March 22, 2022

A Long-term Research Study Investigating the Effect of Planting Date on Soybean Yield Potential in the Northern Plains

TRIAL OBJECTIVE

This research was conducted with an objective of understanding the risks and benefits of planting soybean at various times throughout the spring.
The goal of this study is to provide planting date guidance for to help maximize yield potential.
This data may be used as a reference guide to help growers make replant decisions when stands are reduced by frost or other factors.

On-going trial since 2010 across Northern Plains (North and South Dakota).
This data is a summary of a small data set with limited locations. Values are based on averages and not significantly analyzed.
To compare data across years, results are presented as a percentage of the maximum yield for the year and corn product.
Trial Design: Non-replicated strip trials.

Year and Location of Strip Trials

The highest yields were attained when soybean was planted from late April to Mid-May, with a steady decline as the season progressed (Figure 1).
The potential to maximize yield decreased 20% from May 25^th to June 15^th (20 days), resulting in an average daily loss of 1.0% (Figure 1).

Figure 1. After May 25th, the potential to maximize yield decreased 1.0% per day (identified as the time between the arrows).

Over 10+ years of data, the data indicates that the optimum planting date to maximize soybean yield has a larger timeframe than corn. The data supports the increasingly accepted practice of planting soybean early in the growing season and waiting until conditions are more favorable for planting corn. Please see A Long-term Research Study Investigating the Effect of Planting Date on Corn Yield Potential and Moisture Content in the Northern Plains.
After May 25th, the potential to maximize yield at 100% is greatly reduced (-1.0% per day).
This data is to be used as a guidance for recommendations on optimum planting timeframe. Individual locations and years will vary.
Generally, soybean seed can be planted when soil moisture conditions are satisfactory, regardless of soil temperature and weather forecast.

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