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Harvest Drydown: Grains, Corn, and Soybeans

How to use TerrAvion imagery to help identify optimum moisture levels for harvest.

Corn, soybean and grain fields dry down unevenly, resulting in difficult balance between moisture levels, yield levels, and harvest requirements. TerrAvion imagery helps to identify optimum moisture levels across an entire field to determine the ideal time to harvest.

The NDVI image below of a corn field is taken on September 23rd. In monitoring drydown, the first step would be to ground truth this image, and determine how a certain level of dryness is correlates to the vigor scale. For example, you can correlate measured moisture content of the crop in certain areas to the NDVI scale to get an understanding of moisture - NDVI relationship for the entire field. In this case, let’s assume that the grower determined that optimal moisture level for harvest correlates to .14 - .26 on the NDVI scale, which is illustrated on this map by the yellow and orange.

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If we look at the histogram for this NDVI image, we can see that only 21% of this field has reached the ideal dryness levels. In this specific case the field is not ready for harvest.

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In this NDVI image of the same field taken 2 weeks later, you can see that the field has matured further and looks mostly yellow and orange.

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If we look at the histogram for this image, we can see that 57% of the field has reached the optimum dryness level, while another 29% is approaching the ideal level of dryness. At this point, for this specific case, the majority of relative dryness throughout the field is at or just about to enter to ideal dryness levels for harvest.

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This is an NDVI image of a soybean field taken on September 17th. 13% to 15% moisture, which in this example represents the ideal moisture level for harvest, correlates to .14 - .26 on the NDVI scale.

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If we look at the histogram for this NDVI image, we can see that 69% of this field is at the optimum dryness level. Soybean dryness levels can decrease quickly, and TerrAvion’s quick turnover from the moment the images are taken to the moment they are delivered allows you to rely on our imagery to make time sensitive decisions in determining to optimum time for harvest.

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How To Determine The Ideal Time To Harvest With TerrAvion :

  1. As the time for harvest approaches, ground truth your TerrAvion imagery as soon as possible after they are delivered. TerrAvion delivers you imagery within 24 hours after it was captured. By ground truthing your imagery as soon as you receive it, you will get an accurate understanding of how the moisture levels in your field correlates to NDVI values in your imagery, allowing to you make informed harvest decisions based on your imagery,
  2. After ground truthing your imagery, determine the NDVI value that represents the ideal moisture level for harvest.
  3. Review your imagery and determine how much of your field is of that NDVI value.
  4. Use the histogram tool to get more exact figures on the moisture levels throughout your field.
  5. Use the NDVI representation of moisture levels in your fields to inform a decision on when to begin a harvest.

This is how you can use TerrAvion imagery to determine the ideal time to harvest based on the relative dryness levels across your field.

Please visit TerrAvion.com for more information.