What can of dark smook from the diesel engine?

there is a wrong balancing between air and diesel, if we smoke black we have more gas oil than air, but if we smoke white we have more aspirated air than diesel

clugged  air filter,the enjector nuzzles is low  presure.the timing is advance.

mbalance in the air to fuel ratio - too much fuel to not enough air.

Most common causes of black smoke are faulty injectors, a faulty injector pump, a bad air filter (causing not enough oxygen to be supplied), a bad EGR valve (causing the valves to clog) or even a bad turbocharger. Some of these are easy fixes.

Diesel fuel properties is in contain more sulfur dioxide .so diesel engine making more black smoke.