Estimating crop yields based on available water in semi-arid regions has been made easier by the development of the MultiCalculator CD. This program was developed by agronomist David Nielsen with the ARS Central Great Plains Research Station in Akron, Colorado. It instantly shows the yields farmers can expect for 18 crops, including cereal grains, seed legumes, oilseeds and forages.
Already in use by several hundred farmers in the Central Great Plains, the MultiCalculator uses three simple Excel spreadsheets. First, farmers estimate how much available soil water their fields have. A table helps make that determination. In the next three steps, farmers choose a crop, a location, and guess the%age of average precipitation they expect during the growing season.
The water calculator also works for irrigation purposes. In five steps the farmer chooses a crop, then the target yield. It tells how much irrigation water will be needed to achieve the target yield. In addition, the calculator will also tell farmers how many gallons of irrigation water they will need for each gallon of ethanol produced from the corn they grow.