Table 4. Soil variable means and stratification for soils collected in Spring 2009 and 2010 from 0–10 cm and 10–20 cm depths a,b,c,d,e.
| Depth | System | SOC | POM-C | PMN | FDA | BD | WFPS | WSA | RLD | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| (Mg ha-1) | (mg C cm-3) | (μg cm-3) | (μg cm-3 min-1) | (g cm-3) | (%) | (%) | (cm cm-3) | ||||||||||||
| 0-20cm | 2 (n = 32) | 58.98 (6.64) | a | 1.90 (1.14) | b | 31.24 (17.31) | b* | 0.96 (0.50) | a | 1.13 (0.11) | a | 49.25 (7.56) | a | 55.68 (7.50) | a | 2.72 (0.82) | a | ||
| 3 (n = 48) | 56.05 (7.72) | a | 2.31 (0.66) | a | 40.44 (13.71) | a | 0.96 (0.21) | a | 1.09 (0.13) | a | 46.50 (10.35) | ab | 52.41 (12.13) | a | 2.90 (1.01) | ab | |||
| 4 (n = 64) | 58.40 (7.69) | a | 2.19 (0.66) | a | 37.26 (14.01) | ab* | 0.92 (0.26) | a | 1.11 (0.12) | a | 45.48 (9.97) | b | 55.73 (7.12) | a | 3.41 (0.93) | b | |||
| 0–10 cm | 2 (n = 16) | 28.34 (3.42) | a | 2.91 (0.61) | a* | 44.46 (12.63) | a | 1.29 (0.44) | a | 1.05 (0.10) | a | 43.92 (6.67) | a | 55.56 (6.31) | a | 3.35 (0.48) | a | ||
| 3 (n = 24) | 26.35 (3.93) | a | 2.50 (0.58) | a | 42.05 (14.42) | a | 1.00 (0.22) | b | 1.00 (0.12) | a | 37.83 (5.13) | b | 46.66 (12.15) | a | 3.23 (1.07) | a | |||
| 4 (n = 32) | 27.00 (4.62) | a | 2.35 (0.67) | a* | 39.62 (14.67) | a | 0.96 (0.26) | b | 1.04 (0.09) | a | 37.80 (6.57) | b | 52.32 (7.23) | a | 3.80 (0.96) | a | |||
| Mean (n = 72) | 27.23 (4.16) | B | 2.59 (0.65) | A | 42.04 (14.01) | A | 1.08 (0.32) | A | 1.03 (0.10) | B | 39.85 (6.60) | B | 51.52 (9.42) | B | 3.46 (0.92) | A | |||
| 10–20 cm | 2 (n = 16) | 30.97 (3.57) | a | 0.89 (0.41) | b | 18.02 (12.48) | b | 0.62 (0.34) | b | 1.22 (0.07) | a | 54.59 (3.78) | a | 55.81 (8.32) | a | 2.09 (0.27) | b | ||
| 3 (n = 24) | 29.87 (4.80) | a | 2.12 (0.72) | a | 38.82 (13.15) | a | 0.92 (0.21) | a | 1.17 (0.09) | a | 55.17 (5.72) | a | 58.16 (9.38) | a | 2.57 (0.84) | ab | |||
| 4 (n = 32) | 31.60 (4.54) | a | 2.03 (0.62) | a | 34.90 (13.13) | a | 0.88 (0.25) | a | 1.17 (0.11) | a | 53.16 (6.23) | a | 59.14 (6.69) | a | 3.03 (0.72) | a | |||
| mean (n = 72) | 30.81 (4.36) | A | 1.68 (0.79) | B | 30.58 (14.93) | B | 0.81 (0.28) | B | 1.18 (0.10) | A | 54.30 (5.63) | A | 57.70 (7.94) | A | 2.56 (0.78) | B | |||
| Stratification ratio | |||||||||||||||||||
| 2 (n = 16) | 0.87 (0.09) | a | 3.34 (1.96) | a | 2.40 (1.29) | a | 1.85 (1.09) | a | 0.90 (0.10) | a | 0.83 (0.12) | a | 0.90 (0.08) | a* | 1.71 (0.33) | a | |||
| 3 (n = 24) | 0.86 (0.12) | a | 1.09 (2.19) | b | 1.00 (0.45) | b | 1.06 (0.26) | b | 0.88 (0.08) | a | 0.69 (0.08) | b | 0.73 (0.18) | a* | 1.40 (0.67) | ab | |||
| 4 (n = 32) | 0.86 (0.14) | a | 1.18 (0.46) | b | 1.14 (0.49) | b | 1.08 (0.29) | b | 0.90 (0.11) | a | 0.72 (0.11) | b | 0.86 (0.08) | a | 1.30 (0.32) | b | |||
SOC, Soil organic C; POM-C, particulate organic matter C; PMN, potentially mineralizable N; FDA, enzymatic activity; BD, bulk density; WFPS, water-filled pore space; WSA, percentage of water-stable macro-aggregates; RLD, Root length diameter. All analyses run with clay as a covariate. Overall system differences values are linear combinations of the LSMEANS of all crops within each rotation, over both dates and both depths. Rotation by depth values are linear combinations of the LSMEANS of all crops within each rotation averaged over both dates but separated by depth. System differences are obtained by contrast statements comparing means of all crops within the rotations.
a With the exception of SOC, which was measured on samples collected in Fall of 2009, and RLD, which was measured on soils collected in summer 2009
b Standard deviations are in parenthesis.
c Different lowercase letters represent significant differences between the systems at p<0.05 or significant differences between rotations at each depth at p<0.05, using a stepdown bonferroni adjustment for estimates.
d Asterisks * represent differences between systems in a specified crop that were significant at p<0.10.
e Different uppercase letters represent differences that were significant at p<0.05 between values for each crop averaged over all rotations and both depths.