How OneSoil Yield and the HarvestLab™ sensor help pick a nitrogen application strategy

Check out the experiment results on variable-rate application (VRA) of nitrogen for winter wheat. In this article, we show how the rate of nitrogen affected both the yield and grain protein content.
Usevalad Henin
Usevalad is an expert in GIS and agricultural chemistry. He has been developing precision farming tools since 2013. He is also the co-founder of OneSoil.
Before, I only shared about my experiments on this blog. But this time, we're talking about the experience of a farmer from the Czech Republic, Lukáš Podhola. His farm grows wheat, corn, rapeseed, and barley as well as grass to feed 2300 cows. The total area of the farm is about 3000 hectares. Lukáš works with our partners, STROM Praha (the official John Deere dealer in the Czech Republic) and uses the OneSoil Yield app. He used it for this experiment as well.
Some photos of Lukáš's farm

About the experiment

This season, Lukáš applied nitrogen to his winter wheat field twice: in February (regenerative fertilization) and in March (production fertilization). Both times, he applied nitrogen by VRA maps based on vegetation data: increasing the standard rate in high vegetation areas and decreasing in low ones.
  • Lukáš Podhola
    Thanks to the variable-rate application, I managed to significantly save on fertilizers this season!
For the first application, Lukáš added control strips to his task map. Thanks to these control strips we are able to assess the results of VRA after harvest. The nitrogen rates for this application were 250, 300, and 320 kg/ha.
Productivity zone in the OneSoil web app_OneSoil Blog
VRA maps used by Lukáš: with control strips (right) and without them (left)
Without control strips, you can't assess the effectiveness of VRA technology in the field. In the past, I used to create them manually for every experiment. Now, we've taught the OneSoil Yield algorithms to do it just as well, but much faster. With OneSoil Yield, you can create task maps with or without control strips; based on vegetation or productivity data; for fertilization or seeding.

Experiment results: yield

After the harvest, Lukáš uploaded the yield map to OneSoil Yield to compare it with the task map and get a report on the experiment.
Slope map_OneSoil Blog
Yield map (left) and the task map used for nitrogen application (right) in OneSoil Yield
From the results, we see that the nitrogen rate barely affected the yield. When reducing the nitrogen rate, there was a slight yield increase in low and medium vegetation areas. This means in future seasons, we can consider reducing the application rate, which will allow us to spend less on fertilizers without compromising the yield. Considering that Lukáš already saved on fertilizers this season, the field's profitability might increase even more in the future!

However, keep in mind that the weather has a significant influence on how the nitrogen works. So if next season's weather conditions differ greatly, the results of the same nitrogen application strategy might change.
Slope map_OneSoil Blog
In OneSoil Yield, we show which rate worked best for each zone

Experiment results: protein content

But that's not all! Our field was harvested by a combine equipped with a new sensor from John Deere — the HarvestLab™ 3000. This sensor can measure the protein content in the grain right during the harvest! So, in addition to the yield data, we also obtained information about the protein content at every point in our experiment field.

In OneSoil Yield, there's an option to visualize maps with protein or starch content, and to compare them with task maps. Let's see how the variable-rate nitrogen application affected the protein content in the wheat.
Slope map_OneSoil Blog
Protein content map (left) and the task map used for nitrogen application (right) in OneSoil Yield
We can see that the protein content increased in each zone when the nitrogen rate was reduced.
Slope map_OneSoil Blog
Here is how the nitrogen rate affected the % of protein in the grain (average percentage indicated for each rate)


Next season, we can consider reducing the nitrogen application rate: it won't decrease yield but will allow us to save on fertilizers and increase protein content.

We reached this conclusion thanks to two things: the HarvestLab™ 3000 sensor (it gave us additional data about protein content) and the control strips from OneSoil Yield (they allowed us to compare the effects of different application rates in each zone).

Experiment conducted by Lukáš Podhola
Text written by Usevalad Henin
Text edited & article layout by Katya Zhurauliova
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