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Pumpkin Creek Home | About the Project | Pumpkin Creek History | Farmer-Cooperators | How to Get Started

 

Limited Irrigation Cropping for Conserving Water Resources
In the Pumpkin Creek Watershed

 

The Project:

Dr. Gary Hergert, soils specialist at the University of Nebraska Panhandle Research and Extension Center, secured a Conservation Innovation Grant (CIG) from the U.S. Department of Agriculture to implement a water conservation demonstration project in cooperation with the Natural Resource Conservation Service (NRCS) and the North Platte Natural Resources District. The project began in the fall of 2004, and the demonstration work accelerated after an extension educator was hired.

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 and the crop will be stressed. The goal is to manage cultural practices and irrigation timing so the resulting water stress has less of a negative impact on yield. WaterMark soil sensors, ET gauges (atmometers) and rain gauges were utilized to help the cooperators schedule and mmanage irrigation in a timely manner.

View a Map of the Area

 

The cooperators:

Three cooperators were selected for demonstrating limited irrigation and no-till cropping management systems.  Crops that use lower amounts of water were selected for the demonstration and have included spring and winter canola, winter wheat, sunflowers, dry beans, and corn was also included. 

Alton Lerwick’s site represents a medium size no-till farm and livestock operation located in the western part of the watershed.  Alton uses a continuous cropping system on 230 acres irrigated and 2,400 acres dryland with minimal or no fallow to maximize crop residue to conserve soil and moisture.  Alton Lerwick applies less than 6-inches water per acre to produce various ‘conventional’ and ‘alternative’ crops, which require less moisture.  These include corn, winter wheat, sunflowers, canola, forage sorghum and millet.  Alton’s yields were 1,650 lb/ac spring canola in 2005, 60 bu/ac winter wheat (hailed) in 2006 and 1650 lb/ac sunflowers in 2007; applying approximately 4-inches water each year.

Lane and Gary Darnall’s site represents a large no-till farm and livestock operation with a large feedlot in the central part of the watershed.  Lane farms 1,950 acres irrigated and 4,000 acres dryland.  Lane Darnall utilizes his water allocation to grow more conventional crops such as corn and alfalfa for his feeding operation and also grow alternative crops such as winter wheat, irrigated pasture and canola which require less moisture.  Lane’s yields were 1,100 lb/ac spring canola (high weed infestation) in 2005, 1,200 lb/ac winter canola (winter kill) in 2006 and 52 bu/ac winter wheat in 2007; applying approximately 5-inches water each year.

Kirk Laux’s site represents a medium size no-till farm and livestock operation with a medium feedlot in the eastern part of the watershed.  Kirk farms 930 acres irrigated. Kirk Laux utilizes a similar water allocation plan as Lane, but with a different cropping system and uses water from irrigated acres he has ‘retired’ back to dryland to gain additional water for use on his crops.  Kirk grows corn, alfalfa, winter wheat, dry beans and forage turnips for fall / winter grazing for his livestock.  Kirk’s yields were 48 bu/ac dry beans plus approximately 3.8 tons/ac forage turnips for grazing in 2005 and 40 bu/acre dry beans in 2006; applying approximately 10-inches water each year.  Kirk is also trying something new to the Panhandle - no-till dry beans.  He has planted no-till dry beans into corn stalk residue, in 15-inch and 30-inch row spacing’s along with drilling.  To maintain a no-till system (no undercutting of the dry beans at harvest), he has tried swathing and direct harvest methods.  Currently, Kirk has also gone to planting 20-inch row corn and dry beans.  The narrow row spacing provides quicker canopy cover to help compete with weeds and help shade the soil surface sooner for moisture conservation.  Kirk is also developing a method to direct harvest his dry beans with a Shelbourne Reynolds stripper-header, to maximize crop residue left on the soil surface for soil and moisture conservation.

 

Project Objectives:

Research on limited irrigation (Hergert et al., 1993, Schneekloth et al, 1991) and field scale deficit irrigation studies (Klocke et al. 2004) have shown that applying precise amounts of water to an optimum number of acres at the proper stage of growth provides more profit potential than irrigating less acres with more water.

Research on limited irrigated no-till cropping systems was initiated in 2005 at the Panhandle Research and Extension Center in conjunction with the Pumpkin Creek Demonstration sites.

The objectives of the demonstration project were to:

1.  Demonstrate limited irrigation and no-tillage cropping systems to maximize efficient use of groundwater.

2.  Educate area producers, local government and agricultural businesses about
different management options for limited irrigated areas on production, cultural practices, economics and natural resources impacts.

3.  Develop economic case studies for limited irrigation cropping systems.

 

Watermark

Most crops currently grown in the Panhandle can fit into limited irrigation cropping systems in the Pumpkin Creek Watershed. Since the NPNRD allocated 14 acre-inches per certified irrigated acre, ‘water transfers’ are allowed within a designated allocation unit. This means that unused water from one field may be used on other crops / fields within the allocation unit that require more water, or the water could be carried over from one year to the next, up to half the prior year’s allocation. Since this is a no-till demonstration, we have only been looking at grain and / or forage crops, no root crops like beets or potatoes.

With the water allocation in place, the cooperators have become more diligent in scheduling irrigation by using the WaterMark™ soil moisture sensors, ET gages and rain gages as management tools.  Partly as a result of the irrigation scheduling skills developed and the imposition of the 14 acre-inches pumping limit, groundwater users have consistently complied with the water allocation regime. 

As an example, the graph of Alton Lerwick’s Watermark soil moisture records for his 2007 sunflower crop is shown below.  Using a moisture probe, it was determined that this field had a full moisture profile down to six feet at the start of the growing season.  Following the green line (1-foot soil depth), the crop gradually starts to remove soil moisture until he applied water on July 10th and again on July 22nd.  Rainfall occurred on July 27th and again on August 2nd.  The red line (2-foot soil depth) shows the same trend by the crop removing soil moisture from that depth as the roots develop.  The blue line (3-foot soil depth) and the black line (4-foot soil depth) show similar trends later in the growing season in soil moisture removal as the crop and root systems develop.

Since Alton can only pump 4 to 5-inches and that the water will run out around August 1st, knowing the amount and when the precipitation was received from the rain gage and how much potential ET the crop was using from the ET gage is very beneficial.  Alton was able to apply the limited amount of water he has available in a timely manner to get the crop developed to the point it could draw soil moisture from deeper in the profile later in the season when his irrigation water is gone.

Gary Hergert demonstrates a Watermark
soil moisture monitor.

Watermark sensors, monitor, rain and ET gauges

Lessons Learned:

  • The project has demonstrated that no-tillage can be adapted for the sandy soils in the Pumpkin Creek basin.  The three cooperators are using no-till for common and alternative crops and making it work. 
  • There is still much work to do to match crops and cropping systems due to the wide range of water availability.  Producers practicing limited irrigation must think like a dry land producer who has some irrigation water for only part of the season. 
  • There are also many agronomic and production factors we must ‘perfect’ before making no-till and limited irrigation production systems common practice.  There is also the need for additional research information for a wide range of cropping systems over a 3 to 5 year period to look at conventional and alternative crops that fit the Panhandle and surrounding areas before we can implement this on more farms.  Work also needs to be done to ‘fine tune’ irrigation systems for improved pumping efficiency. 
  • Field days and tours have demonstrated to neighbors what can be done with less water.  Additional field days and / or meetings need to be held to inform more growers and the agricultural community (fertilizer-chemical, implement, financial) to promote the benefits and potential problems with these systems so they can understand them better and work through them. 
  • Using limited irrigation cropping and no-till systems can be successfully accomplished if the producer is willing to be patient when switching to these practices.  Cropping practices / systems need to be determined and refined by the individual producer for their operation and the producers become more flexible in their management and marketing practices.

 

 

References:

Acknowledgements:

A special “Thank You” to the North Platte Natural Resources District, the NRCS and the University of Nebraska for their support and cooperation with this project.

  • NRCS CIG Grant: $120,000.00
  • North Platte NRD: $60,000.00
  • UNL-PHREC: $60,000.00

The mention of trade names or commercial products is solely for the information of the reader and does not constitute an endorsement or recommendation for use by the authors or the University of Nebraska – Lincoln Extension.

 

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