Question

does black soil undergo leaching

Answer 1

Leaching is defined as the washing away of the nutrients of soil by the rainwater .For black soil there are certain properties which prevents its leaching
these are 
1.Black soil has water retention capacity.It can retain water for long amount of time.
2.Black soil occurs in the region of high temperature and low rainfall which diminishes the risk of leaching.

Answer 2

Black soil does not get leached because it is clayed and sticky and moisture retentive / non-porous and therefore the rain cannot wash out the silicates.

Hope it helps you