Soil quality evaluation as a decision-making tool to improve understanding of soil quality is essential for grading croplands and adopting proper agricultural practices. Various methods of soil ...quality evaluation have been developed, which have occasionally generated inconsistent evaluation results between differing soil types. The applicability of these techniques is seldom tested before implementing an evaluation method on a specific soil region. Fluvisol is an important soil resource for agriculture in China, especially for irrigation districts along the lower Yellow River. In the present study, the soil quality of two typical agricultural counties (Yucheng and Kenli) along the lower Yellow River was evaluated using four commonly utilized methods. In the two counties, the overall spatial patterns of soil quality derived from the four methods were similar, with differences in details existing among these methods. The soil quality in Yucheng, ranging from moderate to high, is superior to that observed in Kenli, where salinity is the primary limiting factor. In addition, the applicability of soil quality evaluation methods on the Fluvisol was investigated. It was found that the integrated quality indexing-linear scoring (IQI–LS) and the Nemoro indexing-linear scoring (NQI–LS) methods were the most accurate and practical of the four methods studied. These methods, which are based on the total data set of indicators, show better performance for soil quality evaluation on a Fluvisol. Further, different evaluation methods based on the minimum data set of indicators were compared, considering both the accuracy of the evaluation and the economic cost of obtaining the soil data. The results from the present study indicate that the IQI–LS method based on the minimum data set of indictors is recommended for large-scale soil quality evaluations.
•Four soil quality evaluation methods were compared for a Fluvisol.•IQI–LS and NQI–LS methods performed better in soil quality evaluations.•For large-scale studies, the IQI–LS based on a minimum data set is recommended.
The use of treated wastewater (TWW) for crop irrigation is practiced in many countries worldwide as a strategy to offset water scarcity. Soil quality assessment is required to ensure that the ...application of this non-conventional irrigation water is sustainable over long periods. A relatively limited number of studies have used soil quality indexing approaches to investigate the impacts of TWW irrigation on soil quality. Therefore, this study aimed to assess the impacts of more than three decades of TWW irrigation on Fluvisol in semi-arid agrosystem to develop soil quality indices and evaluate their use as a practical tool to support TWW irrigation management. Overall, a total of 13 key soil attributes, used as soil quality indicators, were monitored in three TWW-irrigated plots and their adjacent non-irrigated control in eastern Tunisia. These selected indicators were used to develop a soil quality index (SQI) based on either a total data set (SQI-TDS) or a minimum data set (SQI-MDS) indexing approach. In comparison to the control, TWW application significantly increased saturated hydraulic conductivity (Ks) (+740%), saturation percentage (SP) (+20%), aggregate stability (AS) (+64%), field capacity (FC) (+52), electrical conductivity (EC) (+72%), phosphorous (P) (+472%), potassium (K) (+43%), organic matter (OM) (+90%) and basal respiration (BMR) (+117%) and decreased hydrophobicity (−17%), bulk density (BD) (−13%), cone penetration resistance (CPT) (−17%) and pH (−4%). The two developed SQI-TDS and SQI-MDS indices were sensitive to distinguish the impacts of TWW irrigation on soil quality in the study area. In comparison to the control, the TWW-irrigated soils exhibited higher SQI ratings by 42 and 52% based on SQI-MDS and SQI-TDS, respectively. Based on the monitored soil quality indicators in TWW-irrigated and control plots, this study indicates that long-term TWW application improved the overall soil quality and supports SQI-MDS’s efficiency in providing an adequate evaluation of soil quality in the study area.
•Dry sub-humid floodplain soils accumulated 15 % more C than soils under semiarid.•Dry sub-humid climate favored the largest natural fertility of floodplain soils.•Overgrazing causes more negative ...impacts on floodplain soils than agriculture.•Overgrazing reduced natural C and N stocks in floodplain soils by 65 and 62 %.
Floodplain soils represent important food production sites worldwide due to their high natural fertility and large carbon (C) storage capacity. In this study, 27 soil profiles, along an aridity gradient, were used to estimate how climate (semi-arid and dry sub-humid) and land-use (agriculture and overgrazing) affect soil C and nitrogen (N) storage and chemical properties of surface horizons in floodplain soils in tropical drylands, northeastern Brazil. The results indicated that soils under dry sub-humid climate (wetter) accumulated 15.1 and 17.0 % more C and N than soils under semi-arid climate (drier), respectively. The Ca2+, Mg2+, K+, Na+, H+ contents and P availability of the soils were favored in the wetter condition. In the land-use analysis, the results indicated that soils under overgrazing showed lower C and N stocks by 35.7 % and 36.7 % respectively, when compared to soils managed under agriculture. Soils under overgrazing presented, on average, 36.0, 44.4 and 26.0 % less Ca2+, K+ and CEC than the soils under agriculture, respectively. For P, both overgrazing and agriculture reduced its availability by 21.2 and 31.4 % respectively, when compared to the forest soil (reference). The significant effect of overgrazing was evident in the reduction of C and N stocks and natural fertility of the floodplain soils. The results of this study can be useful for the correct management and definition of strategies for sustainable uses of floodplain soils in drylands globally.
Increased soil total phosphorus (P) or available P has been reported in biochar‐amended soils, although the underlying mechanisms need to be fully understood. In the present study, two contrasting ...soils (acidic Haplic Luvisol and alkaline Calcaric‐Fluvisol) amended with wheat straw biochar were sequentially extracted with modified Hedley method to study the P transformation in the soils. Our results showed that biochar application significantly increased (positive effects) P fractions (except for NaHCO3‐Pi and residual‐P) content in Haplic Luvisol. The increased soil microbial activity and reduced soil acidity or increased cation exchange capacity may be accounted for enhanced P transformation. The reduced NaHCO3‐Pi content may be related to P immobilization with increased soil microbial activity induced by biochar addition because the high C:P ratios of biochar (ranged from 234 to 357) suggested net P immobilization occurred when biochar was incorporated into soil. Biochar application first (4 days) increased soil NaHCO3‐Po content and then decreased it with longer incubation time (30 days). The decrease in NaHCO3‐Po suggested that the labile organic P was converted into nonlabile inorganic or organic P. In comparison with those in Haplic Luvisol, almost all P fractions showed negative effects with biochar addition into Calcaric‐Fluvisol. The results may be caused by the P precipitation or sorption with increased soil pH with biochar application. On the basis of P transformation, biochar is recommended to be used in Haplic Luvisol (acidic soil) and not to Calcaric‐Fluvisol (alkaline soil) because of the positive effects and negative effects observed on P fractions in biochar‐amended soils.
Riparian woodlands consist of different landscape units characterized by different hydroecomorphological site conditions that are reflected in the distribution of soils and tree species. These ...conditions are determined by flooding frequency and duration, distance to river channels, elevation and water flow velocity. The influence of these environmental drivers on the stabilization of soil organic matter (SOM) has as yet not been investigated. Hence, the aim of our study is to link soil formation and its drivers with stabilizing processes of SOM in riparian floodplain forests. We investigated soils and sediments at two sites in the ash–maple–elm–oak alluvial forest zone (AMEO sites) and two sites in the willow-poplar alluvial forest zone (WiP sites) within the riparian zone of the Danube near Vienna (Austria). Sediments and soils were characterized based on texture, contents of organic carbon (OC), nitrogen, Fe oxides, and soil pH. Density fractionation was used to separate OC fractions in terms of stabilization process and resulting organic matter (OM) turnover time: the free light fraction (fast turnover), the light fraction occluded in aggregates (intermediate turnover) and the heavy fraction of OM associated tightly to mineral surfaces (slow turnover).
At both sites, soil and sediment properties reflect the hydroecomorphological site conditions for formation of the landscape units in the riparian zone: Soils at AMEO sites develop during constant deposition of fine-textured sediment while water flow velocity is low. Progressing soil development causes a continuous decrease in OC content with increasing soil depth, mainly from fractions with fast and intermediate turnover. As a consequence the heavy fraction clearly dominates with around 90% of OC. Temporally variable flooding conditions with occurring turbulences found at WiP sites result in a discontinuous change of soil properties with increasing soil depth. Former topsoil horizons buried by huge amounts of sediments seem to keep the OC fractionation typical for topsoil horizons with extraordinarily high amounts of light fraction OM (free and occluded) representing 20–40% of total OC. The presented results confirm that sedimentation and soil formation are simultaneous processes at AMEO sites. At WiP sites both processes seem uncoupled with alternate phases of sedimentation and soil formation. Thus, the frequent burial of topsoil material formed at WiP sites seems to enable the conservation of unstable organic matter fractions at this part of active floodplains.
•Tree species composition was used as proxy for hydroecomorphological conditions.•Hydroecomorphological conditions in the riparian zone drive soil formation•Hydroecomorphological conditions control SOM stabilizing mechanisms•Close to the river, sedimentation and soil formation are temporally uncoupled.•Distant to the river, sedimentation and soil formation occur simultaneously.
Climate warming has significantly impacted the ecosystems of the Subarctic and Arctic. It has most strongly affected highly productive ecosystems, including those formed in river floodplains. Due to ...the initially high (background) values of NDVI, remote monitoring methods are not suitable for detecting changes in the biological productivity of floodplain vegetation. Research for both individual regions and landscapes is needed. However, for the floodplains of many rivers in Western Siberia, there are no primary descriptions of soils and vegetation. We have studied the soils and vegetation of the riverside floodplains in the lower reaches of the Taz River within the Pur–Taz interfluve. The studies were carried out within the hydrological continuum from the stream to the main Taz River. A regular change in soils and vegetation along the hydrological continuum was established, with fluvial processes intensifying. Ecosystems with the greatest diversity of plants, with thick layered soils such as Pantofluvic Fluvisol (Polyarenic, Polysiltic, Humic), are formed in the valleys of the tributaries of the Taz River on the natural riverside levee. The floodplain of the Taz River is distinguished by small differences in the heights of topographic elements, loamy soil texture, waterlogging and permafrost. The soils of the studied hydrological continuum were assigned to two Reference Soil Groups (Gleysol and Fluvisol). To describe the diversity of basic soil properties, six principal qualifiers and nine supplementary qualifiers were used. An assumption was made about the replacement of willow bushes by alder bushes during the warming period with the growth of some species of forbs (Parasenecio hastatus). The study made it possible to outline ways of further studying the floodplains of the Subarctic of Western Siberia.
•Study of soil organic matter in 124 samples from floodplain soils.•Differentiation of thermostable and thermolabile soil organic matter.•Black carbon is a common feature of mollic horizons in ...floodplain soils.•Variety of formation pathways of mollic horizons in floodplain soils likely.
Soils on riverine floodplains in temperate climate may be characterized by a mollic epipedon, i.e. by dark colour, enhanced content of soil organic matter (SOM), high ‘base’ saturation and developed structure in the topsoil. We studied 124 soil samples from ten central/east European countries to investigate whether SOM in mollic horizons has similar chemical features. We determined carbon contents with a thermal-gradient method to differentiate SOM with varying thermal stability, and carbonates. We characterized SOM by diffuse reflectance infrared Fourier-transform (DRIFT) spectroscopy. According to the World Reference Base for Soil Resources, 102 of the samples fulfilled all criteria of a mollic horizon. Mollic features were not restricted to the uppermost horizon but also detected in buried former surface horizons. Soil colour was mostly the criterion to exclude non-mollic samples. Mollic and adjacent non-mollic horizons contained thermostable SOM, indicating SOM stabilized by interaction with minerals or as black carbon (BC), to very similar extent, up to 20.4% of total soil organic carbon (SOC). However, the correlation between the contents of thermostable SOC and total SOC, the SOC:N ratios of the thermostable fraction, and the smaller extent of metal complexation of carboxyl groups, pointed to a larger contribution of BC to SOM of mollic samples than to SOM in non-mollic samples. Thus, like in mollic horizons in Chernozems and Phaeozems not affected by fluviatile dynamics, SOM in mollic horizons of floodplain soils seemed to consist of SOM affected by natural or anthropogenic fires, constituting a common chemical feature of SOM. Thus, BC may contribute to soil colour and SOM stability in mollic horizons of floodplain soils. However, apart from BC contribution, SOM in mollic horizons of floodplain soils may have further pathways of formation and development, as SOM may be inherited from deposited material or form/transform by degradative or constructive processes.
•First long-term CA experiment on magnesic fluvisol in New Caledonia.•Soil health index was 1.3-fold higher under CA than under CT.•Maize yield under CA systems were 1.3-fold higher than under CT ...system.•SEM discriminated relationships between cropping system management and performance.
Conservation agriculture (CA) is one strategy with which both sustainability and productivity can be achieved by improving soil health. However, linkages between practices, soil health and cropping system performance remain poorly disentangled. We assessed the relationships between soil health and cropping system performance for three maize-based cropping systems in New Caledonia. Two CA systems, one with direct seeding into a mixed species dead mulch (CA-DM) and one into a stylo living mulch (CA-LM), were compared to a conventional tillage (CT) system. CA vs. CT experiment started in 2011, whereas the differentiation between CA-DM and CA-LM was initiated in 2017 only. In 2018, soil health was evaluated using Biofunctool®, a set of ten in-field tools that assess soil carbon transformation, structure maintenance and nutrient cycling functions. The performance of the three cropping systems were assessed by monitoring weeds, maize growth and yield components. Structural equation modelling (SEM) was used to disentangle the links between agricultural management, soil health and cropping system performance. Soil structure maintenance and nutrient cycling functions were higher under CA-DM and CA-LM than under CT, and carbon transformation function was higher under CA-DM than under CT and CA-LM. Overall, the soil health index (SHI) was 1.3-fold higher under CA systems than under CT. Cropping system management had both direct and indirect effects on soil functioning and crop productivity leading to a 1.3-fold higher yield under CA than under CT. The direct and indirect effects of CA systems on soil health had positive impacts on ecosystem services (i.e., productivity, weed regulation and soil ecosystem services). Such integrative approaches that account for the relationships and possible trade-offs between cropping system components enable a better understanding of the effects and the performance of practices, and support adaptive agricultural management.
•Treated wastewater irrigation system has affected lateral and vertical metals distribution.•Relative metals vertical distribution can be qualitatively investigated by the calculation of ...logRatio.•Isovolumetric mass balance determines quantitatively the loss or the gain in the stocks of metals for soil pedon.
Treated wastewater irrigation, usually, leads to the increase of metals contents in soils and affects their mobilities and distributions. The aim of this study is to evaluate the effects of treated wastewater irrigation systems on the vertical and lateral distribution of metals in soils. Two irrigated sites with treated wastewater were chosen. The first is composed of a calcisol soil type, irrigated since 17 years with a furrow irrigation system. The second one, fluvisol, irrigated since 4 years with a bowl irrigation system. In both sites, a vertical soil sampling is made as a pedological profile in the irrigated soil and the non irrigated one (control). Moreover, in the calcisol, another lateral soil sampling is carried out in the same direction of irrigation water flux. All the soils samples were characterised by their major and metal contents as well as some soils physicochemical properties. To evaluate the vertical distribution of metals in soils, two parameters are calculated: the logRatio and the isovolumetric mass balance as qualitative and quantitative tools respectively.
In the irrigated calcisol, the logRatio shows a slight enrichment of metals in the upper soil layer mainly for Cr. The isovolumetric mass balance confirms this trend for Cr but, in contrast, the stocks of Zn and Cu in the soil have decreased. The logRatio for the fluvisol reveals an accumulation of all the metals in a new created horizon at 90 cm of the depth. Quantitatively, the stocks of Cr, Zn and Cu, in this soil, have increased. However, in the case of calcisol, the furrow irrigation system favors the lateral distribution of metals rather than the vertical variability.
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