December 16, 2021
Trial Objective
The success of a rainfed soybean crop can be determined by one factor such as missing a late-season herbicide application. When water is the driving factor for potentially high yields, good management is a key.
The objective of this study was to evaluate the impact of five rainfed soybean production systems that may or may not include treatment factors such as tillage, herbicides, fertility, and a fungicide on yield potential.
Experiment/Trial Design
| Location | Gothenburg, NE | ||
| Soil Type | Hord silt loam | ||
| Previous Crop |
Soybean | ||
| Tillage Type |
Conventional-Till, No Till |
| Planting Date | 5/12/21 | ||
| Harvest Date | 10/16/21 | ||
| Potential Yield (bu/acre) |
45 | ||
| Seeding Rate (seeds/acre) |
160K |
A 2.5 maturity group XtendFlex® soybean product was planted into a rainfed field with no additional supplemental moisture and subjected to five crop production systems (Table 1). Two of the systems were conventional till and three were no-till.
The trial was a randomized complete block design with four replications of the five treatments.
The planter was a fully mounted 4-row, 30-inch planter utilizing Precision Planting® DeltaForce® for downforce control and Precision Planting® vDrive® for seeding rate control.
A base fertilizer application of 50 lb/acre Phosphorous (P), 21 lb/acre Sulfur (S), 0.2 lb/acre Zinc (Zn) was broadcast with stream bars across all treatments on April 13, 2021.
No insecticides were applied.
Plots were combine-harvested.
Grain moisture content, test weight, and total weight were determined.
Statistical analysis for Fisher’s LSD was performed.
Table 1. Treatment Systems
Understanding the Results
Yield
The lowest average yield of the soybean production systems was observed with the base system (Figure 1). The base system was a conventional tillage system with no residual herbicides which had very high weed pressure (Figure 2).
The residual herbicides, Zidua® SC Herbicide, Valor® Herbicide, and Dimetric® Liquid Herbicide plus XtendiMax® Herbicide with VaporGrip® Technology (a restricted use pesticide that must be used with VaporGrip® Xtra Agent* or and equivalent reduction agent) applied at planting almost doubled yield potential over the base system; however, late season weeds were problematic (Figures 1 and 3).
Yields trended higher with the post residual treatments and very low weed pressure was observed in the plots at harvest (Figure 4).
Figure 1. Average yield for five rainfed soybean production systems at Gothenburg, NE in 2021.
Figure 2. Weed growth in the base system was dramatic because of conventional tillage and no herbicide applications.
Figure 3. Late-season weeds were problematic when no residual herbicides were applied after planting during the post application timing; however, yields were almost double those of the base system.
Figure 4. Very low weed pressure was observed with the post residual treatments and yields trended higher.
Test Weight
The lowest test weight was recorded with the base system which had high levels of weed pressure at harvest. Grain quality was decreased due to excessive weed seed.
Figure 5. Average test weight for five rainfed soybean production systems at Gothenburg, NE in 2021.
Key Learnings
Farmers should evaluate their soybean production system for procedures to help maximize water retention and to decrease weed growth that competes for water.
The layering of residual herbicides had the biggest impact on yield potential in this rainfed soybean trial.
- Including a residual herbicide at planting and four weeks after planting provided excellent weed control at harvest, increased yield potential, and reduced the number of potential weed seeds for the following crop.
1020_R5