Most people, who have heard of hydroponics, think of fancy high-tech systems costing thousands of dollars and requiring lots of energy and automation to run. While that certainly may be the norm, any system that does not rely on soil but does rely on periodic flooding technically is a hydroponic system.
In this video, Jack Spirko demonstrates a very rudimentary hydroponic system consisting of a number of stacked 5-gallon buckets with holes drilled in the bottom of all but one. He uses it to sprout grains to feed to his poultry. This is useful because grains contain a number of factors that lessen their nutritional value, but these are reduced by fermentation or germination. In addition, a number of vitamins, most notably vitamin C, are generated in the sprouting process — not that poultry needs vitamin C, but it is useful for humans on a survival diet.
His article detailing the system is at http://brinkoffreedom.net/homesteading/dead-simple-fodder-system/