Changes in surface structure (crusting) after application of sewage sludge and pig slurry to cultivated agricultural soils in Northern Italy

Abstract

The first results of a cooperative research project on changes in cultivated agricultural topsoils after treatment with sewage sludge and pig slurry are discussed for a silty clay soil (Vertic Xerochrept) and a sandy loam soil (Typic Psammaquent). Such changes are expressed in the surface structure, including crusts, of the soils and have a direct effect on their fertility. To measure these changes, special attention was paid to porosity characteristics; especially increases in porosity after application of organic manures to agricultural soils with crusting problems. Light microscopy, SEM-EDXRA (scanning electron microscopy — energy dispersive X-ray analysis) and Quantimet (electro-optical image analysis) were applied and allowed quantitation and visualisation of pores. Initial results clearly demonstrate that the porosity of the topsoil increased after treatment with urban refuse or pig slurry and that crusting decreased.