Table 5: Paired comparisons using MP as baseline to determine no-till (NT) and chisel plow (CP) effects after 24 years of tillage treatments on the volumetric SOC content change of the Grantsburg soil.

Tillage treatmentDepth
cm
June 2012Comparison method NT or CP versus MP 24 yr total SOC retained above MP Paired comparison annual SOC retention rate above MP the comparison baseline
Mg C ha−1 layer−1

0–1526.3a**+7.5+0.31
NT15–7524.6a+0.3+0.01
0–75 (all)50.9a+7.8+0.32

0–1520.3b**+1.5+0.06
CP15–7521.7a−2.6−0.11
0–75 (all)42.0b−1.1−0.05

0–1518.8b
MP15–7524.3a
0–75 (all)43.1b

**Means six replications with the same letter and in the same year and depth with a different tillage treatment are not significantly different at .