The only sure way to have your yard NOT smell like dogs live there is to - not let them out there... sounds silly right? Well - if dogs use the same land for evacuating it will eventually smell like dogs - poo and pee there. Best thing to do is clean up solid waste everyday and keep the yard well watered. The upside is that if you smell it long enough it won't bother you anymore. You will get used to it. Personally I have 4 dogs using my yard and the only time I smell the distinct pungent odor of dog crap and pee is when it is freshly deposited. You could also consider some aromatic bushes and plants to adorn the yard. Using any chemicals, "natural" or "organic" additives would be my last choice.