Center Pivot Research |
|
| Water
is the life support of irrigated agriculture in Nebraska and the state's
8.2 million acres of irrigated lands are extremely vital to the economy.
Concern about availability of irrigation water in Nebraska is growing.
Maximizing the net benefits of irrigated crop production through an
appropriately designed agricultural water management program is of
growing importance because many areas in the state are experiencing
significant management changes to conserve irrigation water. Growers
are challenged to practice conservation practices, reduce runoff and
other losses from irrigation, and increase crop water use efficiency
while meeting the crop water requirements for maximum net return.
As Nebraska growers enter a new era of water-limiting crop production, questions such as "how can we make a maximum use of limited water supply?" need to be addressed. Successful farming in water-limiting conditions cannot be achieved without knowing: How much stress can be imposed on the corn crop and what are the possible consequences of these stress levels on the final grain yield? How crop water stress-yield-crop water use efficiency are related to each other under water-limiting conditions? These are fundamental questions that we need to research and answer in the new era of water-limiting conditions to help growers make better use of their water supply. In addition, there is a lack of information on the crop evapotranspiration (ET) and crop coefficient for corn and soybean crops under deficit irrigation as most of the past research projects in this field have focused on determining crop evapotranspiration and crop coefficients under full irrigation settings. |
Objectives: To initiate research to address aforementioned and other research questions, a hydrostatic and continuous-move, four-span center pivot irrigation system was installed on a 40-acre field in the summer of 2005 to study the following objectives:
The experiment is designed as randomized complete block design with three replications. In 2005, the center pivot research field was used to collect preliminary data treating the entire field as one treatment (100% daily crop ET). Irrigations were scheduled based on the daily crop ET values and not based on the soil-water status. In 2005, the seasonal gross irrigation application was 12.1 inches and the corn yield was 238 bu/ac, with uniform yield across the field. Research on aforementioned objectives will continue in the 2006 and 2007 growing seasons. |
Figure 1. Field plot design of center pivot crop water use efficiency, evapotranspiration, and corn hybrid evaluation research facility.
Print a larger version of this map. PDF file, Acrobat Reader required. |
Soil and crop management practices:
|
||||||||||||||||||||||
|
||||||||||||||||||||||
Weed
Control
Soil Practices: Cultivation, Tillage The previous
field crop was dryland corn. After the harvest in 2004, stalks were shredded
and the field was cross ripped twice to a depth of 18". Field was
then disked. Ridges were put in using Hawkins "hiller bottoms"
so corn could be planted on top of a ridge in 2005. |
Long-term Rainfall
|
Rainfall in 2004 and 2005
Precision Mobile Drip Irrigation (PMDI)The first span of the center pivot system is equipped with PMDI. This technology is being used at the demonstration site and will be tested for uniformity of water application, crop yield, and water use efficiency at SCAL (Figures 2, 3, and 4). The PMDI system consists of thin black drip lines spaced every 30 or 60 inches, depending on soil type, and the drip hoses follow the continual movement of the center pivot system. The water application rate can be adjusted based on the length of the drip lines. Unlike sprinklers, the water application is not effected by the wind drift with PMDI. |
Figure 2. Four-span hydrostatic drive and continuous-move center pivot irrigation system.
|
Figure 3. First span of the pivot is equipped with PMDI and drop nozzle sprinklers.
|
| Figure 4. Low-drift nozzle (LDN) with a 10 psi pressure regulator and control valve (left) and PMDI drip lines in the first span (right) | |
|
 |
Figure 5. Pivot Manager Controller allows varying water application rates based on the degree angle at the end tower.
|
|
Acknowledgments: Disclaimer: The mention of trade names or commercial products is solely for the information of the user and does not constitute an endorsement or recommendation for use by the University of Nebraska-Lincoln or the author(s). |
