Agriculture Reference
In-Depth Information
SPECIFIC CHARACTERISTICS OF CSTC
Based on the Diagnostic Horizons and Diagnostic Characteristics
Diagnostic horizons are the horizons used to identify the soil types and that have a series of
quantiÝed properties. They are the building blocks of the taxonomy.
There are several taxonomic soil classiÝcations, developed by individuals, institutions, or
through international cooperation. They all have features in common, but differ in some other major
aspects. Most national systems tend to highlight soils that are of largest extent, form their major
agricultural base, or even that have major constraining properties. In highlighting some, there is a
concomitant effect to de-emphasize others, and this results in differences in the systems. Over the
last few years, however, there has been increasing similarity in the approaches to identiÝcation and
deÝnition of diagnostic horizons. Consequently, a common language for international exchange
and understanding on taxonomic soil classiÝcations is now becoming available. In view of the
practical needs of Chinese Soil Taxonomy, we have established a set of 33 diagnostic horizons and
25 diagnostic characteristics. These were established based on the following considerations:
¤
Some are adopted directly from other systems, if they are applicable to the Chinese situation; in
such cases, we have used the original terms and deÝnitions. Examples include mollic, umbric, and
ochric epipedon; albic, glossic, spodic, hypersalic, gypsic, hypergypsic, calcic, hypercalcic hori-
zons, lithic contact, paralithic contact, permafrost layer,
value, andic property, and alic property.
Only the petrocalcic horizon was renamed as calcipan, according to the traditional use in China.
¤ In some cases, terms and deÝnitions of other systems were modiÝed or expanded to serve our
local needs. These are histic epipedon, cambic horizon, ferralic horizon, agric horizon, agric
horizon, alkalic horizon, salic horizon, sulfuric horizon, organic soil materials, vertic features, soil
moisture regimes, soil temperature regimes, gleyic features, humic property, sodic property, calcaric
property, and sulÝdic materials.
¤A number of diagnostic horizons and diagnostic characteristics, totaling 12 and 9, respectively,
are proposed based on the special soil resources, especially anthropogenic soils in old agricultural
areas, apline soils in Tibet plateau, extreme arid-desert soils in Xinjiang, etc., and their available
information in China, such as mattic, irragric, cumulic, Ýmic, anthrostagnic, aridic epipedon, salic
crust, LAC-ferric horizon, hydragric horizon, claypan, salipan, phosphipan, lithologic character-
istics, anthro-silting materials, anthroturbic layer, frost thawic features, redoxic features, isohumic
property, allitic property, phosphic property, and base saturation.
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Using Soil Genetic Theories as the Guide
Following the Russian approach in soil genesis, soils were divided into clastic soils, halogenic
soils, carbonate-genetic soils, siallitic soils, and ferrallitic soils, according to the developing stages
of soil geochemistry. These divisions may be stable, but difÝcult to be identiÝed in Ýelds. Soil
taxonomy paid great attention to the morphogenesis, which was not very stable. We emphasize the
historical genesis in the First Proposal, and combine it with morphogenesis in our system, shown
in the table below:
Historical
Geno-sequence
Clastic
Soil
Halogenic
Soils
Carbonate-genetic
Soils
Siallitic
Soils
Ferrallitic
Soil
CSTC system:
Primosols
Halosols
Aridosols
Aridosols
Isohumosols
Cambosols
Cambosols
Argosols
Spodosols
Ferrosols
Ferralosols
