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Against the background of increasing salinisation of land, the use of environmentally friendly plant growth-promoting bacteria (PGPB) resources for soil improvement is particularly important. The aim of this study was to investigate the effects of Pseudomonas cedrina DY1-3 on maize seedling growth, soil physico-chemical properties, and bacterial community structure. The study also evaluates the effects of this microbial agent on plant growth and saline soil improvement, providing theoretical references for microbial agents in promoting plant growth and improving saline soils. We found that there were significant differences between arable and saline soils in terms of soil physico-chemical properties and bacterial community structural composition, and that total salt was the main environmental factor influencing microbial communities. In both arable and saline soils, the application of DY1-3 bacterial suspension had a significant positive effect on the growth of maize plants and bacterial community richness. In arable soil, it could promote the growth of maize seedlings and significantly increase the Shannon and Simpson index, and AK was a key factor influencing the bacterial community. In saline soil, it could alleviate the mitigation stress and promote the growth of maize seedlings and cause a significant increase in Shannon's and Chao1 index, and the application of DY1-3 and potting could cause a significant decrease in total salt. In addition, DY1-3 and maize plants acting together in the soil can better improve the saline soil. The above results indicate that DY1-3 has potential for saline soil improvement and crop yield enhancement. [ABSTRACT FROM AUTHOR]

Coal mining activities affect the soil by causing soil erosion, formation of sinkholes, and leaching chemicals into the soil. The overburden dumps deposited in un-mined areas create mine spoils causing various environmental problems. Present study compared soil physico-chemical properties from an open cast coal mine of Raniganj (Bansra OCP) and a protected forest Ballavpur Wildlife Sanctuary (BWS) to investigate the effects of open cast coal mining on soil quality. Layer wise (0-10, 10-20 and 20-30 cm) soil samples were collected from 0-, 4-, 7- and 26-year old overburden dumps of Bansra OCP and also from BWS. Layer wise, no significant variations were observed in soil properties. ANOVA indicated significant variations in soil properties among overburden dumps and forest. Soil pH, calcium, sodium, magnesium and electrical conductivity were higher in overburden dumps than in the forest. These cations showed 51 to 91% increase in overburden dumps compared to the forest soil. Mining activity altered the soil quality due to decline in organic carbon, available nitrogen, potassium and phosphorus in the young aged overburden dumps. With the increase in the age of overburden dumps, significant recovery in organic carbon, mineral nitrogen and magnesium was observed, while pH, moisture, calcium and sodium declined significantly. No significant increase was observed in soil potassium and phosphorus, while clay and silt contents remained lower in all the overburden dumps. [ABSTRACT FROM AUTHOR]

Natural and anthropogenic changes in the composition of tropical forests are expected to alter soil properties. Thus, an understanding of the effects on changes in crop/plant composition on soil properties is needed to choose better land-use options. So, the primary goal of this study was to examine the impacts of land-use change (from shifting cultivation to teak and rubber plantation) on some physico-chemical features (available P, K, N, pH, moisture content (MC), bulk density, organic matter (OM)) of soil. Soil physico-chemical properties were compared to a shifting cultivation land with a 14-year-old teak plantation and a 16-year-old rubber plantation that had previously been used for shifting cultivation. Results showed that soil properties change with the changes of crop/plant composition, such as phosphorus (P), K, and OM was significantly high in teak and rubber plantation than the shifting cultivation area both in surface (0–10 cm) and sub-surface (10–20 cm) soil layers. Teak (3.5689 mg/kg) and rubber (3.5478 mg/kg) plantations exhibited significantly higher mean P content (p < .01) compared to shifting cultivation (3.4678 mg/kg). Shifting cultivation had the maximum K levels (0.2233 meq/100 g), while teak (0.2833 meq/100 g) and rubber (0.2733 meq/100 g) plantations showed significantly higher values (p < .05). Moisture content was 1.13% higher in teak and 1.2% higher in rubber plantations than in shifting cultivation. Furthermore, OM content was significantly higher in teak and rubber plantations (5.2744%, 5.2567%) compared to shifting cultivation (4.5067%). On the other hand, total nitrogen (N) and pH levels showed no significant difference among the land-use types. Finally, the study showed that conversion to teak and rubber plantation could lead to positive change in the soil properties. Hence it suggested that this can be undertaken/chosen as a better land cover option for shifting cultivated land in Chittagong Hill Tracts (CHTs) from soil conservation point of view. [ABSTRACT FROM AUTHOR]

Land degradation in the form of soil erosion and fertility reduction is a major environmental problem in Ethiopia. Various efforts to control soil erosion through the introduction of soil and water conservation measures have been underway for nearly five decades in Ethiopia. The purpose of this research was to assess the effects of soil bunds on selected soil physical and chemical properties in the Anole watershed of Rift Valley of Ethiopia. A reconnaissance survey was conducted to identify a representative soil sampling site. 18 composite soil samples were collected from soil bund and no conservation practice (control) with three replications at three slope positions from 0 to 30 cm depth, whereas, 18 undisturbed soil samples were collected for bulk density analysis from both land uses. The analysis was carried out using analysis of variance (ANOVA). Clay, sand, BD, CEC, TN, and OM showed significant variation (P < 0.05) between the soil bund and control plots. Whereas, for slope positions, sand, clay, BD, CEC, TN, and available phosphorus in the Anole watershed were found to be statistically significant (P < 0.05). In steep, middle, and lower slopes, contents of OC and exchangeable potassium were greater in fields with soil bunds than without. Lower slope fields showed greater clay, OM, and nutrients than steep slopes. Because of the implementation of soil bund in the study watershed, the majority of soil’s physical and chemical characteristics have shown improvement. Proper implementations of soil bunds in the study area have a pronounced positive impact and should be practiced and applied in adjacent watersheds and similar agroecologies in the Rift Valley of Ethiopia.

Against the background of increasing salinisation of land, the use of environmentally friendly plant growth-promoting bacteria (PGPB) resources for soil improvement is particularly important. The aim of this study was to investigate the effects of Pseudomonas cedrina DY1-3 on maize seedling growth, soil physico-chemical properties, and bacterial community structure. The study also evaluates the effects of this microbial agent on plant growth and saline soil improvement, providing theoretical references for microbial agents in promoting plant growth and improving saline soils. We found that there were significant differences between arable and saline soils in terms of soil physico-chemical properties and bacterial community structural composition, and that total salt was the main environmental factor influencing microbial communities. In both arable and saline soils, the application of DY1-3 bacterial suspension had a significant positive effect on the growth of maize plants and bacterial community richness. In arable soil, it could promote the growth of maize seedlings and significantly increase the Shannon and Simpson index, and AK was a key factor influencing the bacterial community. In saline soil, it could alleviate the mitigation stress and promote the growth of maize seedlings and cause a significant increase in Shannon’s and Chao1 index, and the application of DY1-3 and potting could cause a significant decrease in total salt. In addition, DY1-3 and maize plants acting together in the soil can better improve the saline soil. The above results indicate that DY1-3 has potential for saline soil improvement and crop yield enhancement.

Unreasonable cultivation methods and management measures have led to widespread obstacles in tobacco continuous cropping in planting areas, resulting in reduced tobacco yield and soil degradation. Therefore, intercropping tobacco with other crops is an effective strategy to improve continuous cropping barriers. In this study, flue-cured tobacco NC102 and conventional planting varieties of Salvia miltiorrhiza were used as materials, and four treatments of flue-cured tobacco monoculture (CK), flue-cured tobacco, and Salvia miltiorrhiza at a ratio of 1:1 (TS11), 2:2 (TS22), and 2:3 (TS23), respectively, were set up to study their effects on soil microorganisms, physical and chemical properties, and yield and quality of flue-cured tobacco. The results showed that intercropping Salvia miltiorrhiza increased the number of soil bacteria and actinomycetes, decreased the number of fungi, and increased the activity of urease and sucrase. The content of available nitrogen and available phosphorus in intercropping Salvia miltiorrhiza soil was significantly higher than that of the flue-cured tobacco monoculture, while the content of available potassium was lower than that of the flue-cured tobacco monoculture. The soil environment was more conducive to the growth of flue-cured tobacco. Compared with the flue-cured tobacco monoculture, the proportion of superior tobacco in intercropping Salvia miltiorrhiza increased by 2.2–3.4%, and the ratio of potassium to chlorine in leaves of different parts of flue-cured tobacco increased by 12.3–75.0%. The content of total sugar and soluble sugar in middle and upper leaves of intercropping flue-cured tobacco was higher than that of the flue-cured tobacco monoculture, which improved the quality of flue-cured tobacco. From the analysis of the chemical composition of tobacco leaves, TS11 (flue-cured tobacco and Salvia miltiorrhiza intercropping row ratio of 1:1) had the best treatment effect, potassium content, total sugar, reducing sugar content, and potassium chloride ratio of flue-cured tobacco were the highest, the chlorine content was the lowest, and the quality was better than other treatments. From the analysis of total output value, the total output value of TS22 (flue-cured tobacco and Salvia miltiorrhiza intercropping row ratio of 2:2) was higher than that of other intercropping treatments. In 2018 and 2019, the total output value increased by 21.3% and 22.4%, respectively, compared with the flue-cured tobacco monoculture. The intercropping advantage was obvious, and the treatment effect was the best. [ABSTRACT FROM AUTHOR]

Introduction: The pivotal roles of both abundant and rare bacteria in ecosystem function are widely acknowledged. Despite this, the diversity elevational patterns of these two bacterial taxa in different seasons and influencing factors remains underexplored, especially in the case of rare bacteria. Methods: Here, a metabarcoding approach was employed to investigate elevational patterns of these two bacterial communities in different seasons and tested the roles of soil physico-chemical properties in structuring these abundant and rare bacterial community. Results and discussion: Our findings revealed that variation in elevation and season exerted notably effects on the rare bacterial diversity. Despite the reactions of abundant and rare communities to the elevational gradient exhibited similarities during both summer and winter, distinct elevational patterns were observed in their respective diversity. Specifically, abundant bacterial diversity exhibited a roughly U-shaped pattern along the elevation gradient, while rare bacterial diversity increased with the elevational gradient. Soil moisture and N:P were the dominant factor leading to the pronounced divergence in elevational distributions in summer. Soil temperature and pH were the key factors in winter. The network analysis revealed the bacteria are better able to adapt to environmental fluctuations during the summer season. Additionally, compared to abundant bacteria, the taxonomy of rare bacteria displayed a higher degree of complexity. Our discovery contributes to advancing our comprehension of intricate dynamic diversity patterns in abundant and rare bacteria in the context of environmental gradients and seasonal fluctuations. [ABSTRACT FROM AUTHOR]

A total of 30 topsoil, subsoil samples, and 11 new and used cupels were collected around a Pb fusion fire-assay laboratory in Ouagadougou, Burkina Faso, and their physico-chemical parameters and major and potentially toxic (PTE) element concentrations were determined. The results showed that the soil samples in the immediate vicinity of the used-cupel disposal site were highly polluted with Pb (up to 8900 mg/kg). Cluster analysis identified the used-cupels as the primary source of Pb, As, Cr, Cu, Ni, and Ca contamination of topsoils. Furthermore, principal component analysis revealed that abundance and mobility of Cr, Cu, Ni, and Pb were likely controlled by clay and Fe- and Al-oxyhydroxides, whereas that of As and Mn appeared to be a function of pH and oxido-reduction reactions. With pollution loading indices higher than unity, the status of all the sampling sites ranged from very high to moderate polluted. Similarly, the used-cupel disposal site had a very high average ecological risk index compared to the two relatively distant sites. Lead, As, and Cr proved to have non-carcinogenic effects on children in all sites, whereas these elements only showed non-carcinogenic effects on adults in the used-cupel disposal site. Direct ingestion was the major pathway of PTE exposure. The carcinogenic risk index for all sites and all elements exceeded the threshold. Moreover, the average total carcinogenic risk indices for Cr, Ni, As, and Pb in all sites were high enough to pose lifetime cancer risks to the exposed population with the used-cupel disposal site having the highest average value. Urgent remediation is necessary to prevent the spread of pollution to larger areas. [ABSTRACT FROM AUTHOR]

Purpose A field study was conducted at Dire Dawa, Eastern Ethiopia, with an objective to find out an optimum combination of inorganic (NP) fertilizer and excreta-based vermicompost for best economic yield and quality of tomato and to assess their effect on selected physicochemical properties of amended soil after crop harvest. Methods The experiment consisted of eight treatments where the mineral (NP) fertilizer and the excreta-based vermicompost were combined in different proportions being arranged in a completely randomized block design replicated three times. Results Growth, yield and quality attributes of tomato as well as the post-harvest soil nutrient status were markedly influenced by the nutrient treatments. The highest values for the various growth, yield and quality attributing parameters were recorded for the treatment combination consisting 75% of the recommended rate of NP fertilizer ? 11.25 ton ha-1 vermicompost (T6), this treatment was also observed to have the highest net benefit with acceptable economic return as well as a fairly high residual soil nutrient status. Following this treatment, is the integration of 50% of recommended rate of NP fertilizer ? 7.5 ton ha-1 vermicompost (T3) which surpassed the sole mineral fertilizer and vermicompost in terms of the cropâs yield and its economic return. Conclusion 25â50% of the recommended rate of chemical fertilizer can be supplemented through vermicompost. However, in order to generate more reliable information, there is a need to conduct more such studies using more integration ratios of these nutrient sources (NP fertilizer and vermicompost) at various soil and agro-climatic conditions.

Agroforestry is one of the land use practices that is perceived to be sustainable and that has beneficial impacts on soil properties. However, as a universal statement, this may not be true as best documented successful agroforestry practices are located largely on good soils. Its impacts on dryland soils have rarely been quantified and studied in detail. This study determined the impacts of selected agroforestry practices on soil properties in Makueni, Eastern Kenya. A total of 252 soil samples were collected along transects located within mixed tree woodlots established in 2007, 2010 and 2013 and adjacent parklands and grazing lands at depths of 0–15 cm, 15–30 cm, 30–45 cm and 45–60 cm. Tree density per agroforestry practice was also determined using the quadrat technique. The soil samples were analyzed using laboratory soil physico-chemical properties techniques. The results showed that Soil Organic Carbon (SOC) and Total Nitrogen (TN) were significantly higher in the woodlots than in the parkland and grazing lands (p ≤ 0.05). SOC was significantly higher in woodlots established in 2007 than those established in 2013 and strongly correlated with the tree density. Phosphorus was significantly higher in parkland as compared to woodlots and grazing lands. Phosphorus and Potassium were significantly higher at 0–15 cm depth compared to other soil depths. bulky density was significantly higher with a corresponding lower total porosity in grazing lands than in the woodlots and parklands. Mixed woodlots positively influenced soil property and could be considered as a strategy to restore degraded dryland soils as well act as important carbon dioxide and nitrogen sinks.

In dryland areas, integrating biochar soil amendment with in situ rainwater harvesting systems may decrease soil erosion, improve soil quality, and increase crop productivity and yield. This study was conducted to investigate the effect of maize straw biochar amendment and ridge‐furrow rainwater harvesting systems on run‐off, sediment yield and the physico‐chemical properties of a Calcic Cambisol soil in semiarid areas. The experiment was conducted on alfalfa (Medicago sativa) production land at the Anjiagou Catchment experimental station in Gansu province, China. The experimental layout was a split‐plot design with three replications. Biochar was applied at a rate of 0 and 30 t ha−1, respectively. The tillage treatments were flat planting, open‐ridging, and tied‐ridging (TR). Overall, the integration of maize straw biochar with TR decreased soil bulk density at 0–40 cm depth. Biochar application reduced run‐off by 37.8% and soil loss by 55.5% during alfalfa‐growing seasons compared to the control. In general, biochar addition increased soil total potassium, but the same effect was not observed for soil pH, total nitrogen, total phosphorus, and available phosphorus. These findings demonstrate the potential of integrating maize straw biochar and tillage systems to reduce soil erosion and improve soil quality for rainfed crop production in semiarid areas. Further studies on the effect of biochar‐tillage system interaction are warranted to improve soil conditions for plant growth and increase crop yield in dryland areas. [ABSTRACT FROM AUTHOR]

Abstract Context In temperate hardwood forests, increased intensity of soil and canopy disturbances tends to increase species richness due to the establishment of numerous early-successional plant species. However, while competitive pioneer species from early stages of succession can become recalcitrant and alter patterns of natural regeneration, very few studies have examined longer-term effects of these treatments on plant biodiversity. Aims In this study, we investigated mid-term (ca. 20 years) effects of different regeneration treatments with varying soil and canopy disturbance intensities. We compared understory plant communities in temperate hardwood forests from all the South of Quebec (Canada). Methods Using circular experimental plots of 1962.5 m2 (radius = 25 m), we measured taxonomic and functional diversity indices and soil properties using four levels of disturbance intensity in six temperate hardwood forests of Quebec distributed along a longitudinal gradient. Reference forests, i.e. control forests with no silvicultural treatment known for ≥ 80 years, were compared to 20-year-old single-tree selection cuts, group-selection cuts and group-selection cuts with soil scarification. Results Species richness in both group-selection treatments was higher than that in reference forests. Plant equitability and beta diversity among sites in both group-selection treatments were lower than in single-tree selection cuts and control forests. More intense treatments contributed to the mid-term persistence of recalcitrant competitor species (e.g. Rubus idaeus L., Prunus pensylvanica L.f.) whereas soil scarification appears to have negative sustained effects on species known to be sensitive to regeneration treatments (e.g. Monotropa uniflora L., Dryopteris spinulosa Kuhn). Conclusions In temperate hardwood forests of Southern Quebec, silvicultural treatments of higher intensities resulted in detrimental effects on soil properties, especially in the surface horizon, 20 years after disturbance. This legacy, in turn, affected the composition and diversity of understory plant communities. The more intense silvicultural treatments contributed to the persistence of pioneer species better adapted to a wider range of environmental conditions and resulted in a decrease in understory plant community heterogeneity among sites. Conversely, single-tree selection cutting appeared to be the most appropriate silvicultural treatment for maintaining soil functions and heterogeneity of understory plant communities after 20 years; composition and structure being similar to long-undisturbed forests.

This study was carried out to assess the influence of tillage systems on soil characteristics as well as barely yield. The two-year experiment with the tillage systems (NT, no-tillage; MT, minimum-tillage; and CT, conventional-tillage) and barley cultivars was done. Vetch was pre-planting in the rotation with barley. About 30% of vetch residue remained in the NT and MT systems, but in CT, these residues were buried by moldboard. Results showed that NT was superior to MT and CT in terms of the soil properties, earthworm number and earthworm body mass. Remains of vetch, as a pre-planted crop, were effective in increasing these indicators. Also, the improvement of these indicators made the no-tillage superior to the MT and CT in terms of geometric mean diameter, mean weight diameter and soil moisture content. In contrast, soil porosity was higher in CT system. In conclusion, soil structure improved during the two years of the experiment when MT or NT was used, while CT was not effective in improving the soil structure. Grain yield (5973 kg ha−1) and NFS (5163) were higher in NT than MT and CT, suggesting that the change in soil structure has provided a better environment for the yield. [ABSTRACT FROM AUTHOR]

Trichoderma is a genus of widespread filamentous fungi widely used in agriculture as biofungicides for controlling a wide range of plant diseases. Trichoderma, as is well known, can not only effectively control crop diseases but also improve soil physico-chemical properties and increase soil productivity. However, the effects of its control on crop growth and the soil's ecological environment are unclear. The results of Trichoderma on disease resistance, yield, and crop growth as well as the effects of Trichoderma on the soil ecological environment from the standpoint of soil physical, chemical, and microbial properties were therefore reported in this study. Furthermore, this paper highlighted the shortcomings of the existing research on the impact of Trichoderma on crop and soil properties and emphasised opportunities to address the gaps in the existing research on the effects of Trichoderma on crops and soil attributes. This review will provide a theoretical foundation for further research and application of Trichoderma in agricultural production. [ABSTRACT FROM AUTHOR]

Context: In temperate hardwood forests, increased intensity of soil and canopy disturbances tends to increase species richness due to the establishment of numerous early-successional plant species. However, while competitive pioneer species from early stages of succession can become recalcitrant and alter patterns of natural regeneration, very few studies have examined longer-term effects of these treatments on plant biodiversity. Aims: In this study, we investigated mid-term (ca. 20 years) effects of different regeneration treatments with varying soil and canopy disturbance intensities. We compared understory plant communities in temperate hardwood forests from all the South of Quebec (Canada). Methods: Using circular experimental plots of 1962.5 m2 (radius = 25 m), we measured taxonomic and functional diversity indices and soil properties using four levels of disturbance intensity in six temperate hardwood forests of Quebec distributed along a longitudinal gradient. Reference forests, i.e. control forests with no silvicultural treatment known for ≥ 80 years, were compared to 20-year-old single-tree selection cuts, group-selection cuts and group-selection cuts with soil scarification. Results: Species richness in both group-selection treatments was higher than that in reference forests. Plant equitability and beta diversity among sites in both group-selection treatments were lower than in single-tree selection cuts and control forests. More intense treatments contributed to the mid-term persistence of recalcitrant competitor species (e.g. Rubus idaeus L., Prunus pensylvanica L.f.) whereas soil scarification appears to have negative sustained effects on species known to be sensitive to regeneration treatments (e.g. Monotropa uniflora L., Dryopteris spinulosa Kuhn). Conclusions: In temperate hardwood forests of Southern Quebec, silvicultural treatments of higher intensities resulted in detrimental effects on soil properties, especially in the surface horizon, 20 years after disturbance. This legacy, in turn, affected the composition and diversity of understory plant communities. The more intense silvicultural treatments contributed to the persistence of pioneer species better adapted to a wider range of environmental conditions and resulted in a decrease in understory plant community heterogeneity among sites. Conversely, single-tree selection cutting appeared to be the most appropriate silvicultural treatment for maintaining soil functions and heterogeneity of understory plant communities after 20 years; composition and structure being similar to long-undisturbed forests. [ABSTRACT FROM AUTHOR]

Identifying the primary factors influencing spatial distribution of soil organic carbon (SOC) stock is critical for improving the accuracy of soil organic carbon stock estimation. The primary objective of the current study is to determine the effects of land use-land cover, and some soil characteristics on SOC stock in an area of 111 km2 in Vezirköprü district, Samsun province in the Central Black Sea Region of Turkey. To determine land use and land cover of the study area, Triplesat satellite image was used. Four main land use and land cover that are forest, pasture, settlement, and cultivated land were determined. According to the results obtained, it was determined that some soil characteristics and land use-land cover in the study area had a statistically significant effect on the spatial variation of SOC density. The amount of SOC stock in the study area varies between 4.79- and 94.10-tons ha-1 in surface (0-20 cm) soils and between 5.16- and 8.86-tons ha-1 in subsurface (20-40 cm) soils. Among the different land uses, it was determined that the highest amount of SOC stock in the surface soil was 53.356 tons ha-1 in forest areas, while the lowest amount of SOC stock was in agricultural lands with 34.048 tons ha-1.

This experiment was carried out during 2019 at Department of Soil Science, University of Sargodha, Pakistan to judge the toxic effect of sodium bicarbonate (NaHCO3) commonly recognized as sodicity on soil chemical characteristics using rice as test crop. There were seven treatments with three replicates applied using completely randomized design (CRD). Various levels of sodicity were developed artificially including 15, 20, 25, 30, 35 and 40 SAR by using sodium bicarbonate (NaHCO3). Sufficient time was given for development of desired level of sodicity. Rice was used as test crop. Practices like irrigation, hoeing and weeds eradication were done as per crop requirement. Recommended doses of chemical fertilizer was applied. Crop was raised for 120 days and then collection of soil and plants samples were carried out from all pots for analysis of sodium (Na) and potassium (K) ion concentrations. Similarly, pH, EC and SAR were also determined from all soil samples. Results revealed that deterioration of soil properties (pH, EC and SAR) occurred by the addition of NaHCO3 as values of these properties were negatively affected by increased levels of sodicity. Numerical values of soil pH raised from 7.78 to 9.35, EC from 1.85 to 6.13 dS/m, SAR from 9.80 to 41.53 and ESP from 11.64 to 37.49 me/ L respectively. Regarding ionic composition of rice, an increase in Na ion and decrease in K ion concentration was observed in all treatments in comparison with control. Potassium content in rice decreased from 2.3 to 1.2% while sodium concentration was raised from 102.26 to 410.14 me/L. Toxic effect of sodicity on soil pH, EC, SAR and ESP as well as Na/K ratio in rice plants were enhanced with increasing levels of NaHCO3. [ABSTRACT FROM AUTHOR]

Simple Summary: Super-high density olive orchards are spreading in Italy to reduce production costs and increase yields per hectare. The objective of this study was to assess the orchards' effect on the soil nematode community in five sites located in the main Italian olive cultivation areas compared to the adjacent traditional olive orchard system. Super-high density olive orchard management combined with conventional tillage and mineral fertilization decreased total organic carbon compared to traditional management. The soil nematode community was affected by the depletion of organic matter, especially for plant-parasitic nematodes, which increased. Moreover, this investigation evidenced that the Super-high density olive orchard management system could change the soil plant-parasitic nematode composition of olive orchards. In fact, the families Telotylenchidae, Paratylenchidae, Meloidogynidae, and Criconematidae were favored in the Super-high density olive orchard system, while Longidoridae, Heteroderidae, and Pratylenchidae were disadvantaged. However, conservative and sustainable soil management might maintain or improve the soil nematode community functionality and reduce plant-parasitic nematodes. The soil nematode community plays an important role in ecosystem services. The objective of this study was to assess the effect of Super-high density (SHD) olive orchards on the nematode community in five sites with different soils, climates, and cultivars. At each site, the SHD management system was compared to the adjacent olive orchard traditional (TRAD) system, in which the same soil management and phytosanitary measures were applied. Soil management was assessed by total organic carbon content (TOC), while the soil nematode community was evaluated using the nematode taxa abundances and soil nematode indicators. TOC was significantly decreased in the SHD olive orchard system compared to TRAD in the sites characterized by conventional tillage and mineral fertilization. The two-way ANOSIM analysis on nematode abundance showed no difference between the two olive management methods, instead showing only a significant difference per site mainly due to variabilities in plant-parasitic nematode assemblage. However, a negative impact of SHD management was evident in environments stressed by summer droughts and conventional tillage: the ratio of obligate plant-parasites to bacterivores and fungivores (Pp/(B+F)) was significantly higher in SHD than in the TRAD olive orchard system, and the prey-to-predator θ mass ratio showed the lowest values in the sites under organic fertilization or green manure. The canonical correspondence analysis showed that the free-living nematodes were only slightly affected by SHD olive orchards; instead, the presence of plant-parasitic nematodes families such as Telotylenchidae, Paratylenchidae, Meloidogynidae, and Criconematidae was favored, in comparison to Longidoridae, Heteroderidae, and Pratylenchidae. [ABSTRACT FROM AUTHOR]

Understanding the spatial patterns of soil microbial communities and influencing factors is a prerequisite for soil health assessments and site-specific management to improve crop production. However, soil microbial community structure at the field scale is complicated by the interactions among topography and soil properties. The objectives of this study were to (1) characterize the spatial variability patterns of soil microbial communities at the field scale; (2) assess the influence of soil physico-chemical properties, topography and management on soil microbial biomass spatial variability. This study was conducted in a 194-ha commercially-managed field in Hale County, Texas, in 2017. A total of 212 composite soil samples were collected at 0–0.15 m depth and analyzed via the ester-linked fatty acid methyl ester (EL-FAME) method to characterize the microbial community structure and biomass. Soil electrical conductivity (EC), pH, soil texture, soil water content (SWC), soil organic carbon (SOC) and total nitrogen (TN) were determined for each soil sample. Topographic attributes, including elevation and slope, were derived from real-time kinematic (RTK) point elevation data. Interpolated microbial community maps at this scale revealed a spatially structured distribution of microbial biomass and diversity with patches of several hundred meters in different directions corresponding to the distribution of soil types and topography. Most of the microbial communities were autocorrelated at greater ranges within the same soil types than across different soils. The distribution of total soil microbial biomass was mainly affected by SOC and SWC. Soil pH and C:N ratio had a negative impact on the biomass of bacterial communities. Biomass of fungal communities was negatively influenced by slope and elevation. The results of this study have the potential to provide a basis for designing soil sampling plans in characterizing microbial community distribution and site-specific soil health management. [ABSTRACT FROM AUTHOR]

Herbaceous vegetation is of great ecological importance and responds quickly to environmental changes. The present study was aimed to understand the variation in herbaceous species composition, biomass and soil physico-chemical properties in the naturally formed gap and the understory of semi-arid forests in the Aravalli hills. Four permanent plots consisting of the gap as well as the understory were established. To study herbs phytosociological attributes and biomass, 10 quadrats of 0.5 × 0.5 m size were laid in each plot. For soil physico-chemical properties, 5 soil samples were collected randomly at 0–10 cm depth from each plot. Relationships among biodiversity indices, herbaceous biomass and soil physico-chemical properties were determined using Redundancy Analysis (RDA) and correlation analysis. Across the sites, Poaceae was the dominant family. All species showed a contagious distribution pattern. In the understory, Importance Value Index (IVI) was the recorded highest for Oplismenus burmannii, ranging from 138 to 230.5 while in the gap, it was the highest for Achyranthes aspera (56.15) followed by Eragrostis ciliaris (53.1). Both sites included, herbaceous community biomass in the gap ranging from 700 to 900 g m−2 while in the understory it ranged from 30 to 70 g m−2. Cenchrus ciliaris (597.97 g m−2) and Chrysopogon sp. (391.2 g m−2) contributed a major proportion of herbaceous community biomass in the gap. Oplismenus burmannii (52.2 g m−2), Dipteracanthus prostratus (16.6 g m−2) and Cynodon dactylon (9.6 g m−2) contributed a major proportion of herbaceous community biomass in the understory. The understory soil had significantly (p < 0.05) higher soil moisture (%), electrical conductivity (EC), soil organic carbon (SOC) and soil total nitrogen (TN) compared to the gap. Even though canopy had positive effects on soil physico-chemical properties, it has negatively influenced herbaceous species composition, diversity and biomass, due to significant reduction in solar radiation reaching the ground. [ABSTRACT FROM AUTHOR]

Transformative change is required to achieve conservation of the globe's natural resources. Ambitious forest restoration can help achieve this change. Restoration success depends on trees persisting through multiple stressors, with drought standing out as one of utmost importance. However, research tends to focus on tree inciting factors of tree decline, like drought, whilst ignoring the fundamental importance of context, potentially leading to the wasted restoration effort. Indeed, the propensity of trees to succumb to, or resist, drought depends on whether they are predisposed to fail or succeed. Here, I argue that this predisposition crucially depends on the nature and characteristics of the former land use at the restoration site and propose a research agenda that will help enable the successful upscaling of forest restoration ambitions by revealing the land‐use history‐determined conditions under which tree species are likely to succeed in an era of environmental challenges. [ABSTRACT FROM AUTHOR]

Elevation gradient can reflect the effects of soil physico-chemical properties on plant species diversity. Alpine grassland on the QTP has suffered from a serious decline in plant species diversity. In this study, we investigated 112 sites recording plant community characteristics and collecting soil samples along an elevation gradient (3,500–5,200 m asl) in alpine meadow on the QTP. We analyzed the effects of soil physico-chemical properties on plant species composition and diversity by canonical ordination and spatial regression along an elevation gradient. The results showed that species richness of the overall plant communities decreased with the increasing elevation, and the Simpson dissimilarity index (β sim ) had a maximum at low elevation (3,500–4,000 m) with the value of 0.37. Soil available nitrogen content was the primary soil parameter affecting plant species composition and diversity in alpine grassland. The effect of soil available nitrogen content on plant species richness varied at different elevations. For Gramineae plants (G), plant species richness declined with the increase in soil available nitrogen content at low elevation (3,500–4,000 m), but rose at middle elevation (4,000–4,500 m). Soil available nitrogen content had a more significant limiting effect on species richness at high elevation (>4,500 m). These findings increase our understanding about the drivers of plant species diversity changes in alpine grassland on the QTP, and will provide insights into grassland restoration and sustainable management. [ABSTRACT FROM AUTHOR]

Background: Phosphorous is a limiting crop nutrient in highly weathered tropical soils due to fixation, and its availability for plants’ uptake is influenced by soil physico-chemical characterics, land use type and management practices. Objective: To evaluate the relationship between selected physico-chemical properties and phosphorous sorption characteristics of a humic nitisol (Alfisol) from Tigoni, Kiambu County, central Kenya. Methodology: The soil was sampled from the same area with different land uses that include tea plantation, maize field and natural forest at 0-25, 25-50 and 50-75 cm depths. P solution at the rates of 50, 100, 150, 200 mg P L−1 in a 24 h contact time were used in the study for maximum sorption. The data was analysed by simple regression and Pearson correlation analysis. Results: The adsorption data was fitted more to Langmuir model (R2 = 0.9100-0.9994) compared to Freundlich (R2 = 0.6815-0.9971). The values of P sorption maxima ( ) determined by Langmuir model ranged from 3,333-5,000 mg kg-1 and bonding energies ( ) ranged from 0.2308-1.5385 L mg-1. The buffering capacity of soil ranged from 769-5000 L kg-1 and the external P requirement at 0.2 mg kg-1 ( ranged from 147-1176 mg P kg-1 both increasing with soil depth. P sorption maxima were negatively and significantly correlated with organic carbon (r2 = -0.700*) and Ca2+ (r2 = -0.703*) contents. The pH of soil and clay content were negatively correlated with adsorption parameters ( ) while Al content was positively correlated though none of them was statistically significant. Implication: The data revealed a highly P-sorbing soil particularly tea plantation, a situation that can be alleviated by management practices such as liming and enhancing soil organic matter content. Field experiments are however, recommended to validate the findings of this study. Conclusion: Land use type influences P-sorption capacity of soil hence, fertilizer recommendations should be based on soil physico-chemical characteristics besides crop nutrient requirements.

Elevation gradient can reflect the effects of soil physico-chemical properties on plant species diversity. Alpine grassland on the QTP has suffered from a serious decline in plant species diversity. In this study, we investigated 112 sites recording plant community characteristics and collecting soil samples along an elevation gradient (3,500–5,200 m asl) in alpine meadow on the QTP. We analyzed the effects of soil physico-chemical properties on plant species composition and diversity by canonical ordination and spatial regression along an elevation gradient. The results showed that species richness of the overall plant communities decreased with the increasing elevation, and the Simpson dissimilarity index (βsim) had a maximum at low elevation (3,500–4,000 m) with the value of 0.37. Soil available nitrogen content was the primary soil parameter affecting plant species composition and diversity in alpine grassland. The effect of soil available nitrogen content on plant species richness varied at different elevations. For Gramineae plants (G), plant species richness declined with the increase in soil available nitrogen content at low elevation (3,500–4,000 m), but rose at middle elevation (4,000–4,500 m). Soil available nitrogen content had a more significant limiting effect on species richness at high elevation (>4,500 m). These findings increase our understanding about the drivers of plant species diversity changes in alpine grassland on the QTP, and will provide insights into grassland restoration and sustainable management.

Field experiment was conducted in the 2019 and 2020 early cropping seasons at the University of Calabar Teaching and Research Farm, Calabar, to assess the foliage yield of fluted pumpkin (Telfairia occidentalis Hook F.) as affected by organic manure and cutting frequency on soil of Calabar. The experiment was a factorial combination of four poultry manure rates (0, 3, 6 and 9 tonnes per hectare) and three cutting frequency (2, 3 and 4 weekly intervals), laid out in randomized complete block design (RCBD) with three replications. Data were collected on vine length, number of leaves, internode length, fresh leaves, dry matter weights and soil physico-chemical properties, and analyzed. Significant means were compared using Fisher's Least Significant Difference (FLSD) at 5 % probability. Results indicated that the sand proportions decreased after harvest while the silt and clay proportions, the soil pH, total nitrogen, organic carbon, organic matter, potassium, magnesium, effective cation exchange capacity (ECEC) and base saturation all increased after harvest in both cropping years. There were significant (p <.0. 05) effects of PM, cutting frequency and their interactions on vine length, number of leaves, internode length, fresh leaves and leaves dry matter weights in both years of study. Plots treated with 9 t/ha of PM produced the longest vines, higher number of leaves, heavier fresh leaf and leaf dry matter. This was followed by plots treated with 6 t/ha of PM while the lowest was the plot with zero PM treatment. Foliage harvest at 3-weekly cut intervals produced the highest cumulative number of leaves, fresh leaf and leaf dry matter weights, followed by the 4-weekly cut intervals while the lowest was the 2-weekly cut intervals. The interaction of 9 t/ha PM with 3-weekly cut intervals produced the best effect and is therefore recommended. [ABSTRACT FROM AUTHOR]

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Vegetation recovery is essential in land restoration after the eruption of Mount Merapi in 2010. Vegetation is a source of organic material that produces root exudate containing organic acids. These acids accelerate the dissolution process of volcanic material so that it affects the soil characteristics. This study was conducted to analyze the effect of four types of perennial plants on soil chemical and physical characteristics. The soil samples were taken on the area planted with cinnamon, albizia, bamboo, and acacia, at depths of 0 – 10 cm, 10 – 20 cm, 20 – 30 cm, 30 – 40 cm, and 40 – 50cm. The soil chemical analysis carried out included pH H2O, pH KCl, pH NaF, C-organic, Humic acid and Fulvic acid, cation exchange capacity, Ca, Mg, K, Na, available P, base saturation, and particle size distribution. The results show that pH H2O, pH KCl, C-organic, humic acid and fulvic acid, CEC, K, Na, Ca, Mg, available P, base saturation, and particle size distribution were significantly affected by vegetation type. Meanwhile, the pH of NaF was not significantly influenced by vegetation type. Cinnamon is a plant that gives the strongest influence in the improvement of soil chemical-physical properties compared to the other three types of vegetation. Therefore cinnamon is quite prospective plant to be developed for post-eruption land reclamation.

Anthropic activities and agricultural practices have increased the rate of pollutants in ecosystems. Consequently, this can alter soil chemical properties, biological functioning, and fertility. Our work aimed to evaluate the impact of nickel (Ni) contamination on rhizospheric soil's physico-chemical properties and microbiological activities in the presence of alfalfa plants. For this purpose, five concentrations of Ni (0, 50, 150, 250, and 500 mg.kg−1) were applied to Tunisian agricultural soils cultured with Medicago sativa. At the end of the experiment, the physico-chemical properties of these soils and the Ni uptake by alfalfa plants were analyzed. Additionally, soil enzyme activities were assessed. Finally, the microbial biomass and functional diversity of microbial communities were determined using SIR (Substrate-induced respiration) and Biolog Ecoplates™ techniques, respectively. The results revealed that Ni accumulation was dose-dependent, with a significant amount of Ni being translocated from the roots to the shoots. With respect to the physico-chemical properties of soil, the most important Ni concentration led to the lowest organic matter content and cation-exchange capacity (CEC). Our data also showed a decrease in soil enzyme activities following Ni contamination. However, a crucial increase on microbial biomass of soils was revealed with the high Ni contamination. Moreover, the microbial functional diversity index and substrate utilization pattern were observed to increase in soils exposed to the most potent Ni concentrations. Our data provided evidence regarding the apparent toxicity of Ni and the fact that enzymatic activities and microbial biomass could be exploited as Ni-stress bioindicators. [ABSTRACT FROM AUTHOR]

The present investigation was conducted at the Research Farm, Khalsa College, Amritsar during rabi season of 2017-18 in order to evaluate the impact of organic manures (FYM, Vermicompost, Poultry manure) and inorganic fertilizers on soil physico-chemical properties and available nutrient status in soil after onion (Allium cepa L.) harvest. The experiment was laid out in randomized block design with twelve treatments and replicated thrice. It was observed that significant variation in organic carbon, bulk density, available macro (N, P, K and S) and micro (Fe, Mn, Zn and Cu) nutrients status was noticed when organic manures were integrated with inorganic fertilizers as compared to sole use of inorganic fertilizers and initial status of soil. The maximum available nutrient status was recorded with treatment T12 {25% RDNF + 25% N (FYM) + 25% N (VC) + 25% N (PM)} whereas lowest was recorded with treatment T1 (control). The soil properties such as pH, EC, particle density and porosity did not showed any significant difference. [ABSTRACT FROM AUTHOR]

Question: The impact of ants on the vegetation and soil seed bank of alpine meadows on the Qinghai‐Tibetan Plateau is largely unknown. We questioned how the mound‐building ant, Camponotus herculeanus, affects the above‐ground vegetation, the soil seed bank and physico‐chemical properties of the soil. Location: An alpine meadow in the northeast margin of the Qinghai‐Tibetan Plateau (37°40′ N, 102°32′ E), China. Methods: We used field and greenhouse studies to determine the above‐ground vegetation parameters and soil physico‐chemical properties, and the soil seed bank composition under the mound (UM), the herbage circle at about 10 cm width around the outside of the mound (mound edge, ME) and the area 1 m from the center of the mound (control). Results: (a) The mound edge had higher vegetation height, greater above‐ground biomass, lower vegetation coverage and lower plant richness than controls; (b) Gramineae had a higher total importance value, which was based on the height, coverage and biomass of each plant species, and composed a higher biomass proportion in the mound edge than in controls (68% vs. 38%), while most of the perennial dicotyledons were restricted to the controls; (c) dicotyledons were the main seed group in the 0–8 cm layer of soilUM (43%), soilME (51%) and soilcontrol (60%), while Gramineae had a significantly higher seed density and percentage of total seeds in the soilUM (16,507 ± 2,882.7 seeds/m3, 28.1%) than in the soilcontrol (4,200 ± 799.5 seeds/m3, 10.2%); and (d) soil in the 0–8 cm layer under the mound had lower water content and lower bulk density than soil on the mound edge and in controls. Conclusions: Mound‐building activity of Camponotus herculeanus increased the proportion of Gramineae and decreased the proportion of dicotyledons at the site of the study indicating, that mound building could enhance the transformation of a grass and sedges community to mainly a grass community in the alpine meadow. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to clear the effects of different biological agents on tomato growth. [Method] This study designed field split plot experiment and adopted biometrical method to research the effects of Bacillus subtilis agent(30 kg·hm-2), Trichoderma humatum agent(22.5 kg·hm-2), Yufeng ‘99’agent(30 kg·hm-2), Zhongnonglyukang agent(45 kg·hm-2) on tomato growth, yield, quality and soil physico-chemical properties in 2017-2018, and the application effects were compared and analyzed with the conventional chemical fertilizer(2179.5 kg·hm-2) simultaneously. [Result] There were obvious promotion effects on tomato growth, yield and quality when four biological agents applied. The tomato height increased by 10-26 cm and the stem diameter increased by 0.6-3.0 cm compared with the control. The fruit yield was increased significantly under different biological agents application, which was 1.22-1.53 times higher than that of the control and was 34.33 %-53.65% higher than that of the chemical fertilizer treatment.Besides, the incidence rate of umbilical rot and gray mold diseases of tomato were significantly reduced. The external and internal quality of tomato were improved in each agent application treatment, comparing with the chemical fertilizer treatment, the fruit color uniformity and maturity were increased significantly, and comparing with the control, the fruit Vc content increased by 14.40%-49.94 %, the sugar content increased by 8.68 %-37.85 %, and the titratable acidity reduced by 28.89%-56.76%.Meanwhile, these biological agents application through drip irrigation had significant effect on physico-chemical properties, compared with the chemical fertilizer treatment, the organic matter content increased by 30.43 %-83.48 %, and the soil pH and conductivity decreased slightly, which reduced the occurrence of soil salinization, and compared with the control treatment, the organic matter content increased by 66.67%-134.44 %, and the available nitrogen, phosphorus and potassium also increased significantly. These data showed that the four biological agents could improve soil fertility. [Conclusion] This stuly indicated that the four biological agents could promote tomato growth, reduce diseases and improve yield and quality, the order of the promotion effects was as follows:yufeng‘99’agent> Zhongnonglyukang agent> Bacillus subtilis agent> Trichoderma humatum agent, which was closely related to component and mechanism of different biological agents and the effects of agents on soil microenvironment. [ABSTRACT FROM AUTHOR]

This study investigated effects of soil amendments with ramial chipped wood (RCW) derived from Gmelina arborea and Sarcocephalus latifolius , together with poultry manure, on soil chemical properties and fungal communities in northern and southern Benin. The trial was a split-plot experiment, where treatments included volume of irrigation water (V1 and V2 = 0.5 *V1) as the whole-plot factor, with organic amendment (45 t/ha RCW; 15 t/ha poultry manure, PM; 45 t/ha RCW + 15 t/ha of PM, RCW_PM; and control) as the sub-plot factor. Topsoil was sampled before and after 24 months of in situ organic amendment application. Humic acid (HA) was extracted from soil and purified prior to FTIR spectroscopy, NMR, and Py-GC-MS analyses. RCW treatments (RCW and RCW_PM) contributed substantially to organic carbon storage and soil nutrient (N, P, K, Ca, Mg) increases (the latter by up to 1.5 times) compared to the control. Accordingly, soils that were amended with the RCW produced significant amounts of HA. High concentrations of lignin-related compounds were determined in pyrolysis products from humic acids in the RCW-amended soils. Using ITS2 region sequencing on the Illumina Miseq platform, RCW amendments markedly altered fungal compositions, with increased relative abundance of Ascomycota (up to 92% of total fungal community), Mucoromycota (2.7%), Basidiomycota (2.5%) and Rozellomycota (0.3%). These fungal phyla contain species that participate in organic matter decomposition and compound transformations but did not selectively degrade lignin in RCW. Our results suggest that RCW amendments significantly increased fungal activity and improved soil nutrient availability. Thus, this agrotechnology is recommended for regenerative agriculture. • Ramial chipped wood (RCW) significantly contributed to soil organic carbon storage. • RCW improved soil N, P, K, Ca, Mg content by up to 1.5 times compared to the control. • RCW Amended contributed significantly to humic acids formation in soil. • Humic acids isolated from amended soils were determined to contain lignin-related compounds. • RCW amendment promoted an increase of fungal community beneficial to soil health. [ABSTRACT FROM AUTHOR]

Polychlorinated biphenyls (PCBs) belong to the organic pollutants that are toxic to humans and harmful to environments. Numerous studies dealing with the impact of PCBs on soil microorganisms have focused on bacterial communities. The effects of PCBs on fungal communities in three different PCB-polluted soils from former industrial sites were investigated using high-throughput sequencing of the internal transcribed spacer 1 region. Significant differences in fungal alpha diversity were observed mainly due to soil physico-chemical properties. PCBs only influenced the richness of the fungal communities by increasing it. Fungal composition was rather strongly influenced by both PCBs and soil properties, resulting in different communities associated with each soil. Sixteen Ascomycota species were present in all three soils, including Stachybotrys chartarum, Fusarium oxysporum, Penicillium canescens, Penicillium chrysogenum,Penicillium citrosulfuratum and Penicillium brevicompactum, which are usually found in PCB-polluted soils, and Fusarium solani, Penicillium canescens, Penicillium citrosulfuratum and Penicillium chrysogenum, which are known PCB degraders. This study demonstrated that PCBs influence the richness and the composition of fungal communities. Their influence, associated with that of soil physico-chemical properties, led to distinct fungal communities, but with sixteen species common to the three soils which could be considered as ubiquitous species in PCB-polluted soils.

Sustainable soil management is essential for maintaining proper soil health for future production of crops. A comparative study was carried out at Dumuria soil series in Khulna district to observe the current fertility and physical changes of soils over a period of time due to different land use. Soil physical (soil texture, water holding capacity, bulk density and total porosity) and chemical properties (Nitrogen (N), Phosphorous (P), Potassium (K), Sulphur (S), soil organic matter (SOM), soil organic carbon (SOC) along with cation exchange capacity (CEC), sodium absorption ratio (SAR), exchangeable sodium percentage (ESP), base saturation percentage (BSP) and % salt properties were determined. Except for the control, all the soils had silt loam texture. Water holding capacity varied from (33.57 ± 3.3 to 55.57 ± 5.2)% and all soil indicated good porosity (average 47 ± 5.59)%. Soil pH (5.96 to 7.4) indicated that the soils were neutral to alkaline in nature and had an average salt percentage (0.11% ± 0.05). The SOM was higher in natural vegetative soil (2.45 ± 0.46)% and decreased over the period of land use for cultivation. In terms of ESP and SAR, 50 to 10 years cultivated soil showed the highest value and a significant difference was observed among the treatments (p ≤ 0.05). For BSP, 100 to 50 years cultivated soil showed the highest value and uncultivated soil showed the lowest value and was statistically insignificant among treatment (p ≤ 0.05). Overall observation showed that long term land use resulted in a significant decline in soil quality. So, sustainable soil management should be incorporated in the development of suitable agricultural management such as the use of organic matter or incorporate organic mixed with inorganic fertilizer and adaptation of soil conservation farming. Proper strategies should be adopted to seek a sustainable solution that better addresses of soil fertility management. [ABSTRACT FROM AUTHOR]

Knowledge of the spatial and temporal variabilities of soil respiration is important in estimating the soil carbon budget and in understanding how soils may respond to global changes. In areas with complex terrain, the topography can modify the hydrological conditions and other biophysical variables, which complicates the spatial and temporal heterogeneity of soil respiration. Herein, we investigated soil respiration along topographic transects with ridge, middle slope, lower slope and valley positions in a humid subtropical mountain forest in China to assess the driving factors of the variations in soil respiration. Our results showed that there were substantial temporal and spatial variations in soil respiration. The temporal variation of soil respiration could be well explained by the dynamics of soil temperature and moisture. Soil respiration rates also showed clear topographic pattern and decreased significantly from the ridge to valley soils, with the mean rates equaled 3.43 ± 0.13, 2.64 ± 0.30, 2.13 ± 0.26 and 1.88 ± 0.24 μmol m−2 s−1 at the ridge, middle slope, lower slope, and valley, respectively. Correlation analyses revealed that the spatial variation of soil respiration could be explained by multiple variables (e.g., soil temperature, basal area of the trees, thickness of the forest floor, root biomass and stock of soil dissolved carbon, soil C/N and soil bulk density). Results from partial least squares path modeling suggested that the topography modified the fine root distribution and the lateral losses of light and dissolved organic materials that created areas of high carbon sources for soil respiration at the ridge. The topographically regulated processes further resulted in a high soil C/N at the ridge that favored SOC decomposition. The higher respiration rate for the ridge soil and its higher sensitivity to soil temperature and moisture changes suggested that the ridge position was a potential hot spot for future environmental changes. Future studies and management practices regarding the soil carbon efflux in forest ecosystems with topographical variations should take into account the topographic effects. [ABSTRACT FROM AUTHOR]

The effect of Spartina alterniflora (thereafter, abbreviated as Spartina) invasion on N2O emission has been debated, which is possibly related to difference in invasive areas. Therefore, the study investigated N2O emission rate using invasive gradients (native, native-Spartina coexisted and Spartina-dominated vegetations) and areas (Sanmen, Linhai and Jiaojiang) as fixed factors. Meantime, plant, soil and microbial parameters were determined for analyzing the mechanisms behind the N2O emission. The results showed that N2O emission rate significantly increased with Spartina invasion (p < 0.05), and was also impacted by invasive area (p < 0.05), as shown by two-way analysis of variance. Redundancy analysis showed that plant biomass, microbial biomass, potential denitrification rate, nitrate reductase activity, pH, soil organic carbon and NH4+-N contents correlated positively with the N2O emission rate (p < 0.05 or p < 0.01). Reversely, urease activity, total nitrogen and NO3− -N contents negatively affected the N2O emission rate (p < 0.05). These results suggest that except for Spartina invasion gradient, the invasive area is also a crucial factor in mediating soil N2O emission. [ABSTRACT FROM AUTHOR]

Chloropicrin (Pic) and biofumigation are both considered effective chemical and non-chemical alternatives to methyl bromide, respectively, for controlling crop-limiting soil-borne pests and diseases. In this study, we evaluated the effects of Pic alone and 'chloropicrin alternated with biofumigation' (CAB) on the soil's physico-chemical properties and strawberry yield, as well as their effects on soil bacterial and fungal communities. The contents of NO 3 −-N, available phosphorus and potassium, and electrical conductivity were all significantly increased when CAB was used. In addition, CAB also significantly increased the strawberry marketable yield. High-throughput gene sequencing showed the species abundance of some soil bacteria and fungi was significantly increased such as the phyla Proteobacteria, Bacteroidetes, Actinobacteria and Ascomycota when CAB was used. However, CAB decreased the relative abundance of the phyla Firmicutes, Chloroflexi, Gemmatimonadete and Zygomycota. These results indicated that CAB could improve the physico-chemical properties of soil for strawberry production, increase the genetic diversity of microbes in the soil and enhance marketable fruit yield. Unlabelled Image • Our study introduced a new method of soil fumigation to reduce the use of chemical fumigants. • Chloropicrin alternated with biofumigation (CAB) can improve nutrient elements in chloropicrin fumigation plots. • Chloropicrin alternated with biofumigation (CAB) also increased strawberry yields • Chloropicrin alternated with biofumigation (CAB) significantly impacts soil bacterial and fungal community diversity. [ABSTRACT FROM AUTHOR]

Topography drives spatial variation of soil edaphic factors at the landscape scale however, it is unclear how it influences the spatial distribution of bacterial communities in distances relevant to agro-ecosystem management. This study examined the influence of soil physico-chemical properties and topographic features on bacterial communities and diversity in a commercial potato field with a rolling landform. Eighty-three soil samples were systematically collected across a transect 1100 m long. A significant negative correlation ( r  = −0.73) between soil pH (range 4.3–7.0) and slope gradient (range 1.8–11.9%) was observed. Regressions and/or a canonical correspondence analysis showed that pH, slope gradient and organic carbon were the major factors influencing bacterial α-diversity based on 16S rRNA gene sequences. Semivariogram analyses revealed that the bacterial α-diversity, the relative abundance of most phyla, pH and slope gradient showed strong to medium spatial autocorrelations with a range between 20.8 and 217.8 m. These results evidenced that soil pH and slope gradient were the major factors explaining variation in the spatial structure of the bacterial community. Our results showed that the soil bacterial communities varied in a systematic and predictable pattern in an agricultural field in response to variation in soil physico-chemical properties and topographic features. [ABSTRACT FROM AUTHOR]

Sugarcane cultivation in Japan has not yet focused on suppressing plant-parasitic nematodes. For proper nematode management, it is essential to know the spatial distribution of economically important plant-parasitic nematodes and free-living nematodes that play important roles in terrestrial ecosystems. We aimed to reveal nematode fauna and soil properties in 85 sugarcane fields of three major sugarcane producing islands in Japan, and to examine their relationship by using the mixed-effect model and by visualizing the spatial distributions using the inverse distance weighting (IDW) approach. The nematode community structures were analyzed by non-metric multidimensional scaling (NMDS). Among plant-parasitic nematodes in sugarcane, the root-lesion nematodes (Pratylenchus sp.) and the stunt nematodes (Tylenchorhynchus sp.) were widely distributed in these islands, yet the abundance and the species varied geospatially. Soil pH was significantly correlated with the abundance of Pratylenchus and Tylenchorhynchus species. The abundance of Pratylenchus and Tylenchorhynchus species were significantly correlated with soil pH. The abundance of Pratylenchus was significantly correlated with the abundance of free-living nematodes, the number of free-living nematode species, and exchangeable cation K+, as were the abundance of Tylenchorhynchus to the clay content and that of non-Tylenchorhynchus. This study also revealed that the three islands had different nematode faunas, which were explained especially by soil pH, texture, and exchangeable basic cations.