The Yellow River Delta has abundant land resources, but the land exhibits heavy degeneration because of long-term exposure to harsh natural conditions and improper human activities, and the soil ...quality is poor in some areas. All these factors have adversely affected agricultural development and ecological protection in the Yellow River Delta. This study selected multiple physical and chemical indicators and used principal component analysis (PCA) to construct a minimum data set (MDS) to determine a comprehensive set of indicators for assessing soil quality in the Yellow River Delta. Moreover, a fuzzy logic model was used to assess soil quality and analyze the spatial distribution of the primary land use types in different soil quality grades. The results indicate that the MDS includes six soil indicators: total nitrogen (TN), available phosphorus (AP), available potassium (AK), soil organic matter (SOM), soil salinity (SS) and pH. According to the spatial distribution maps of the indicators, SS gradually declined from the coast to the inland areas, while TN and AP had opposite characteristics. AK and pH were evenly distributed around the study area, and SOM was highest in the center and gradually declined toward the edge of the study area. The soil quality was higher in inland areas than in coastal areas, and most of the study area was classified as grade III. Most of the farmland, forest, and garden plots were distributed in high-grade soil levels, but some of these plots were distributed in areas classified as grades V or VI. Many areas with high soil quality were unused, which indicated that the land resources of the study area should be planned reasonably.
•A minimum data set (MDS) was established for soil quality assessment.•The soil quality values increased from coastal areas to inland areas.•A few of farmland and forest were distributed in low soil quality areas.•Many areas with high soil quality were sill unused.•The result was more detailed than that of other researches.
•A global meta-analysis on soil physical properties under conservation tillage.•Conservation tillage has higher aggregate size, stability and available water capacity.•Increased bulk density under ...conservation tillage remains non-harmful for crop growth.•Soil pH decreased under conservation tillage.•The response of soil physical properties vary with experiment duration.
Conservation tillage practices, here defined as no-tillage (NT) or reduced tillage (RT) with/without residue retention, have been widely used to alleviate the negative effects caused by intensive tillage practices. Implementing effective and sustainable agriculture requires a deeper understanding of the impacts of conservation tillage practices on soil physical properties. This study examined the effects of conservation tillage practices on soil physical properties, including soil bulk density, aggregate size and stability, hydraulic properties, and soil pH; based on data collected from 264 studies published worldwide since 1980. The results indicated that no-tillage (NT), NT with residue retention (NTS), and reduced tillage (RT) increased bulk density by 1.4, 2.6, and 2.1%, respectively, compared with conventional tillage (CT). Soil bulk density decreased by 2.9% in NTS compared with NT, and 3.9% in RT with residue retention (RTS) compared with RT. The effect size of bulk density significantly decreased with the increasing experimental duration under NT and NTS practices. Compared to CT, conservation tillage practices increased aggregate mean weight diameter (MWD), geometric mean weight diameter and water stable aggregate (WSA) regardless of the residue retention or minimum tillage systems. The largest effect size of MWD (51.9%) and WSA (54.9%) appeared under NTS as compared to the CT. The effect size of MWD and WSA increased under NT with the increasing experimental duration. NT increased saturated hydraulic conductivity by 24.6% compared to CT. All conservation tillage practices increased soil available water capacity (AWC) compared with CT and NTS with a 10.2% increase in AWC compared with NT. The effect size of AWC increased under RT and NT practices with the increasing experimental duration. Soil pH decreased by 1.7 and 1.0% under RTS compared with RT and CT, respectively; and NT led to a 2.8% reduction in soil pH compared with CT. The effect size of soil pH decreased under RT and NT treatments with the increasing experiment duration. Overall, conservation tillage practices positively affected many soil physical properties; and the extent of the effects varied with the duration of the experiment.
Analytical tools for evaluating reclamation success in terms of soil quality are the prime requisite in order to address sustainable mining issues. Identification of the influential parameters of ...reclamation success and prediction of soil health in terms of soil quality indexing and modelling remain obscure. Therefore, the present study aims to formulate reclaimed mine soil quality index (RMSQI) using the indicator selection method and scoring function analysis. Furthermore, for identification of the relationship between RMSQI and predictor variables, statistical (Multiple linear regression; MLR) and machine learning (Random Forest; RF) approaches were applied to determine the suitable soil quality assessment technique for chronosequence afforested post-mining site in India. The results indicated that the organic carbon, exchangeable potassium, cation exchange capacity, sand percentage, microbial biomass carbon, dehydrogenase activity and fluorescein diacetate acitivity were the most influential variables impacting soil quality. The linear scoring-minimum dataset (LSF-MDS) was considered as the most suitable approach to estimate RMSQI due to its highest correlation coefficients F, and coefficient of variance (CV) values. The lower error matrices and higher R2 for RF than MLR indicating the aptness of RF model in predicting soil quality in terms of evaluation of reclamation success. The present study concluded that the superiority of RF is associated with its ability to address hierarchical and non-linear relationship between RMSQI and its predictors.
•Reclamation success of post mining derelict ecosystem was evaluated with chronosequence approach.•RMSQI was formulated using the indicator selection method and scoring function analysis.•Biodiversity indices was found highest in older revegetated ecosystem (RMS 26).•Highest RMSQI in RMS 26 amongst chronosequence afforested dumps reflects the ecosystem recovery trajectory.•MLR and RF indicated diverse strategies in addressing relationship between RMSQI and its predictor variables.
The adsorption characteristics and mechanism of Cd2+ on microbial inoculant (MI) mainly composed of Bacillus subtilis, Bacillus thuringiensis and Bacillus amyloliquefaciens, and its potential for ...remediation Cd polluted soils through batch adsorption and soil incubation experiments. It was found that the Freundlich isotherm model and the pseudo–second–order kinetics were more in line with the adsorption processes of Cd2+. The maximum adsorption capacity predicted by Langmuir isotherm model suggested that of MI was 57.38 mg g−1. Scanning electron microscopy and energy dispersive spectroscopy (SEM–EDS) images exhibited the surface structure of MI was damaged to varying degrees after adsorption, and Cd element was distributed on the surface of MI through ion exchange. X–ray diffraction (XRD) results showed that CdCO3 was formed on the surface of MI. Moreover, the functional groups (–OH, C–H, and –NH) involved in the adsorption of Cd2+ through fourier transform infrared spectroscopy (FTIR). After applying MI to Cd–contaminated soil, it was found that soil pH, conductivity (EC) and soil organic matter (SOM) increased by 0.84 %–2.43 %, 31.6 %–241.48 %, and 8.11 %–24.1 %, respectively, when compared with the control treatments. The content of DTPA–Cd in the soils was significantly (P < 0.05) reduced by 15.48 %–29.68 % in contrast with CK, and the Cd speciation was transformed into a more stable residual fraction. The activities of urease, phosphatase and sucrose were increased by 3.5 %–45.18 %, 57.00 %–134.18 % and 52.51 %–70.52 %, respectively, compared with CK. Therefore, MI could be used as an ecofriendly and sustainable material for bioremediation of Cd–contaminated soils.
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•MI exhibited effectively remediate Cd-contaminated water and soil.•MI can immobilize Cd through ion exchange, precipitation and complexation.•MI reduced the availability of soil Cd and improved soil chemical properties.
In ecologically fragile areas heavily affected by human disturbance, it is imperative to restore soil quality to preserve nutrient cycling and ensure ecosystem stability. However, our understanding ...about the underlying mechanisms of dynamic change in soil quality associated with revegetation in alpine areas remains incomplete. In this study, data from 96 plots were collected to reveal the response of soil quality to vegetation restoration in alpine mines. The soil quality index (SQI) was developed utilizing 19 measured indicators to assess differences in soil quality between various vegetation restoration modes (natural restoration (CK), planting with Elymus dahuricus (ED), Medicago sativa (MS), and multi-plant mixed (Avena fatua L. + Elymus dahuricus + Medicago sativa + Oxytropis coerulea, MM)) and restoration periods (1, 3, 4, and 6 years). A partial least squares structural equation model (PLS-SEM) was constructed to recognize the impact of 14 variables related to topographical features, plant biodiversity and community stability, aboveground plant productivity characteristics, root functional traits, and soil erosion on soil quality. The results revealed significant variations in soil quality among different vegetation restoration modes. Within the initial four years following vegetation restoration, the discernible discrepancies in SQI values were as follows: ED > MM > MS > CK; by the sixth year, the order shifted to MM > ED > MS > CK. Aboveground plant productivity characteristics and functional root traits significantly contribute to soil quality. In contrast, plant biodiversity and community stability had no significant effects on soil quality. Topographical features and soil erosion adversely affected soil quality, with soil erosion exerting the most prominent effect.
•Artificial vegetation restoration significantly contributed to soil quality.•Soil quality was best improved by planting multi-plant mixed.•Soil erosion exerted the most prominent adverse effects on soil quality.
► This study compared soil quality indices based on 3 sets of indicators. ► The effects of land management practices on soil functions were evaluated. ► Soil quality was best assessed using a set of ...29 indicators. ► However, fewer-indicators sets (8 and 4) showed the same trends. ► Soil quality index approach provides great information for land management decisions.
Efforts to define and quantify soil quality are not new, but establishing consensus about a set of standardized indicators remains difficult. Also, the view of land managers is usually not taken into account when evaluating various sets of indicators. Our objective was to compare, in functional terms, soil quality assessments based on 29 indicators, a subset with 8 of those indicators, and 4 indicators selected independently by farmers, based on their perceptions of soil quality. The assessments were made for three different rice management systems in Camaquã, Rio Grande do Sul state, Brazil, on soils of four soil textural classes based on clay content (<200, 200–400, 400–600, or >600gkg−1). The effects of land management practices on soil functions (water infiltration, storage and supply; nutrient storage, supply and cycling; and sustained biological activity) were evaluated. Soil quality was best assessed using the entire set of 29 indicators, but use of smaller indicator sets showed the same trends among management systems, textural classes, and soil functions, thus providing meaningful information on soil quality for land managers.
•Optimized N fertilization and irrigation show a large potential for N2O mitigation.•Reduced tillage and crop residues management show a large potential for reducing net GHG emissions.•CH4 fluxes ...from paddies are controlled by management of water table and organic inputs.•Factors beyond the plot scale may outweigh mitigation measures.•Training to farmers on the application of practices will overcome barriers for implementation.
An integrated assessment of the potential of different management practices for mitigating specific components of the total GHG budget (N2O and CH4 emissions and C sequestration) of Mediterranean agrosystems was performed in this study. Their suitability regarding both yield and environmental (e.g. nitrate leaching and ammonia volatilization) sustainability, and regional barriers and opportunities for their implementation were also considered. Based on its results best strategies to abate GHG emissions in Mediterranean agro-systems were proposed. Adjusting N fertilization to crop needs in both irrigated and rain-fed systems could reduce N2O emissions up to 50% compared with a non-adjusted practice. Substitution of N synthetic fertilizers by solid manure can be also implemented in those systems, and may abate N2O emissions by about 20% under Mediterranean conditions, with additional indirect benefits associated to energy savings and positive effects in crop yields. The use of urease and nitrification inhibitors enhances N use efficiency of the cropping systems and may mitigate N2O emissions up to 80% and 50%, respectively. The type of irrigation may also have a great mitigation potential in the Mediterranean region. Drip-irrigated systems have on average 80% lower N2O emissions than sprinkler systems and drip-irrigation combined with optimized fertilization showed a reduction in direct N2O emissions up to 50%. Methane fluxes have a relatively small contribution to the total GHG budget of Mediterranean crops, which can mostly be controlled by careful management of the water table and organic inputs in paddies. Reduced soil tillage, improved management of crop residues and agro-industry by-products, and cover cropping in orchards, are the most suitable interventions to enhance organic C stocks in Mediterranean agricultural soils. The adoption of the proposed agricultural practices will require farmers training. The global analysis of life cycle emissions associated to irrigation type (drip, sprinkle and furrow) and N fertilization rate (100 and 300kgNha−1yr−1) revealed that these factors may outweigh the reduction in GHG emissions beyond the plot scale. The analysis of the impact of some structural changes on top-down mitigation of GHG emissions revealed that 3–15% of N2O emissions could be suppressed by avoiding food waste at the end-consumer level. A 40% reduction in meat and dairy consumption could reduce GHG emissions by 20–30%. Reintroducing the Mediterranean diet (i.e. ∼35% intake of animal protein) would therefore result in a significant decrease of GHG emissions from agricultural production systems under Mediterranean conditions.
There is growing interest in the applications of soil enzymes as early indicators of soil quality change under contrasting agricultural management practices. However, despite there being an abundant ...literature on this subject, most comparative assessments have been based on a limited number of experimental farms and, therefore, conclusions are not as robust as desired. In this study, we compare 18 pairs of organic and neighbouring conventional olive orchards in southern Spain. These sites were selected to allow the definition of the relative contributions of site-landscape features, soil type, and time since organic accreditation and tillage intensity, on the soil quality. Soils were analysed for physico-chemical properties, the activities of dehydrogenase, β-glucosidase, arylsulphatase, acid and alkaline phosphatase, and potential nitrification. The geometric mean of the assayed enzymes (GMea) was validated with an independently performed Principal Component Analysis (PCA), and used as a combined soil quality index. The effects of tillage intensity and time since organic accreditation on the improvement of soil quality were also evaluated within the subset of organic farms. Overall for the 18 sites, contrasted management practices did not differ in their impact on basic soil physico-chemical properties, except for loss of on ignition and available inorganic N which were higher and lower in organic farms, respectively. Organic management resulted in significantly higher soil enzyme activities. However, differences were not significant in some of the paired comparisons when considered individually. This highlights the need for extensive comparative assessment, as in this study, to draw clear conclusions concerning the changes to soil quality under sustainable management practices. The GMea was significantly correlated with the first axis of the PCA and shown to be appropriate for condensing the set of soil enzyme values to a sole numerical value. Soil quality changes in organic versus conventional farms, as measured by the GMea, ranged from −23% to 97%, and was highly dependent on time since organic accreditation (
r
=
0.88;
P
<
0.01). On the other hand, tillage intensity clearly tended to delay any progress in soil quality in the organic farms.
Soil degradation has become an emerging global problem limiting sustainable upland crop production. Soil erosion, soil acidity, low fertility, inorganic/organic contamination, and salinization ...challenge food security and lead to severe economic constraints. Therefore, a new research agenda to develop cost-beneficial amendments for improving upland soil quality and productivity is urgently required. Biochar has been used in recent years to mitigate the problems mentioned above. Application of biochar improves the upland soil quality through significant changes in soil physicochemical and biological properties, thereby substantially increasing crop yield. This review article aims to discuss the effects of biochar on upland soil quality and productivity based on biochar-soil interactions. The yield of various upland crops can be enhanced by biochar-induced increases of nutrient availability and topsoil retention/recovery. Furthermore, biochar can assist in controlling unsuitable soil acidity/alkalinity/salinity and remediating a contaminated soil while increasing the retention of soil organic carbon, water content, and thereby high crop yield. Biochar is strongly recommended as one of the best management practices to meet the challenges of upland agriculture. However, the properties of biochar and soil type should be considered carefully prior to application.
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•Potential uses of biochar to address the emerging global problem of soil degradation are reviewed.•Biochar-soil interactions trigger beneficial changes in soil physical, chemical, and biological characteristics.•Biochar is a cost-effective amendment for remediating upland soil quality and improving crop productivity.•Selection of biochar must match substrate type and production conditions to desirable soil attributes and intended uses.
Partial substitution of chemical fertilizers by organic amendments is essential for improving the soil quality without yield loss. Fungi play an important role in soil quality because they decompose ...organic matter and cycle nutrients in the soil. However, there is limited information regarding the effect of different organic substitution rates (OSRs) on the soil quality and fungal community. This study investigated the relationship between the soil quality index and fungal community in a tea plantation under different OSRs of N, from a single application of synthetic fertilizer (NPK) to 100% N substitution with organic fertilizer (OM100). The OSRs were positively correlated with the soil physicochemical and biological soil quality index (SQI), but only the physicochemical SQI exhibited a significant relationship with tea production. The OSR also shifted the soil fungal community composition. Soil pH, soil organic C (SOC), microbial biomass C (MBC), and available potassium (AK) were the key characteristics that were significantly correlated with the variation of soil fungal community. Network analysis indicated that additional organic substitution can enhance the soil fungal network complexity, which also showed a positive correlation with the SQI. These results confirmed the feasibility of organic substitution for soil quality improvement, and implied that the soil fungal network complexity could be a new indicator for soil quality assessment.
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