Soil samples were taken out from plots of an experiment with manure, lime and mineral fertilizers applied to corn plants. The aggregates were separated into the following size classes: 7.0 to 4.0 mm, 4.0 to 2.0 mm, 2.0 to 1.0 mm, 1.0 to 0.5 mm, 0.5 to 0.105 mm, and less than 0.105 mm. Mechanical analyses were made, as well as determinations of pH and of C and total N and Ca + +, Mg + + and K + exchangeable and capacity of cathion exchange. All of the samples showed similar behaviors; the percentage of clay decreased in a progressive form from larger sizes of aggregates to the size class 1.0 to 0.5 mm, increasing afterwards until reaching the maximum value in the size class "less than 0.105 mm". Finally, the authors studied the influence of different types of fertilizers upon the characteristics of aggregates.