What were the criteria to delimet the textural classes (i.e loam, silt loam, loamy sand, etc) ?
The USDA soil texture triangle has been built using line limits among the textural classes. Does someone know how were the criteria used ?
This might help...
http://www.wcc.nrcs.usda.gov/ftpref/wntsc/H&H/training/soilsOther/soil-USDA-textural-class.pdf
Starting Page 15, there's an explanation on how the textural classes were defined with regard to the sand, silt and clay percentages.
http://www.wcc.nrcs.usda.gov/ftpref/wntsc/H&H/training/soilsOther/soil-USDA-textural-class.pdf
Milton Whitney (1911) published the first plot of soil class boundaries in Cartesian coordinates ( which became a right angle triangle because all fractions must add to 100). The coordinates of this diagram are silt fraction on X-axis (0-100%) and clay fraction on Y-axis( 0-100%). This work was truly an international landmark in giving the desired fillip to first quantitative basis for classification of soil textural classes. Davis and Bennett (1927) published first equilateral textural triangle ( Sand, silt and clay fractions represented on equal axes) .
An empirical method was used ( see below)
from:http://umnsoilsteam.blogspot.com.br/2014/09/the-historical-development-of-usda.html
Soil scientists involved with survey work at the time were asked to classify soils in the field based on accepted class names in their region. These samples were then sent to the USDA Soils Bureau laboratory, which performed mechanical analysis on 8,664 samples. The results of these analyses were used to provide field limits (and hence class boundaries) for 8 soil textural classes. The approach of matching textural class boundaries based on mechanical analysis to perceived field textures and class names (and not the other way around), has driven the lasting utility of the USDA triangle.
Dear Igo, Annop and Raghanvendra. Thank you so much. Now I understood the "crazy" boundaries among the textural classes, and they does not looks like so crazy anymore. Im trying to understand the correlation between soil water retention in the wilting point and soil textures classes. Maybe I will need other boundaries for this purpose, the nowadays boundaries are more related to mechanical properties than with my goal. Let see.
Anyway: Some native speakers can explain why the names of the class is silty clay and silt loam (why it is not silty loam ?). The same to sandy loam and silt loam (not silty loam ?)
Yes, Dr. Anoop Kumar and others explained well the history and the way, the textural triangle was constructed. I think, this material in response to the question is appreciable.
Textural triangle for soil textural classification is for guidance only and it should not be taken in absolute sense for its precision since soils are extremely dynamic entities which keep on changing their properties in the course of their exposure to climatic and biological factors of soil development.
Many physical chemical and biological properties are inter related. Drainage related to the aeration and water retention and availability affect the chemistry and biology. The use of one single group of parameters for example physical alone does not do justice to the others chemistry and biology parameters which are all inter related.
Ideally all should be used together physical, chemical and biological but the limits of human intelligence can out strip our human ability to understand their interactions and utilize the information effectively.
The use of multivariate statistical approaches and factorial experimentation is helping however and our informational tools are rapidly improving. This may be changing for information limited system to human intelligence limited one as our technology is becoming so sophisticated with the machine make the mind unnecessary.
I often complain that my phone has become smarter than I am. As we depend more and more on machine power do will lose our native ability to calculate and problem solve and does it make any difference if the machine resolved the issue?
Dear Wenceslau Geraldes Teixeira.
I would recommend you:
1. Canarache A., Motoc E. A new criterion for selecting soil separate size limits // Proc. 8th Intern. Congress of Soil Science.- Bucharest, 1964. V.2, P. 313-325
2. A. Nemes, J.H.M. Wosten, A. Lilly, J.H. Oude Voshaar Evaluation of different procedures to interpolate particle-size distributions to achieve compatibility within soil databases / Geoderma 90 1999 187–202
and their References
3. Minasny, B., McBratney, A. (2001). The Australian soil texture boomerang: a comparison of the Australian and USDA/FAO soil particle-size classification systems / AUSTRALIAN JOURNAL OF SOIL RESEARCH 39(6):1443-1451
Try to contact:
https://www.researchgate.net/profile/Budiman_Minasny
https://www.researchgate.net/profile/Alex_Mcbratney
Good luck
https://faculty.unlv.edu/buckb/COUNTY_DCP/Nemes%20et%20al%201999.pdf
Dear colleagues,
I guess one advantage of this kind of question forum in the Researchgate is to facilitate the exchange of information in specific topics and the inputs that are recorded for future use.
I have found a nice package wrote in R to explore soil texture data '(The soil texture wizard: R functions for plotting, classifying, transforming and exploring soil texture data wrote by Julien Moyes) it is available here: https://cran.r-project.org/web/packages/soiltexture/vignettes/soiltexture_vignette.pdf
Enjoy
Dear Dr. Wenceslau Geraldes Teixeira,
Quite a while ago, you asked a very interesting question about the naming of the soil classes, as shown below;
"... Anyway: Some native speakers can explain why the names of the class is silty clay and silt loam (why it is not silty loam ?). The same to sandy loam and silt loam (not silty loam ?)"
Did you get any answer to this very interesting and challenging question? Recently, I saw this correspondence and have a great curiosity about the answer.
Really, is there any explanation about these naming ?
Dear colleagues. Someone has this publication ? I m quite curious to learn about
the sand drop phenomena - "sand drop" - that is, on the sandy side of the triangle, the threshold clay percentages are lower than for the subsequent loam or silt loam classes. This is largely due to work by Marshall (1947)
Marshall, T.J. 1947. Mechanical composition of soil in relation to field descriptions of texture. Council for Scientific and Industrial Research, Australia, Bulletin No. 224.
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