Table 2.

Percentages of the largest aggregates (>2 mm) and mean weight diameter (MWD in mm) indexes generated following each stability test performed on the incubated soil aggregates from Organic and Conventional cropping systems.

		Test 1 Fast-wetting		Test 2 Slow-wetting		Test 3 Mechanical breakdown
		[>2 mm]	MWD	[>2 mm]	MWD	[>2 mm]	MWD
Organic soil aggregates	Ref	2.5 ± 0.7 b	0.38 ± 0.03 a	5.4 ± 0.8 b	0.77 ± 0.04 b	3.9 ± 0.7 a	0.64 ± 0.03 ab
	Dark	1.4 ± 0.3 a	0.31 ± 0.02 a	2.3 ± 0.7 a	0.68 ± 0.03 b	2.2 ± 0.2 a	0.56 ± 0.04 ab
	Light	14.9 ± 3.0 b	0.75 ± 0.09 bc	21.5 ± 4.8 d	1.24 ± 0.11 cd	18.6 ± 3.3 c	1.02 ± 0.09 de
	Light + IPU	9.6 ± 2.9 b	0.59 ± 0.08 b	12.5 ± 2.4 c	1.03 ± 0.09 c	10.9 ± 2.0 b	0.82 ± 0.07 cd
Conventional soil aggregates	Ref	1.9 ± 0.5 a	0.28 ± 0.01 a	3.1 ± 0.5 a	0.57 ± 0.02 ab	3.7 ± 0.5 a	0.53 ± 0.03 ab
	Dark	1.0 ± 0.3 a	0.22 ± 0.02 a	1.2 ± 0.4 a	0.48 ± 0.03 a	1.9 ± 0.5 a	0.49 ± 0.03 a
	Light	21.7 ± 1.5 c	0.92 ± 0.06 c	32.5 ± 4.1 e	1.40 ± 0.11 d	28.3 ± 4.0 d	1.25 ± 0.11 e
	Light + IPU	10.1 ± 3.1 b	0.58 ± 0.11 b	16.9 ± 4.6 cd	0.99 ± 0.13 c	11.0 ± 4.1 bc	0.73 ± 0.12 bc
Two-way ANOVA statistics	Treatment	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
	Crop_syst	0.036	0.738	0.004	0.040	0.582	0.682
	interaction	0.007	0.007	0.002	0.001	0.014	0.007

Reference soil samples (Ref) are the initial soil aggregates at day 0, before incubation). Dark, Light and Light + IPU are soil aggregates at the end (day 50) of the different incubation conditions (see Table 1 for acronym description). The values are the means with the standard deviation (n = 3). For each disaggregation test, different letters indicated significant differences between incubation conditions (two-way ANOVA, with treatment and cropping systems as factors, followed by Tukey’s post hoc test, p < 0.05). See Figure 4 for the overall class size distributions.