NASIS Concepts

In making the change from SSSD to NASIS, you will encounter two major new concepts: the relationship between legends and data mapunits recorded in the correlation table, and “owned objects” (described below). You’ll also find some new terms for data you’re already familiar with: in NASIS, inclusions are termed components, and layers have become horizons. NASIS will accommodate as many components and horizons as you need to document your mapunit composition. You’ll be able to record representative values (RVs) for some data in NASIS, in addition to high and low values.

Legend and Data Mapunit Correlation

NASIS is intended to improve automated mapunit management in several ways:

1. Correlate mapunits in an on-going survey.
2. Join mapunits between survey areas.
3. Share mapunits between projects (for example, an MLRA survey and other subsets).
4. Maintain multiple mapunit legends (survey area, state, MLRA).
5. Maintain complete correlation records.
6. Maintain complete mapunit data for mapunits correlated out of the survey area legend.

To accomplish these aims, the “map unit” has been separated into two parts:

• the legend, which contains the mapunit symbol, mapunit name, type (consociation, complex), acres, and correlation notes; and
• the data mapunit, which includes mapunit composition, interpretation ratings, physical, chemical, and morphological properties, components, and horizons.

In SSSD, a map symbol is hard-linked to unique data in the database. In NASIS, a map symbol is part of a legend, which is linked through a correlation table to a data mapunit in the database. This allows different legend mapunits linked to the same data mapunit (i.e., with the same database data) to be joined exactly. The linkage capability provided by the correlation table between legends and data mapunits in NASIS replaces the functions of the MUUF, SSSD-MUIR, SOI-6, and parts of the SOI-5.

Because NASIS supports a many-to-many relationship between legends and data mapunits, several new ways to handle soil data are possible:

You may use multiple legends for single survey areas.

For example, a mapunit delineation could have two different symbols, one for the survey area, and one for a larger MLRA survey. In addition, if the delineation crossed a county line, a third legend might be used. You can think of this as a mapunit having several different “aliases.” The correlation table will correctly connect the different legends with the same database data.

Information about additional (inactive) mapunit symbols is retained in the database.

Instead of deleting a mapunit symbol which is no longer being used, you may flag it as “additional.” The data associated with the additional legend is attached to another legend. You may or may not want to use this data to represent that legend; if so, specify it as “representative.” If, in the future, a different correlation scheme is desired, the database will still reflect the connection between the inactive legend and the data it was originally associated with.

Owned Objects in NASIS

In SSSD, only the Soil Dataset Manager can edit or delete data. In NASIS, every row in the main database tables (“object”) may be “owned” by a separate group, as specified in the security table. The owner of an object has the authority to change the data as needed.

In NASIS, the major owned objects are Area Type, Legend, Data Mapunit, and Pedon. The first three objects are an extension from SSSD, and the Pedon object is an extension of the old PDP program. The Area Type object contains area and area text entry. The Legend object contains mapunit, correlation, and related tables. The Data Mapunit contains component, horizon, and repeating group tables. For example, the owner of a legend also owns the correlation of each legend mapunit to a data mapunit.

Display the NASIS database structure diagrams.