The tool shown is a type of sickle, not a scythe. All sickles are used
in one hand - when harvesting grain, the user grasps a handful of stems
and chops them off with the sickle. It is much slower and more
strenuous (think lower back pain) than reaping with a scythe, though it
wastes nearly none of the precious grain. If harvesting rice in a wet
paddy, the scythe may be impractical because the grain and straw will
be on the ground in a windrow when cut.
A scythe always has a longer handle, with one or two short handgrips,
and is used with both hands.