5. Conclusions
Rice strawincorporation increased the puddlability as indicated
by the decreased sinkage resistance after puddling and promoted
the regeneration of soil structure during the rice growth period as
indicated by the increased tensile strength and porosities after
repeated drying. Shallow tillage increased the penetration resistance
more than deep tillage due to shallower depth of the plough
layer and may have negative effect on root growth when no
sufficient rice strawwas incorporated. Soil organic C influences the
stability of porous system upon swelling and shrinkage and then
the mechanical properties after puddling and during the rice
growth period. The results suggested that sufficient rice straw
should be incorporated to the plough layer to maintain SOC and
then to improve soil puddlability and the recovery of pore
structure with wetting and drying cycles.