Vince Láng

Organic Carbon as a Major Differentiation Criterion in Soil Classification Systems

Soil is the largest terrestrial pool of organic carbon (OC), however the spatial distribution of the estimated 1.5–2.3 Tt organic carbon content of the soil cover has great variation horizontally and vertically. As organic carbon is one of the most important soil constituents, governing important functions and properties of soils, it is one of the major differentiation criteria in internationally used soil classification systems, such as Soil Taxonomy (ST) and the World reference base for soil resources (WRB), and most national systems. Several soil units at the highest level of the systems, such as surface and subsurface horizons, modifiers and qualifiers are defined on the basis of presence and amount of OC and/or depth and thickness of OC rich soil layers. As a result of the evaluation of current definitions of ST and the WRB, and analyses of international soil data sets (US NASIS and the ISRIC WISE) it was concluded that there are sufficient number of categories for expression of the amount, kind and vertical distribution of OC, however several of the definitions are very complicated, and not always consistent throughout the systems. This makes interpretation and also computation of categories difficult. With globally available data and mathematical tools, there is an opportunity to improve definitions and adjust arbitrarily set limits. An improved set of organic carbon related diagnostics could serve the needs of a future global classification system, mapping and monitoring OC, and also modeling of related estimations and processes.

Digital Soil Morphometrics Brings Revolution to Soil Classification

Soil classification systems are grouping soils with similar properties. The distinguishing properties are the ones that we are able to observe or measure. As the state of knowledge and the need of users are changing, the definitions should be tested and changes should be accommodated. The recent boom of observation technologies, data storage, and data processing achievements provided new opportunities to predict similarities and differences in soils. The tools of digital soil morphometrics are resulting in new parameters and properties and in deriving continuous depth functions. This chapter reviews the criteria of soil parameters and their novel methods for field observation and definition (horizon depth, texture, color, structure, organic matter, mottling, and carbonates). The internationally endorsed soil classification systems could potentially be supported with these new approaches. The review is based on the WRB and is supplemented with an example of predicting soil diagnostic horizons using digital soil morphometrics. The application of faster, efficient, and more objective measurements can bring revolution to the classification of soils.

Javaslat talajosztályozási rendszerünk megújítására: alapelvek, módszerek, alapegységek

A jelenlegi, 1960 evekben kidolgozott genetikus alapokon nyugvo magyar talaj-osztalyozasi rendszerunk modernizalasara az elmult evtizedek hazai tapasztalatai, dokumentalt adathalmazai, valamint a nemzetkozi standardok es elvarasok alapjan teszunk javaslatot. Munkank kiindulasi alapja az elődeink altal definialt 29 talaj-kepző folyamat, 39 talajtipus, es az azokhoz kapcsolodo tartalmi leiras es vizsgalati adatokbol nyert informacio. Modszereink az egyszerű elemzesek es statisztikai szamitasok mellet a pedometria modszerere, a taxonomiai tavolsagszamitasra es klaszteranalizisre tamaszkodtak. Eredmenyeink alapjan a jelenlegi hazai talajtipusok egy resze jol elkulonithető, masok pontosabb definiciora szorulnak, vagy egyes esetekben osszevonasra kerul-hetnek. A nemzetkozi gyakorlatban meglevő es hazankban is jellegzetes tipusokat pedig, bevezetesre javaslunk. A szigorubb es mind a melysegi, morfologiai es osszetetelbeli tulajdonsagok te-kinteteben szamszerűbb meghatarozasokon alapulo javasolt struktura kozpont...