Soil great group

Paleortid

Of the Ortid suborder; it is very old and evolved: very thick clay horizon, or a petrocalcic horizon (calcareous hardpan) indicating a long time of formation.

Paleortid is a name from the 1975 taxonomy, which many INTA soil survey maps were made with. The current edition no longer has this group: today it would be classified as Petrocalcid.

What the name says

Soil Taxonomy names are built from parts, and each part says something about the soil. From general to specific:

Taxonomic orderAridisolSoil arid climate: water is lacking most of the year and the profile accumulates what the rain cannot wash away (carbonates, gypsum, salts) or clay from more humid times.
SuborderOrtidAridisol without clay horizon.
Great groupPaleortidWithin the Ortid suborder, it is very old and evolved: very thick clay horizon, or a petrocalcic horizon (calcareous hardpan) indicating a long time of formation.

What it means for farming

Without irrigation there is no agriculture: they are soils of native woodland, extensive grazing or, with water, irrigated oases (Mendoza, San Juan, the valleys of the NOA).

Most common surface texture
Sandy loam
Most common drainage
Well drained
Typical effective depth
50 cm

Where it is found

According to the 1:500.000 national map, it covers about 2.886.924 ha, spread over 36 districts.

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National map units that list it. The scale is 1:500.000: good for seeing the region, not a single property.

ProvinceArea
Río Negro857.047 ha
Neuquén676.239 ha
La Pampa483.688 ha
Chubut373.867 ha
Mendoza185.982 ha
San Juan84.524 ha
La Rioja82.265 ha
Santa Cruz73.453 ha
Buenos Aires46.996 ha
San Luis22.863 ha

Districts where it is most common

How productive it is

Where it is the main soil of the map unit, the productivity index has a median of 13 (very low); half of the units fall between 13 and 20.

Taken from the maps that include this data. A map unit with several soils has a single index, and it is only attributed to the dominant soil.

Subgroups on the maps

The definitions are a plain-language summary of the USDA Keys to Soil Taxonomy. The formal definition includes thickness, color and percentage thresholds that are left out here.

Sources