hello i'd  love to know when man start the practice of agriculture
Agriculture is the cultivation and breeding of animals, plants and fungi for food, fiber, biofuel, medicinal plants and other products
ok this is getting interesting
More so, Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food 
Does Agriculture have branches?
agronomy, plant breeding, agrochemicals such as pesticides and fertilizers, and technological developments are some branches