How do you fix the soil if a plant has a defiencey? ... are there any organic ferts. that you can use...
The short answer is yes.
What you would use would depend on what nutrients are missing. The only certain way to tell what is missing is to have a soil test. Often the plant will seem to 'tell' you. Chlorosis is a good example, but there are different types of chlorosis from a lack of different nutrients. Without a soil test it might be difficult to know for certain. You might find this helpful.