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Get the most for your irrigation buck
The drought of the last year has only added to concerns that water supplies in the nation's center -- namely those underground -- are dwindling. As a result, water resources for crop use are being limited, leaving farmers in states like Nebraska to raise their crops with less of a key resource.
Now, "deficit irrigation" is a part of many Plains farmers' lexicon. It's a system of irrigating crops that's based on lower overall water allottments driven by groundwater, well, and surface water moratoriums, and groundwater allocations.
That's got water experts in the affected states turning to efficiency. In one effort to stretch the necessary effects of irrigation, specialists at the University of Nebraska have designed a support system to determine how to most efficiently use the precious resource.
"Water Optimizer is a suite of optimization programs to predict the profit maximizing cropping strategy and corresponding amount of applied irrigation water when water supplies are limited," according to a university report. "These tools are Microsoft Excel spreadsheets that allow users to describe a field in terms of soil type, irrigation system options, well and pump characteristics and water supply. Irrigation options include center pivot or gravity irrigation systems, well or canal delivery, and systems powered by electricity, diesel, or natural gas."
After nailing down these variables, farmers can use the tool to glean the most profitable convergence of inputs cost and irrigation water amounts to best balance the costs and returns for growing a crop, whether alfalfa, corn, soybeans, sorghum, wheat, or others.
"The values we're looking at are what we call a net return. We're looking at what the increase of income is in making these irrigation decisions," says University of Nebraska Extension biological systems engineer Derrel Martin, a lead developer of the Water Optimizer project. "This is not profit. This is not land costs, taxes, and other fixed costs. We're simply looking at variable increases by irrigation. We're looking at how much value you get out of water."
There is a point at which the amount of water applied through irrigation reaches a diminishing return. Helping irrigate up to that point -- not beyond it -- in the context of maximizing profit potential, and keeping down variable costs is the ultimate goal of using a tool like Nebraska's Water Optimizer, Martin says.
"Think about marginal net return -- how much I increase income by the fact I'm putting on another unit of water. The other net return is the average net return for the water you have. Our goal is to maximize that average net return for that water you have. If I maximize the value of the water I have, that's the optimal decision point," he says. "We try to look at how water can be managed generally at the farm level to achieve the goals farmers have in order to be profitable and efficient. We also look at how that impacts that watershed. We're trying to take this dual view of managing water."
Martin recommends a few tips to stretch your irrigation water efficacy:
Consider irrigation timing. Applying water in cooler times of the day, namely in the evening, helps that water "go straight to the evapotranspiration line" where it's most readily used by targeted plants.
Balance irrigated and dryland acres. Here, it's important to answer a few key questions. "Say I have 10 inches of water, a 130-acre pivot, and I have 1,300 acre-inches of water. How am I going to spread that water over that pivot? Water the whole field, or water 100 acres of that field with 30 acres of rain-fed or dryland? Which one of those might be more economically attractive? Are they that much different?" Martin says.
Don't just push for higher yields alone. Consider all the costs involved in raising that crop and how much bang you can get out of your irrigation water buck. "We're looking at a net return," Martin says. "If you produce a little more yield, you have a higher cost."
Base decisions on irrigated systems, not dryland. When you're working to nail down your deficit irrigation strategy, do so based on an irrigated crop. "We need to know the yield we would get for irrigated acres and if we didn't irrigate. We need to estimate what that yield would be," Martin says. This includes variables like plant population, which is considerably higher in an irrigated system than on dryland acres.
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