This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development is uncertain. The modern form combines 耒 (plow) and 少 (few/little), but the original semantic and phonetic roles are unclear.
A plow 耒 beside 少 (few/little) could suggest a tool for light tilling or a rare farming implement, but the meaning is uncertain.
For ソウ, imagine sowing seeds with a plow: sow -> ソウ, and the plow 耒 tills the soil.