SOIL CHEMICAL-PROPERTIES DURING SUCCESSION FROM ABANDONED CROPLAND TO NATIVE RANGE

The purpose was to assess soil transformations under abandoned cropland reverting back to native range in the Brown and Black Chernozemic soil zones of southern Alberta, Canada. Total extractable organic acids and phenols were generally greater in abandoned cropland soils than in adjacent native range soils. Ammonium N increased with succession but nitrate N decreased. A change in quality of soil organic matter towards a more complex and stable form occurred with time. Regression analyses of the Brown Chernozemic soils abandoned at various dates are interpreted to show that response of chemical characteristics was essentially linear with time. In order to form the type of organic matter that occurs in these 2 soil types, recovery of abandoned cropland may take at least 150 years in the former and 75 years in the latter under moderate grazing. -from Authors