The macrofarm will be able to afford innovations before each microfarm will. Suppose a tool is developed that harvests vegetables better than existing methods. Let's say it's less likely to crush the vegetable it's picking. It's new technology so it's expensive, but if you're operating at a large enough scale, it might be worth the cost.

In this case, each microfarm will produce less vegetables than a macrofarm of the same size.

I wasn't trying to be a jerk by linking to the Wikipedia article. It seemed to me like you weren't familiar with the concept.