May 18, 2007

The Nebraska Agricultural Water Management Demonstration Network

Figure 1. Modified Atmometer (ETgage®)

The Nebraska Agricultural Water Management Demonstration Network (NAWMDN) was established to increase adoption of newer technologies to conserve water and energy resources associated with irrigated crop production. It established a system for testing improved technologies for measuring crop water use and soil water status and created a network of growers, crop consultants, UNL extension, NRDs, NRCS, and others to enable the adoption of water and energy conservation practices. The network was established in early 2005 in partnership between UNL Extension and the Upper Big Blue Natural Resources District (UBBNRD). The Natural Resources Conservation Service (NRCS) became a valuable partner in 2006.

The type of technology used to monitor crop water use and soil water status is critical to the project's success. Tools need to be accurate but easy to understand and operate, and data gathered from these tools should not be difficult to interpret. Atmometers (ETgage, Figure 1) were used to monitor crop water use in the network. An atmometer (ETgage) is one of the alternative tools that can be used to mimic evapotranspiration (ET) rates. This information along with crop growth stage can be used for irrigation management. The simplicity of the use and interpretation of the ETgage data, as well as its economic feasibility, makes it easy for farmers to monitor their own crop water use for effective irrigation management. In this project ETgages are used to estimate crop water use, and Watermark sensors are used to measure soil moisture to determine irrigation timing and amount. For more information on the atmometers or ETgage see the UNL Extension NebGuide, Modified Atmometers (ETgages) for Irrigation Management (G1579). The ETgages are usually placed at the edge of the irrigated field or service road for easy access. Watermark Granular Matrix sensors (Figure 2) are simple, economical, durable, and accurate tools to monitor soil water status. Water conditions inside the Watermark sensor change with corresponding variations in water conditions in the surrounding soil. These changes within the sensor are reflected by differences in electrical resistance between two electrodes imbedded in the sensor. Resistance between the electrodes decreases with increasing soil water. The new transmission material (sand) used in the sensor was designed to respond more quickly to soil wetting and drying cycles. The Watermark sensor does not dissolve in the soil over time, which generally occurs with a gypsum block. The sensor has been proven to be accurate and provide good indication of soil matric potential in a variety of soil types. The matric potential can be converted to soil water content and available soil water per foot of soil layer can be determined. For more information on the Watermark sensors see the UNL Extension Circular, Watermark Granular Matrix Sensor to Measure Soil Matric Potential for Irrigation Management ( EC783).

Initial Progress of the NAWMDN

One ETgage and four Watermark sensors were installed (every 12 inches up to 4 feet deep) in the soil profile in each demonstration field. In 2005, there were 18 demonstration sites and some of the ETgage and Watermark sensors were read by the growers and some were read weekly by the Network core members. In 2006, the second year of the project, there were more than 50 demonstration sites and we expect to have more than 120 in 2007. Each year, the Network team organizes several educational meetings during the growing season and over the winter to implement the project, teach participants how to use the ETgage and Watermark sensors for irrigation management, review the results, assess progress, set goals, and obtain grower feedback. The progress of this project also has been reported at local, regional, and national meetings.

2007 NAWMDN Efforts

This year the Network is expanding with additional growers, crop consultants, extension educators and specialists, state and federal water regulatory agencies, and other partners. Meetings were held in Scottsbluff and York for Extension Educators and NRD personnel to inform them of the efforts and encourage participation. The Upper Big Blue NRD has recruited cooperators for more ETgage sites and the Little Blue NRD has recruited over 20 cooperators and will have 20 ETgages located across the district. ETgages also will be added in 2007 in the northeast, central and Panhandle areas.

Reference ET information will be posted on the Upper Big Blue and Little Blue NRD Web sites at: http://www.upperbigblue.org/pages/Watertip.htm and http://www.littlebluenrd.org/html_pages/Crop_Water_Page.htm. Plans are underway to develop a statewide Web site similar to the NeRAIN site for the 2008 growing season for easy data entry and sharing.

Growers, crop consultants and others who would like to learn more about these tools and become a cooperator can contact the personnel listed below.

Gary Zoubek
Extension Educator
Suat Irmak
Extension Irrigation Specialist