties than their single application, which only slightly and transiently modified the soil properties. Sewage sludge applied to the soil contributed to improving pH value, increasing soil sorption capacity, content of bioavailahle phosphorus and organic matter, but decreasing the degree of its humification and Ch : Cr ratio. In result of intensive fertilization with sewage sludges total contents of heavy metals and polycyclic aromatic hydrocarbons increased in the topsoil, however it had no influence on modification of their amount in the subsoil. Despite these unfavourable changes, because of improvement of soil physicochemical properties, bioavailability of the metals, particularly cadmium and nickel from the soils fertilized with sewage sludges was lower than from the soils receiving mineral fertilizers. PAHs content was lower than permissible in agricultural soils, however a visible tendency for accumulation of organic impurities points to a risk of these soils pollution with these substances if sewage sludges are applied too frequently. Considerable quantities of organic matter supplied to the soil with sewage sludges increased its macroporosity, which led to formation of spheroidal soil structure and advantageously affected soil biological activity increasing the number of microorganisms and mesufauna activity. Summing up obtained results of research it. was determined that following the legal regulations currently in force, as stated in the decree of the Minister of the Natural Environment on municipal sewage sludges, despite missing legal provisions about polycyclic aromatic hydrocarbons, should efficiently reduce the risk of excessive pollutant accumulation in the environment.
|Other language title versions||Fertilizer value of municipal sewage sludges and their effect of physicochemical properties and biological activity of soils|
|Publisher||Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie, MNiSW |
|Publishing place (Publisher address)||Kraków|
|Book series /Journal (in case of Journal special issue)||Zeszyty Naukowe Uniwersytetu Rolniczego im. Hugona Kołłątaja w Krakowie. Rozprawy, ISSN 1899-3486, (0 pkt)|
|Publication size in sheets||6|
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