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Fig. 2. Total C concentrations of macroaggregate-protected microaggregate-associated fractions in 0- to 5- and 5- to 20-cm soil layers under no-tillage (NT) and conventional tillage (CT) management. (2:1 = temperate soil from Sidney [NE] dominated by 2:1 clay minerals; mixed = moderately weathered soil from Lexington [KY] dominated by mixed [2:1 and 1:1] clay mineralogy and oxides; 1:1 = highly weathered soil from Passo Fundo [Brazil] dominated by 1:1 clay minerals and oxides; mineral-mM-C = C associated with the mineral fraction of microaggregates; intra-mM-POM-C = C associated with particulate organic matter protected inside microaggregates; inter-mM-POM-C = C associated with particulate organic matter located outside microaggregates). Values followed by a different lowercase letter within a tillage treatment, C fraction and soil layer are significantly different among soils. Values followed by * within a soil, C fraction and soil layer are significantly different between tillage treatments. Statistical significance was determined at P < 0.05. (*) indicates P < 0.06.
