Tillage and Compaction Effect On Soil Aggregate Associated Carbon and Nitrogen.

The effect of compaction and tillage on soil aggregate size fractions, and aggregate associated carbon (C) and nitrogen (N) content under continuous corn-soybean rotation was evaluated. The experiment was established on Hoytville clay loam in randomized complete block design with 3 compaction levels (Control, 10 and 20 tons) and 2 tillage systems (no-till vs. annual tillage) at the Northwest Agricultural Experiment Station, Wood County, northern Ohio. Composite soil samples at 0-15 and 15-30 cm depth were randomly collected; 2-mm sieved; and analyzed for penetration resistance, bulk density (rb), and total C and N content. Among the soil aggregate size fractions, the concentration and stock of >2 mm size aggregates decreased by increasing soil compaction. Soil under no-till (NT) had higher >2 mm size aggregagtes. The macroaggregate stability, mean weight diameter (MWD), and geometric mean diameter (GMD) have decreased with increasing soil compaction. However, NT increased the macroaggregate stability, MWD, and GMD over CT.