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PFR Report

Fall Wheat with Interseeded Soybeans

Published on Wednesday, January 4, 2017

One thing we are testing at the Ohio Practical Farm Research (PFR)® site is planting soybeans into a wheat crop before harvest. While some farmers throughout Ohio are already practicing interseeding soybeans into wheat, there are still two perspectives to really consider. The first question you need to ask yourself is, “if you are going to plant wheat, should you interseed soybeans, plant double-crop soybeans, or not plant soybeans at all?” The second thing you need to consider is, “if you are going to plant soybeans, is it best to plant your wheat in the fall and interseed soybeans, plant your wheat in the fall and plant double-crop soybeans, or just plant early-season soybeans?” 

For this study, the wheat crop was planted in the fall of 2015 on October 6. Throughout the fall, a  300 lb./A. application of 8-17-25-7S was made and then in the spring, a topdress application of 30 gal./A. of 28% UAN along with 0.15 gal./A. of Nutrisphere-N® was applied at Feekes 3.5. Once the crop reached Feekes 6, a herbicide application of Harmony® Extra SG was made at a rate of 0.9 oz./A. The soybeans were then planted into wheat on April 20 (with wheat at Feekes 7) and May 20 (when the wheat was at Feekes 10.5.1). At each date, the soybeans were planted into wheat with two row spacings of 7.5 and 15 in. Late season weeds were controlled with 1 qt./A. of Liberty®.

Wheat damage during soybean planting posed a challenge for us in 2015. The wheat recovered quickly from damage caused by the planter early in the season when the wheat was at the second node (April 20). The later planting date, however, resulted in down wheat that did not recover as shown in the images below. 

On the day of harvest, pictures were taken before and after wheat was harvested. The 15 in. wheat allowed for less interspecies competition between the wheat and soybeans. The amount of soybean growth present in the 15 in. row spacing compared to the 7.5 in. row spacing demonstrates that these plants encountered less competition, as seen in the photos below. While wheat row spacing clearly impacted wheat yields, the impact on soybean yields was negligible. In these treatments, the planting date had a greater impact on soybean yields.

When comparing the two interseeding dates, the earlier interseeded soybeans had more growth and showed a clear advantage in the amount of wheat damage during planting. The greater damage with the later planting date was further proved by the 30 Bu./A. yield decrease in the 7.5 in. row spacing, and a 7 Bu./A. decrease at the 15 in. row spacing (see Graph 1 below). One thing to note was that the soybeans in the later planting date were able to grow taller, which allowed more room for pod production and greater yields.

Soybeans were also planted in this study in both a traditional double-crop format and onto fallow ground. The soybeans planted onto fallow ground were planted on the same dates as the interseeded soybeans (April 20 and May 20). When we evaluated soybean yields from this season, the treatments where no wheat was present resulted in the greatest yields due to a lack of competition when compared to the interseeded system. They also produced the greatest yields as a result of an earlier planting date when compared to the traditional double-crop format (see Graph 2 below). These systems with soybeans alone were planted during what we consider the earlier planting period (mid-April to mid-May). Previous data has shown a yield advantage in this earlier planting period over both later planted soybeans (mid-May to Mid-June) and double-crop soybeans.  

**Nutrisphere-N $62.50/gal.; 28% UAN $0.51/unit N; Harmony Extra SG $13.00/oz.;
8-17-25-7S $485/ton + $20 to spread; Liberty $75.95/gal.

The soybean systems alone resulted in the greatest ROI. Fewer inputs were necessary in this system and soybean yields were nearly double those that were interseeded. Additionally, late-season rains in 2016 led to greater pod fill and higher overall soybean yields in Ohio. We will conduct this study again in 2017 at both the Ohio and Southern Illinois PFR locations.   

Practical Farm Research (PFR)® is a registered trademark of Beck’s Superior Hybrids, Inc. Nutrisphere-N® is a registered trademark of Verdesian Life Sciences. Harmony® Extra SG is a registered trademark of E. I. du Pont de Nemours and Company. Liberty® is a registered trademark of Bayer Crop Science. 


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Alex Knight

Alex Knight

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2 comments on article "PFR Report"

David Schafer

1/5/2017 7:40 AM

Do you have a comparison of wheat not interplanted and doublecrop beans planted after harvest of wheat for the ROI

Alex Knight

1/10/2017 8:16 AM

Hi David, thanks for your question. The table toward the bottom (with Crop, Wheat and Soybeans across the top) lists the ROI for wheat that is not interplanted in the row labeled "Wheat Only." There is a row for double cropped soybeans planted after wheat labeled "Wheat + Double-crop Soybeans." The "Wheat Only" will have ROI listed under the wheat "Profit" column, and overall ROI for the "Wheat + Double-crop Soybeans" will be under the "Total Profit" column. Here is the link to the chart:

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