I will try to find a few old publications.  Basically atctivities can alter texture, such as after Hurricane Hugo, there was a site logged too wet where soil puddled - lost its structure.  Also a publication of a soil scientist that showed the filling of macropores by fines and increased runoff by repeated farming of piedmont soils.  If I cannot find digital copies, I will send the citations.  Of course plowing, deep shearing and buldozing of soils would mix surface horizons and organics, and some textural effects are unavoidable.  Erosion also would contribute to change. 

Dear Dr. Hansen, thank you for your interest in helping me. I really appreciate that. I am interested more specifically on textural changes due to water (run-off) erosion related to LU/LC changes.

Dear Dr, Sobrinho, I agree with the valuable comments made by Dr. Hansen. However if you are very interested in textural changes brought about by water erosion in relation to LU/LC changes, i think that comprehensive reviews on this topic are sparse. However, there are many works that could help you have a synthesis. I therefore give you the following:   1) Assessment of soil particle redistribution on two contrasting cultivated hillslopes. https://doi.org/10.1016/j.geoderma.2005.05.014

2) Changes in soil texture on the slope as affected by water erosion. by J Antal (2003)

3) Effect of Slope Position and Land-Use Changes to Bio- Physical Soil Properties in Nakasongola Pastoral Rangeland Areas, Central Uganda (book chapter) by M. Buyinza and M. Nabalegwa. DOI: 10.5772/24979

Best regards.

Professor Kogge, Thank you for the references. They are very interesting indeed. From what I could grasp from a quick reading of the texts you have sent to me, I couldn't support the hypothesis that a given area of soil can be enriched in sand content by the loss of finer particles as clay and silt because of rain erosion (runoff)... Is that right?

Dear Dr. Sobrinho, you just raised another important concern. I think that an area can be enriched in sand due to loss of fine particles (particularly the silt fraction). Soil can also be enriched in clay content. These changes are related to the type of aggregation formed in the soil, which itself (aggregation) is a function of type of management or land use type. 

I hereby attach a book chapter (see Table 7 on page 33) which gives evidence of sand enrichment for three soil types (Mollisols, Alfisols and Aridisols) following erosion and land use over a period of 36 years (1948 to 1984). 

Here is another good, long-term example of the effect of land use on soil properties.  It also emphasizes that the traditional sand, silt, clay concept of soil texture is not all important since organic matter content and aggregation may be more important.

Robert G. Qualls

Professor, Dept. of Natural Resources and Environmental Science

University of Nevada, USA

Citation: Devine S, Markewitz D, Hendrix P, Coleman D (2014) Soil Aggregates and Associated Organic Matter under Conventional Tillage, No-Tillage, and Forest Succession after Three Decades. PLoS ONE 9(1): e84988. https://doi.org/10.1371/journal.pone.0084988

Dear Professor Kogge, I apologize for not mentioning before, but I'm not Dr. yet :-D Thanks for the references and thought on my question. Indeed Table 7 shows clearly what I was wondering to be plausible.

Dear Professor Qualls, thank you for your answer and reference. Interesting conclusion indeed. For example, I think that for my case (tropical semi-arid - BSh) soil organic matter would not be so expressive in avoiding a sand enrichment due to finer particles loss. 

Dear Sobrinho - I am not responding directly to your query. There are good number of reports that  land use has added OC to the soils and also enhanced aggregation of soil particles. This fact is revealed when soil texture is determined when cementing agents are not used during such determination. But  for real content of sand, silt and clay particles   it is mandatory  to  remove the cementing agents like OC, Fe2O3 and CaCO3 and such size fraction values  represent the inherent soil physical properties under normal soil condition. 

Dear Dr. Dilip. Thank you for your comment. So, perhaps the methodology for texture determination can be introducing a bias on the interpretation of LU/LC effects. It makes sense for me. In my specific situation, we are dealing with semi-arid conditions very unfavorable to OM/OC humification/stabilization, i.e., very oxidizing conditions (low precipitation, high temperatures, non-conservational soil practices, etc). Even in such cases do you think the traditional methods for particle size quantification could be introducing a bias?

Yes, another cementing agent like CaCO3 as inorganic form of C will come to play in soils of dry climate.

Dear Dr. Dilip, Thank you for the very interesting dialog. The soils I find in my study area are quite acidic and there is no evidence of periodic fire in such region. Do you think inorg-C and CaCO3, or any other cementing agents could be present?

Dear sir,

Based on my experience  I am putting my view here. The particle content change for land use is happening but when we express results in relative terms (as %) it is not visible to us. Secondly, there is a wide range of particle content for sand ,silt and clay size under given textural class that it may take long time for this significant change which has not been studied so for. This may be easily to detected in shorter period of time in medium coarse texture soils rather it in coarse and fine texture soil. Similarly it is in the subsurface soil layer over the surface due to soil movement.     

Dear Rajagopal, Thank you for your answer. Indeed depending on the magnitude of erosional processes all top soil (including any particle size fraction) may be washed away with runoff. However, I am interested in supporting the hypothesis of a "selective" depletion: modest runoff is capable of removing lighter particles (Clay minerals and nanoparticles), leaving behind the heavier ones (silt, sand, etc). What do you think about such situations?