Soil Survey

New R-Forge Site for Quantitative Pedology

Submitted by dylan on Mon, 2009-11-09 01:31.

Just back from the annual meetings, and it looks like there is a significant interest in collaborative R coding of soils-related algorithms and visualization. A new R-forge site has been created to host Algorithms for Quantitative Pedology. Public release of the 'soil' package should be ready in a couple weeks.

Soil Profile DendrogramSoil Profile Dendrogram

Aggregating SSURGO Data in R

Submitted by dylan on Thu, 2009-09-10 15:36.

 
Premise
SSURGO is a digital, high-resolution (1:24,000), soil survey database produced by the USDA-NRCS. It is one of the largest and most complete spatial databases in the world; and is available for nearly the entire USA at no cost. These data are distributed as a combination of geographic and text data, representing soil map units and their associated properties. Unfortunately the text files do not come with column headers, so a template is required to make sense of the data. Alternatively, one can use an MS Access template to attach column names, generate reports, and other such tasks. CSV file can be exported from the MS Access database for further use. A follow-up post with text file headers, and complete PostgreSQL database schema will contain details on implementing a SSURGO database without using MS Access.

If you happen to have some of the SSURGO tabular data that includes column names, the following R code may be of general interest for resolving the 1:many:many hierarchy of relationships required to make a thematic map.

 
This is the format we want the data to be in

    mukey     clay      silt      sand water_storage
   458581 20.93750 20.832237 20.861842     14.460000
   458584 43.11513 30.184868 26.700000     23.490000
   458593 50.00000 27.900000 22.100000     22.800000
   458595 34.04605 14.867763 11.776974     18.900000

 
So we can make a map like this
So we can make a map like this

Potential Loss of Arable Land in the Central San Joaquin Valley, CA

Submitted by dylan on Mon, 2009-08-17 15:19.

Rapid urban and sub-urban expansion in the San Joaquin Valley have resulted in the loss of millions of acres of prime farmland in the last 100 years. Approximately 11% of class 1 (irrigated) land and 7% of class 2 land have already been paved over in the Fresno-Madera region (first image below). Recent projections in the expansion of urban areas in this region suggests that by 2085 an additional 28% of class 1 and 25% of class 2 land will be paved over (second image below). This is a preliminary summary-- details to follow.

Fresno Area Urban Areas vs Irrigated LCC: grey regions are current urban areasFresno Area Urban Areas vs Irrigated LCC: grey regions are current urban areas

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Fresno Area Urban Areas vs Irrigated LCC (2085)

Submitted by dylan on Sun, 2009-08-16 18:10.
Fresno Area Urban Areas vs Irrigated LCC (2085)

grey regions are projected urban areas in 2085

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Fresno Area Urban Areas vs Irrigated LCC

Submitted by dylan on Sun, 2009-08-16 18:09.
Fresno Area Urban Areas vs Irrigated LCC

grey regions are current urban areas

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Pedology and Soil Survey

Submitted by vbullard on Thu, 2009-06-11 18:16.

Soil Web

Submitted by vbullard on Thu, 2009-06-11 16:58.

Making Sense of Large Piles of Soils Information: Soil Taxonomy

Submitted by dylan on Wed, 2009-05-27 18:43.

Western Fresno Soil Hierarchy: partial view of the hierarchy within the US Soil Taxonomic systemWestern Fresno Soil Hierarchy: partial view of the hierarchy within the US Soil Taxonomic system

 
Soil Data
Field and lab characterization of soil profile data result in the accumulation of a massive, multivariate and three-dimensional data set. Classification is one approach to making sense of a large collection of this type of data. US Soil Taxonomy is the primary soil classification system used in the U.S.A and many other countries. This system is hierarchical in nature, and makes use on the presence or absence of diagnostic soil features. A comprehensive discussion of Soil Taxonomy is beyond the scope of this post. A detailed review of Soil Taxonomy can be found in Buol, S. W.; Graham, R. C.; McDaniel, P. A. & Southard, R. J. Soil Genesis and Classification Iowa State Press, 2003.