University of Nebraska-Lincoln Extension, Institute of Agriculture and Natural Resources

April 14, 2006

Figure 1a. Lane Darnall looks over his fall planting of winter canola Figure 1b. Alton Lerwick views his spring canola field shortly before harvest.

Figure 1c. Kirk Laux in no-till dry beans in 15- and 30-inch rows.

Early results from Pumpkin Creek Limited Irrigation Demonstration Project

Declining ground water is not a new dilemma in Nebraska, however, the drought across the High Plains during the past four years has magnified the problem.

In March 2001 the NPNRD established the Pumpkin Creek ground water management subarea and closed it to new well drilling. In 2004 they approved a yearly pumping allocation of 14 inches.

One way to meet the challenge of less irrigation water is for farmers to adopt no tillage, water conserving cropping systems. Under limited irrigation, less water is applied than is required to meet the full evapotranspiration demand which results in crop stress. The goal is to manage cultural practices and irrigation timing so the resulting water stress has less of a negative impact on grain yield.

Past and current UNL research on deficit irrigation at North Platte and in field demonstrations in southwest Nebraska have conclusively shown that water stress can be managed without major grain yield reductions. Because the Pumpkin Creek Watershed area has a short growing season, lower rainfall and sandier soils than other areas of Nebraska where limited irrigation is being practiced, research and demonstration was needed for these conditions. With this background, a three-year demonstration project funded by an NRCS Conservation Innovation grant with matching funds from the North Platte NRD was started in 2005 by the University of Nebraska Panhandle Research and Extension Center in the Pumpkin Creek Watershed.

Limited irrigation cropping systems

  • Less water is applied than required to meet full ET demand.
  • The crop will be stressed.

Goal: Manage cultural practices and irrigation timing so the water stress has less impact on yield.

Why the system works:

  • Stores as much natural precipitation between the last crop and the next.
  • Saves 1-2 inches of stored soil water by not tilling the soil.
  • Crop residue suppresses evaporation during the irrigation season for higher efficiency of applied water (saves 2-4 inches of water).
The project objectives are to:

  1. demonstrate limited irrigation and no-tillage cropping system that maximize the return from groundwater supplies, and
  2. educate area producers, local government and agricultural businesses about different management scenarios on production, cultural practices, economics, and natural resources impacts.

Three cooperators who were already using no-till were selected for the demonstration (Figure 1):

The three sites were selected to represent the range of conditions present across the Pumpkin Creek basin as reflected by the amount of water pumped for the 2004 growing season. (See Map of Pumpkin Creek Basin with acre inches of water pumped in subareas of the Pumpkin Creek basin during 2004.)

Crops that use lower amounts of water were selected for the demonstration and included spring canola and dry beans. The 2005 yield of spring canola on Alton Lerwick’s half circle was near 1800 lbs/acre and at Lane Darnall’s site it was about 1500 pounds/acre. Canola uses about the same amount of water as winter wheat, but also can be used for biodiesel production. Kirk Laux tried something really new to the Panhandle – no-till dry beans. He planted no-till dry beans into corn stalk residue in 15-inch and 30-inch rows. To maintain a no-till system (no undercutting), he swathed the beans with a draper header. Yields are shown in Table 1.

Table 1. Yield from no-till dry bean at three sites in the Pumpkin Creek Basin Demonstration Project, 2005.
Site Feedlot Pivot
Sherwood Pivot
Huber Pivot
  Beryl GN beans Marquis GN beans Winchester Pinto beans
Bu/acre 30-inch rows 30-inch rows 15-inch rows 30-inch rows 15-inch rows
Final Yield 46.1 40.4 39.1 40.7 41.2

These yields compare favorably with “conventional” full tillage production. Narrower rows did not provide a yield advantage, but late season weed control was better for 15-inch rows. Harvest losses were higher than desired (about 3-5 bu/acre) but details for direct combine harvesting or swathing will be part of the research and demonstration project for the coming year.

Lessons Learned

The project has demonstrated that no-tillage can be adapted for the sandy soils of the Pumpkin Creek basin. The three cooperators are using no-till for common and alternative crops and making it work. Because of the wide range in water availability, we still have work to do to match crops and cropping systems with water availability. Depending on how limited the water supply is, producers practicing limited irrigation must think like a dryland producer who has some irrigation water for only a part of the season.

We also have learned that there are many agronomic and production factors we must perfect before making no-till and limited irrigation common practice. We know we need additional research information for a wide range of cropping systems over a three- to five-year period to look at common and alternative crops that fit the Panhandle before we can implement this on more farms. We also learned that work needs to be done to fine-tune irrigation systems for improved pumping efficiency. (CropWatch will feature a story on improving irrigation pumping efficiency in an upcoming issue.)

Gary W. Hergert
Extension Nutrient Management and Soil Quality Specialist
Aung K. Hla
Extension Education
Pumpkin Creek Project
Dean Yonts
Extension Irrigation Engineer
Jim Schild, Extension Educator
Scotts Bluff & Morrill Counties
Panhandle REC, Scottsbluff

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Copyright 2006 by the University of Nebraska Board of Regents. All rights reserved.
Published by University of Nebraska-Lincoln Extension in the Institute of Agriculture and Natural Resources Cooperating with the counties and the U.S. Department of Agriculture.
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