Western Nebraska Farmers Likely To Have Irrigation Water Shortages

UNL specialists suggest using Water Optimizer computer model and soil moisture sensors.

Published on: Jun 14, 2013

The area is still in a severe to exceptional drought in the Panhandle and parts of western and southwestern Nebraska. The predicted surface-water irrigation supply may be in the 50- to 60-day range. Groundwater users continue to be under allocations and, in a few cases, may have exceeded their pumping amounts.

With all of this uncertainty, what are producers to do? A number of tools are available to help you manage water resources, according to Gary Stone, Extension educator at the UNL Panhandle Research and Extension Center in Scottsbluff.

One is Water Optimizer. It is a Microsoft Excel-based program that can estimate a profit-maximizing cropping mix based on a limited amount of water. The Water

Watermark soil moisture sensors help farmers decide when to irrigate.
Watermark soil moisture sensors help farmers decide when to irrigate.

Optimizer program has four "models" to calculate a cropping mix: single-field, single-year; single-year, multi-field; multi-year, multi-field; and an independent budget calculator to estimate production costs. Each model seeks to maximize the average net return based on the producer's estimated water supply and crop production preferences.

This tool has several options that allow users to customize the model to reflect their farm, according to Stone. Water Optimizer asks for information such as soil type, well/pump specifications, preferred nitrogen levels, production costs, and anticipated

market price for commodities. Through these selections, producers can compare a

variety of commodity mixes. "We suggest starting with the single-field, single-year model, as it is the simplest form of the program," he adds.

Be sure to download the Operator Manual for the model you select. For additional help with crop budgets or Water Optimizer use, contact Jessica Johnson or Gary Stone at 308-632-1230.

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Producers who have already selected a cropping mix should consider no-till or limited tillage operations as part of their water management this season. Each tillage pass could potentially remove 0.5 to 0.75 inch of moisture from the profile.

"These management practices can leave more water in the soil for to produce a crop. In some instances a tillage operation will be necessary for seedbed preparation or weed management. Consider strip-tillage for planting operations in order to leave the crop residue in place," Stone points out.

For producers who have limited amounts of water, another tool to consider is deficit irrigation, a strategy where the producer uses stored soil moisture and in-season precipitation to get the crop established and growing through vegetative stages. The majority of the irrigation water is then applied during the reproductive and grain-fill stages of the crop.

Other water management tools are soil water sensors and ETgages, Stone says. Soil water sensors are placed in the field of the growing crop at different depths relative to the root zone of the crop. The producer takes readings from the sensors every two to four days to determine how much soil moisture is available for the crop and how much irrigation is needed to fill the soil profile.

ETgages, also called atmometers, are instruments that simulate the evapotranspiration of an alfalfa crop. Readings from ETgages are taken weekly and used to estimate the crop water use for that week based on the given crop and crop growth stage. The producer can then know how much irrigation water to apply to each field to replace the water used by the crop.