This proposal covers the deployment of six small-plot research studies on three cooperating famers’ fields. To vary the intensity of IDC, small-plot studies will be located in a ‘hot-spot’ on each producer field as well as in an area of each field that is representative of the majority of the acres in that field or less chlorotic. We have developed an efficient protocol whereby we are able to increase the intensity of IDC symptoms through the application of supplemental N. Therefore, in addition to the primary treatments, each study will be blocked with and without supplemental N application.
In total, we will therefore replicate this study across 12 unique IDC environments (3 fields, 2 areas within each field, and 2 levels of IDC intensity within each study area). With four replications, we are planning for 768 individual plots.

• 2 Variety treatments
o Moderately tolerant
o Highly tolerant

• 2 Populations
o 125,000
o 175,000

• 4 Iron Chelate (SoyGreen) rates
o 0
o 2 lbs
o 3 lbs
o 4 lbs

• 2 IDC levels
o With N
o Without N

• 2 Locations within fields
• 3 Producers

Three cooperating producers will be selected to represent district IDC environments so that unique soil and climate factors are examined annually to allow a broad inference of research findings. The six field studies will be planted in production soybean fields by the Naeve project. A split-block design will be utilized, where N rate will be a main block and varieties and populations will be randomized within the first split, iron chelate rate.
After emergence, plots will be evaluated weekly for IDC systems through visual scoring, ground based NDVI as well as though high-resolution drone imagery. These data will be utilized to evaluate each treatment for timing and intensity of IDC symptomology relative to yield.
Upon completion of field activities, a complete economic analysis will be conducted. Yield data will be examined relative to a range of grain prices and appropriate input costs. Economists will be consulted on the more appropriate analyses based on the recorded data.

Update:

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Managing Iron Deficiency Chlorosis with Agronomics and Economics
Maykon da Silva and Seth Naeve

Abstract
Iron Deficiency Chlorosis (IDC) is a major yield-limiting stress for soybean [Glycine max (L.) Merr.] grown on the calcareous soils of the U.S. upper Midwest. During the 2021 growing season, six on-farm research trials were established at three locations in Western Minnesota (Graceville, Foxhome, and Danvers) on two IDC-prone field areas (hotspot vs. non-hotspot) to evaluate the effectiveness of three of the most often used management strategies for IDC from a system’s approach: variety selection, seeding rates, and iron chelates. Three Fe-EDDHA rates (0, 2 and 4 lbs. Soygreen? acre-1) were applied in-furrow at the time of planting either a highly tolerant (AG13XF0) or a moderately tolerant (AG12XF1) variety at 125,000 and 175,000 plants acre-1. Nitrogen was supplied to create a range of IDC symptomology. Visual chlorosis scores (VCS), drone imagery, and ground based NDVI were assessed as methods for measuring the severity of symptoms. Our preliminary results suggest different management strategies to be recommended depending on the field location and the intensity of IDC symptoms. At Graceville non-hotspot, the application of Soygreen? increased soybean yield by 54 to 60% in the susceptible variety where IDC was amplified by N addition. At Graceville hotspot, regardless of variety, Soygreen? application increased yield by at least 35 bushels when N was applied. Where N was not applied and no Soygreen? was added, the highly tolerant variety yielded 72% more than the moderately tolerant one. At Foxhome non-hotspot, the yield of the moderately tolerant variety was decreased by 25% when N was added. At Foxhome hotspot, the highly tolerant variety produced 28% more than the moderately tolerant variety when IDC intensity was not increased by N application. At Danvers non-hotspot, there were no differences in grain yield between treatments. Differently, at Danvers hotspot, three main things were found. At higher seeding rate treatments, the application of 4 lbs. Soygreen? acre-1 significantly increased the yield of the moderately tolerant variety. Without Soygreen? applied, increasing the seeding rate of the highly tolerant variety from 125,000 to 175,000 plants acre-1 resulted in a yield increase of 36 bushels. At increased seeding rates and without Soygreen? application, the highly tolerant variety produced 52% more than the moderately tolerant one. Overall, variety selection, increased seeding rate, and in-furrow application of iron chelates were effective in controlling IDC and minimizing yield losses. Further research will evaluate the impact of these three management strategies individually and collectively on return on investment. Coupled with an economic analysis, this work will provide producers with more refined recommendations for managing IDC and will support them in their efforts to achieve the greatest economic return on every farm.