Irrigation Strategies for Soybean Production in Nebraska

Trial Overview

  • There are many different irrigation environments across the Great Plains. In some areas, water applications are restricted by pumping capacity or by allocation, but there are still many fully-irrigated fields.
  • Farmers need information on how soybean products perform in various irrigation environments to help them choose the best products for their fields.
 

Research Objective

  • To determine the effects of different irrigation strategies on the final yield and profitability of soybean in various irrigation environments.
Location
Soil Type
Previous Crop
Tillage Type
Planting Date
Harvest Date
Potential Yield
Planting Rate
Battle Creek, NE
Loamy sand
Corn
Conventional
05/23/2017
10/12/2017
90 bu/acre
140,000
Gothenburg, NE
Silt loam
Winter wheat
Strip tillage
05/15/2017
10/17/2017
80 bu/acre
160,000
Bruning, NE
Silt loam
Corn
Conventional
05/16/2017
09/30/2017
80 bu/acre
160,000

Site Notes:

Rainfall totals and irrigation amounts by location were as follows: 
          - Battle Creek, NE: rainfall = 12.3 in., full irrigation = 7.0 in. 
          - Gothenburg, NE: rainfall = 10.83 in., full irrigation = 6.25 in.
          - Bruning, NE: rainfall = 12.3 in., full irrigation = 8.4 in.
Two Roundup Ready 2 Xtend® soybean products were planted in four irrigation blocks at each location with 1 repetition per location, so the site was used as a repetition when analyzed.Irrigation treatments included: 
          - Full irrigation (FI) to meet the evapotranspiration needs of the crop 
          - Irrigation only from the R1 growth stage through physiological maturity (R1-PM)  
          - Irrigation only from the R3 to R6 growth stages (R3-R6) 
          - Dryland
Each trial location was irrigated with an overhead irrigation system equipped with variable rate technology.

 

 

Understanding the Results

 
Figure 1. Aerial image of the trial at Gothenburg, NE. This image was taken on September 13th, 2017 and displays how the plots were laid out and the earlier senescence (yellowing) in the dryland treatment blocks.
  • No significant difference was found in yields between the FI treatment or when delaying the first irrigation until the R1 growth stage (R1-PM).
  • Yields in the dryland treatment did not differ significantly from yields in the R3-R6 treatment.
  • No statistically significant yield difference was found between delaying initial irrigation until the R1 growth stage compared to the R3 stage.
  • Starting irrigation in the vegetative stages (FI) resulted in increased plant height and lodging in both products at the Bruning, NE location (data not shown).
 

What Does This Mean for Your Farm

  • Growers may want to consider delaying the initial irrigation of soybean at least until the R1 stage of growth (beginning flowering).
  • Irrigating soybean during the vegetative stages can lead to increased plant height and potential lodging.
  • Growers should consider the price per bushel of soybean when developing a strategy for irrigating their crop. 
  • Monsanto intends to repeat these trials to evaluate the yield response to irrigation strategies for the 2018 season. Readers should keep in mind that these results are from only one year, and that additional data collected in future trials may provide additional insight into this research topic.