Yield Data Analysis

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{{#customtitle:Analyzing average yields by management zones|Analyzing average yields by management zones}} In this tutorial, you can download a sample dataset with Yield Maps and management zones layers, to review the process of analyzing yield data.

This will show how to carry out data analyisis of  two variables by:

  • relating one variable to another - e.g.: for each yield data point, assign a management zone
  • exporting to excel to summarize and analyze data. In this case, we will evaluate what were the average yields in each management zone.

Download sample data

For these exercises we are going to use  a sample dataset: 'Sample_Farm_Yield_Analysis'.

For this purpose, you can follow the steps detailed in Download sample data, with the following parameters:

  • Create new Project with the name: 'Sample_Farm_Yield_Analysis'
  • As the initial dataset, select 'Sample_Farm_Yield_Analysis', which can be found under the 'Tutorials_en' folder:

  • After importing it, you will see the screenshot below, showing you the layers that will be imported and information regarding whether their structures are already available in your GeoAgro GIS setup, or not. Click on "Accept" to import the yield structures which are not already in your computer (doing otherwise will result in not importing the Yield layers, and not having them available for the excercises below)

Image:Yieldmaps structures.png

Review management zones

The sample farm is located in Argentina's pampas, and sample fields were planted with wheat.

  1. Double click on the 'Farm' layer, to zoom to the farm's extents.

  2. Double click on the 'Management Zones' layer to turn it on and zoom to its extents.
    click to see full screen

  3. Click on the '+' sign to view the legend for the management zones. In this case, the Management zones definition is based on Topography, Low to High in the legend refers to the topography of the farm.

  4. You may change the management zones Layers transparency to see how they relate with underlying imagery, and low zones can be appreciated.
    Yieldmaps 03b.jpg

Review Yield data

  1. Double click on the 'YieldP_Wheat_F4' layer to turn it on and zoom to its extents.
    Please note that YieldP_Wheat_F4 has yield information by Point, YieldG_Wheat_F4 has yield information by Grid, and Yield_Wheat_F4 has yield information by Polygon
    Click to see full screen

  2. Click on the '+' sign to view the legend for the yield maps.

    It's interesting to see that ranges vary from under 41 bushels/acre to more than 83 bushels/acre, which is comparable to average wheat yields in wheat areas in the US and Canada, as detailed in this article: Average yield of wheat

Base Layers - a tool for relating data from different layers

To be able to analyze data, GeoAgro GIS works with the concept of a 'Base Layer'. This is how it works:

  • First, you define a base layer and attribute
  • All overlapping features from other layers, with the same attribute in their data structure, will have the attribute value autocompleted.

For instance, in our project, the Base layer is 'Management Zones', and the attribute is 'Productiv'.

Thus, all yield points will have the same value for attribute 'Productiv' as the management zone underneath.

  1. Zoom in to Field 04
  2. turn off the 'YieldP_Wheat_F4' layer.
  3. select the Query Data by Feature option
  4. Select the "Management Zones" layer
    Screenshot 73.png
  5. Click on the selection tools, and then on any of the management zones, to see the 'Productiv' value. In the figure below 'Productiv' = 'MEDIUM' 

    Yieldmaps 05.jpg

  6. turn on the 'YieldP_Wheat_F4' layer, and click on it to make it active.
  7. Select some of the points on the previous management zone using selection tools
  8. then use the Query tool, and select the option 'Quey data by selection'.

  9. The attribute table for the selected yield data will open, and you can verify that it has the same 'Productiv' value
    Click to see full screen

  10. So if we represent yields by management zone, we will see that it has the same attribute as the base layer:
    . turn off the 'YieldP_Wheat_F4' layer and turn on the 'YieldP_Wheat_F4_MZ' which is classifed by 'Productiv'
    . zoom in to see the represented yield points

    Click to see full screen

Export to Excel and analyze Yield Data 

By relating Management zones and yield data, we can apply it to yield data analysis. You can select a group or all of the yield points, export to excel and analyze the relationship between yields and management zones.

Now, we are going to export all yield points to excel for analysis.

Note Note: This process may take some time, in this example it took 1:30 min, in a system with these characteriscitcs:

Yieldmaps 08.jpg

  1. Make the 'YieldP_Wheat_F4' layer active by selecting it on the Legend panel.

  2. Then use the Query attributes by layer tool


    The query will be performed on all the objects of the layer without previously selecting them. And select the YIELDDRY field from the attribute dropdown list to see its summary statistics.


  3. Now click on the Export button to export the table to Microsoft Excel.


  4. Once the results are in Microsoft Excel, you can apply various statistics functions to analyze the data.

    For this example please download this sample spreadsheet. Click on the 'Avg Yield per MZ' tab to see the summary of Yield average per management zone.

    Yieldmaps 11.jpg

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