Soil crusting is one of the most common aspects of physical degradation of agricultural soils, having negative effects on water infiltration, soil erosion, gaseous exchange and crop establishment. Aggregate stability is fundamental in order to maintain adequate soil structural conditions. Previous research has demonstrated dispersible clay, as evaluated by turbidimetry, being able to provide good indications about soil structural stability. This paper reports the results of a research aimed to verify the effectiveness of turbidimetry in evaluating crusting susceptibility of a silt loam soil after 2 years of organic amendment treatments (compost from lignocellulosic biomass and organic fraction of urban waste, and livestock manure). Treatments put into comparison were: 1) compost-derived organic matter (o.m.) addition at 40 Mg ha-1 rate (C40); 2) compost-derived o.m. addition at 10 Mg ha-1 rate (C10); 3) manure-derived o.m. addition at 10 Mg ha-1 rate (L); 4) control (T). Normalized turbidity values were used to calculate an aggregate stability index (It). Different treatments showed low It values (<0.4), due to the high crusting susceptibility of this type of soil. However, significantly higher It values (P<0.05) were observed for C40 and L treatments. Results also showed that dispersible clay values are affected by soil moisture content. Determination of crust macroporosity by image analysis on soil thin sections, did not evidence significant differences between treatments, both as total porosity and as pore size distribution; nevertheless, as a trend, porosity of the crust was higher in amended soil. Under the climatic and management conditions of the experimental area, the increase of soil organic matter content due to amendments was not able to significantly modify soil crusting susceptibility. Turbidimetry seems to be a valuable technique for the assessment of soil structure conditions due to its potential in evidencing differences induced by different management systems, to its easy use and to its analytical confidence. Key words: Soil crusting; Turbidimetry; Aggregate stability; Compost; Manure; Macroporosity.