App: TerrHum
Developer: Augusto Zanella
Genres: Education

TerrHum is a University of Padua free app that allows the main content of a field guide to be stored on an app. The name TerrHum is an abbreviation of the words “Terrestrial” (not hydromorphic, not submerged) and “Humipedon” (organic and organic-mineral soil horizons).
With this application, it is possible to classify all non-submerged forest topsoils of our planet. The app is built on the indications about humus forms and systems reported in eight scientific articles collected in an Applied Soil Ecology special issue entitled Humusica 1 (Zanella, A., Ascher-Jenull, J., 2018. Editorial. Appl. Soil Ecol. 122, 1–9. doi:https://doi.org/10.1016/j.apsoil.2017.11.029). 
The articles are the fruit of many years of researches and meetings of a Humus Group gathering more than 50 soil ecologists, biologists, and naturalists.
Once all figures (about 150) have been opened a first time (with a fiber connection, the download of all the figures takes few minutes), the device on which the application has been downloaded does not need to be connected to the Internet to run the application. The recall through touch-buttons of photographs allows a classification of the humus forms and the main groups of animals that live there even for beginners.

Let us consider a user faced with a soil profile to be classified. A cubic volume of 50×50×50 cm is generally sufficient for studying humus systems and forms in a forest environment, while a larger hole or many well-distributed small holes are necessary for surveying a heterogeneous area. As a humus form is made of superposed humus horizons, the app asks the user to indicate one-by-one which types of humus horizons are present in the observed profile. The user is asked to answer a series of YES/NO questions. He can use the touch-buttons for help and display examples of horizons, types of transition or humus systems, as well as forms and tables of composition/classification of humus horizons, or groups of animals and droppings. At the end of the survey, a photograph of the target humus form appears, along with a list of the chosen horizons. 

By clicking on the screen, each photograph may be magnified. A caption that appears at the bottom of the picture provides access to the morpho-functional features of the soil profile that lead to the result: the final classification of the humus system. The app is freely downloadable and in continuous evolution (automatic update). To contribute to its improvement, simply send your suggestions, photographs, schemes, etc. to: augusto.zanella@unipd.it. Your name will be reported alongside a photograph or a relevant improvement, as in an open source app. 

Information about the topsoil classification and indications about the topsoil functioning are given in Humusica 1, articles 1, 2 and 3. Supplemental specific information about diagnostic horizons and humus forms may be found in Humusica 1, articles 4, 5 and 6. Sampling panel and pedofauna are illustrated in Humusica 1, articles 7 and 8.

Humusica 1 articles here: https://www.sciencedirect.com/journal/applied-soil-ecology/vol/122/part/P1.
Corresponding author: augusto.zanella@unipd.it

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