Lesson 3 - Processing a Multi-Layer Yield History

Background
Yield maps represent probably the most valuable data layers when it comes to identification of problematic field areas and setting up spatially variable yield goals. In most instances, at least 5 years of yield history is needed to make strong conclusions in terms of spatial and temporal variability of field productivity. The preliminary step toward yield data analysis is converting log files from proprietary binary code to an ASCII text with columns corresponding to geographic latitude, longitude, yield and other relevant attributes. During conversion, or right after it, each layer of yield data should be adjusted for various combine dynamics delays and filtered to remove all the records containing erroneous data. This can be achieved with the number of options. Most agriculturally-oriented software packages with GIS components (e.g., SMS, FarmWorks, FOViewer, etc.) can be used to open binary yield files and to extract data corresponding to individual fields. Some portion of data filtering can be accomplished during this conversion. However, additional, more advanced, data processing should be pursued to recognize less obvious problematic records and assure higher quality of the resulting yield maps. Yield Editor and Yield Check are two examples of free software designed for advanced filtering of yield data. Clean layers of yield data should be integrated through the averaging of normalized surfaces or various classification procedures aimed at the establishment of management zones. This lesson provides an example of yield history analysis based on two years of corn and three years of soybean records.

Objectives

Remove erroneous yield data records
Process yield data corresponding to individual growing seasons
Develop a yield goal map
Establish an elementary yield classification routine

Instructions	Objective	Input data	Output project
Exercise_3-1.pdf	Yield data cleanup	Yield_2002s_raw.txt	Yield_2002s.txt
Exercise_3-2.pdf	Single season yield map display	Boundary.zip & Yield.zip	Project_3-2.map
Exercise_3-3.pdf	Yield goal estimation	Project_3-2_all.map	Project_3-3.map
Exercise_3-4.pdf	Yield classification	Formula_3-4.txt	Project_3-4.map
Exercise_3-5.pdf	Yield map layout		Project_3-5.map

Please e-mail vadamchuk2@unl.edu to obtain the password allowing complete access.

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