Variability Of Soil Physico-chemical Properties Research Articles

Spatial Variation in Soil Physico-Chemical Properties along Slope Position in a Small Agricultural Watershed Scale

Both cropland management and slop erosion are important factors influencing soil properties, but there are relatively few studies on their combined effects. Studies at the agricultural watershed scale can satisfy both of these conditions, and to reduce the effects of soil heterogeneity due to differences in spatial scale, it is better to select different slopes in the same small watershed. To understand how soil properties will respond to the variation of slope position and cropland management at an agricultural watershed, we present the distribution of soil bulk density (BD), saturated hydraulic conductivity (Ks), water-stable aggregates, soil organic carbon (OC), nitrogen (N), and phosphorus (P) at four slope positions in two cropland management systems of a small agricultural watershed in the black soil region of northeast China. The selected four slope positions include upper slope, middle slope, lower slope, and footslope positions. The two cropland management systems consist of a sustainable cropland system (i.e., contour ridge tillage at upper slope position, longitudinal ridge tillage at middle slope and lower slope positions, and grassland at footslope position) and a conventional cropland system (i.e., contour ridge tillage at upper slope position, longitudinal ridge tillage at middle slope, lower slope positions, and footslope positions). The results showed that soil bulk density and microaggregates decreased but the concentration of OC and nutrients, Ks, and small-macroaggregate increased from the upper slope position to the lower slope position in both the conventional and sustainable croplands, which was due to the interaction effect of cultivation with erosion. In comparison with conventional cropland, sustainable cropland has greater Ks, large-macroaggregate, small-macroaggregate, microaggregate, and concentrations and stocks of OC, N, and P, but showed lower bulk density and silt + clay fraction. However, the prominent differences in both croplands were presented in the footslope position, which is ascribed to the interaction of cultivation, erosion, and cropland management. These results highlighted that sustainable cropland management practice has the potential to improve soil structure and prevent soil and nutrient loss.

Short-term recovery of soil and pine tree canopy after late prescribed burning in a semi-arid landscape

Climate change worsening due to global warming and progressive abandonment in rural areas mean that wildfires are increasing in extent and severity terms, and are one of the major disturbances in the Mediterranean Basin. To mitigate these disturbances, preventive management tools need to be used. Fire employment is being implemented, known as prescribed burnings, as forestry actions to change vegetation lines both vertically and horizontally to eliminate forest fuel load continuity. This study aimed to know the ecological effects of late prescribed burning treatments under mixed trees. Prescribed burns were carried out in October 2019 in the municipality of Ayna, Albacete (SE Spain). To assess the short-term (12-month) fire impact on soil, we measured soil respiration with a CO2 flow chamber and analyzed soil physico-chemical properties. We also used minidisc infiltrometers to analyze soil repellency and soil hydraulic conductivity over a 1-year monitoring period. In addition, we evaluated the effects on tree strata by performing chemical nature analyses of fallen needles in Pinus pinaster after prescribed burning. According to our initial hypotheses, the results did not show significant changes in any parameter evaluated during the study period. However, some variables were affected in the first 3 months, needlefall and in microbiological activity, such as variations in soil physico-chemical properties, which can be due to long dry seasons combined with prescribed burning. This study attempts to observe and make known the effects that low-intensity prescribed burning has on soil and needlefall, which are relevant for updating forest management tools.

Variability of soil physicochemical properties under different land use types in the Guinea savanna zone of northern Ghana

Variability of soil physicochemical properties under different land use types in the Guinea savanna zone of northern <i>Ghana</i>

Variations in soil properties and stoichiometric ratios with stand age under agarwood monoculture and polyculture on smallholder farms

Smallholder plantations have gained increasing attention in land management and conservation of the remaining forest resources locally. Plantation of agarwood (Aquilaria malaccensis), a critically endangered tree species, has become a promising source of income for smallholders because of its high economic value in parts of Asia. Agarwood is considered profitable with plantation cycles of 15 years or more. The objectives of the present study are to (i) quantify variations in soil physico-chemical properties, (ii) quantify variations in soil organic carbon (SOC) stocks, and (iii) evaluate variations in stoichiometric ratios with stand type, age and soil depth. Soil texture, bulk density, water holding capacity (WHC), soil pH, available nitrogen (N), phosphorus (P), potassium (K), exchangeable calcium (Ca), magnesium (Mg) and soil organic carbon (SOC) stocks in very labile, labile, less labile and non-labile pools were determined in different soil depths (0–100 cm) under <10, 10–20 and >20 years old monoculture and polyculture stands of agarwood on smallholder farms. Soil texture and bulk density did not significantly vary with stand type or age, but significantly higher WHC was found in >20 years old stands. Across stand ages and soil depths, available N and P concentrations were higher in monoculture, while available K concentrations were higher in polyculture. SOC content significantly varied with the stand type, age and soil depth and their interaction effects. The highest SOC content (28.9 g kg−1) was recorded in the 0–10 cm of >20 years old monoculture stands, while the lowest (4.2 g kg−1) in the 51–100 cm depth of 10–20 years old polyculture stands. SOC stocks significantly increased with increase in stand age in both monoculture and polyculture stands. The highest total SOC stock (40.7 Mg ha−1) was recorded in the 51–100 cm depth of >20 years old monoculture stands, while the lowest (13.4 Mg ha−1) was in the 31–50 cm depth of <10 years old polyculture stands. The SOC stocks in the recalcitrant (passive) pools, which are the main drivers of long-term soil carbon sinks, were 1.5-fold more in monoculture than polyculture stands.

Variations in Soil Physico-Chemical Properties as Influenced by Landuse in a Toposequence

Soil, water and air work interchangeably for optimum growth and productivity. Soil as a resource provides crops with essential nutrients necessary for growth and human consumption. With the insurgence of high population growth leading to pressure on lands, poor land management etc., this tendency of the soil as a nutrient pool is seen to be dwindling. It is therefore prudent to investigate and understand the dynamism of soil properties to inform proper management. Understanding topography effects and assessing soil properties on different slope positions is a first-hand step in ensuring proper soil management practices. This paper considers the assessment of physico-chemical properties of soils located on different slope gradients and land use types on the Wamaso research site in Ghana made principally of cape coast granite. In all, eighteen samples were collected from identified horizons of five distinctive subsections of the slope were delineated as follows, summit (PP1), shoulder (PP2), middle (PP3), foot slope (PP4) and toe slope (PP5) respectively. Remarkable variations were observed within PP1 to PP3 and then PP5. Pearson’s correlation index revealed that the associations between most of the soil physico-chemical were not consistent across the identified slope positions. The biplot of the first two principal components together is 68.3% of the total variation and might be interpreted as change in Cation exchange capacity, sodium, sand and clay. On the first axis highlights the influence of sand and clay on soil fertility, also the relationship between pH and Na. Organic carbon derived from organic matter contributes to the availability of the basic soil cations and therefore enhances ECEC of the soils and hence the relationship obtained from the biplot. In sum, this research achieved the objective which sought to substantiate indeed the impact topography has on soil physico-chemical properties thereby serving as a reference for the classification of the soils identified.

Variation in Soil Physico-Chemical Properties in Temperate Forests of Khatling Valley, Western Himalaya, India

The current study seeks to understand the physico-chemical properties of soil along different altitude in Khatling valley of Western Himalaya. Four sites were examined for different physico-chemical characteristics between 1500-3500m amsl. The investigation found that the soils at all of the study sites were acidic and had a sandy loam texture. The range of the water holding capacity and moisture content values across the research area was 35.59±4.22 to 38.91±3.97% and 14.77±0.12 to 17.39±1.13% respectively. In the studied area the values for total nitrogen ranged from 0.19±0.02 to 0.37±0.04%, available phosphorus (10.23±2.45 to 15.97±2.63kg ha-1), available potassium (122.95±17.58 to 212.90±19.67kg ha-1), organic carbon (0.92±0.35 to 3.09±0.63%) and organic matter (1.58±0.60 to 5.32±1.09%) respectively. Organic carbon and total nitrogen displayed a positive correlation with altitude (r = 0.992 and r = 0.865, respectively) but a negative correlation with soil depth. In contrast, there was a negative association between altitude and the amounts of available phosphorus (r = -0.941) and potassium (r = -0.941). The available phosphorus indicates a positive relation with the depth of soil, whereas available potassium did not exhibit a consistent pattern with depth. This finding of this study suggest that soil physico-chemical properties vary with altitude and soil depth.

Estimation of baseline levels of bacterial community tolerance to Cr, Ni, Pb, and Zn in unpolluted soils, a background for PICT (pollution-induced community tolerance) determination

The PICT method (pollution-induced community tolerance) can be used to assess whether changes in soil microbial response are due to heavy metal toxicity or not. Microbial community tolerance baseline levels can, however, also change due to variations in soil physicochemical properties. Thirty soil samples (0–20 cm), with geochemical baseline concentrations (GBCs) of heavy metals and from five different parent materials (granite, limestone, schist, amphibolite, and serpentine), were used to estimate baseline levels of bacterial community tolerance to Cr, Ni, Pb, and Zn using the leucine incorporation method. General equations (n = 30) were determined by multiple linear regression using general soil properties and parent material as binary variables, explaining 38% of the variance in log IC50 (concentration that inhibits 50% of bacterial growth) values for Zn, with 36% for Pb, 44% for Cr, and 68% for Ni. The use of individual equations for each parent material increased the explained variance for all heavy metals, but the presence of a low number of samples (n = 6) lead to low robustness. Generally, clay content and dissolved organic C (DOC) were the main variables explaining bacterial community tolerance for the tested heavy metals. Our results suggest that these equations may permit applying the PICT method with Zn and Pb when there are no reference soils, while more data are needed before using this concept for Ni and Cr.

Responses of Soil Microbial Community and Enzyme Activities to Shrub Species Artemisia gmelinii in Relation to Varying Rainfall in a Semiarid Land, SW China

Widely distributed shrubs in drylands can locally alter soil physicochemical properties, which distinguish soil under plant canopy from soil outside the canopy. In the present study, we used a dominant shrub species Artemisia gmelinii in a semiarid land, SW China, to investigate the consequences of “shrub resource islands” for soil microbial communities and enzymatic activities. Such investigation was made at four sites that differed in rates of rainfall to examine how the consequences were altered by variation in the local climate. The results showed that A. gmelinii enhanced fungal abundance but did not influence bacterial abundance, resulting in higher total microbial abundance and fungal-to-bacterial ratio in under-canopy soil compared to outside-canopy soil. Microbial community composition also differed between the two soils, but this difference only occurred at sites of low rainfall. Redundancy analysis revealed that such composition was attributed to variation in soil water content, bulk density, and total phosphorus as a result of shrub canopy and varying rates of rainfall. Activities of hydrolytic enzymes (β-1,4-glucosidase, β-1,4-N-acetylglucosaminidase, alkaline phosphatase, and leucine aminopeptidase) were higher in under-canopy soil than in outside-canopy soil, among which C-acquisition enzyme, β-1,4-glucosidase, and P-acquisition enzyme, alkaline phosphatase, were also higher in the soil of high rainfall. The overall pattern of enzyme activities did not show differences between under- and outside-canopy soils, but it separated the sites of high rate from that of low rates of rainfall. This pattern was primarily driven by variation in soil physicochemical properties rather than variation in soil microbial community, suggesting that the distribution pattern of enzyme activities may be more sensitive to variation in rainfall than to shrub canopy. In conclusion, our study shows that shrub species A. gmelinii can shift the soil microbial community to be fungal-dominant and increase hydrolytic enzyme activities, and such effect may depend on local climatic variation, for example, rainfall changes in the semiarid land. The findings of this study highlight the important roles of shrub vegetation in soil biological functions and the sensitivity of such roles to climatic variation in semiarid ecosystems.

Seasonal variations in soil physicochemical properties and microbial community structure influenced by Spartina alterniflora invasion and Kandelia obovata restoration

Spartina alterniflora invasion has initiated one of the greatest changes to occur in coastal wetlands in China, and ecological replacement using mangrove species such as Kandelia obovata is an effective method for controlling these invasions. The effects of S. alterniflora invasions and subsequent K. obovata restorations on soil microbial community structures in different seasons are still not fully understood. In this study, soil samples were collected from six vegetation types (unvegetated mudflat, invasive S. alterniflora stands, one-/eight-/ten-year K. obovata restoration areas, and native mature K. obovata forests) in summer and winter. The variations in the soil microbial community structure between the vegetation types across two seasons were then characterized based on 16S rRNA gene sequencing, and the physicochemical properties that shaped the microbial communities were also determined. The invasion and restoration processes significantly influenced microbial community diversity, composition, and putative functions in different seasonal patterns. Microbial communities from a ten-year restoration area and a native mature K. obovata area shared more similarities than other areas. In both seasons, the key environmental factors driving microbial community included total carbon and nitrogen content, the ratio of carbon to nitrogen, and the soil pH. In addition, total sulfur and total phosphorus contents significantly contributed to structuring microbial communities in summer and winter, respectively. This study provides insights into microbial diversity, composition, and functional profiles in association with physicochemical impacts, with the aim of understanding microbial ecological functions during the invasion and restoration processes in wetland ecosystems.

Peach-Morchella intercropping mode affects soil properties and fungal composition.

ObjectiveThis study aims to explore a three-dimensional planting mode in orchards and provide theoretical basis for the efficient peach-Morchella planting and soil management after Morchella cultivation.MethodsNext-generation sequencing was performed to investigate the variations in soil physicochemical properties, enzyme activities and fungal composition under peach-Morchella intercropping for one year and two years, by using the soil without peach-Morchella intercropping as the control group.ResultsPeach-Morchella intercropping decreased the soil bulk density, and significantly increased the maximum field capacity, non-capillary porosity and total porosity, organic matter, available potassium and available zinc, which together improved soil structure and soil fertility. Besides, the intercropping mode obviously enhanced soil enzyme activities and mineral absorption and transformation in peach orchard soils. The intercropping also resulted in a decline of soil fungal diversity, and the 2-year soil samples were of higher abundance of Zygomycota. More importantly, peach-Morchella intercropping elevated the yields of both peach and Morchella, bringing about obviously higher economic benefits.ConclusionContinuous peach-Morchella intercropping improves the soil structure and fertility while decreases soil fungal diversity, which can contribute to greater economic benefits of the peach orchard. Our findings shed new light on the intercropping-fungus-soil relationship, and may facilitate the further development of peach-Morchella intercropping.

Diversity and abundance of soil-litter arthropods and their relationships with soil physicochemical properties under different land uses in Rwanda

ABSTRACT Soil-litter arthropods are critical for ecosystem functioning and sensitive to land use change, and hence to the variations in soil physicochemical properties. The relationships between soil-litter arthropod communities and soil physicochemical properties, however, remain poorly studied in Rwanda. We explored the relationships between the families of soil-litter arthropods and soil properties in exotic and native tree species, and in varieties of coffee and banana plantations. Soil-litter arthropods were sampled by using Berlese funnels, hand sorting, and pitfall traps, and were identified to the family level. Soil cores were collected and analysed for soil pH, available phosphorus, total nitrogen, soil organic carbon, silt, clay and sand. A total of 3176 individuals of soil-litter arthropods were collected, identified and classified into 13 orders and 23 families. Higher abundance was found in soil and litter sampled in plots of native tree species and banana plantations compared to exotic tree species and coffee plantations. Higher diversity was found in plots of native and exotic tree species. The analysis of soil physicochemical properties indicated that native tree species offer suitable conditions of studied soil properties. The study of the relationships between the land use, soil properties and families of soil-litter arthropods indicated positive correlations and relationships mainly in native tree species. We conclude that forest with native tree species play an important role in the conservation of soil-litter arthropods and for maintenance of better soil conditions.

Vegetative and reproductive phenology in a tropical grassland–savanna–forest gradient

AbstractQuestionClimate, particularly precipitation, is the primary factor driving tropical plant phenology because of its relevant role in regulating water availability. However, differences in soil physicochemical properties can also drive resource availability, potentially affecting plant phenology, especially under similar environments in terms of rainfall regime. We determined whether the seasonality and synchrony of the vegetative and reproductive phenophases differ along a grassland–savanna–forest gradient under the same climate regime in a Neotropical seasonal ecosystem. We hypothesized that species growing on shallow, nutrient‐impoverished soils have a higher capacity to respond to precipitation pulses than those on rich soils.LocationSerra do Cipó, southeastern Brazil.MethodsWe quantified soil physicochemical properties associated with fertility and water retention of the grassland (campo rupestre), savanna (cerrado) and forest, and determined the phenological strategies of 70 species across the three vegetation types by monitoring vegetative and reproductive phenophases over one year. For each phenophase, in each vegetation type, we evaluated the seasonality and synchrony of phenological patterns. We quantified the phylogenetic signal for phenophases to disentangle the relative roles of historical vs ecological drivers of plant phenology.ResultsSoils from campo rupestre were more nutrient‐ and water‐limited than those of cerrado and forest. Cerrado and forest communities had similar phenological strategies, whereas species from campo rupestre showed strategies that maximize resource acquisition and conservation. In the cerrado and forest, leafing and flowering patterns were seasonal, with leaf flushing and flowering peaking at the onset of the rainy season and leaf senescence in the dry season. Conversely, species from campo rupestre showed continuous leafing and flowering patterns, while fruiting was seasonal. Phenophases did not show a phylogenetic signal.ConclusionsWe demonstrated changes in vegetative and reproductive phenology that are likely associated with variations in soil physicochemical properties. We argue that more severe edaphic filters may have shaped different phenological patterns in campo rupestre.

Patterns and predictors of soil organic carbon storage across a continental-scale network

The rarity of rapid campaigns to characterize soils across scales limits opportunities to investigate variation in soil carbon stocks (SOC) storage simultaneously at large and small scales, with and without site-level replication. We used data from two complementary campaigns at 40 sites in the United States across the National Ecological Observatory Network (NEON), in which one campaign sampled profiles from closely co-located intensive plots and physically composited similar horizons, and the other sampled dozens of pedons across the landscape at each site. We demonstrate some consistencies between these distinct designs, while also revealing that within-site replication reveals patterns and predictors of SOC stocks not detectable with non-replicated designs. Both designs demonstrate that SOC stocks of whole soil profiles vary across continental-scale climate gradients. However, broad climate patterns may mask the importance of localized variation in soil physicochemical properties, as captured by within-site sampling, especially for SOC stocks of discrete genetic horizons. Within-site replication also reveals examples in which expectations based on readily explained continental-scale patterns do not hold. For example, even wide-ranging drainage class sequences within landscapes do not duplicate the clear differences in profile SOC stocks across drainage classes at the continental scale, and physicochemical factors associated with increasing B horizon SOC stocks at continental scales frequently do not follow the same patterns within landscapes. Because inferences from SOC studies are a product of their context (where, when, how), this study provides context—in terms of SOC stocks and the factors that influence them—for others assessing soils and the C cycle at NEON sites.

Altitudinal Variation in Soil physico-chemical properties of a Western Himalayan Forest , Uttarakhand, India

The physico-chemical properties of soil vary with the variation in the topographic features, climatic conditions and forest types. In any forest ecosystem, both vegetation and soil influence each other through nutrient cycles. The altitudinal variation in soil physico-chemical properties was analyzed in a temperate forest (Radi forest) of Upper Yamuna Forest Division in Uttarkashi district of Uttarakhand (Western Himalaya, India). A total of three forest sites were selected at different altitudes (the lower, middle, and upper) to collect composite soil samples from each site covering 0–10 cm, 11–20 cm and 21–30 cm depths. The textural class of the soils was sandy loam. The colour of the soil samples varied from brown to very dark brown. The water holding capacity (r = 0.994), soil organic carbon (r = 0.967), organic matter (r = 0.966), nitrogen (r = 0.993), phosphorus (r = 0.982) and potassium content (r = 0.994) had positive correlation with altitude whereas negative correlation was observed between altitude and soil pH (r = -0.983) in the study. The present study concludes that soil physico-chemical properties in temperate forests of Uttarakhand Himalaya vary significantly with variation in altitude.

Floral Diversity of Abandoned Mansions and the Influence of Soil Properties on These Unique Vegetations

Abandoned land and mansions are always a matter of curiosity to the human beings. They are treated as haunted places in many societies. In the present research, three decrepit abandoned mansions from the southern Bangladesh were investigated to measure their floral diversity, physico-chemical properties of soil and the soil-plant interrelationship which is responsible for the diversification of wild flora within the regions. From Shannon and Simpson diversity indexes, it can be deducted that the floral diversity within the abandoned mansions has a positive relationship with their territory size. The high values of Margalef’s and Menhinick’s species richness indexes confirmed that these areas are a rich source of a large number of plant species. A great variation in soil physico-chemical properties has been observed during the analysis. Soil organic matter, nitrogen, phosphorus, potassium & moisture contents were varied significantly from one quadrat to another in every site. Biplot analysis showed that the distribution of plant species in abandoned mansions is primarily determined by the organic matter, pH, moisture and potassium contents of soil. As these factors were present in versatile distribution within the studied regions, a great number of plants can grow in the same area simultaneously. So these areas should be protected from human intervention to process natural selection and in situ conservation of plant species.

Effects of human disturbance activities and environmental change factors on terrestrial nitrogen fixation.

Biological nitrogen (N) fixation plays an important role in terrestrial N cycling and represents a key driver of terrestrial net primary productivity (NPP). Despite the importance of N fixation in terrestrial ecosystems, our knowledge regarding the controls on terrestrial N fixation remains poor. Here, we conducted a meta-analysis (based on 852 observations from 158 studies) of N fixation across three types of ecosystems with different status of disturbance (no management, restoration [previously disturbed], and disturbance [currently disturbed]) and in response to multiple environmental change factors (warming, elevated carbon dioxide [CO2 ], increased precipitation, increased drought, increased N deposition, and their combinations). We explored the mechanisms underlying the changes in N fixation by examining the variations in soil physicochemical properties (bulk density, texture, moisture, and pH), plant and microbial characteristics (dominant plant species numbers, plant coverage, and soil microbial biomass), and soil resources (total carbon, total N, total phosphorus (P), inorganic N, and inorganic P). Human disturbance inhibited non-symbiotic N fixation but not symbiotic N fixation. Terrestrial N fixation was stimulated by warming (+152.7%), elevated CO2 (+19.6%), and increased precipitation (+73.1%) but inhibited by increased drought (-30.4%), N deposition (-31.0%), and combinations of available multiple environmental change factors (-14.5%), the extents of which varied among biomes and ecosystem compartments. Human disturbance reduced the N fixation responses to environmental change factors, which was associated with the changes in soil physicochemical properties (2%-56%, p<.001) and the declines in plant and microbial characteristics (3%-49%, p≤.003) and soil resources (6%-48%, p≤.03). Overall, our findings reveal for the first time the effects of multiple environmental change factors on terrestrial N fixation and indicate the role of human disturbance activities in inhibiting N fixation, which can improve our understanding, modeling, and prediction of terrestrial N budgets, NPP, and ecosystem feedbacks under global change scenarios.

Quantitative Evaluation of the Spatial Variation of Surface Soil Properties in a Typical Alluvial Plain of the Lower Yellow River Using Classical Statistics, Geostatistics and Single Fractal and Multifractal Methods

The spatial variability of soil properties has always been a significant research field in geoscience. The types of soil properties cover a wide range, but most studies have focused on the spatial variability of soil physicochemical properties over the past decades. Studies on soil hydraulic characteristics are limited, and most of them are limited to the farmland scale. However, the spatial variability of regional soil properties (soil texture and hydraulic properties) is valuable for the study of sedimentation processes and soil water transport. Therefore, here, the spatial variation of six soil properties (sand, silt, clay content, bulk density, saturated water content and saturated hydraulic conductivity) in the typical alluvial plain area of the lower Yellow River is quantitatively studied, by using classical statistics, geostatistics and single fractal and multifractal methods. This study mainly quantitatively analysed the spatial variability of different soil properties and compared four research methods. Although the coefficient of variation, nugget coefficient, single fractal dimension and multifractal spectral width can reflect spatial variability, diverse conclusions are drawn (on variability) if different methods are used, and the different soil properties show large disparities. These four methods show a different variation order of soil properties, but there are some common conclusions based on analysis and judgment. In general, the silt content in the study area is stable, mainly originating from loess transported by Yellow River erosion, which is also reflected in the Kriging interpolation maps under the geostatistical models. The variation in bulk density and saturated water content is weak, and the spatial variability of sand and clay content is moderate. In addition, the saturated hydraulic conductivity fluctuates violently. This may be related to the differences in local topography, human activity and the content of sand and clay, each of which significantly affects the saturated hydraulic conductivity. Classical statistics has a limitation because it fails to corelate with spatial location. Due to the small sample capacity and calculation error of lag distance, the accuracy of geostatistics and single fractal dimensions needs to be improved. Multifractal spectral analysis does not need to consider the normality of data and can quantitatively represent local characteristics; therefore, its results have high reliability.

Long-term effects of gravel mulching and straw mulching on soil physicochemical properties and bacterial and fungal community composition in the Loess Plateau of China

Gravel and straw mulching are the most effective and widely used surface coverage practices used to mitigate drought stress and soil erosion in Loess Plateau of northwestern China. Unlike for straw mulching, however, benefits of gravel mulching fluctuate on a long-term scale, possibly leading to soil degradation. Here we investigated variation in soil physicochemical properties and the bacterial and fungal communities in soil after 10 years of applied gravel mulching (GM), straw mulching (SM), and non-mulching (CK). Proteobacteria (30.46–31.39%) was the most abundant phylum in all three treatments. We found Actinobacteria (19.10–24.92%) enriched in both GM and SM soils, while Acidobacteria (13.53–19.42%) had a higher relative abundance in gravel mulching soil only. A heatmap and principal component analysis (PCA) revealed that gravel or straw mulching significantly changed the soil bacterial and fungal community structure. Soil fungal community is more sensitive to gravel than straw mulch applications, under SM, the relative abundance of Mortierellomycota and Glomeromycota phyla increased while that of Ascomycota was decreased. In-depth taxonomic analysis of Proteobacteria demonstrated that the relative abundance of the class Alphaproteobacteria in straw mulching soil significantly exceeded that in the non-mulching soil. Comparing the three treatments, relative abundances of Nitrosomonadaceae family members were significantly higher in gravel mulching soil, while those of Steroidobacteraceae were significantly higher in the non-mulching soil. Redundancy analysis (RDA) suggested pH and soil water content were key factors driving these long-term changes in soil bacterial community structure.

Assessment of Spatial Variability of Physico-chemical Properties of Soil at Crop, Soil and Pest Management Research Farm, FUTA

Soil is an important natural resource for growing plants and the suitability of the soil for crop production is based on the quality of the soil’s physical, chemical and biological properties. The objectives of the study were to determine the soil physical and chemical properties and characterize the spatial variability of soil physico-chemical properties across the study area. The study was conducted at Crop, Soil and Pest Management Research Farm, Futa. Soil samples were collected from six sampling depths between 0-60 cm at an interval of 10 cm at different 20 points across the field while coordinates of the soil sampling points were determined using Global Positioning System (GPS) procedures. The test for variance was carried out on the physical properties of %sand, %silt, %clay, bulk density (g/cm3), %porosity, %water holding capacity (WHC) and soil hydraulic conductivity and chemical properties on pH, organic matter content (%), total nitrogen (%), available phosphorus (ppm), calcium, magnesium, sodium and potassium (cmol/kg), and effective cation exchange capacity (cmol/kg). The laboratory analysis (soil textural analysis) revealed that the soil types at the site were predominantly Sandy Clay Loam. Gravimetric soil moisture content and the water holding capacity (WHC) in all the 20 sampling spots at the topsoil has a mean value of 9.13% ± 1.90 and 52.43%±2.45 respectively. The minimum and maximum hydraulic conductivity (K) value at the distribution show a moderately skewed distribution of the K data and the distribution is positively skewed. The mean pH value of the soil in the study site was found to be slightly acidic and the soils were low in soil OM. The CEC, Mg2+, OC, TEB and TN indicated a significant difference for soil chemical properties. The physical and chemical properties of the study were found to be optimal for crop production, fertility assessment and land use management practices for crop productions and drip irrigation is suitable for the study area. Keywords: Spatial variability, Soil physico-chemical property, GPS procedures, Sampling point, Land use management practices, fertility assessment

Responses of soil microarthropod taxon (Hexapoda: Protura) to natural disturbances and management practices in forest-dominated subalpine lake catchment areas

Disturbances are intrinsic drivers of structure and function in ecosystems, hence predicting their effects in forest ecosystems is essential for forest conservation and/or management practices. Yet, knowledge regarding belowground impacts of disturbance events still remains little understood and can greatly vary by taxonomic and functional identity, disturbance type and local environmental conditions. To address this gap in knowledge, we conducted a survey of soil-dwelling Protura, across forests subjected to different disturbance regimes (i.e. windstorms, insect pest outbreaks and clear-cut logging). We expected that the soil proturan assemblages would differ among disturbance regimes. We also hypothesized that these differences would be driven primarily by variation in soil physicochemical properties thus the impacts of forest disturbances would be indirect and related to changes in food resources. To verify that sampling included two geographically distant subalpine glacial lake catchments that differed in underlying geology, each having four different types of forest disturbance, i.e. control, bark beetle outbreak (BB), windthrow + BB (wind + BB) and clear-cut. As expected, forest disturbance had negative effects on proturan diversity and abundance, with multiple disturbances having the greatest impacts. However, differences in edaphic factors constituted a stronger driver of variability in distribution and abundance of proturans assemblages. These results imply that soil biogeochemistry and resource availability can have much stronger effects on proturan assemblages than forest disturbances.