Harvesting, planting, fertilizing, irrigating... are all uniform processes. Larger farms can invest in more machinery (and more expensive machinery), and build

Harvesting, planting, fertilizing, irrigating... are all uniform processes. Larger farms can invest in more machinery (and more expensive machinery), and build more infrastructure for themselves. They can do more sophisticated testing of their crops/animals, can monitor the things they need to monitor to a higher level, they can absorb loss-incurring seasons more readily. All of that is economies of scale.