Investigation of Soybean Seed Treatment and Inoculant vs. No Treatment No Inoculant

Methods:

With a wetter than average spring in southeastern SD, this plot was planted into suitable, but wet soils. However, the end of June and July proved to be dry, and excess moisture from early summer helped to keep crops growing during that dry period. This field was hit with large hail 6/29/17, and again on 8/21/2017; hail damage in combination with dry growing conditions throughout June, July, and early August lowered crop yields overall.

Introduction:

Soybean seed treatment products are widely utilized by many farmers in southeastern South Dakota and the surrounding area. These products often consist of an insecticide/fungicide combination, and/or inoculant that is mixed and placed on the seed as a pre-treatment before the grower plants the crop. Many insecticide/fungicide combination seed treatment products are marketed and developed to protect seeds and seedling plants from insects and plant diseases that may damage the seed or suppress/kill the seedling. In addition, inoculant is designed to enhance soybean performance using rhizobia by adding beneficial bacteria to the soil. The effects of inoculant are often most prevalent in soybean crops that have not had soybean in the rotation for several years.

Objective:

Although these products have become commonplace, understanding the positive effects of soybean seed treatments and inoculant is not commonly measured. Therefore, a study was developed near Tyndall, SD to measure soybean stand and yield performance where various seed treatments were placed in an on-farm trial in a randomized complete block design.

Summary:

There were slight yield variances between treatments, but there was no significant differences, meaning seed treatments did not significantly boost yields at this site (Table 2). Plant stand was also non-significant by treatment, but replications did have significantly different plant stands, which may be attributed to low areas within treatment strips that were accentuated due to the early, wet conditions.

Seed treatments did not significantly affect yield or plant stand in this trial. This treatment would cost approximately $13/unit (140,000 seeds) if treated by the seed dealer- in this study site and year, seed treatment and inoculant was not economical for crop production.

ACKNOWLEDGEMENTS:

Coauthored by: Sara Berg, David Karki, Anthony Bly

This project partially funded by the South Dakota Soybean Research and Promotion Council and SDSU Extension. We would like to thank the cooperator for providing the field and planting the treatments for us.