His Harvest Is War

Lucas Ashton, a PhD, time-travels to Qian Dynasty's Yellow Sand Pass as a soldier. Amidst a drought, Captain Zane Shaw embezzles water, and Nomads poison the well, endangering soldiers. Lucas cultivates 'miracle melons', quenching thirst and using rinds to defeat Nomads' cavalry. He tricks a corrupt official with inferior seeds, leading to conviction. Lucas cultivates sweet potatoes, ending famine, proving seeds are true weapons of state.