SUMMARYSamples from six ash soils were chosen with a range of Fe and C contents. Stabilities over the aggregate size‐range from2 mm were measured by selectively removing aggregating agents from fresh soil samples. Wet‐sieving was also carried out on both field‐moist and air‐dried 3.4–2.0 mm macroaggregates.Macroaggregate stabilities were closely related to C contents and were also enhanced by high contents of allophane and/or Feox. High water contents decreased the stability of field‐moist macroaggregates.Clay‐sized material was most readily dispersed with Na resin after pretreatment with hydrogen peroxide; removing the latter alone was usually ineffective in d