Tillage and Compaction Impact On Soil Aggregate Associated Properties.

Soil aggregate associated properties are important to protect C and enhance soil quality. The evaluate the impact of tillage and crop rotation on soil aggregate associated properties, a randomized complete block design with three levels of compaction (0, 20 and 20 kPa) and two tillage systems (annual plowing, CT vs. no-till, NT) in 3 x 2 factorial arrangement was established. Composite soil samples were collected at 0-15 and 15-30 cm depth, processed, and analyzed for aggregate size distributions (<53, 53-125, 125-250, 250-500, 500-1000, 1000-2000, and >2000 um, respectively) macro- and microaggregate stability, mean weight diameter (MWD), geometric mean diameter (GMD), penetration resistance, and bulk density. Among the aggregate size fractions, the concentration and stock of 1000-2000 and >2000 um aggregates, macro- and microaggregate stability, MWD, GMD, and aggregate ratio (macro/micro) decreased significantly with an associated increase in <53 um aggregates by compaction. However, the cone penetration resistance and bulk density of soil increased by compaction. The impact was more pronounced at 20 kPa. The NT significantly increased the proportion of >2000 um size aggregates, macro- and microaggregate stability, MWD, and GMD with CT. However, there was an increase in cone penetration resistance and soil bulk density under NT compared with CT. Soil aggregate associated properties decreased significantly by soil depth. However, the interactive effects of soil depth with compaction or tillage on aggregate properties did not vary significantly. Likewise, the impact of compaction and tillage interaction on soil aggregate size distribution was non-significant. When plotted, the proportion of macroaggregates increased and microaggregates decreased with increasing mean weight diameter of aggregates. Results suggest that compaction consistently affected soil aggregate properties, irrespective of tillage systems. However, NT, to some extent, can improve the aggregate properties of soil.