Improving Soybean Yield with Spot Weed Treatment


About the Project- A New Service is Validated



Agriculture could be the most inefficient industry, but still with a trend of an increasing number of innovations.  A farm in the Midwest, USA, adopted a spot spraying solution this season with DJI drones and Agremo AI weed detection to precisely target weed infestation.

Weed management is an almost mandatory part of a farmer's life. On a normal corn soybean rotation farm, studies show that controlling volunteer corn could prevent a 15% and 60% yield loss from individual and clumped volunteer corn, respectively. Furthermore, the farmer saved money by opting for spot treatment instead of a blanket treatment. By using drone imageries and Agremo’s weed detection function, 3.75 acres of individual volunteer corn and 6 acres of clumped corn infestation was found in this 64-acre soybean farm. The farmer then flew DJI’s spraying drone, T30, to spot treat these volunteer corn. As a result, he only used 60% of herbicide, and his crops were spared losses due to driving. In the end, the farmer saw a 68.39% boost to his income by opting for spot treatment over flat treatment.

These results validated the technical feasibility and economic return of mapping + AI analyses + spot spraying for precise treatment in agriculture.



Growers' Requirements and Challenges



Corn, followed by soybean, is a standard crop rotation in many parts of the US. However, corn kernels dropped during harvest can germinate in the next season and compete with soybean.

Volunteer corn is problematic as it robs soybean of nutrients, sunlight, and water and can reduce yield. Volunteer corn is more competitive than any other weed, and more and larger plants increase soybean yield losses. One volunteer corn plant per 10 square feet reduces yield by 8% to 9%, and one corn per square foot reduces yield by 71%.

If growers allow volunteer corn to grow large, they require more herbicides to control them. Volunteer corn also attracts rootworms, which can become a problem for the next season's corn crop. If untreated with additional herbicides, glyphosate-resistant volunteer corn can't be controlled by Roundup used for soybean weeds, and the chances of resistance buildup can increase.





Individual volunteer corn in the soybean field


Traditionally, growers used tractors fitted with sprayers for whole-field post emergence spraying, swelling the cost of treatment. Moreover, the tractor's movement caused soil compaction, reducing yield per acre. Since it is necessary to travel in opposite directions to avoid shadows of sprays and improve herbicide application around and on weeds, growers were driving more, resulting in more damage to their crops.



How DJI and Agremo Approached the Challenge



Drones offer solutions for both field scouting and spraying. As a result, not only crop loss due to soil compaction and crop destruction can be avoided, weed infestation can be treated precisely with spraying drone’s spot spraying capability. DJI’s partner, Agremo, offers a key function in this precise spraying solution – Weed Detection Analysis. This analytical tool can precisely identify the exact location, extent, and degree of weed infestation, and prepare an AGRAS drone spraying map, using the crop insights from the analysis, allowing drones to make spot Variable Drone Spraying (VDS) applications of herbicides where the weeds are present, instead of the entire farm.

A farmer agreed to try the VDS application to help in validating the new Agremo-DJI technology.



The DJI Phantom 4 Multispectral drone for field scouting



The volunteer corn weed detection result



The DJI T30 AGRAS drone for herbicide spraying



The Process and Solution - A New Collaborative Service



The farmer went about creating the VDS maps for DJI drones based on Agremo analysis, and the ease of use and accuracy were tested on their field, using the following technology workflow:


  • Ground truth process: Field data on weeds' identity and densities were collected manually from one point in the test farm. A location pin or polygon can mark the plot to integrate it later into digital maps.
  • Mapping & AI analyses: DJI drones P4M collected imagery of the farm, which were stitched to prepare field maps.
  • Agremo analysis: The stitched map was analyzed automatically by Weed Detection analysis, based on AI, machine learning, and computer vision, informed by state-of-art vegetative indices for weed analysis.
  • Project report: The analysis result was a report that showed the analyzed data and map depicting three zones with varying intensities of volunteer corn infestation.
  • Spraying maps: Agremo used the analyzed map to prepare a prescriptive VDS map compatible with the AGRAS drone platform.
  • Field spraying: The farmer used a DJI AGRAS T30 drone equipped with the new spraying map prepared by Agremo to spot-treat the specific zones where volunteer corn infestation occurred.


By comparing detection result with ground truth, the Agremo analysis was over 95% accurate.



Farmer’s gains from the Agremo & DJI Service



The DJI Agras drone flew and sprayed only the spots where the farmer had volunteer corn in soybean.

Of the total 65 acres of farmland, the farmer had 3.75 acres of individual corn and six acres of clumped corn, and if the farmer had not controlled the volunteer corn, they would have suffered a loss of 15% and 60% yield, respectively. See Table 1.

Table 1: Weed infestation areas and possible losses if volunteer corn were not controlled.




Weed area (acre)

*Yield reduction %


(bushels per acre)

Soybean prices (per bushel)

Yield losses


Individual volunteer corn






Clumps of volunteer corn






Total yield losses






Avg yield losses per acre








The expected farm yield is 50 bushels per acre sold at $15 per bushel. The farmer would have incurred a total loss of $3122, $422 due to individual corn, and $2700 due to clumped corn. That would have been a loss of $48 per acre.

With the new technology from Agremo and DJI, the farmer treated only 9.75 acres instead of treating the entire farm with flat spraying rates, saving considerable money. So the increased yield that the farmer obtained by treating the crop was not the only benefit of the new technology.



Returns on Investment



Using the spot treatment increased the farmers' ROI in two ways:

1.      Reducing the amount and cost needed for herbicide treatment.

2.      Eliminating crop losses due to driving.

Table 2: Comparison of flat and Agremo-DJI spot treatment costs shows that the prices per acre are lower, and yield and profits are higher.




Area (ac)

Herbicide cost per acre

Yield lost to driving

Yield loss if not sprayed

Weed management cost


Profit per acre



















The cost of flat spraying the entire field at $7 per acre would have cost the farmer $455, and the yield losses due to soil compaction caused by driving would have been $975 (or $15 per acre). So the total cost to the farmer from flat spraying would be $1430.

AGRAS sprays only those places that Agremo AI identified, so the farmer had to spend only 60% of the herbicides. The cost for the chemicals was only $4.20 per acre or $273 for the entire weed management. Moreover, the yield was higher as there were no crop losses due to driving. So their ROI from spot treatment is significantly higher than from flat treatment.

With a savings of $17.80 per acre, the farmer's ROI from the Agremo-DJI spot treatment was 68.39% higher than the flat treatment! And that is a bottom line hard to beat.


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