Some Studies of New Zealand Quaternary Pyroclastic Rocks

<p>The development of volcanic "ash" studies in New Zealand can be traced through three broad periods (Jeune 1970). During the late 19th century the extensive pumice deposits surrounding Lake Taupo received considerable comment (Crawford 1875, Smith 1876 and Cussen 1887). Thomas (1887) recognised a covering of younger andesitic ash from Mts. Tongariro and Ruapehu overlying the pumice from Taupo and in his 1888 report on the eruption of Mt. Tarawera in 1886, Thomas provided a valuable description of the eruption and the deposits resulting from it. Tephra deposits received only cursory attention during the following years until soil surveys initiated as part of the research effort into bush sickness demonstrated a relationship between incidence of the disease and soil derived from tephra (Aston 1926). Extended soil surveys followed (Granger 1929, 1931, 1937, Taylor 1930, 1933, Grange and Taylor 1931, 1932) during the course of which many important soil forming tephras were named, described and mapped. On the basis of minerals studies, contributions were recognised from four recently active volcanic centres; Taupo, Rotorua, Tongariro National Park and Mt. Egmont.</p>

Some Studies of New Zealand Quaternary Pyroclastic Rocks

<p>The development of volcanic "ash" studies in New Zealand can be traced through three broad periods (Jeune 1970). During the late 19th century the extensive pumice deposits surrounding Lake Taupo received considerable comment (Crawford 1875, Smith 1876 and Cussen 1887). Thomas (1887) recognised a covering of younger andesitic ash from Mts. Tongariro and Ruapehu overlying the pumice from Taupo and in his 1888 report on the eruption of Mt. Tarawera in 1886, Thomas provided a valuable description of the eruption and the deposits resulting from it. Tephra deposits received only cursory attention during the following years until soil surveys initiated as part of the research effort into bush sickness demonstrated a relationship between incidence of the disease and soil derived from tephra (Aston 1926). Extended soil surveys followed (Granger 1929, 1931, 1937, Taylor 1930, 1933, Grange and Taylor 1931, 1932) during the course of which many important soil forming tephras were named, described and mapped. On the basis of minerals studies, contributions were recognised from four recently active volcanic centres; Taupo, Rotorua, Tongariro National Park and Mt. Egmont.</p>

Time for non-illuvial Bt horizons?

The Bt horizon is the diagnostic horizon of the Luvisolic Order in Canada. According to the Canadian System of Soil Classification (CSSC), the Bt must be formed from clay illuviation through the processes of lessivage (i.e., physical transport of clay). In a study of a Luvisol catena in the central Saskatchewan, we demonstrate that Ae/Bm horizons overlying IIBt horizons are formed in a sandy mantle overlying till (i.e., a lithological discontinuity) and that the sandy mantle contributed negligible amounts of illuvial clay despite the presence of clay skins on ped surfaces in the IIBt horizon. We extended the results of this study to the regional scale by examining sand fractions in 63 pedons of Luvisol-dominated soil associations from soil surveys in the Northern Forest Reserves (between latitudes 53^oN and 55^oN). Of the 63 pedons, 13 had lithological discontinuities identified in their profile description and a further 27 had discontinuities identified through shifts in the sand fractions between horizons. For the profiles with discontinuities, inherited particle size differences are a more likely cause of coarse-over-fine textural contrasts than lessivage. A regional analysis of the distribution of Luvisol-dominated associations showed distinct zonations that account, in part, for the differences in the occurrence of lithological discontinuities. Based on these results, we suggest that the criteria for Bt horizons in the CSSC should be broadened to include non-illuvial coarse-over-fine texture-contrast horizons and that the criteria for the Luvisolic order also be broadened to include these non-illuvial Bt horizons.

GIS IN SOIL SURVEY AND SOIL MAPPING

The main goal of this paper is to present a methodology for land evaluation by supporting decision-makers with reliable information for the land-use planning process. One of the focuses of this paper is given to the survey process and interpretation between soil survey, soil survey interpretation, and physical land evaluation. Such processes are realized using mobile mapping tools with integrated Global Position Systems (GPS) and Geographic Information Systems (GIS). Both have increased the efficiency of data communication technologies by enabling real-time communication between people located in the field and office as well. For the soil classification as a key component of soil surveys is used World Reference Base (WRB) for Soil Resources. This is a common tool to summarize the wealth of information from soil profiles for the purpose of land evaluation. The final results showed a soil classification map. Such results are derived from many activities, since it includes a preliminary land evaluation, field soil survey with auger holes and profiles as well. This methodology is used for the first time in the selected study area.

Soil mapping in “Pochvovedenie” journal (review of publications since 1899)

The overview of publications on soil cartography in “Pochvovedenie”/“Eurasian Soil Science” journal for the period 1899–2020 demonstrates a high diversity of themes and certain trends in the number and dynamics of papers. Their total number (365), calculated per 5-year-long intervals, was distributed rather evenly among these 121 years: approximately 10–15 papers in each interval, although three maximums are rather clear. The first one fell on the post-war interval and was followed by 1965–1970 and 2010–2015 maximums. Discussion of large-scale maps dominated the early publications, many of them tackled soil surveys and applied problems; in the mid-century papers, soil maps of various regions of the country were described since it was time of extensive terrain investigations; numerous were also papers concerning methodology of soil mapping. New approaches and technique were actively discussed in the papers at the turn of centuries, such as remote sensing or digital soil mapping. Along with map compilation issues, there are publications on applying information provided by soil maps for both traditional and novel purposes: schemes of zoning in the former case and development of prognostic maps or assessment of pedodiversity in the latter case. The majority of papers on zoning, concern soil-geographical (later soil-ecological) schemes, whereas the derived types of zoning, for example, ameliorative or erosional, are discussed in few papers. The performed overview may be regarded as summing up the results of traditional soil mapping development with emphasizing its most valuable achievements, as well as indicating the initial signs of new trends.

Silt-sized sediments and gypsum on surface formations in the Ebro valley. A disambiguation of the term gypsiferous silts

Since the 60’s, many authors have reported the presence of common silt-sized materials in the Ebro valley, on surface formations and positions that have given rise to several interpretations, sometimes contradictory. According to the references, three main terms are used (gypsiferous silts, loess and flour-like gypsum) applied to silts and fine sands with gypsum accumulations. The two first terms are applied to materials with carbonate contents up to 40-50%, coarse silty to fine sandy textures, and located in different positions. Loess normally appears as thick outcrops on slopes leeward from the main wind direction, with a limited pedogenesis consisting of a partial carbonate mobilisation and gypsum contents between 0 and 30%. The third (gypsum-rich) type has a variable spatial distribution, appearing between limestone layers, along footslopes, outcropping as metric surface formations, or as generalized karstified subsurface accumulations. Their composition is almost 100% silt- to fine sand size lenticular gypsum. While some authors claim for an aeolian origin to all these materials, only part of them (loess) has a clear aeolian origin, while flour-like gypsum derives from on-site weathering of gyprock or by precipitation of calcium- and sulfate saturated watertables as it is reported to occur in many other arid regions; and the rest (gypsiferous silts sensu stricto) are mainly colluvial-alluvial. This distinction is necessary since they differ in their geotechnical behaviour and properties relevant for agricultural land uses, therefore they should be taken into account when carrying out geological mappings or soil surveys in this and similar arid regions.

Silt-sized sediments and gypsum on surface formations in the Ebro valley. A disambiguation of the term gypsiferous silts

Since the 60’s, many authors have reported the presence of common silt-sized materials in the Ebro valley, on surface formations and positions that have given rise to several interpretations, sometimes contradictory. According to the references, three main terms are used (gypsiferous silts, loess and flour-like gypsum) applied to silts and fine sands with gypsum accumulations. The two first terms are applied to materials with carbonate contents up to 40-50%, coarse silty to fine sandy textures, and located in different positions. Loess normally appears as thick outcrops on slopes leeward from the main wind direction, with a limited pedogenesis consisting of a partial carbonate mobilisation and gypsum contents between 0 and 30%. The third (gypsum-rich) type has a variable spatial distribution, appearing between limestone layers, along footslopes, outcropping as metric surface formations, or as generalized karstified subsurface accumulations. Their composition is almost 100% silt- to fine sand size lenticular gypsum. While some authors claim for an aeolian origin to all these materials, only part of them (loess) has a clear aeolian origin, while flour-like gypsum derives from on-site weathering of gyprock or by precipitation of calcium- and sulfate saturated watertables as it is reported to occur in many other arid regions; and the rest (gypsiferous silts sensu stricto) are mainly colluvial-alluvial. This distinction is necessary since they differ in their geotechnical behaviour and properties relevant for agricultural land uses, therefore they should be taken into account when carrying out geological mappings or soil surveys in this and similar arid regions.

Spectral Assessment of Organic Matter with Different Composition Using Reflectance Spectroscopy

Soil surveys are critical for maintaining sustainable use of natural resources while minimizing harmful impacts to the ecosystem. A key soil attribute for many environmental factors, such as CO2 budget, soil fertility and sustainability, is soil organic matter (SOM), as well as its sequestration. Soil spectroscopy is a popular method to assess SOM content rapidly in both field and laboratory domains. However, SOM source composition differs from soil to soil, and the use of spectral-based models for quantifying SOM may present limited accuracy when applying a generic approach to SOM assessment. We therefore examined the extent to which the generic approach can assess SOM contents of different origin using spectral-based models. We created an artificial big dataset composed of pure dune sand as a SOM-free background, which was artificially mixed with increasing amounts of different organic matter (OM) sources obtained from commercial compost of different origins. Dune sand has high albedo and yields optimal conditions for SOM detection. This study combined two methods: partial least squares regression for the prediction of SOM content from reflectance values across the 400–2500 nm region and a soil spectral detection limit (SSDL) to judge the prediction accuracy. Spectral-based models to assess SOM content were evaluated with each OM source as well as with a merged dataset that contained all of the generated samples (generic approach). The latter was concluded to have limitations for assessing low amounts of SOM (<0.6%), even under controlled conditions. Moreover, some of the OM sources were more difficult to monitor than others; accordingly, caution is advised when different SOM sources are present in the examined population.

Spectral assessment of organic matter with different composition using reflectance spectroscopy

&lt;p&gt;Soil surveys are critical for maintaining sustainable use of natural resources while minimizing harmful impacts to the ecosystem. A key soil attribute for many environmental parameters, such as CO2 budget, soil fertility and sustainability, is soil organic matter (SOM), and its sequestration. Soil spectroscopy is a popular method to assess SOM content rapidly in both field and laboratory domains. However, the SOM source composition differs from soil to soil and the use of spectral-based models for quantifying SOM may present limited accuracy when applying a generic approach for SOM assessment. We therefore examined the extent to which the generic approach can assess SOM contents of different origin using spectral-based models. We created an artificial big dataset composed of pure dune sand as a SOM-free background which was artificially mixed with increasing amounts of different organic matter (OM) sources obtained from commercial compost of different origins. Dune sand has high albedo and yields optimal conditions for SOM detection. This study combined two methods: partial least squares regression for the prediction of SOM content from reflectance values across the 400&amp;#8211;2500 nm region, and soil spectral detection limit (SSDL) to judge the prediction accuracy. Spectral-based models to assess SOM content were evaluated with each OM source as well as with a merged dataset that contained all of the generated samples (generic approach). The latter was concluded to have limitations for assessing low amounts of SOM (&lt;0.6%), even under controlled conditions. Moreover, some of the OM sources were more difficult to monitor than others; accordingly, caution is advised when different SOM sources are present in the examined population.&lt;/p&gt;