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Journal ArticleDOI

Total, cold and hot water extractable organic carbon in soil profile: impact of land-use change

16 Jun 2014-Zemdirbyste-agriculture (Lithuanian Research Centre for Agriculture and Forestry)-Vol. 101, Iss: 2, pp 125-132
TL;DR: The results of this study show that HWEOC is much more informative indicator of soil organic matter quality than CWEOC, and this thin soil layer to be defined as soil stress-sensitive zone is suggested.
Abstract: The content of labile, especially water extractable organic carbon (WEOC) is a sensible indicator of soil organic matter quality. The main objectives of this study were: i) to investigate the profile changes of cold and hot water extractable organic carbon in forest and arable soils; ii) to evaluate the correlation between these labile fractions of soil organic matter and total organic carbon content. The experiments were carried out on a Gleyic Albeluvisol (ABg) in the upper part of Dniester basin, Western Ukraine. The soil samples were taken from 50-cm depth soil profile with 5-cm step. Total organic carbon (TOC), cold water extractable organic carbon (CWEOC) and hot water extractable organic carbon (HWEOC) contents in soil were determined as well as pH (H 2 O) and electrical conductivity of soil:water suspensions. The results of this study showed that in 0–50 cm layer of arable soil TOC content decreased by 32%, CWEOC – by 23% and HWEOC – by 74% compared to forest soil that confirmed a high informative role of HWEOC fraction. The profile changes of WEOC percentage were analysed. They also show that HWEOC is much more informative indicator of soil organic matter quality than CWEOC. The most prominent changes of soil chemical properties, TOC, CWEOC and HWEOC contents in response to deforestation were observed in the top 5-cm soil layer. We suggested this thin soil layer to be defined as soil stress-sensitive zone.

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Citations
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Journal ArticleDOI
TL;DR: In this article, the authors evaluated the effects of PFM on N 2 O emissions, yield-scaled emissions and the seasonal EFs in cover crop residues amended soil during maize cultivation.

42 citations

Journal ArticleDOI
01 Mar 2019-Catena
TL;DR: In this article, the authors used an Artificial Neural Network (ANN) and Linear Regression Methodology (LRM) to predict soil respiration in arid areas of Iran using 150 data points obtained from soil samples collected from the surface to 20 cm of depth under different land use categories.
Abstract: Soil respiration is a biological process in microbes that convert organic carbon to atmospheric CO2. This process is considered to be one of the largest global carbon fluxes and is affected by different physicochemical and biological properties of soil, land use, vegetation types and climate patterns. Soil respiration recently received much attention, and it could be measured in two states basal respiration (BR) and substrate induced respiration (SIR) which together gives a good representation of the general soil microbial activity. The aim of this study was to estimate the BR and SIR of 150 data points obtained from soil samples collected from the surface to 20 cm of depth under different land use categories using the Artificial Neural Network (ANN) and Linear Regression Methodology (LRM). This study is bringing data from an arid area, and there is little information on this issue. Soil samples were chosen from three provinces of Iran, with humid subtropical and semi-arid climate patterns. In each soil sample a variety of characteristics were measured: soil texture, pH, electrical conductivity (EC), calcium carbonate equivalent (CCE), organic carbon (OC), OC fractionation data e.g. light fraction OC (LOC), heavy fraction OC (HOC), cold water extractable OC (COC) and warm water extractable OC (WOC), population of fungi, bacteria, actinomycete, BR and SIR. Our goal was to use the most efficient ANN-model to predict soil respiration with simple soil data and annual precipitation (AP) and mean annual temperature (MAT) and compare it with LRM. Our results indicated that for an ANN model containing all the measured soil parameters (14 variables), the R2 and RMSE values for BR prediction were 0.64 and 0.05 while these statistical indicators for SIR obtained 0.58 and 0.15, respectively; whereas the addition of AP and MAT data to this model (16 variables) caused a decrease in statistical indicators. When the R2 and RMSE values of the BR-ANN and SIR-ANN predicted using an ANN model with only 7 variables (including OC, pH, EC, CCE and soil texture) they were estimated to be 0.66, 0.043 and 0.52, 0.16, respectively. Overall, LRM in comparison to ANN had a lower R2. Therefore, the results show that ANN modeling is a reliable method for predicting soil respiration, even when based on easy to measure data. Our results revealed that highest and lowest BR and SIR were recorded in rice paddy soils and saline lands, respectively. In total, soil respiration (BR: 0.09 vs 0.06 and SIR: 0.46 vs 0.32 mg CO2 g−1 day−1) was higher in agricultural land compared to natural covered land.

35 citations

Journal ArticleDOI
TL;DR: In this paper, the impact of different land uses on water extractable organic carbon (WEOC) fractions and the interaction between the WEOC fractions and other soil properties was evaluated.
Abstract: Soil organic carbon (SOC) has a high impact on the sustainability of ecosystems, global environmental processes, soil quality and agriculture. Long-term tillage usually leads to SOC depletion. The purpose of this study was to determine the impact of different land uses on water extractable organic carbon (WEOC) fractions and to evaluate the interaction between the WEOC fractions and other soil properties. Using an extraction procedure at 20°C and 80°C, two fractions were obtained: a cold water extractable organic carbon (CWEOC) and a hot water extractable organic carbon (HWEOC). The results suggest that there is a significant impact from different land uses on WEOC. A lower relative contribution of WEOC in SOC and a lower concentration of labile WEOC fractions are contained in arable soil compared to forestlands. Chernozem soil was characterized by a lower relative contribution of WEOC to the SOC and thus higher SOC stability in contrast to Solonetz and Vertisol soils. Both CWEOC and HWEOC are hig...

23 citations


Cites background from "Total, cold and hot water extractab..."

  • ...Significantly lower concentrations of WEOC fractions in arable soil compared to the forest soil were reported by Hamkalo and Bedernichek (2014)....

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  • ...The same attitude was proposed by Hamkalo and Bedernichek (2014)....

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Journal ArticleDOI
TL;DR: In this paper, the seasonal variability of two organic carbon fractions, particulate organic matter (POM) and dissolved organic carbon (DOC), under maize cropping was studied, and the results indicated the importance of the time of soil sampling during the course of a year, especially when investigating WESOC.

14 citations

Journal ArticleDOI
TL;DR: In this article, the authors provide an overview on current knowledge on origin, structure, chemical composition and factors inflencing dissolved organic matter cycling in agricultural soils as well as it role in functioning of agroecosystems.
Abstract: The aim of the paper is to provide an overview on current knowledge on origin, structure, chemical composition and factors infl uencing dissolved organic matter (DOM) cycling in agricultural soils as well as it role in functioning of agroecosystems. DOM is considered as one of the most sensitive indicators of changes overlapping in the soil environment. It is the most mobile and active soil component serving as an easily available source of nutrients and energy for microbes and other living organisms. It participates in the soil forming processes, transports nutrients and pollutants into deeper soil horizons and actively supports processes of soil structure formation. DOM transformation in agroecosystems is impacted by many chemical, physical and biological factors and modifi ed by climatic conditions and agricultural activities therefore the quantity and quality of DOM is very diffi cult to predict and control. Although, the role and the fl uxes of DOM have been widely investigated in previous decades, but the research interest was focused mainly on forest soils and water reservoirs while less attention was paid to soils of agricultural usage. New challenges facing agriculture related to the protection of soil functions infl uencing ecosystem services, mitigation of climate changes and sequestration of organic carbon indicate DOM as a potential factor enabling to reach these goals. Keywords

11 citations


Cites background from "Total, cold and hot water extractab..."

  • ...Strong adsorption of DOM deeper in soil profile was confirmed by Silveira Azevedo (2005) and Hamkalo and Bedernichek (2014) who noticed negative correlations between the net removal of hydrophobic acids and increasing soil depth....

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References
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Book
01 Jan 1971
TL;DR: Probability Theory. Statistical Inference. Contingency Tables. Appendix Tables. Answers to Odd-Numbered Exercises and Answers to Answers to Answer Questions as discussed by the authors.
Abstract: Probability Theory. Statistical Inference. Some Tests Based on the Binomial Distribution. Contingency Tables. Some Methods Based on Ranks. Statistics of the Kolmogorov-Smirnov Type. References. Appendix Tables. Answers to Odd-Numbered Exercises. Index.

10,382 citations

Journal ArticleDOI
TL;DR: In this paper, the 100th anniversary of Galton's first discussion of regression and correlation is celebrated, and 13 different formulas representing a different computational and conceptual definition of Pearson's r are presented.
Abstract: In 1885, Sir Francis Galton first defined the term “regression” and completed the theory of bivariate correlation. A decade later, Karl Pearson developed the index that we still use to measure correlation, Pearson's r. Our article is written in recognition of the 100th anniversary of Galton's first discussion of regression and correlation. We begin with a brief history. Then we present 13 different formulas, each of which represents a different computational and conceptual definition of r. Each formula suggests a different way of thinking about this index, from algebraic, geometric, and trigonometric settings. We show that Pearson's r (or simple functions of r) may variously be thought of as a special type of mean, a special type of variance, the ratio of two means, the ratio of two variances, the slope of a line, the cosine of an angle, and the tangent to an ellipse, and may be looked at from several other interesting perspectives.

3,251 citations

Journal ArticleDOI
TL;DR: In this article, the SOM fractions obtained with such operational fractionation procedures are described in terms of their pool sizes, chemical properties, and turnover rates, and the main objective is to evaluate these operationally defined fractions with respect to their suitability to describe functional SOM pools that could be used to parameterize SOM turnover models.
Abstract: Soil organic matter (SOM) consists of various functional pools that are stabilized by specific mechanisms and have certain turnover rates. For the development of mechanistic models that predict changes in SOM storage, these pools have to be quantified and characterized. In the past, numerous fractionation schemes have been developed to separate and analyse such SOM fractions. In this review, the SOM fractions obtained with such operational fractionation procedures are described in terms of their pool sizes, chemical properties, and turnover rates. The main objective of this review is to evaluate these operationally defined fractions with respect to their suitability to describe functional SOM pools that could be used to parameterize SOM turnover models. Fractionation procedures include (1) physical separation of SOM into aggregate, particle size, and density fractions and fractions according to their magnetic susceptibility, and (2) various wet chemical procedures that fractionate SOM according to solubility, hydrolysability, and resistance to oxidation or by destruction of the mineral phase. Furthermore, combinations of fractionation methods are evaluated. The active SOM pool with turnover rates

1,172 citations


"Total, cold and hot water extractab..." refers background in this paper

  • ...These findings further support the idea that even principally different SOM extraction techniques may evaluate chemically similar fractions of SOM that form its active pool (von Lützow et al., 2007)....

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Journal ArticleDOI
TL;DR: Using pre-established trial sites on allophanic soils, the impacts of long to medium-term pastoral management practices, such as fertilisation and grazing intensity, on a range of soil biological and biochemical properties; hot water-extractable C (HWC), water-soluble C (WSC), hot-water extractable total carbohydrates, microbial biomass-C and N and mineralisable N These properties were examined for their usefulness as soil quality indicators responding to changes in the rhizosphere caused by management practices as discussed by the authors.
Abstract: Using pre-established trial sites on allophanic soils, we investigated the impacts of long to medium-term pastoral management practices, such as fertilisation and grazing intensity, on a range of soil biological and biochemical properties; hot water-extractable C (HWC), water-soluble C (WSC), hot-water extractable total carbohydrates, microbial biomass-C and N and mineralisable N These properties were examined for their usefulness as soil quality indicators responding to changes in the rhizosphere caused by management practices Adjacent cropping, market garden and native bush sites located on similar soil types were included to determine the changes in soil biological and biochemical properties resulting from changes in land use The seasonal variability of HWC and its relationship with other labile fractions of soil organic matter was also examined Microbial biomass-C, mineralisable N and extractable total carbohydrates showed promise in differentiating treatment and land use effects However, HWC was one of the most sensitive and consistent indicators examined at 52 different sites The impact of different land uses on the amounts of HWC in the same soil type was far greater than that was observed for the soil organic carbon The average values of HWC for soil under different land use were: native (4000 μg C g−1 soil), sheep/beef pastures (3400), dairy pastures (3000), cropping (1000) and market gardening soils (850) HWC was also sensitive to differences within an ecosystem, eg effects of grazing intensities and effects of N or P fertilisers on pastures The sheep and beef/cattle grazed pastures always had higher amounts of HWC than the intensively grazed dairy pastures Nitrogen fertiliser application (200 and 400 kg N ha−1 yr−1) over the previous 5 yr had significant (P<0001) negative impacts on HWC and other soil microbial properties In contrast, long-term application of P fertilisers had a significant (P<0001) positive effect on the HWC levels in pastoral soils In the case of long-term P trials, HWC increased even though no increase in the total soil carbon pool was detected HWC was positively correlated with soil microbial biomass-C (R2=084), microbial nitrogen (R2=072), mineralisable N (R2=086), and total carbohydrates (R2=088) All these correlations were significant at P<0001 level of significance The HWC was also positively correlated with WSC and total organic C However, these correlations were poorer than those found for other soil parameters Most of these measurements have been actively promoted as key indicators of soil quality Given the strong correlations between HWC and other biochemical measurements, HWC could be used as an integrated measure of soil quality When HWC is extracted, other pools of labile nutrients are also extracted along with C Therefore it is suggested that decline in HWC would also indicate a decline in other labile organic pools of nutrients such as nitrogen, sulphur and phosphorus About 40–50% of the C in the HWC extract was present as carbohydrates

926 citations


"Total, cold and hot water extractab..." refers background or methods in this paper

  • ...Content of water extractable organic carbon (WEOC) was determined according to the method of Haynes and Francis (1993) modified by Ghani et al. (2003) that consists of two-step water extraction....

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  • ...Therefore two functional pools of WEOC are usually studied: cold water extractable organic carbon (CWEOC) and hot water extractible organic carbon (HWEOC) (Ghani et al., 2003)....

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Journal ArticleDOI
TL;DR: In this paper, the authors present a practical nonparametric statistical model for non-parametric statistics, which they call Practical Nonparametric Statistics, 3rd Ed. (3rd Ed.).
Abstract: (2001). Practical Nonparametric Statistics, 3rd Ed. Journal of Quality Technology: Vol. 33, No. 2, pp. 260-260.

791 citations