Soil puddlability, a measure of susceptibility of soil to puddling, affects regeneration of soil structure
during the rice growth period, but the intrinsic controlling factors are unclear. It was hypothesized that
rice straw incorporation and tillage depth influence soil puddlability and soil mechanical and hydraulic
properties during the rice growth period as they influence soil organic carbon (SOC) in the plough layer.
Using a three-year experiment, the objectives of this study were (1) to determine the effects of rice straw
incorporation and tillage depth on root growth traits, sinkage resistance after puddling, and tensile
strength, shrinkage capacity, water retention curve and penetration resistance during the rice growth
period, and (2) to determine whether mechanical properties from puddling tillage, through the rice
growth period, to harvest are correlated with SOC concentration. Rice straw was incorporated partially
(C1) and fully (C2) to different depths of plough layer by shallow tillage (ST) and deep tillage (DT).
Compared with no rice straw incorporation (C0), rice straw incorporation decreased the sinkage
resistance after puddling (C2