I stumbled across some interesting information on extension.org about the water needs of corn.
A high-yielding corn crop of 200 bushels per acre requires about 22 inches of water during the season to complete its life cycle. About 15 to 16 inches of water is enough to produce a low yield of maybe 100 bushels of corn.
A corn crop uses around two inches of water per week from the V12 growth stage to R3 or milk stage of development. About 10 of the 22 inches of water are needed over the two weeks before corn silking until two weeks after silking.
One inch of water per acre is about 27,000 gallons per acre, so one acre of corn uses about 594,000 (22 times 27,000) gallons of water in a season. If the yield is 200 bushels per acre, that means that a good corn crop uses almost 3,000 gallons of water for each bushel of yield.
Looking at it from another angle, on average, each inch of water produces about nine bushels of corn per acre (200 bushels divided by 22 inches of water). So what is an inch of water worth? At the current cash price of about $3.50 a bushel, an inch of water is conservatively worth about $31.50 an acre. If you have 500 acres of corn, the value of an inch of water on average is about $15,750!
Of course, we know that rain or irrigation water between tasseling and silking is critical to achieving high yields, so that late season inch of water is probably more valuable than an inch applied earlier in the season.
I have seen estimates that the out-of-pocket direct costs to apply an inch of irrigated water can vary from $2 to $8 per acre, depending on the source of water, type of power and the effectiveness of the system. In addition, most growers will have some added expense associated with higher production goals, such as fertilizer, seed and pesticides. Still, after these expenses are subtracted, there is usually plenty of wiggle room to cover the fixed costs of owning the irrigation equipment.
Those of you who irrigate know it can be a muddy, uncomfortable job, with middle-of-the-night emergencies and potential risks associated with electricity. Maybe there can be a little comfort in knowing some of these figures are working in your favor.
Jeff Burbrink is an extension educator in agriculture and natural resources. Write to him at 17746 E. C.R. 34, Goshen, IN 46528; call 533-0554; or fax 533-0254.