The crater environment of Ratu Crater, Tangkuban Parahu Volcano was largely shaped by chemical processes that occurred in the geothermal centre in the form of fumarole and solfatar. A range of five representative profiles were identified in the toposequences of the crater i.e. A (toeslope), B, D (backslope), G and J (summit). Soil samples were physically, chemically, and mineralogically analysed. Mineralogical analysis showed that the sand fraction of heavy minerals (specific gravity> 2.87) were opaque, augite, and hipersten, while light minerals (specific gravity< 2.87) were volcanic glass, zeolite, andesin, labradorite, bitownite and rock fragments. Extraction with oxalate and pyrophosphate showed Profile D (backslope) to contain the highest mineral content of allophane (1.414 %), imogolite (0.391 %), and ferrihydrite (2,091 %). The lowest content was found in Profile A (toeslope), which had a smaller content than Profile J (summit). XRD analysis results (no treatment) showed that all profiles of A, B, D, G, J had almost the same reflection pattern consisting of calcite (3.03 angstrom), cristobalite (4.04 angstrom), feldspar (3.1-3.25 angstrom, gibbsite (4.85 angstrom), kaolinite (7.1 angstrom) and quartz (3.34, 4.27 angstrom). XRD analysis (Mg+glycol) of the profiles showed each profile to be mostly dominated by non-crystalline minerals (amorphous); however Profile J (Summit) and Profile A (toeslope) were dominated by crystalline minerals that had been developed from amorphous minerals, i.e. mineral 2:1 (smectite and chlorite) and mineral 1:1 (halloysite and kaolinite).

Data were collected from 10 universities in the United States on declared academic majors and gender of students enrolled in seven different soil science courses over a 5-yr period. Combined trends for all courses and trends for each individual course were evaluated. Data were also collected on the number of students participating in soil judging as well as tenure track and non-tenure track full time equivalent (FTE) soil science faculty positions. Environmental science, crop science/horticulture/agronomy, and other agricultural students enrolled in soil science courses in the greatest numbers. Environmental science and engineering students showed rapid increases in enrollment, while crop science/horticulture/agronomy and soil science student enrollment declined. Soil physics was the only class where declared soil science students were the single largest enrolled group. Soil judging numbers were consistent, while FTE faculty showed a slight decline. Students from many different academic majors took soil science courses at the universities investigated, and the most common majors in these courses depended on the course and the material it addressed. Overall student enrollment increased in all subject areas investigated except soil physics. While the results from this study are somewhat mixed, the overall growth in student enrollment in soil science courses at the investigated universities, as well as the broad range of majors enrolled in soil science coursework, indicate an upward trajectory in soil science education at these universities.

Soil developmental processes on young volcanic cinders in cool, semiarid climates are not well understood and previously under-studied, but present a unique setting within which to study neoformation of soils under well-dated time constraints. This study investigates the development of physical, chemical, and mineralogical soil properties on a chronosequence of basaltic cinder cones, aged approximately 2.1, 6.9, and 13.9 ka, at Craters of the Moon National Monument and Preserve in southern Idaho. Representative parent material, coarse fragments, and soil samples were analyzed using selective dissolutions and total elemental digests. Elemental mass balance data were used together with the soil physicochemical data to investigate weathering and secondary mineral formation within each soil profile. The highest degree of weathering was identified on the 13.9 ka profile, followed by the 6.9 and 2.1 ka soils. Short-range ordered minerals, including allophane and ferrihydrite, dominate the colloidal fraction of all soils, with greatest proportions in the oldest soil. Dominant soil-forming processes documented along the chronosequence of basalt-derived soils are the accumulation of organic carbon, weathering of rock fragments, loss of base cations, redistribution of Fe, Al, and Ti, and the accumulation of secondary short-range order and crystalline minerals. This study provides critical information to elucidate rates and processes of early stage weathering, dust influence, and soil evolution on cinders in cool and dry climates.

Landscapes of the Northern Rocky Mountains Major Land Resource Area (MLRA 43A) are dominated by andic soils, which occupy more than 4.7 million ha in the region. This paper reviews research conducted on these soils over the past three decades and describes three primary pathways by which these soils form. Two of these pathways-allophanic and non-allophanic-are similar in that they are variations of the general process of andisolization in which in situ weathering leads to the formation of various nanoscale minerals and metal-organic complexes that impart andic soil properties. The third pathway is defined by the dominance of podzolization, in which distinct translocation of the weathering products has occurred and andisolization is a subsidiary process. The majority of andic soils in the region have silandic properties and have formed via the allophanic pathway. In areas where forest vegetation has been replaced by bracken fern communities, non-allophanic soils form and develop aluandic properties in which the majority of secondary Al is contained in organic complexes. At higher elevations and sites with greater snowpack and effective precipitation, podzolization replaces andisolization as the dominant pedogenic process, resulting in the formation of Spodosols and spodic intergrades. Each of these three pedogenic pathways can be altered by disturbance. When disturbance is followed by erosion, diminishment or in extreme cases, complete loss of andic properties can occur.

Core IdeasPodzolization is a widespread pedogenic process in the Northern Rocky Mountains.Podzolization is strongly influenced by terrain attributes and environmental gradients.Northern Rocky Mountain landscapes are dominated by Spodosols, spodic intergrades, and Andisols.Although not recognized on land system inventory maps, Spodosols have been documented in the volcanic ash–mantled landscapes of the Northern Rocky Mountains (Major Land Resource Area 43A). This study focuses on terrain attributes and environmental gradients as potential predictors of the distribution and properties of podzolized soils in the region. Seventy‐two forested sites were sampled using hierarchical randomization. Podzolization, as indicated by the presence of a spodic horizon, was observed at 43 sites. Soils meeting all or most taxonomic criteria for Spodosols were present at 26 sites. These Spodosols are concentrated above elevations of approximately 1100 m and on northerly aspects. In this mountainous region, more northerly aspects and increasing elevation serve as proxies for lower temperatures, increased effective precipitation, and greater snow cover, all of which promote podzolization. Spodosol E horizons are very strongly acidic, with pH values as low as 3.1 and Al saturation as high as 89% of the effective cation exchange capacity. Other soils exhibit evidence of podzolization as interpreted from subsurface increases in pyrophosphate‐ and oxalate‐extractable Fe and Al. However, most of these soils have darker and/or higher‐chroma colors in the surface mineral horizon and lack the albic–spodic morphology of Spodosols. Results indicate that podzolization is a widespread pedogenic process in the Northern Rocky Mountains and occurs under different climatic conditions, topographic settings, and parent materials than those of the upper Midwest and northeastern United States.

Site preparation following timber harvests is widely used to increase seedling establishment postharvest. Historically, dozer piling and ripping were the most common forms of site preparation in the Intermountain West. Less commonly, terracing of hill slopes was another form of site preparation on the Bitterroot National Forest in western Montana from 1961–1970 on marginally productive lands. Our objective was to compare soil physical and chemical propertie sa s well as timber productivity as evidenced by diameter-at-breast height (dbh) between terraced and standard-site preparation methods as well as unharvested stands. We collected and analyzed soil samples for bulk density, mineral cations, total C, total N, organic matter, particle size, and pH, forest floor measurements, tree dbh, and ground cover. Even after 45 years, visual soil disturbance in site-prepared stands was still observable with a majority of sites having some degree of compaction or rutting damage. Many soil chemical and physical properties were not significantly different among the two site treatments and the unharvested control stands. However, soil organic matter was significantly lower in the terraced and standard site-prepared stands than in the unharvested stands. Ponderosa pine dbh was greater in the terraced stands than in the nonterraced stands, but understory species diversity was low. The loss of surface soil organic matter and understory species associated with both forms of site preparation is a concern for future forest management. Leaving forest residue during harvest operations, limiting travel routes during management operations, and minimizing forest floor displacement may allow for limited soil impacts on future site-prepared stands.

Differentiation of horizons in soils formed in volcanic ash can be problematic as recent ash deposits often have the same morphological appearance as eluvial albic horizons. Furthermore, differentiation of spodic horizons can be difficult as multiple horizons can appear homogeneous. A portable x-ray fluorescence (PXRF) spectrometer was utilized to scan volcanic ash-derived Spodosols, Andisols, and Inceptisols in northern Idaho and southern Alaska. Distinct patterns of elemental concentrations were identified in soil profiles. These data can be used to quantitatively differentiate seemingly nondescript horizons. Organic carbon variability within soil profiles was found to significantly correlate to elemental concentrations as evidenced by strong regression r2 and low root mean squared errors (RMSEs). Specifically, Fe/Zr ratios proved useful for documenting spodic horizons in the studied profiles, and showed some potential for differentiating volcanic ash from true E horizons. In areas of frequent saturation or inundation, the PXRF also demonstrated the ability to distinguish depleted soil matrix materials from reduced Fe. Summarily, the PXRF proved to be a useful instrument for rapid, on-site analysis of volcanic ash soils.

Volcanic ash mantles many landscapes of the Inland Pacific Northwest region of the United States. Because of the close link to forest productivity in the region, understanding processes that have affected the present-day distribution and characteristics of these ash mantles is important for forest soil management. Presence or absence, thickness, and degree of ash mantle mixing were evaluated at 84 randomly selected stratified sites in the Palouse Range of northern Idaho. A 1-m digital elevation model (DEM) was generated for the Palouse Range using light detection and ranging (LiDAR) data and resampled to 10-, 15-, 20-, and 30-m grid resolutions. Terrain attributes derived from these DEMs were used to model volcanic ash mantle presence or absence, thickness, and degree of mixing using classification and regression trees. Model accuracy for ash presence was assessed using 572 data points collected by the NRCS as part of a soil survey update. Overall, elevation was the single variable most related to the presence or absence, degree of mixing, and thickness of a volcanic ash mantle; other terrain attributes had less predictive value in modeling ash mantle characteristics. The 30-m grid resolution provided the best model of ash presence or absence, with 78% accuracy, indicating good promise for digitally mapping Andisols and related soils across the region. The various grid resolutions had little effect on the outcome and predictive ability of the models, and the overall accuracy of the models varied by only 2%. Moister, higher elevation plant communities provide a protective forest canopy and thick litter layer, which result in a relatively undisturbed ash mantle. At lower elevation where forest canopy is less dense, ash mantles are thinner, highly mixed, or absent.

This chapter contains sections titled: Definitions Distinction between Soil Taxa and Soil Map Units Kinds of Soil Map Units Orders and Standards of Soil Surveys Assessing Map Unit Composition Relation Between Soilscape and Soil Classification Perspective

Soils are the products of weathering from some parent rocks. All soils initially come from some pre-existing rocks. They are called as ‘parent materials’. The Parent Material may be directly below the soil, or at great distances away from it. It is necessary to understand the factors and processes that are responsible for the formation of soils. The major objective of studying this lesson is to understand the various factors of soil formation and the host of processes that result in the formation of various kinds of soils.

Authors vii Preface to the First Edition ix Preface to the Second Edition x Preface to the Third Edition xi Preface to the Fourth Edition xiii Preface to the Fifth Edition xiv Preface to the Sixth Edition xv 1. Introduction 3 2. Morphology and Composition of Soils 35 3. Soil-forming Factors: Soil as a Component of Ecosystems 89 4. Soil Materials and Weathering 141 5. Soil-forming Processes 163 6. Modern Soil Classification Systems 181 7. U.S. Soil Taxonomy 207 8. Alfisols: High Base Status Soils with Finer-textured Subsoil Horizons 233 9. Andisols: Soils with Andic Soil Properties 249 10. Aridisols: Soils of Dry Regions 265 11. Entisols: Recently Formed Soils 283 12. Gelisols: Very Cold Soils 293 13. Histosols: Organic Soils 307 14. Inceptisols: Embryonic Soils with Few Diagnostic Features 321 15. Mollisols: Grassland Soils of Steppes and Prairies 331 16. Oxisols: Low Activity Soils 349 17. Spodosols: Soils with Subsoil Accumulations of Humus and Sesquioxides 361 18. Ultisols: Low Base Status Soils with Finer-textured Subsoil Horizons 375 19. Vertisols: Shrinking and Swelling Dark Clay Soils 385 20. Spatial Arrangement of Soils: Soilscapes and Map Units 397 21. Interpretations of Soil Surveys and Technical Soil Classification 425 Bibliography 437 Index 531 Color plate section located between pages 232 and 233