Factors affecting aggregate stability and water dispersible clay of recently cultivated semiarid soils of Argentina

The aggregate stability and water dispersible clay of 18 surface soils rang ing from 0 to 32 years of soybean monoculture after clearance from a farm o f approximately 5000 ha in the semiarid Chacopampeana plain (Argentina) was studied. Both stability variables were correlated with soil properties inf luencing aggregate stability. Aggregate stability and water dispersible cla y were correlated with the length of agricultural use, organic carbon (OC) content, cation exchange capacity, free Al oxides and hydroxides to clay ra tio, exchangeable Ca2+ content and exchangeable Na+ percentage. A synergist ic effect was observed between OC and free Al oxides and hydroxides. Clay c ontent and electrolyte concentration of the saturation extract had no effec t on aggregate stability and on water dispersible clay. From the results of this study it was concluded that the changing factors along agricultural u se that affect water aggregate stability and water dispersible clay were ex changeable Ca2+ content and OC content.