Soil subgroup

Hapludol tapto nátrico

It has a natric horizon (sodium clay) buried under newer sediments.

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.
SuborderUdolMolisol humid climate (udic moisture regime): the profile almost never spends more than three months dry.
Great groupHapludolWithin the Udol suborder, it It is the simplest of the suborder: it does not have a clay horizon or any other feature that places it in a more specific group..
Subgrouptapto nátricoIt has a natric horizon (sodium clay) buried under newer sediments.

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.

It dominates the Pampa Arenosa of the west of Buenos Aires and the south of Córdoba and Santa Fe: soils looser, with good drainage, which depend more on rain.

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 1.646.379 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
Buenos Aires1.617.497 ha
Santa Fe28.882 ha

Districts where it is most common

It also appears on the detailed maps of: Buenos Aires.

How productive it is

Where it is the main soil of the map unit, the productivity index has a median of 51 (average); half of the units fall between 50 and 51.

Land capability

III
IV
VI
VII

class III: 16% · class IV: 58% · class VI: 16% · class VII: 10%

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 Hapludol subgroups

Soil series

Series are the specific soils, named after places, that detailed maps describe under this name. Two properties with the same series have the same soil.

Buenos Aires

La Albina · Pichincha · Nueve de Julio · Lazzarino · El Carmen · La Pandorga · Carlos Salas · Santa Regina · Cristiano Muerto · Orense · Juancho · Cachari · Las Delicias

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