Mixed farming is a type of farming in which you grow two or more than two types of crops together.Say, along with tomatoes you are growing a dal too,on the same land. Shifting cultivation, on the other hand,refers to the technique of cultivation in which you use a piece of land to grow crops and then, once you have harvested the crop,you leave that piece of land and find some other piece of land to grow some other crop.And this keeps going and going and going. Hope,it's what you asked.