A SEMI-AUTOMATED MODEL TO ASSESS POSITIONAL ACCURACY OF SOIL SURVEY PEDON POINT DATA FOR INDIANA Minerva J. Dorantes, Phillip R. Owens, PhD., Darrell G. Schulze, PhD., Zamir Libohova, PhD.

IMPORTANCE OF SOIL PEDON DATA Input for predictive models Regional to field scale and smaller

CURRENT STATUS OF SOIL PEDON DATA Due to database migrations, limited quality control, and inherent error associated with soil surveying Soil pedon data is often Incomplete Not in a usable format Erroneous “…the database has not been edited to remove all of the erroneous or sometimes misleading data. Users are responsible for the assessment of the accuracy and applicability of the data.” (NCSS Soil Characterization Data General Info.)

OBJECTIVES 1.) Develop a methodology to improve the positional accuracy of pedon point data for Indiana collected before GPS was widely used in the field 2.) Place pedon points in a geographic location within an environment and soil forming factors that were originally described 3.) Assign a measure of positional accuracy to all pedon points

HYPOTHESES 1.) Legacy data and expert knowledge are necessary tools to improve the positional accuracy of pedon points 2.) Pedon points can be moved to a more accurate location by matching their soil environment to information stored in the Survey databases 3.) ArcGIS tools can be developed to assign a clear measure of positional accuracy

U.S. SOIL SURVEY PEDON DATA Pedon data for Indiana: First collected in 1967 Cooperative effort between U.S. Soil Survey and Purdue University Strict guidelines outlined in the Soil Survey Manual Site Descriptions included: Landscape details Describer’s information Date

U.S. SOIL SURVEY PEDON DATA Pedon data for Indiana: Migrated into NASIS in 2007 Source used to Georeference pedon data: Prior to 1995, 5-point system for location After 1995, GPS unit for location

U.S. PUBLIC LAND SURVEY SYSTEM PLSS – tier system of grids of decreasing land area Standard lines: principal meridians and baselines Townships and ranges Sections Quarter sections (Q) Quarter Quarter sections (QQ) Quarter Quarter Quarter sections (QQQ)

U.S. PUBLIC LAND SURVEY SYSTEM Northwest corners of a Township are very irregular Excess or deficiency here Convergence/divergence of the meridians Correction lines installed Portions of Indiana were surveyed using different systems

5 – POINT SYSTEM FOR LOCATION 5-point system describes a location Distance and cardinal direction from corner or center of section Soil scientists used orthophoto or 7.5” topo map SE1/4 of SE1/4 of SW1/4 of Sec.10 T2N R3W Second Principal Meridian (Steinhardt et al., 2013)

NRCS METHOD TO LOCATE PEDON POINTS Thomas Reinsch’s PLSS Conversion Model Textual location description  coordinate point The X, Y coordinates generated are official pedon locations in NASIS Issues with the PLSS Conversion Model 1. Accuracy of the model depends on equal-area polygon sections 1. Assumes corners are ½ mile North or South and ½ mile East or West of the section centroids 2. Does not describe locations beyond the section 3. Computer code is difficult to follow

ACQUIRING A STATEWIDE SET OF PEDON POINTS Extracted 4,141 pedons with location details from NASIS Pedon data was exported from multiple tables: unique identifier or User Site ID County, location description, PLSS meridian, range, township, section, section details, coordinate locations (lat/long and DD) and datum, drainage class, parent material, taxonomy Missing information in the location descriptions was populated whenever possible

U.S. Soil Survey Pedons for Indiana in their Official Locations Pedon placed in : Greenland Atlantic Ocean Missouri Ohio

POPULATING MISSING DATA Missing principal meridian Missing or erroneous directionality (N, S, E, W) of townships and ranges Ex. “T2W, R3N” not the correct “T2N, R3W” If PLSS details did not contain 5-point reference, we assumed point was sampled in center of smallest parcel

CREATING A MORE DETAILED PLSS GRID Trace surveyor’s steps Albert White’s, A History of the Rectangular Survey System (1926) 1850, General Instructions to His Deputies By the Surveyor General of the United States, for the States of Ohio, Indiana, and Michigan Meticulous details of how IN was surveyed into PLSS

CREATING A MORE DETAILED PLSS GRID General Instructions translated to visual representation 4 sets of sections with different dimensions for N, S, E, W boundaries Corners of the Q sections defined mathematically for a computer model Coordinates of corners defined in relation to section corners and to each other

CREATING A MORE DETAILED PLSS GRID ArcPython script to automatically generate a Q PLSS grid for Indiana “New PLSS grid” contained full PLSS component information for every section and subsection QQ and QQQ section grids derived from the Q section grid Attribute table information for the NW ¼, NW ¼, NW ¼ Sec 36, T22N R5W, 2 nd Principal Meridian subsection

VALIDATING THE NEW PLSS GRID Q Q Q Sections

NEW PLSS GRID VS. DNR’S PLSS GRID Q Q Q Sections DNRNew PLSS Grid

GENERATING PLSS MODEL PEDON POINT LOCATIONS

COMPARING POINT LOCATIONS

MATCHING THE SOIL ENVIRONMENT DESCRIBED Accuracy of point locations in relation to original soil described at sampling site Pedon site description details to define “soil environment” Drainage Class, Parent Material, Taxonomic classification (order, suborder, great group, subgroup, and family particle size) Soil Environment compared to data in SSURGO Mukey  component details Up to three major components

“SOIL ENVIRONMENT MATCH MODEL” – RESULTS

“NAUTILUS MATCH MODEL” Applied the Soil Environment Match Model to each pixel in a 21x21 neighborhood Search radius of 140 meters Assigned new X, Y coordinate at pixel of matching soil environment

“NAUTILUS MATCH MODEL” - RESULTS Model UsedNo. PedonsPositional Accuracy Soil Environment Match Model1308Exact match to soil environment, 0 meters Nautilus Match Model – No Match2550No match to soil environment, > 140 meters Nautilus Match Model283Match to soil environment found, < 140 meters

LIMITATIONS deficiencies in the input pedon data Updates? level of detail contained in location descriptions SSURGO components of “soil environment” are a generalization of the soils High computer processing power to run Nautilus Match Model Exponential increase in computing power with one level increase in search radius

CONCLUSION 3 models developed to assess positional accuracy of pedon points: PLSS Model Soil Environment Match Model Nautilus Match Model Multi-purpose models Tools did not exist in this format in ArcGIS Only way of truly knowing where the point was sampled, to use original field sheets and validation at the site Best estimate of soil pedon location is the soil environment Inform soil scientists of errors Model to help guide countries that are developing soils database now

Thank You…. My advisors: Phillip Owens, Darrell Schulze, and Zamir Libohova Mike Wigginton, Henry Furgeson, Thomas Reinsch, Gary Struben, Rick Nielsen