Huge problem with stray cats please help?

Before anything please note that in the country I live there is no animal support agencies that do removals or anything. Even kids chase these cats and throw stones at them which I find it real disgusting. However I also have a problem. We have a small garden area on the front yard ofthe house and cats go there a lot to poop or pee and destroy the plants. Now the part that annoys me too much is when they go and mate over there. I dont know why but they love my front yard and Ive chased them a lot in the night while theyre screaming and wailing. The 1 time I even found urine stains and pieces of fur all over my front yard. And the plants destroyed. I want a pacific non hurting solution for these cats. Again the authorities cant help me and there arent any animal protection agencies to help me either and Ive actually contemplated shooting them with bb guns. I love animals but you guys havent seen the mess they do. Thanks guys.