Soil subgroup

Argiustol údico

It is more humid than the typical one of the group: its humidity regime is on the border with the udic.

What the name says

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

Taxonomic orderMolisolSoil with a thick, dark surface horizon rich in organic matter (the mollic epipedon), with more than half of its exchange capacity occupied by calcium, magnesium, potassium and sodium. It forms under grassland.
SuborderUstolMolisol from subhumid to semi-arid climate (ustic moisture regime): water is enough in the growing season but there are long dry periods.
Great groupArgiustolWithin the Ustol suborder, it has a clay accumulation horizon (argillic): clay washed from the surface accumulated lower.
SubgroupúdicoIt is more humid than the typical one of the group: its humidity regime is on the border with the udic.

What it means for farming

They are the soils agricultural lands par excellence: the Pampas grassland formed them and most of Argentine agriculture is done on them. They retain water and nutrients; its limitation, when there is one, is below: clay, sodium, calcareous hardpan or drainage.

Most common surface texture
Loam
Most common drainage
Well drained
Typical effective depth
100 cm

Where it is found

According to the 1:500.000 national map, it covers about 2.408.823 ha, spread over 56 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
Salta872.694 ha
Chaco658.509 ha
Santiago del Estero323.250 ha
Córdoba236.741 ha
Jujuy156.914 ha
Río Negro67.300 ha
Catamarca58.237 ha
Tucumán35.177 ha

Districts where it is most common

It also appears on the detailed maps of: Salta, Santiago del Estero.

How productive it is

Where it is the main soil of the map unit, the productivity index has a median of 66 (Well); half of the units fall between 50 and 68.

Land capability

I
II
III

class I: 52% · class II: 40% · class III: 9%

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.

Other Argiustol subgroups

Soils it shares map units with

Several soils share each map unit. These are the ones most often found alongside this one: on a property, you will likely find them in the nearby low ground or on the next rise.

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