INFLUENCE OF CORN CROPPING AND OF MEADOW ON AGGREGATION AND ON ORGANIC-MATTER ASSOCIATED WITH PARTICLE-SIZE FRACTIONS OF 7 SOILS

Water-stable aggregation and organic matter associated with particle-size fractions were compared for seven pairs of soils that were either under meadow or continuous corn cropping for more than 5 yr. Soils that have remained under meadow contained 25 and 29% more carbon and nitrogen than those under continuous corn. Carbon contents of the sand- and silt-size fractions were also 61 and 15% higher, respectively, under meadow than under continuous corn. The cropping system had no significant effect on the carbon and nitrogen contents of the clay-size fractions. The amount of water-stable aggregates (>1 mm) was on average 34% higher in soils under meadow than in soils under corn cropping. -from English summary