Soil great group
Natrustalf
Of the Ustalf suborder; it has a natric horizon: accumulation of clay with a lot of exchangeable sodium, which disperses the clay and blocks the passage of water and roots.
What the name says
Soil Taxonomy names are built from parts, and each part says something about the soil. From general to specific:
| Taxonomic order | Alfisol | Soil with a clay accumulation horizon (argillic or natric) and good base saturation, but without the thick, dark surface of a Molisol. |
|---|---|---|
| Suborder | Ustalf | Alfisol from subhumid to semi-arid climate (ustic moisture regime). |
| Great group | Natrustalf | Within the Ustalf suborder, it has a natric horizon: accumulation of clay with a lot of exchangeable sodium, which disperses the clay and blocks the passage of water and roots. |
What it means for farming
Acceptable fertility, but the surface layer is thinner and poor in organic matter. In the Pampas region many Alfisoles are sodic or floodable (Natracualfes) and are left for livestock.
- Most common surface texture
- Loam
- Most common drainage
- Moderate
- Typical effective depth
- 60 cm
Where it is found
According to the 1:500.000 national map, it covers about 2.781.969 ha, spread over 32 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.
| Province | Area |
|---|---|
| Formosa | 1.640.894 ha |
| Chaco | 957.736 ha |
| Buenos Aires | 126.918 ha |
| Salta | 31.392 ha |
| Jujuy | 25.030 ha |
Districts where it is most common
- General Güemes · Chaco
- Pirané · Formosa
- Patiño · Formosa
- Pilagás · Formosa
- Bermejo · Formosa
- Pilcomayo · Formosa
- Almirante Brown · Chaco
- Formosa · Formosa
- San Fernando · Chaco
- Libertad · Chaco
- Coronel Dorrego · Buenos Aires
- 1° de Mayo · Chaco
- General Donovan · Chaco
- Villarino · Buenos Aires
- Tapenagá · Chaco
- Bermejo · Chaco
- Libertador General San Martín · Chaco
- Patagones · Buenos Aires
- Orán · Salta
- 12 de Octubre · Chaco
It also appears on the detailed maps of: Salta.
How productive it is
Where it is the main soil of the map unit, the productivity index has a median of 14 (very low); half of the units fall between 10 and 20.
Land capability
class III: 23% · class IV: 41% · class V: 36%
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
- Soil Survey Staff. (2014). Claves para la Taxonomía de Suelos, 12.ª edición. USDA - Natural Resources Conservation Service. · Dominio público (USDA)
- INTA · Dominio público (carta 1:500.000)