If you will allow them to forage in your acre, go for maximum diversity of local plants, and they will attract a diverse range of insects and other fauna, flora and funga, all of which your chickens will enjoy and benefit from, both for nutrition and exercise rummaging around in it, looking for fresh food on the move or actively growing. I would suggest that rather than aiming to meet most of their nutritional requirements, aim to grow plants that will bring what you can't buy in the shops - their natural insect foods - into your acre. Many 'weeds' are nutritious too, especially for the micronutrients they need, and chickens instinctively know what is and what isn't good eating.