Cover crop by tillage treatment

Depth

September 2000 SOC stock

June 2012 SOC stock

12-year tillage effect on SOC total change by treatment using 2000 baseline

12-year tillage effect on SOC total change by treatment using 2000 baseline2

12-year tillage effect on SOC rate of change

cm

Mg C/ha/layer

Mg C/ha/layer

Mg C/ha/layer

% change

Mg C/ha/layer/yr

No-tillage (NT)

Yes

0 - 15

26.8a^**

31.7a^**

5

19

0.42

15 - 75

20.2a

29.5a

9.3

46

0.78

0 - 75 (all)

47.0a

61.1a

14.3

30

1.21

No

0 - 15

26.8a^**

26.3b^**

−0.5

-2

−0.04

15 - 75

20.2a

24.6b

4.4

22

0.36

0 - 75 (all)

47.0a

50.9b

3.9

8

0.33

C grain from

0 - 15

5.4

0.46

cover crop

15 - 75

4.9

0.32

0 - 75 (all)

10.2

0.88

Chisel plow (CP)

Yes

0 - 15

25.0a

23.7a

−1.3

−5

−0.11

15 - 75

18.7a

24.2a

5.5

29

0.46

0 - 75 (all)

43.7a

47.9a

4.2

10

0.35

No

0 - 15

25.0a

20.3b

−4.7

−19

−0.39

15 - 75

18.7a

21.7b

3

16

0.25

0 -75 (all)

43.7a

42.0b

−1.7

−4

−0.14

C grain from

0 - 15

3.4

0.28

cover crop

15 - 75

2.5

0.21

0 - 75 (all)

5.9

0.49

Moldboard plow (MP)

Yes

0 - 15

19.9a

18.9a

−1

−5

−0.08

15 - 75

17.8a

25.4a

7.6

36

0.63

0 - 75 (all)

37.7a

44.3a

6.6

14

0.55

No

0 - 15

19.9a

18.9a

−0.09

15 - 75

17.8a

24.3a

0.54

0 - 75 (all)

37.7a

43.2a

0.45

C grain from

0 - 15

0

0.01

cover crop

15 - 75

1.1

0.09

0 - 75 (all)

1.2

0.1