Agriculture Reference
In-Depth Information
Argosols
M. Other soils that have:
¤A cambic horizon
¤Within 100 cm of the mineral soil surface, any one of the following: an albic, calcic, hypercalcic,
gypsic, hypergypsic horizon, or a calcipan
¤
At least in one horizon (10 cm or more thick) between 20 cm and 50 cm below the mineral soil
surface, either a
value of less than 0.7, or less than 80 g/kg clay in the Ýne-earth fraction; and
one of the following: a histic, a mollic, or an umbric epipedon
¤A permafrost layer and stagnic soil moisture regime within 50 cm of the mineral soil surface for
at least 1 month per year in 6 or more out of 10 years
n
Cambosols
N. Other soils.
Primosols
Characteristics and Distribution of Soil Orders
In CSTC, 14 dominant soil orders are set up, based on diagnostic horizons and diagnostic
characteristics.
Histosols are soils composed mainly of organic soil materials that are accumulated
from plant residuals, and they have a soil organic carbon content of at least 12Ï18%, depending
on soil clay content. They occur dominantly in northeastern China as well as the eastern and
northern margin areas of the Qinghai-Xizang Plateau, in cool temperate and temperate zones. Their
total area is 14,000 km
Histosols.
2
.
Anthrosols are soils with an anthraquic epipedon and hydragric horizon, a Ýmic
epipedon and phos-agric horizon, an irragric epipedon, or cumulic epipedon. Covering an area of
about 313,000 km
Anthrosols.
, these soils occur nearly throughout China. However, they mainly occur in the
eastern and southern parts of China, especially in the deltas, which have intensive human activities
and a long history of agriculture and dense population, such as the Yangtze Delta and Zhujiang Delta.
2
Spodosols are soils that have a spodic horizon within 100 cm of the mineral soil
surface. Spodosols occur mostly in the cool and humid northern Da Hinggan mountains and in the
Changbai Mountains and southern margins of Qinghai-Tibet Plateau. They are in very small areas,
commonly covered by coniferous trees.
Spodosols.
Andosols are soils that developed from tephra or lava and that have andic soil
properties. They occur in volcanic areas of northeastern and southern China, with a total area of
only about 2,000 km
Andosols.
2
.
Ferralosols are soils that have a ferralic horizon within 150 cm of the mineral soil
surface. This ferralic horizon is at least 30 cm thick. It has a texture of sandy loam or Ýner, and
has a clay content of 80 g/kg or more. It has a CEC
Ferralosols.
of lower than 16 mol (+)/kg clay and an
ECEC of lower than 12 mol (+)/kg clay, and it has a weatherable minerals content of <10% in
fractions of 50Ï200 mm, or a total potassium content of <8 g/kg (K
7
O <10 g/kg) in the Ýne-earth
fraction. It has <5% by volume that has rock structure, or it has sesquans on the weatherable mineral
fragments. These soils occur in low hills and terraces in hot and humid tropical and southern
subtropical regions. Their area totals 103,000 km 2 .
Vertosols. Vertosols are soils that have vertic features within 100 cm of the mineral soil surface.
They are mainly derived from river and lacustrine deposit, and occur dominantly on the Huaibei
Plain and in the Nanyang Basin and Xiangfan Basin, in the eastern and central parts of China.
They cover an area of 52,000 km 2 .
2
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