Why were most of the early Chinese inventions related to agriculture?

Chinese inventions made life easier for farmers and made more grain available for trade. For example, a better plow and farm tools helped increase crop production. The invention of a collar harness allowed horses to pull heavy loads. The wheelbarrow made it easier for farmers to move heavy loads by hand. Watermills used river power to grind grain. In a land of mostly farmers, these inventions were valuable.