RATES OF CHANGE IN SOIL STRUCTURAL STABILITY UNDER FORAGES AND CORN

Data on rates of change in soil structural stability under different cropping systems are scarce. Field measurements of changes in dispersible clay (DC) and wet aggregate stability (WAS) were made during 3 yr in six forage treatments and conventional and zero-till corn. The study was conducted on a silt loam soil (fine-silty, mixed, mesic Typic Haplaquept intergrading to fine-silty, mixed, mesic Typic Eutrochrept) near Elora, ON. Canada. No increases in structural stability occurred during the 3-yr time period within the corn treatments. In contrast, all of the forage treatments resulted in highly significant rates of structural improvement. Forages may promote structural improvement through their influence on the amplitude of wetting and drying cycles. In addition, large increases in stability were observed over the intervening winter months, suggesting a freeze-thaw effect. -from Authors