Mega farms typically have lower distribution & transport costs too. Hundreds of miles in a semi-trailer uses less gas per pound than 50 miles in a pick-up.

It's all background noise compared to the gas used to go from the grocery store to your home, though. If you drive further to get to the farmer's market to get local food...

In this case you aren't using any gas to get your food. That doesn't automatically make it less carbon-intensive, though. Producing the equipment, driving to get required inputs, it all adds up.

Yeah, different values lead to different conclusions.

If married to proper waste management, a chicken factory -- with chickens packed into tiny little boxes, egg production per calorie maximized, chickens discarded the moment their egg production drops, bred to mature as rapidly as possible -- is probably to most environmentally friendly way to produce eggs. You minimize land and energy use and human labor as well (humans have environmental costs, after all).

On the other hand, if you care about animals more than the environment, it's probably the worst possible way to raise chickens for egg production. Instead you want to maximize chicken happiness, you probably want small flocks free-ranging in a safe pasture-land, with chickens allowed to live out their dotage after the egg production has waned. This, of course, will require far more land and other inputs. You'll even have higher transportation costs, since you'll need to accumulate eggs over a larger area.

So would you rather have a chicken factory, a hundred acres of corn, and a thousand acres of wilderness, or 1100 acres of happy chicken pastures?

Which use large amounts of pesticide and waste if the crops don't look pretty they are scraped.

And in the UK allotments are a growing trend and of course popular with Guardian readers.

In the Uk there a duty for local government to provide land for alotments

Well yes, of course, but my point is that on mega farms you can use gigantic tractors which process a lot more crops than your tiny tractor or even what you can collect by hand. Just like transporting 50 people is a lot more efficient by bus, instead of having 50 cars. And mega farms don't have to use so much pesticide, and mega farms don't have to throw away ugly crops - this happens due to a stupid system around how we sell vegetables, nothing to do with farm efficiency.

Unfortunately mega farms have issues with getting rid of pesticides and fertilizers. To ensure the soil has enough nutrients for a desired crop, other crops often have to be planted as well, no? Mega farms really only do monocultures well right now AFAIK, and that's a problem.

The fertilizers are actually the solution to (most of) the monoculture problem. Other problems remains, such as erosion, biodiversity, etc. but not efficiency.

The increased use of fertilizer tends to lead to the forced increase of pesticide use IIRC (Source is in my library at home atm, sorry). It also leads to a decrease in nutrient value from the food as well due to the increased pesticide use.

From a pure efficiency note, pesticide and fertilizer use is the best solution in the short term. But I'm curious what the long term repercussions will be for both human and environmental health.

In the long term, we're all dead :)

But I agree with your point. Sadly, long term is too long to have enough information to make decisions ex ante.

And on your pesticide and nutrient value claims, I'd love to see data on that, sounds pretty dubious to be honest.