The Search for a New Paradigm in Pedology: a Driving Force for New Approaches to Soil Classification
Total Page：16
File Type：pdf, Size：1020Kb
EUROPEAN SOIL BUREAU RESEARCH REPORT NO. 7 The search for a new Paradigm in Pedology: a driving force for new approaches to soil classification IBÁÑEZ Juan José1 and BOIXADERA Jaume2 1 Centro Ciencias Medioambientales CSIC 28006 Madrid, Spain 2Generalitat de Cataluña, 25006 Lleida, Spain Abstract Soil is a complex open system, a natural body in which biosphere, lithosphere, atmosphere and hydrosphere come together. Pedology is the subdiscipline of soil science that integrates and quantifies the distribution, morphology, genesis, and classification of soils as natural landscape bodies. Several papers have been published over the last few years that recognise the crisis pedology has been suffering since the 1970s. Soil survey and soil classifications are the branch that has come under most criticism. It is also assumed that the traditional marriage between agriculture and pedology, so called agronomic paradigm, very fruitful in the past, no longer proves so at the present time. Paradoxically society currently demands greater, more diversified pedological information. Thus, we need a change in the epistemology paradigm of pedology since pedology seems to be unable to offer the new, products that society and other scientific disciplines are demanding. Thus, what can be done in order to solve this current problem? In our opinion: (i) We must improve the concept of soil; (ii) We must get better scientific and practical soil classification; and (iii) We must obtain more precise soil survey information. In this paper, our intention is to explain how some characteristics of soil classification adjust to the new demands for practically relevant information. Until the present, pedology has not had any change of paradigm since the fundamental contribution of Dokuchaiev; the same is not true for many other aspects of earth and biological sciences. Since Dokuchaiev, soil has been recognised as a natural body. However, because soil is also a continuum, many soil scientists as well as researchers from other disciplines, think that soil taxonomy has divided the soil continuum into artificial classes. It should not be assumed that any given classification must be superior to another, because each may be equally adequate for representing complementary aspects of the "patterned continuum" of nature. For these reasons, neither biologists nor pedologists obtain a satisfactory definition of living matter and soil or other living matter. All classification systems in nature break the continuum into a number of classes and the problems of classifying any natural resource is conceptually more or less the same. Because the soil is a continuum, several pedometricians consider that current soil classification schemes are subjective and therefore not very useful. Are they right? We show that their arguments are totally arbitrary and unjustified. In fact, after comparing the USDA Soil Taxonomy with biological taxonomies, we can see that both have the same mathematical structure according to MaxEnt Principle. Most if not all classifications in pedology, as well as in other disciplines, are hierarchical, probably because hierarchical structures optimise the flow of information. What is the object that pedologists must be classify? Surprisingly, insufficient attention paid in the last years to consider which should be the object of soil classification. In our opinion, we must classify soil bodies, not soil profiles. The soil body, as a three-dimensional body of the pedosphere, may vary in size by some orders of magnitude. Therefore, the scale of the description of a profile or pedon (window(s) in the pedosphere, but nothing more) does not necessarily correspond to the soil body. Furthermore, in some instances, a soil body needs to include two or more different pedotaxa. The search for a new Paradigm in Pedology: Ibanez & Boixadera. 93 EUROPEAN SOIL BUREAU RESEARCH REPORT NO. 7 One of the main differences between the taxonomies of biology and soil science arises not from the differential characteristics of their respective fields of study, but from their differing histories, their way of coming to consensus on terminology, and the way their activities are carried out. In principle, there is no insurmountable scientific impediment that prevents soil scientists adopting an institutionalized practice similar to that followed by biologists. Man has been altering the soil since prehistoric times Thus, current soilscapes are very different from totally natural ones. This process has been called “metapedogenesis” and it affects soil classification. For example, the role of anthropogenic soils has been growing in the recent years. In our opinion a true change of paradigm in pedology could be based in the following items : (i) The whole land surface including wetland or hydric soils and “sediments” (soils?) of the photic areas of lakes and coastal zones; (ii) Deep continuum: The Whole Soil-Regolith; (iii) Surface continuum: Spatial units; not profiles; (iv) Functional units: Not slides (profiles); (v) Whole of man-made soils not only anthrosol Keywords: pedology, soil concept, continuum, soil classification, paradigm The crisis of pedology Soil is a complex open system, a natural body in which biosphere, lithosphere, atmosphere and hydrosphere come together. The understanding of the pedological processes involved, as well as their synergies, is essential to understand numerous biogeospherical processes, many of which are very common. We are still far from adequately comprehending the soil system behaviour (Ibáñez, et al. 1994a, 1995a, 1998; Catizzone 1998). Pedology is the subdiscipline of soil science that integrates and quantifies the distribution, morphology, genesis, and classification of soils as natural landscape bodies. It is the “glue” that holds soil science together and is the hard core of soil science that does not fit with the theoretical framework of any other science discipline (Simonson 1991). Several papers and notes have been published over the last few years which recognise the crisis pedology has been suffering since the 1970s on an international level (Dudal 1987; Nachtergaele 1990; Jacob & Nordt 1991; Arnold 1992; Hudson 1992; Miller 1992, 1993; Sposito & Reginato 1992; Warkentin 1992; Zinck 1993; Notohadiprawiro 1993; Gardner 1991, 1993; Greenwood 1993; Hillel 1993; Ibáñez 1998; Ibáñez et al. 1993, 1997, 1998; Bouma 1994; British Soc. Soil Sci. 1994; Bullock 1994; Bridges & Catizzone 1996; Yaalon 1995, 1996, 1997a; Basher 1997). Most of these authors basically agree regarding to the drop in credibility of the discipline and of those practising it in the scientific community, as well as among those responsible for national and international scientific policies. An alarm has been lit calling for the need “to move to immediate action” (Gardner 1993; Miller, 1993; Ibáñez et al. 1997). It is also assumed that the traditional marriage between agriculture and pedology, so called agronomic paradigm, very fruitful, scientifically, technically and institutionally in the past, no longer proves so at the present time (Yaalon, 1996, Ibáñez et al. 1993, 2000). Linking pedology with agriculture has led to the isolation of it from other disciplines, and these may provide the basis for emerging application in soil science (Nielson 1987). The idea is not so much to renege on the past or abandon its agronomic applications, but to widen horizons. Soil survey and soil classifications are the branch that has come under most criticism (Basher 1997). Some soil scientists think that current classification schemes and soil survey procedures are obsolete. Paradoxically society currently demands greater, more diversified pedological information (Hartge 1986; Zinck, 1990; Ibáñez et al., 1993). Public opinion in industrialised countries are more concerned with environmental problems than with an increase in agricultural production (Yaalon, 1997a; Rey et al. 1998). In this context, soil degradation problems (e.g. contamination and erosion) are a priority. It is therefore difficult, in this context, to understand the reticence of governments and national and international institutions to promote pedological research and the inventory of soil resources. What are the underlying reasons? Zinck (1990), Basher (1997), Ibáñez et al. (1994a, 1997) and Catizzone (1998), among others, share the opinion that conjunctural issues, external to soil science and the soil survey, and structural issues, inherent to the discipline, have simultaneously combined. It is the latter which are calling for a change in the epistemology paradigm of pedology since pedology seems to be unable to offer the new, high quality products which society and other branches of scientific knowledge are demanding and even less so at an affordable cost in an appropriate time framework (Dudal 1987; Zinck 1993). 94 The search for a new Paradigm in Pedology: Ibanez & Boixadera. EUROPEAN SOIL BUREAU RESEARCH REPORT NO. 7 The search for a new identity for pedology is where strategies proposed by specialists for changing the paradigm diverge. Basically there are three clearly differentiated philosophies. The first one emphasises the need to transform a markedly applied discipline into another of a basic nature, within the earth science context; supporters of this attitude propose basic research with a view to renewing the theoretical corpus of pedology and strengthen the quantification and modelling of soil processes, in consonance with current trends in other branches of knowledge (Wild 1989; Sposito & Reginato 1992;