GIS Ag Maps Preferred Yield Monitor Data Cleaning and Management
(See below for images of yield map cleaning)
Details about yield map cleaning as well as examples are included in the Yield Monitor Data Cleaning & Mgmt. folder on the left menu. Research shows 10 to 50 percent of yield points need to be removed and the erroneous data can strongly effect the resulting yield distribution and “if the errors are not addressed, the user of the yield map may reach erroneous conclusions, calling into question the credibility and validity of the results” (Sudduth and Drummond, 2007).
Preferred Yield Monitor Data Cleaning and Managment, Parts 1 and 2
A description is provided below about how to use free yield monitor data software in order to complete part of the yield cleaning process yourself. The price for GIS Ag Maps to complete Part 1 is $15 plus 10¢ per acre. Proceed to Part 1 if you would like to complete this step yourself.
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Part 1
Use Free Yield Editor 2.0.7 (beta version); it can be downloaded here (outside page; opens in new tab). Yield Editor requires either AgLeader advanced or Greenstar text file (if your files are not in this format, they may be able to be modified; if data cannot be modified to work with Yield Editor, a shapefile can be used). Follow the steps in the tutorial in the download, applying AYCE as shown in the first tutorial then the manual techniques as shown in in the second tutorial. Following these steps if using Yield Editor 2.0.7 (beta version):
Part 1: Step 1
Apply Automated Yield Cleaning Expert (AYCE) settings as shown in the graphic below. AYCE cleans and corrects certain aspects, but there is still more filtering to be done in Yield Editor as is described in Step 2.
Part 1; Step 2
After running AYCE and certain corrections are automatically made, apply the following filters: 1) Correct for start and end pass delay; there will be erroneously low yield values at beginning and ends of rows that can be removed with these filters (there should be connectivity between values at end of rows and valid values in transects on outsides of field that area perpendicular to main transects); 2) Change “Smooth” Velocity to 0.1; 3) Change the standard deviation limit filter to 3; 4) Make header down required; 5) After applying the previously described filters, it is absolutely essential to manually delete erronoues points. Change and apply minimum and maximum yields only if you are certain your yield monitor was properly calibrated when you acquired the data. Call or email GIS Ag Maps if you have questions about this (support@gisagmaps.com or 419-217-6368). After completing Part 1, a yield map should look similar to images 5 and 12 in the slideshow below.
Part 2
The price for GIS Ag Maps to complete Part 2 is $35 per field (flat rate).
If you completed Part 1 and would like GIS Ag Maps to complete Part 2, export the edited yield file as a text file (.txt) and email it to GIS Ag Maps at: gisagmaps@gmail.com
Final edits will be made (if appropriate) and the data will be smoothed and developed as evenly spaced points (four meter spacing is recommended). All yield maps will be processed to have yield values (for whatever the crop may be) at the same point locations as shown here. After completing Part 2, a yield map should look similar to images 6 and 7 as well as 14 and 15 in the slideshow below; images 19 and 20 additionally show that the different yield maps have been processed to have points at the same location. Statistical analysis is included. Contact GIS Ag Maps for zones developed for variable rate application of phosphorus and potassium as shown in slides 8 and 16.
Yield monitor data cleaning and management slideshow; corn and soybean yield map examples
(The examples below are of corn and soybean yield maps; methods can be applied to any crop or size and shape of field. Points are classified with natural breaks [lowest to highest is red, orange, yellow, green, and dark green]).
Images transition every 4 seconds (or click arrows)
Prior to cleaning the map (if correct formats for Yield Editor are not available), GIS software is used to asses the accuracy of grain flow delay; a correction to the yield map may or may not be necessary. Duplicate (co-located) points can occur in yield monitor data; if there are duplicate points after manual removal of yield points, they are removed at that point (prior to outlier removal) as is the case with the soybean yield map. The map is assessed after outlier removal to determine if more manual editing is needed; if it is necessary (as is the case with both examples above), more editing is done at that point.
Points in the clean, smoothed map are calibrated to the yield range and average amount of the last map (step) prior to smoothing (which is outlier removal or [usually] more manual editing); or calibration of a range and average yield amount can be to your specification. The preferred method is for you to clean the map with free Yield Editor to the last manual editing step and have GIS Ag Maps smooth and manage the map.
When one map is cleaned, all subsequent maps can have points at the same location (as is shown in the slideshow) which will help with organization and to determine yield patterns (and statistics) at the same location over time. To do this, the nearest yield points from a clean yield map with one-meter spacing is joined to the points; the average distance a joined point will be is about one foot. Points at the field boundary that essentially encircle evenly spaced yield points can also be included. This is described and shown in the Yield map management and statistical mapping page.
Reference
Sudduth, K.A., and S.T. Drummond. 2007. Yield Editor: Software for Removing Errors from Crop Yield Maps. Agronomy Journal99: pp. 1471–1482 (pdf) (document opens in new window)