2004

2005

2006

Subsurface cultivator steam (control)

0.44

1.56

0.43

0.81

Dump steam

0.43

1.33

0.38

0.71

Combined steam

0.39

1.61

0.31

0.77

Legummed fallow

0.35

1.52

0.32

0.73

Corn

0.31

1.46

0.29

0.68

Wheat

0.29

1.33

0.08

0.56

Sty

0.30

1.40

0.07

0.59

HCP05

0.11

0.17

0.11

0.14