Sometimes a nose will become dry and crusty due to dry air that you're breathing in especially during the winter months.
You can try putting some coconut oil inside your nose to help keep the inside of your nose and nasal passages moist and the coconut oil will also soothe your nose.
Noses can also become dry and crusty because of some medical conditions such as Sjogren's syndrome and other conditions such as infections, nutritional deficiencies, and chronic atrophic rhinitis, which is nasal inflammation caused by having too little nasal mucus in your nose.
If your nose is constantly dry and crusty and the coconut oil doesn't clear it up then it would be good to see a doctor to determine if it's caused by a medical condition or infection and not just by dry air.