Assertion: As a result of intensive irrigation, the traditional crops sown in Rajasthan- gram, bajra and jowar have been replaced by wheat, cotton, groundnut and rice.
Reasoning: This has also caused waterlogging and soil salinity, and thus, in the long run, it hampers the sustainability of agriculture.

Both Assertion (A) and reasoning (R) are correct, but R is not the correct explanation of A.

The traditional crops sown in the area, gram, bajra and jowar have been replaced by wheat, cotton, groundnut and rice. This is the result of intensive irrigation. This intensive irrigation, no doubt, initially has led to a tremendous increase in agricultural and livestock productivity. This has also caused waterlogging and soil salinity, and thus, in the long run, it hampers the sustainability of agriculture.