2023
Is Soybean Desiccation a Tool for Earlier Harvest?
Category:
Sustainable Production
Keywords:
DiseaseField management Pest
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Seth Naeve, University of Minnesota
Co-Principal Investigators:
Project Code:
10-15-48-23159
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:
There is a growing interest from northern farmers in desiccation to control the harvest window, while increasing combine speed and efficiency. But it can cause significant crop damage and yield loss if not managed properly. There is limited information on determining the optimum time for applying the desiccant in the north. In this project, researchers will assess the effect of desiccation timing on soybean yield and seed quality while also assessing the effect on grain dry-down and shattering. Details to be studied include yield impact, harvest timing and efficiency as well as seed quality.
Key Beneficiaries:
#applicators, #extension specialists, #farmers
Unique Keywords:
#agronomy, #desiccants, #harvest, #soybean quality
Information And Results
Project Summary

There is a growing interest in looking at desiccation as a tool for an earlier soybean harvest. While this practice is quite common in the southern U.S., where soybean maturation can be quite problematic, there are multiple smaller factors that have caught the attention of many MN farmers. These include: 1) earlier harvest, 2) harvest moisture management, 3) reduced harvest losses, 4) increased harvest efficiency, 5) late season weed control, and 6) reduced foreign material.

Many of these factors are interacting, and it’s important to note that stress during certain periods can lead to an increased incidence of green stem and delayed leaf senescence in some varieties. Likewise, foliar fungicides can contribute to plants retaining leaves after pods have reached maturity. Desiccation is intended to help manage these concerns. Ultimately, the primary goal of this practice is to control the harvest window, while increasing combine speed and efficiency.

Desiccant application, on the other hand, can cause significant crop damage and yield loss if not managed properly. There has been some previous research on this topic, mainly from southern states (Whigham and Stoller, 1979; Ratnayake and Shaw, 1992; Boudreaux and Griffin, 2011; Bellaloui et al., 2021); however, there is limited information on determining the optimum time for applying the desiccant in the north. Specifically, little is known regarding the earliest phenological stage at which there is no yield depression from desiccant use. Some guidelines established that desiccation by R6.5 stage does not depress yield (Monseley et al., 2021). However, crop growth studies in our lab have reported that total plant and seed biomass can continue to accrue until nearly R8. It is important to generate local information to define the effect of desiccation timing on yield. It is also important to assess the effect on grain dry down to quantify the real advantage of harvest aids. Lastly, there is also limited information about the impact of this technique on soybean grain quality.

Commonly used desiccants in soybeans are paraquat (Gramoxone®), saflufenacil (Sharpen®), and sodium chlorate (Defol 5®). Each product label specifies a pre-harvest interval, which is the minimum amount of time that must elapse from application to soybean harvest. Therefore, it seems relevant to know how the different desiccants and timing combinations affect pod shattering (and other important factors mentioned earlier) during and after this period.

Ultimately, we propose to assess the effect of desiccation timing on soybean yield and seed quality while also assessing the effect on grain dry down and shattering. The questions to address are: How early can soybean be desiccated without affecting yield? How does this practice affect harvest timing and efficiency? How is seed quality affected by desiccation?

Project Objectives

(1) Assess the effect of timing of desiccation on yield for different desiccants.
(2) Assess the effect of timing of desiccation and the desiccant on soybean dry down and on the advancement of harvest.
(3) Assess the effect of timing of desiccation on grain quality and composition for different desiccants.
(4) Evaluate pod shattering and pre-harvest grain loss for different combinations of desiccation timing and desiccants

Project Deliverables

(1) An objective assessment of crop desiccation as a tool to improve harvest efficiency.
(2) We will provide local guidelines for any successful desiccation technique.

Progress Of Work

Update:
- We conducted 3 controlled field experiments at Waseca, St. Paul and Wells.
- Samples were processed.
- We have started the data analysis
- We are going to be able to assess the effect of timing of desiccation on yield and also the desiccation effectiveness of different commercially available products.

Update:
see attached

View uploaded report PDF file

Final Project Results

Updated May 29, 2024:

View uploaded report PDF file

Benefit To Soybean Farmers

(1) This project will allow us to generate science-based recommendations to Minnesota soybean growers so they can decide whether to use desiccants as harvest aids.
(2) This project will indicate when to spray desiccants and what to expect if growers choose to use them

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.