Project Details:

Determining Rye Safety to Soybeans with Soil Moisture Status

Parent Project: This is the first year of this project.
Checkoff Organization:North Dakota Soybean Council
Categories:Crop management systems, Economics, Weed control
Organization Project Code:QSSB
Project Year:2019
Lead Principal Investigator:Michael Ostlie (North Dakota State University)
Co-Principal Investigators:

Contributing Organizations

Funding Institutions

Information and Results

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Project Summary

Rye use prior to soybeans has proven to be effective in many situations (erosion management, weed control, saline areas) and adopted by many producers. In past research, attempts have been made to identify safe planting conditions for soybeans into terminated or living rye. These studies have focused on termination and planting dates based on calendar dates. They have also had inconsistent results for soybean safety. Water availability is the key to soybean safety with this system. This study looks to identify a soil moisture threshold to indicate when to terminate the rye so that soybean yields are protected. There are water use models developed for rye production already. Using a neutron probe, and calibrating the reading to the field site at the Carrington Research Extension Center, we will gather detailed information about soil moisture status in each of our plots. The treatments will consist of seven rye termination dates, three soybean plantings dates, and four soil moisture check plots (bare soil, rye only, soybean only, and rye and soybean together). Soybean emergence, maturity, and yield data will be collected off the site. The rye water use model will be incorporated into our soil moisture data (and soybean yields) to estimate the best time to terminate rye. Information will be compared to soil moisture data collected by NDAWN to determine if that could be used as a tool to assist producers with making termination decisions.

Project Objectives

1). Measure soil moisture status, and rye water use, with different rye termination dates
2). Estimate a soil moisture value that may result in no soybean yield loss from rye

Project Deliverables

Progress of Work

Updated May 8, 2019:
See report downloaded below

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Final Project Results

Updated July 5, 2019:

View uploaded report Word file

Research Conducted
The project goal was to compare soil moisture differences based on how long rye remained in a rye/soybean relay. After rye green-up, rye glyphosate termination occurred weekly for 7 weeks (different plots). Soil moisture was recorded in each plot weekly through rye anthesis and every 2 weeks thereafter. Soybeans were planted at rye boot stage. This research was the focus of several workshops in summer 2018 including the Advance Crop Advisor’s Workshop and CREC Fall Row Crop Tour, and data were prepared for the CREC annual report and Wild World of Weeds Workshop.
Why the Research is Important to ND Soybean Farmers
Winter rye is growing in popularity as a cover crop prior to soybeans. However, past research has documented instances of rye growth reducing soybean yields under dry conditions. During wet seasons the soybeans can be planted ‘green’ (but terminated soon after) into the rye with little change in soybean yield. Other years, rye needs to be terminated several weeks prior to soybean planting to prevent soybean yield reduction. This project aims to develop a set of guidelines for rye termination timing so that producers can predict when their soybean crop may be at risk from the rye.

Final Findings of the Research
Water use patterns were fairly consistent with expectations. Peak rye water use occurred around anthesis, while soybean peak water use peaked in mid-August. Rye that was terminated at or before soybean planting had similar soil moisture as soybean-only plots. Rye continued to use water for approximately 7 days after termination. Even though there was a spike in rye water use when terminated 1 week after soybean planting, the soil moisture status improved enough that soybean yield was not affected. Only further delaying termination removed enough water to reduce soybean yields. Terminating rye at anthesis reduced soybean yields by approximately 10 bu/a. In 2018 1.5” water deficit in the top two feet of soil triggered yield reductions in soybeans.

Benefits/Recommendations to North Dakota Soybean Farmers and Industry
We are continuing to evaluate how water deficit will impact soybean yields over multiple years. Based on this and past research, the safest approach is to terminate rye two weeks prior to planting, which is also consistent with insurance guidelines. We are currently working to build a prediction tool that can be used to determine soybean yield risk from rye to assist with termination timing.

Benefit to Soybean Farmers

Rye use for a cover crop prior to soybeans is a new trend that is being adopted in North Dakota. Rye makes up for a lot of weaknesses that soybeans have in a cropping system. Some of primary benefits include reducing soil erosion, increased weed control, additional grazing/forage material, utilization of excess soil moisture by rye allowing soybean to be planted timely, and allowing soybeans to be planted further into former saline regions. The concept of this system is that winter rye is planted the fall before soybeans. The rye is terminated prior to or shortly after soybean planting. In the spring, prior to soybean planting, the rye is suppressing weeds, reducing wind and water erosion (after soybean planting too), and putting out roots and using water (in saline areas). Rye is best terminated with glyphosate.
Rye provides selective weed suppression, meaning that it is more effective against some species than others. Rye is particularly effective at suppressing kochia (up to 70% control in a heavy kochia infestation), and also does well against pigweed species, ragweed, and yellow foxtail. Rye has very little or no suppression of mint species (like lanceleaf sage), or most legumes. Thus, soybeans are not influenced by the presence of rye, except when moisture is limiting. In 2016 and 2017, when the springs have been very dry in Carrington, we’ve seen heavy injury to soybeans as a result of the limited rain. From 2013-2015 our results have shown rye to be very safe to soybeans when there was more available moisture. This past research has led us to this current proposal which would seek to identify the soil moisture status that would signify a risk to soybeans from the rye. The research leaders involved with this project have had past experience and training in monitoring soil water use and moisture status with other projects.
Many producers are beginning to see the advantages of using rye prior to soybeans. However, as mentioned, this system comes with risks. As more people adopt this system there are more opportunities for things to go wrong (particularly as people get familiar with managing a new system). By accomplishing the stated goals of this study, we would provide the information needed to minimize risk to soybean producers. In 2016, the moisture deficit was so severe in Carrington that the only time rye was safe with soybeans was when it was terminated early in the spring. I haven’t been made aware of any crop failures from rye as of yet, but the potential is there. The key to avoiding that scenario is to identify the risk factors.

Performance Metrics

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