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The amended soils chemical properties as affected by the application of a single dose of sewage sludge were evaluated over a 1-year period. Three soil groups based on their pH values were examined. Data on pH, organic matter, CaCO, electrical conductivity, exchangeable Ca and Mg, concentration of nine metals (Cd, Co, Cr, Pb, Zn, Ni, Fe, Mn, Cu) and nutrients before the application of sewage sludge in 2013 and after the wheat growing period in 2014, were statistically analyzed. Results showed that the application of lime stabilized sewage sludge significantly increased the electrical conductivity, CaCO and Mg in all soil groups as well as pH and Ca of acidic soils, while the organic matter was not affected. The levels of concentrations of most DTPA-extractable metals in soil, either decreased or remained the same as they were before the sludge application. Soil Zn was the only metal that increased in the acidic soil group, however in concentrations largely below ecotoxicological limits. It is concluded that the application of lime stabilized sewage sludge to soils may take place with no risk of increasing heavy metal bioavailability to phytotoxic levels. Further benefits to crops are provided by favoring pH conditions for plant growth in acidic soils and by improving plant nutrition via nitrogen addition. [ABSTRACT FROM AUTHOR]

The spatial representation of the soil properties for agricultural areas is necessary to implement precision agriculture management practices. This can currently be obtained by extensive sampling of soil or plants, which is laborious and not economical. An alternative procedure is presented in this study, where a digitized soil map was constructed for the regional unit of Kastoria. This digitized soil map has provided a useful electronic database for the spatial representation of the soil variation of the region, based on in situ soil sampling, laboratory analysis, GIS techniques and plant nutrition mathematical models, coupled with the local land cadastre. The novelty of these studies is that local agronomists have immediate access to a wide range of soil information by clicking on a field parcel shown in this digital interface. Thus, differential fertilization management can be applied at a large scale, such as for example, the whole regional unit of Kastoria, while precision is not compromised. The software (provided on CD) automatically calculates the fertilization needs for each farm, displays and prints a detailed two-page guideline to the farmer, namely: • on the first page there is a map of the farm as well as information regarding the farm's nutritional status according to soil analysis (see Figure 1). • on the second page the fertilization advice is provided for the particular crop, based on the soil nutritional status. The current study examined the spatial patterns of soil texture, pH, CaCO3, organic matter, EC, soil nitrate, P, K, Mg, B, Mn, Fe, Cu and Zn in the regional unit of Kastoria and 883 field parcels were sampled for the scopes of this work. A characteristic finding was that potassium distribution in the area was structured and thus delineation zones were provided for differential potassium fertilization management. The interest and acceptance shown by the farmers for these pilot scale studies have been extremely positive, so that the Soil Science Institute of Thessaloniki went on further upgrading of the existing software in order to transform it into a dynamically evolving tool for the Internet. Further research is currently carried out to incorporate in the same software other factors, such as meteorological data, irrigation, plant protection, etc. The final aim is to provide a common online platform with a uniform, integrated user - friendly interface in order to facilitate the management of the agricultural land. [ABSTRACT FROM AUTHOR]