Can I do the Shennong stream tour from Yichang and back on the same day? Thanks.

Well, if you take long-distance bus, one day is not enough. Buses usually take around 6 hours on the way. So you don't have time to tour around.
But don't worry. You can take train from YC East Railway Station, and arrive at Badong Train Station directly. The train schedules are 04:42, 07:50, 08:08, 10:39, 10:53, 12:00, 12:22 and 16:56. This way just spends around an hour.

The return train schedules are 09:03, 09:19, 11:33, 16:08, 16:25, 17:00, 20:33, 20:47 and 21:10.