Szent IstvánUniversity Hungary

Erika Michéli Department of Soil Science and Agrochemistry

I belive 

•

Farmers (users) have to know their soils types  (on their own language and level ) 

•

They have to know soil functions•

They have apply agronomic practices 

(or chose land use)based on the soil type – soil function relationships

Why (again) about soil classification?Most currently applied soil classification systems: 

•

were developed for different purposes than  present users are applying or need them for

•

were elaborated before the recent boom of  modern observation technologies, data storage 

and processing developments 

•

are hardly understood / seldom used by non soil  scientists (even by soil scientists)

•

are often criticized to be complicated and boring  by students (even teachers) 

Why (again) about soil classification?

•

Global (digital) soil information coverage is  needed 

•

Harmonization of diverse systems is very difficult

•

Some soils get (need) more attention than before (man made soils, cold soils) 

•

Digital „players”

find  our classes not suitable and  often create their own classes 

•

Some consider soil classification useless or even unnecessary

Type / Name – WHY?Make a guess:

Mammal

Gray colored

Length: 5 ‐

6.5 meters

Average weight: 3t 

Lives south of the tropic of cancer

Pygmy right whale

Asian elephantelephant

Lives in the oceanLives around New ZealandEats plankton

Etc.________________

Lives in the mainlandIn South, South‐East AsiaEats plantsPossible to domesticateHas got tusk etc.

Type / Name – WHY?

Soils with:

OM accumulation

Leached topsoil

Reddish subsoil

Sandy texture

OC 0‐5 cm: 

3.5%OC 5‐20 cm: 

0.5%

pH 0‐5 cm: 

5.0pH 5‐20 cm: 

4.5

Sand 0‐5 cm:  45%

Sand 5‐20 cm:  55%

etc.

Based on these properties it  can be 10 different soil types, 

but do they really differdo they really differ?

PodzolPodzolisationDissolved organic acidsOM and/or Al&Fe oxide rich 

subsoilSandy texture

AlisolClay illuviation← a layer is present in the 

subsoil with high(er) clay  content

high CEC, low base

YES,  we need soil cassification !•

Humans organize knowledge

easier to understand easier to communicate

•

Provides a concise and systematic method for  designating various types of soil

•

Soil classification data feeds many modeling  algorithms (crop, erosion, different properties 

etc.)

•

The unit (class) provides more information than  just properties

What is wrong with them? 

Cryozems

(Russia)

Cryosols

(WRB)

Gelisols

(ST)

Required Characteristics of the Mollic epipedonThe mollic epipedon consists of mineral soil materials and has the following properties:1. When dry, either or both:a. Structural units with a diameter of 30 cm or lessor secondary structure with a diameter of 30 cm or less;orb. A moderately hard or softer rupture-resistance class;and2. Rock structure, including fine (less than 5 mm) stratifications, in less than one-half of the volume of all parts;and3. One of the following:a. All of the following:(1) Colors with a value of 3 or less, moist, and of 5 orless, dry; and(2) Colors with chroma of 3 or less, moist; and(3) If the soil has a C horizon, the mollic epipedon has a color value at least 1 Munsell unit lower or chroma at least 2 units lower (both moist and dry) than that of the C horizon or the epipedon has

at least 0.6 percent more organic carbon than the C horizon; orb. A fine-earth fraction that has a calcium carbonate equivalent of 15 to 40 percent and colors with a value and chroma of 3 or less, moist; orc. A fine-earth fraction that has a calcium carbonateequivalent of 40 percent or more and a color value, moist, of5 or less; and4. A base saturation (by NH4OAc) of 50 percent or more; and5. An organic-carbon content of:a. 2.5 percent or more if the epipedon has a color value,moist, of 4 or 5; orb. 0.6 percent more than that of the C horizon (if one occurs) if the mollic epipedon has a color value less than 1 Munsell unit lower or chroma less than 2 units lower (both moist and dry) than the C

horizon; orc. 0.6 percent or more; and6. After mixing of the upper 18 cm of the mineral soil or of the whole mineral soil if its depth to a densic, lithic, or paralithic contact, petrocalcic horizon, or duripan (all defined below) is less than

18 cm, the minimum thickness of the epipedon is as follows:a. 10 cm or the depth of the noncemented soil if the epipedon is loamy very fine sand or finer and is directly above a densic, lithic, or paralithic contact, a petrocalcic horizon, or a duripan that is

within 18 cm of the mineral soil surface; orb. 25 cm or more if the epipedon is loamy fine sand or coarser throughout or if there are no underlying diagnostic horizons nd the organic-carbon content of the underlying materials decreases

irregularly with increasing depth; orc. 25 cm or more if all of the following are 75 cm or morebelow the mineral soil surface:(1) The upper boundary of any pedogenic lime that ispresent as filaments, soft coatings, or soft nodules; and(2) The lower boundary of any argillic, cambic, natric,oxic, or spodic horizon (defined below); and(3) The upper boundary of any petrocalcic horizon, duripan, or fragipan; ord. 18 cm if the epipedon is loamy very fine sand or finer in some part and one-third or more of the total thickness between the top of the epipedon and the shallowest of any features listed in item 6-c

is less than 75 cm below the mineral soil surface; ore. 18 cm or more if none of the above conditions apply;and7. Phosphate:a. Content less than 1,500 milligrams per kilogram soluble in 1 percent citric acid; orb. Content decreasing irregularly with increasing depth below the epipedon; orc. Nodules are within the epipedon; and8. Some part of the epipedon is moist for 90 days or more (cumulative) in normal years during times when the soil temperature at a depth of 50 cm is 5 oC or higher, if the soil is not irrigated; and 9. The n value is less than 0.7.

1. either or both:a. orb. 

2. and

3. One of the following:a. All of the following:

(1)  and(2) and(3) or

b.  orc.

and4.

and5. 

a. orb.orc. and

6. a. orb. orc.

(1) and(2) and(3)

ord.or

e.and

7. a.  orb.  orc.; 

8. and 

9. 

Required Characteristics of the ST Mollic horizon

The Mollic epipedon occupies 1,5 pages; It has 9 major diagnostic requirements,6 has sub requirements,2 has 3rd level sub requirements,includes 10 ORs and 12 ANDs.

All refer to structure, color, B%, OC, depth  (and n value)

Thickness of the mollic  horizon

All together : 4 critera, 

5 subcritera,  4 sub‐sub criteria

dire

ctly

abo

ve d

ensi

c, li

thic

, or

para

lithi

c co

ntac

t, a

petro

calc

ic h

., or

a

durip

an;

Einar Eberhardt , 2012

Objectives of the IUSS USCS WG 

•

Simplification ‐

Demistification 

•

Apply improved and unifed soil observation  standards?

•

Incorporate (accommodate) new technologies  to support or replace current procedures? 

•

Develop ONE system with different levels  (in terms of scientific detailness, global, local 

level)

Taxonomic relationship studies based on distance calclations

Structure USCS (vision)•

Building blocks  

(diagnostics – that carry information on important  soil functions and can be applied independently 

for interpretation and thematic mapping)•

“Soil types”

defined by methods

that support 

objective decisions •

Levels 

umbrella global level / local levelscientific detainess arrording to users(CENTRAL units, collective classes, subclasses)

`black cotton soils' (USA), Smolnica (Bulgaria)`regur' (India), `vlei soils' (South Africa), 

`margalites (Indonesia), and `gilgai' (Australia).

VERTISOL

Calcic Mollic Vertisol (Pellic) 

Heavy clay soils with a high proportion of 

swelling clays. High nutrient and water 

holding capacity.Very hard massive when 

dry, sticky when wet. Infiltration slow……..

Scientifically (data, classification) same) Scientifically (data, classification) same) 

Utilization (perormance) of functions /Utilization (perormance) of functions / agronomic guidelinesagronomic guidelines

naturally very differentnaturally very different

DEVELOP  CONCEPT, STRUCTURE(FUNDAMETAL SCINECE)

SCIENTISTS

FOOD  PRODUCTION,  MODELLING,USERS (FARMERS, MODELLERS, 

Knowledge (type, function, best practices)

Needsproblems

DEVELOP  CONCEPT, STRUCTURE(FUNDAMETAL SCINECE)

SCIENTISTS

FOOD  PRODUCTION,  MODELLING,USERS (FARMERS, MODELLERS, 

Knowledge (type, function, best practices)

Needsproblems

The missing blockExtension (conservation)

SERVICE(trusted, certified

Promote sustainable management of soil resources for soil protection, conservation and sustainable productivity

Encourage investment, technical cooperation, policy, education awareness and extension in soil

Promote targeted soil research and development focusing on identified gaps and priorities and synergies with related productive, environmental

and social development actions

Enhance the quantity and quality of soil data and information: data collection (generation), analysis, validation, reporting, monitoring and

integration with other disciplines

Harmonization of methods, measurements and indicators for the sustainable management and protection of soil resources

Methods 

•

Overview and expert evaluation of the definitions  and criteria (concept, consistency and 

applicability) supported by data evaluation  •

Numerical study of taxonomic relationships 

between classification units based on distance  methods

Application of the centroids to evaluate OC % and depth criteria

Studies

on

the

calculated

centroidsPrincipal

component

analysis, plotted

on

first

3 components

Alfisols

‐

khakiAndisols

‐

royalblue

Aridisols

‐

salmonEntisols

‐

tan

Gelisols

‐

seashellHistosols

‐

palegreen

Inceptisols

‐

orchidMollisols

‐

red

Oxisols

‐

orangeSpodosols

‐

green

Ultisols

‐

yellowVertisols

–

grey