Drug Screening for a non-drug related offense

Here is my question: I pled guilty to an arizona class-6 felony theft of means and was sentenced to probation. I am a pothead and have been for years as a marijuana advocate. Now that I am on probation, They are requiring random drug screening. I have tried to quit for them, but have been unsuccessful., i have had both many positive and negative test results throughout the entire proceedings (ie last may) I feel this is unfair considering my crime had nothing to do with drugs. Is there any way I can make them stop testing me other than being clean until the end of my probation ???

Honestly probably not. I live in Florida, and its actually part of your probation guidelines to not do any narcotics/drugs or drink alcohol to excess. It has nothing to do with what crime you have, its the fact that your on probation and its just another element to it, just like you cant change jobs or whatever without informing them. Im in almost the same spot, and I feel for you. Best advice, and worse advise, is to quit. No drug is worth jail, or your future. And think of all the green you can buy when you get off of probation and have money to blow.