What is worth the space, water and effort?

Most of my corn has been destroyed by bugs and worms. It takes a lot of water to grow corn. You might get three or four ears and that's the end of it. You get a lot of mulchable bio-material, but if you're going to grow something with this much waste foliage, I think it would be nice to know how much fruit or produce each type of plant produces at harvest.

There's a basic assumption to be stated: none of the crops will be treated with pesticides, at least not chemical formulations commercially available. Can ducks be used to treat infestations of snails and grasshoppers? This needs to be shown in practice for each individual crop. There is always overhead with each type of livestock:

• Feed that is needed.
• Daytime environment
  • Shade
  • Water
  • Dirt for dirt baths
  • Protection from predators
  • Temperature control
• Nighttime environment
  • Protection from predators
  • Temperature control
• Seasonal changes in diet as required
• Veterinary overhead.

Here's a breakdown of what needs to be calculated:

• Optimum spacing per plant.
• Water needed to create a successful harvest per plant and per surface area based on optimum spacing. 
• Fertilizer needed (soil health required along with mulches and other soil amendments).
• Fruit produced per plant per surface area.
• Harvest method utilized to get a harvest and level of effort.
• Effort and infrastructure needed to process harvest.
• Effort and infrastructure needed to store harvest.
• Benefits of the harvest (a subjective number, needs to be broken down more).

We want to get a number that is a distillation of all these factors. Grains take a lot of space and require some kind of mechanism to harvest effectively. It might make sense to still grow grains if they are principal crops for livestock. However that remains to be calculated.