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Plants play an important role in Silicon (Si) cycling of terrestrial ecosystems. However, how plant Si is related to soil Si translocation and transformation in subtropical areas with ample weatherable silicates and agricultural activities is largely unknown. Three typical watersheds with different cropland and forest configurations in subtropical China were selected to investigate the biomass of...
Soil class maps are useful representations of the landscape distribution of holistic soil functions. However these are often only available as generalized classes at small cartographic scales. One reason is that allocating a soil profile to a class in most current soil classification system requires laboratory determination of many diagnostic soil properties. The advantage of reflectance spectroscopy...
Multi-scale soil variations are increasingly employed to improve the accuracy for digital soil mapping (DSM). In this study, we attempted to explore a methodology of wavelet analysis on this topic. The terrain attributes of a study area were decomposed using the wavelet analysis, and the resulted components were applied to map soil organic carbon (SOC) content, pH and clay content using multiple linear...
Evaluating the accuracy of allocation to classes in monothetic hierarchical soil classification systems, including the World Reference Base for Soil Classification, US Soil Taxonomy, and Chinese Soil Taxonomy, is poorly-served by binomial methods (correct/incorrect allocation per evaluation observation), since some errors are more serious than others in terms of soil properties, map use, pedogenesis,...
The Qilian Mountains are generally capped by a productive silty soil layer wherever the environment allows. As Holocene loess is prevalent across the Qilian Mountains, we assume that at least some of these fine sediments are derived from loess deposition and that soils across the region may be genetically linked. To test these hypotheses, nine pedons in different landscapes within a typical alpine...
The stability of soil colloids influences soil physicochemical properties, soil development, and transfer of nutrients and contaminants to surface and ground waters. A better understanding of soil colloids stability dynamics during soil evolution is important for the evaluation of soil's capacity to retain nutrients and/or accommodate toxic contaminants. This study was aimed to determine changes in...
This paper presents an approach to predicting three-dimensional (3D) variation of soil organic matter (SOM) concentration by integrating a similarity-based method with depth functions. It was tested in a small hilly landscape. A depth function model was constructed to fit SOM profile distribution using a linear relation in the topsoil and a power function in the subsoil. Then, under the assumption...
In large heterogeneous areas the relationship between soil organic carbon (SOC) and environmental covariates may vary throughout the area, bringing about difficulty for accurate modeling of the regional SOC variation. The benefit of local, geographically weighted regression (GWR) coefficients was tested in a case study on soil organic carbon mapping across a 50,810km2 area in northwestern China. This...
Chronosequences and associated space-for-time substitutions are an important and fruitful means for investigating the rates and directions of soil and ecosystem evolution across multiple time-scales ranging from decades to millions of years. This paper reviews the use of chronosequences for studying biogeochemistry of paddy soil evolution to improve our understanding of the fundamental processes,...
A series of paddy soil profiles with approximately 50, 300, 700 and 1000years of paddy cultivation history and an uncultivated mud beach profile under nearly identical landscape and climate conditions were studied. The signatures of rare earth elements (REEs) were used to identify sediment provenances and parent material uniformity of the studied profiles and to assess long-term paddy management effects...
The effects of urbanization on soil have been accelerating around the globe and there is a need for these effects to be evaluated precisely. In order to do this, spatial outliers and mapping uncertainty should be handled properly. The present study aimed to deal with these two problems using a case study of soil pH and particle fractions (i.e., sand, silt and clay) in Hong Kong. Based on 133 topsoil...
Fuzzy c-means clustering (FCM) has been used frequently in digital soil mapping. One of the key issues in applying FCM is the determination of the appropriate classification parameters of the fuzzy exponent (m) and the number of clusters (c). To determine the optimal selection of appropriate m and c values, in this study, we first used two simulated datasets to demonstrate the sensitivity of three...
Grain-size and geochemical characteristics of 18 Quaternary Red Clay (QRC) profiles mainly located in the lower and middle reaches of the Yangtze River in subtropical China were studied. The results showed that all the QRC profiles can be classified into three types: Type A, mainly distributed between 29°N and 31°N, share the similar characteristics with the Xiashu Loess, with the uniformity of grain-size...
A series of paddy and non-paddy soil profiles that are developed in chronosequences from approximately 50 to 1000 years of exposure time on fairly uniform marine deposits under nearly identical landscape and climate conditions were sampled from Cixi, Zhejiang Province, China, where rice has been traditionally grown under water submergence. Master horizons were identified and sampled. Selected pedogenic...
Paddy soils are Hydragric Anthrosols and are an important soil resource for food production. They are widely distributed in China and Asia. Soils that can be used for paddy cultivation vary considerably but basically are grouped into three kinds of landscape, i.e., well-drained sloping uplands, alluvial plains with groundwater fluctuation, and poorly drained polder areas with a near-surface water...
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