Preliminary Study on Element Leaching and Current Soil-Forming Process of Red Soils

The leaching characteristics and the element concentration in soil solution of red soils derived from sandstone,granite,Quaternary red clay and basalt have been studied in the Red Earth Ecological Experimental Station,Academia Sinica,using 12 lysimeters.Results obtained show that the element leaching process of red soils occurs mainly from January to the beginning of July annually.The elements with higher concentration in leaching solution of red soils are Si,Ca,Na,K,Mg,and N.The desilication and the leaching process of base cations occur simultaneously in the red soils.Using the first order differential equation and measured parameters of Si leaching,the leaching models of Si for red soils derived from different parent materials are constructed.The leaching process of Si is simulated with the models.Both the absolute and relative ages of red soils derived from different parent materials are discussed based on the simulation result.On the basis of element leaching,composition of soil solution and thermodynamics,the current soil-forming process is discussed.According to the phase diagram,the kaolinization is prevailing in the current formation of different red soils.

Behaviours of Main Elements in Soil-Forming Processesof Fildes Peninsula, the Maritime Antarctic

Nine horizon samples of three soil profiles representative of Dystri-gelic Cambisol, Fibri-gelic Histosoland Relic Ornithosol were taken from Fildes Peninsula of King George Island, Antarctica, to quantitativelydemonstrate the enrichment, migration and loss of the elements (Si, Al, Fe, Ca, Mg, Mn, K, Na and P) insoil horizons and their behaviours within profiles by application of the concept of the enrichment coefficientcalculated in terms of the abundance of Ti. Besides, six horizon samples of 4 other profiles randomly takenfrom the studied area were examined for calculation of the redistributing enrichment coefficient, which wasapplied for a better understanding of the element redistribution between soil and clay fraction along with soildevelopment. The results showed that the enrichment, migration and redistribution of the elements variedstrongly among the investigated soils and horizons, due to the differences of weathering degrees and moisturestatus, influences of sea bird activities, etc.

Role of Lichens in Weathering and Soil－Forming Pro－cesses in Fildes Peninsula，Antarctic

Lichens play an unparalleledly vital role in weathering and soil-forming processes in Antarctic region. Inthis study some related chemical components and micromorphological analyses have been carried out on thesamples of the weathered rocks and the lichens grown on them from Fildes Peninsula, Antarctic. The resultsindicated that the major chemical components in the bioweathering surface layer of the sampled rocks havebeen obviously altered and the weathering potential in this layer has greatly decreased by an average rangearound 4.66 percent in 4 samples. In the weathering surface layer ferruginmation of some minerals in varyingdegrees was seen by means of microscopic examination through the thin section of the weathered rocks, andits products proved to be dominated by hematite, limonite, goethite and free iron oxides Meanwhile, thestudy suggested that the dissolntion and absorption of lichens by their secretion accelerated the process ofcalcitization of minerals in the bicaweathering surface layer. Eventually, the results aIso show that differentspeciesof lichens play different roles in weathering and soilforming processes.

Ratios of Closely Related Elements in Soil and Their Implications

This paper has investigated the ratios of closely related elements such as Mn,Cr,V,Ni,Co,Cu,Pb,Cd,Ba,Sr,La and Ce in the major soils of China,and the factors affecting them,and explored their use as indicators in soil formation,material transport and environmental pollution.Results show that the effect of soil-forming processes on the ratios of closely related elements varied with different elements,and became greater in the sequence of Ce/La <V/Cr≈Ni/Co<Zn/Cu≈Zn/Pb<Zn/Cd<Mn/Cr<Ba/Sr.The magnitude of the variation in the ratios of closely related elements depended on the chemical properties of the elements themselves,on the one hand,and the parent material and climatic conditions on the other.The ratio of Ba/Sr showed a distinct zonality,decreasing gradually in the sequence:cool temperate zone acid soils>grassland soils>desert soils and increasing gradually from the semi-arid subhumid zone soils>the temperate zone neutral soils>the north subtropic zone soils>tropical and subtropical acid soils.

Evolution of technogenic landscapes by the example of apatite-nepheline ore concentration wastes

A primary soil-forming process can take place on the concentration waste of apatite-nepheline ores, whose biological recultivation was carried out more than 40 years ago. This process is characterized by the following features: forming of a thin litter with the content of organic carbon at the level of 8-12%, accumulation of humic substances in the sub-litter layer and the change of рН values. Microorganisms are biocatalysts of primary soil formation processes and one of the main factors that determine the specificity of this process. The prokaryotic complex of the newly formed soils, generated from nepheline sands, is considerably different from that of zonal soils on moraine sediments. The former ones are dominated by gram-positive bacteria, mainly actinobacteria, as well as by their filamentous forms (actinomycetes), whereas the latter ones are dominated by gram-negative bacteria. A common feature of invertebrate’s complexes in nepheline sands is the low species diversity, small-size and quickly development of microfauna and mesofauna representatives and the dependence of succession of microarthropods pioneer groups on the succession of bacteria and fungi.

Digital Soil Mapping Using Artificial Neural Networks and Terrain-Related Attributes

Detailed soil surveys involve costly and time-consuming work and require expert knowledge. Since soil surveys provide information to meet a wide range of needs, new methods are necessary to map soils quickly and accurately. In this study, multilayer perceptron artificial neural networks(ANNs) were developed to map soil units using digital elevation model(DEM) attributes. Several optimal ANNs were produced based on a number of input data and hidden units. The approach used test and validation areas to calculate the accuracy of interpolated and extrapolated data. The results showed that the system and level of soil classification employed had a direct effect on the accuracy of the results. At the lowest level, smaller errors were observed with the World Reference Base(WRB)classification criteria than the Soil Taxonomy(ST) system, but more soil classes could be predicted when using ST(7 soils in the case of ST vs. 5 with WRB). Training errors were below 11% for all the ANN models applied, while the test error(interpolation error) and validation error(extrapolation error) were as high as 50% and 70%, respectively. As expected, soil prediction using a higher level of classification presented a better overall level of accuracy. To obtain better predictions, in addition to DEM attributes, data related to landforms and/or lithology as soil-forming factors, should be used as ANN input data.

Limited Spatial Transferability of the Relationships Between Kriging Variance and Soil Sampling Spacing in Some Grasslands of Ireland:Implications for Sampling Design

Sampling plays an important role in acquiring precise soil information required in modern agricultural production worldwide, which determines both the cost and quality of final soil mapping products. For sampling design, it has been proposed possibile to transfer the relationships between kriging variance and sampling grid spacing from an area with existing information to other areas with similar soil-forming environments. However, this approach is challenged in practice because of two problems: i) different population vaxiograms among similar areas and ii) sampling errors in estimated variograms. This study evaluated the effects of these two problems on the transferability of the relationships between kriging variance and sampling grid spacing, by using spatial data simulated with three variograms and soil samples collected from four grasslands in Ireland with similar soil-forming environments. Results showed that the variograms suggested by different samples collected with the same grid spacing in the same or similar areas were different, leading to a range of mean kriging variance (MKV) for each grid spacing. With increasing grid spacing, the variation of MKV for a specific grid spacing increased and deviated more from the MKV generated using the population variograms. As a result, the spatial transferability of the relationships between kriging variance and grid spacing for sampling design was limited.

An analysis of the origin of CaCO_3 in soils on Fildes Peninsula of King George Island, Antarctica

It has been vague whether the soil-forming processes include calcification or decalcificationin Antarctic Peninsula and its adjacent islands. Everett （1976） reported that carbonate in soilsderived from limestone in the South Shetland Islands; but Bockheim （1990） considered thatcarbonation is maximized in the region. There are no published data reporting CaCO3 con-tent of soils in Fildes Peninsula. Based on the results of soil survey and test in the area, thisnote shows the CaCO3 origin of the present soils, and discusses the relationship between thetransference of CaCO3 and soil-forming environment.