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Fig. 2. Tillage effects on the distribution of soil in four aggregate size classes at 0- to 7- and 7- to 20-cm soil depth. Numbers along the x axis correspond with aggregate size: 2000 = 2000–8000 µm; 250 = 250–2000 µm; 53 = 53–250 µm; and <53 = <53 µm. The May 2003 samples were taken before the second cultivation. Treatment means are shown ± standard error (n = 4). * Indicates statistically significant (P < 0.05) differences between control and tilled treatments within a single sampling date; 
indicates significant differences between depths within a treatment and sampling date. Size classes within a sampling date and treatment with different letters are significantly different.
