Changes In Soil pH Research Articles

Direct and indirect effects of dominant plants on ecosystem multifunctionality

Biodiversity is essential for the provision of multiple ecosystem functions simultaneously (ecosystem multifunctionality EMF). Yet, it remains unclear whether and how dominant plant species impact EMF. Here, we aimed at disentangling the direct from indirect above- and belowground pathways by which dominant plant species influence EMF. We evaluated the effects of two dominant plant species (Dasiphora fruticosa, and the toxic perennial plant Ligularia virgaurea) with expected positive and negative impacts on the abiotic environment (soil water content and pH), surrounding biological communities (plant and nematode richness, biomass, and abundance in the vicinity), and on the EMF of alpine meadows, respectively. We found that the two dominant plants enhanced EMF, with a positive effect of L. virgaurea on EMF greater than that of D. fruticosa. We also observed that dominant plants impacted on EMF through changes in soil water content and pH (indirect abiotic effects), but not through changes in biodiversity of surrounding plants and nematodes (indirect biotic pathway). Our study suggests that dominant plants may play an important role in promoting EMF, thus expanding the pervasive mass-ratio hypothesis originally framed for individual functions, and could mitigate the negative impacts of vegetation changes on EMF in the alpine meadows.

Effects of Hevea brasiliensis Intercropping on the Volatiles of Pandanus amaryllifolius Leaves

Pandanus amaryllifolius Roxb. is a special tropical spice crop resource with broad development prospects. It is widely cultivated under a Hevea brasiliensis (Willd. ex A. Juss.) Muell. Arg. canopy to improve the comprehensive benefits to Hevea brasiliensis plantations in Hainan Provence, China. However, the effects of intercropping with Hevea brasiliensis on the component number and relative contents of volatile substances in different categories in the Pandanus amaryllifolius leaves are still unknown. Therefore, a Hevea brasiliensis and Pandanus amaryllifolius intercropping experiment was set up to clarify the differences between several cultivated patterns on volatile substances in the Pandanus amaryllifolius leaves, and the key regulatory factors of volatile substances. The results showed that the soil pH was significantly decreased, while soil bulk density, alkali-hydrolyzable nitrogen and available phosphorus contents were significantly increased under the intercropping pattern. The component numbers of esters in volatile substances were increased by 6.20%, while the component numbers of ketones were decreased by 4.26% under the intercropping pattern. Compared with the Pandanus amaryllifolius monoculture, the relative contents of pyrroles, esters and furanones were significantly increased by 8.83%, 2.30% and 8.27%, respectively, while the relative contents of ketones, furans and hydrocarbons were decreased by 1.01%, 10.55% and 9.16% under the intercropping pattern, respectively. The relative contents of pyrroles, esters, furanones, ketones, furans and hydrocarbons were associated with changes in soil pH, soil available phosphorus content and air temperature. The results indicated that the reduction in soil pH and enhancement in soil-available phosphorus may be the main reasons for promoting the relative content of pyrroles and reducing the relative content of hydrocarbons under an intercropping pattern. Overall, Hevea brasiliensis intercropping with Pandanus amaryllifolius could not only improve soil properties, but also significantly increase the relative contents of the main volatile substances in Pandanus amaryllifolius leaves, which could provide a theoretical basis for the application and promotion of high-quality production patterns of Pandanus amaryllifolius.

Copper Bioavailability and Leaching in Conventional and Organic Viticulture under Environmental Stress

The continuous use of Cu-based fungicides in viticulture has caused Cu accumulation in soils, which represents a major environmental and toxicological concern. The purpose of this study was to verify whether the organic management would be more resilient to temperature and moisture stresses in comparison to conventional practices. Two organic and two conventional vineyard soils, contrasting in pH, were exposed for six months to temperature stress (29 °C), moisture stress (10% water holding capacity—WHC), and combined stresses (29 °C—10% WHC). Main soil properties, Cu speciation, bioavailability, and leaching were monitored before and after 6 months’ incubation. Results confirm that the increase of temperature caused a decrease in both total organic carbon (TOC) and dissolved organic carbon (DOC) (up to 19% and 49%, respectively), a decrease in available ammonium, and an increase in nitrate. Moisture stress tends to mitigate some of these changes. Despite that, changes of Cu bioavailability and leaching were limited and rarely significant. Moreover, no regular trends between conventional and organic management could be observed. Changes in soil pH and total N (TN) appeared as the most influencing properties to regulate Cu behavior in vineyard soils. Calcareous soils were more resistant to environmental stresses compared to acid soils, regardless of the type of management (conventional or organic).

Globally nitrogen addition alters soil microbial community structure, but has minor effects on soil microbial diversity and richness

Globally increasing nitrogen (N) deposition is recognized as an important regulator of soil microbial communities. However, how N enrichment affects soil microbial diversity, richness and community structure remains unclear at the global scale. Here, by focusing on high-throughput amplicon sequencing data from field experiments using N fertilizers only, we conducted a meta-analysis of a global dataset assessing the responses of microbial diversity (Shannon index), richness (Chao1, OTU richness) and community structure to N addition. Our results showed that N addition significantly reduced soil bacterial diversity (−2.3%), and such effect was significant in cropland (rather than grassland and forest) and with urea addition (rather than ammonium nitrate). However, there was no significant effect of N addition on soil fungal diversity and microbial (bacterial or fungal) richness. Moreover, N addition shifted microbial community structure likely due to the microbial adaptation to N-excess, but had no significant effect on microbial beta-diversity. Model-selection analysis further showed that the change in soil pH was the most important factor regulating the responses of soil bacterial diversity and richness to N addition. Overall, our results contribute to an in-depth understanding of the effects of N addition on soil microbial diversity and community structure in terrestrial ecosystems at the global scale.

Effects of organic and inorganic fertilizers on soil properties related to the regeneration of ecosystem services in peat grasslands

Worldwide, agricultural grasslands on drained peat contribute to CO2 emission but provide also provisioning and supporting ecosystem services that are managed by farmers. This paper evaluates the performance of organic and inorganic fertilizers in relation to soil biotic and abiotic properties linked to soil ecosystem services of peat grasslands with biodiversity goals. Effects of cattle slurry, compost, farmyard manure, solid fraction of cattle slurry and inorganic nitrogen (N) fertilizer with and without added sawdust were compared to those of an unfertilized control in a three-year field experiment. Total N input was targeted at 120 kg N ha−1 year−1; total carbon (C) input was variable due to different C:N ratios of source materials. The abundance of earthworms in spring was increased with solid fraction (+35 % as compared to the control), which had the largest C input, and was reduced with inorganic N (−24 %). Combining inorganic N with sawdust did not affect earthworm abundance. Bacteria (determined by phospholipid fatty acid analysis) were increased following inorganic N fertilizer application with (+65 %) or without (+52 %) sawdust. Arbuscular mycorrhizal fungi were reduced by all fertilizers (−40 to −88 %), but less so by those with large C input (solid fraction) or with lignin-rich C input (sawdust + inorganic N fertilizer). Physical and chemical soil properties related to water infiltration and soil organic matter (SOM) decomposition were marginally influenced by fertilizers. The measured changes in soil pH, P availability and (micro)biology may affect SOM dynamics in the longer term. Grass dry matter yield was similarly increased by all fertilizers (+7 to 11 %) whereas grass N yield was increased by fertilizers only when the applied N was in mineral form (+16 to 20 %). From our results, we propose that the moderate use of organic fertilizers with a high and non-humified organic matter content such as solid fraction of cattle slurry can be part of a regeneration strategy in peat grasslands with biodiversity goals.

Primary Factors Affecting Soil Bioavailable Cadmium and Asenic by Different Properties of Silicon Fertilizer

To clarify the primary factors affecting soil bioavailable cadmium (Cd) and arsenic (As) by silicon fertilizer, we chose different properties of silicon fertilizer, including three types of alkaline silicon fertilizer[Na2SiO3, CaSiO3, and ASSF (pH 9-11)] and one weak acid neutral soluble silicon fertilizer (NSSF, pH 5-6), to carry out a pot experiment by adding different amounts of Si fertilizer (25-800 mg·kg-1, calculated as Si). After 21 days of flooding, soil basic physical and chemical properties, along with diffusive gradients in thin film Cd and As (DGT-Cd and DGT-As) were investigated. The results showed that the application of Si fertilizer with different properties had different significant effects on the basic physical and chemical properties of soil. Specifically, the three types of alkaline silicon fertilizer significantly increased the soil pH (P<0.05), among which Na2SiO3 exhibited the strongest ability; however, the application of NSSF remarkably reduced soil pH (P<0.05), and per unit (mg) Si application of NSSF could reduce soil pH by 0.0017 units. Furthermore, with each fertilizer application rate that reached 400 mg·kg-1 (calculated as Si), the changes in soil pH and Eh tended to be gentle. The ability of the four types of silicon fertilizer to improve soil available silicon ranked as NSSF>Na2SiO3>ASSF>CaSiO3. Additionally, the application of the three types of alkaline silicon fertilizer apparently decreased soil DGT-Cd while increasing soil DGT-As (P<0.05). When the addition rate of CaSiO3 was up to 100 mg·kg-1(calculated as Si), soil DGT-Cd concentration could be significantly decreased by approximately 50.89% without causing a significant increase in soil DGT-As concentration. Conversely, when the NSSF application rate was up to 400 mg·kg-1 (calculated as Si), the soil DGT-As basically reached its steady-state, and the DGT-As reduction rate reached 85.87%. Strikingly, the correlation analysis of the influencing factors of soil DGT-Cd and DGT-As showed that soil pH was the main factor affecting soil bioavailable Cd and As (DGT-Cd and DGT-As), and the effect of soil available Si and P on soil Cd and As bioavailability was negligible. Consequently, soil DGT-Cd and soil DGT-As could reach a minimum when soil pH was adjusted to 6.5-7.0 or 5-5.5 by alkaline silicon fertilizer or NSSF, respectively. It is undoubtedly of great significance, to clarify the primary factors that influence soil bioavailable Cd and As to ensure food security production.

Stability of solid form Cr(VI) after being loaded onto hydrochar under different soil pH conditions

Heavy metal ions such as Cr(VI) leaching from agricultural soil is one of the significant environmental pollution threats. Hydrochar from hydrothermal co‑carbonization (HtcoC) of digested sewage sludge (DSS) and rice straw (RS) shows excellent adsorption potential of Cr(VI). Still, its stability at soil pH change is not well understood. This study examined solid form Cr(VI) stability at soil pH 3.5 and 8.0 (i.e., the average arable land soil pH range) in soil, hydrochar (HtcoC1:1) and soil + HtcoC1:1 mixture systems. Results indicate that HtcoC1:1 and soil + HtcoC1:1 mixture systems exhibited 100 % Cr(VI) adsorption at pH 3.5 while with comparative decline at pH 8.0. Moreover, Cr fractionation reflected the increased environmental risk in the HtcoC1:1 system at pH 8.0, suggesting its relatively high Cr leaching risk. This work implies that soil application of hydrochar produced from HtcoC of DSS and RS is relatively safe as most of the loaded Cr(VI) is stable within soil pH 3.5–8.0.

Perbandingan Konsentrasi Detergen Akibat Pandemi COVID-19 dan Kebiasaan Baru (New Normal) Pada Kualitas Air Permukaan Kota Palangka Raya

Currently, the Indonesian nation is facing challenges that require human resources adapt to the COVID-19 pandemic situation. Has the discovery of a vaccine and the implementation of ongoing vaccination does not guarantee avoid the spread of COVID-19. Thus, the obligation to implement the protocol health continues. One of the health protocol policies is provide adequate hand washing facilities for the management public facilities. The behavior of washing hands with soap is part of the program Clean and Healthy Life Behavior (PHBS) in the household. Washing hands Using soap is an effective step to break the chain of transmission COVID-19. However, please note that hand soap contains detergent. The results of using detergent (hand soap) will produce residue in the form of liquid waste, which is then discharged into the environment directly cause the balance of nature to be disturbed, namely soil pollution which causes capable of changing soil pH, changing mineral content and nutrient disturbances from soil for plant life and polluted groundwater sources. On research In this case, identifying and analyzing the waste from washing hands with soap in public facilities can affect the environment and the amount of content detergents that dissolve in water and whether nature can neutralize water pollution that occurred before and after the COVID-19 pandemic.

Soil health responses of circular grass buffer strips in center‐pivot irrigated agriculture

AbstractDecline in water table in the Ogallala Aquifer, along with soil degradation, has threatened the sustainability of agriculture in the US High Plains region. Circular grass buffers in center pivot irrigated cropping systems could support sustainable crop production by providing multiple ecosystem services. This study evaluated soil organic matter (SOM), nutrients, and other selected soil health indicators under circular buffer strip grasses (BSG), adjacent buffer strip corn (Zea mays L.) (BSC), and continuous conventional corn (CCC) in the 0–80 cm soil profile. Soil samples were collected from the center of corn and grass strips for 5 years (2017–2021) and analyzed for nitrate N (NO3−‐N), soil pH, electrical conductivity, cation exchange capacity, SOM, and soil nutrients. The NO3−‐N under CCC in 0–20 cm (18.4 mg kg−1) and 60–80 cm (4.97 mg kg−1) were 1.56 and 1.96 times higher than BSC. The NO3−‐N was significantly lower under BSG than other treatments in 0–20 cm, 20–40, and 40–60 cm depths. The SOM was similar among all treatments. Response of other nutrients varied among treatments and inter‐annually. Soil pH in 0–20 cm depth was 0.1 and 0.3 units lower in CCC (pH = 7.7) than in BSC and BSG. Soil electrical conductivity was 37.5% and 25% greater in CCC than BSG (0.24 and 0.24 dS m−1) in 0–20 and 20–40 cm depths, respectively. Grass buffer strips maintaining SOM despite no irrigation, less residual N under corn with grass buffer, and less rapid changes in soil pH suggest the potential of grass buffer to maintain soil health in semi‐arid cropping systems facing the transition to dryland.

Seven years phosphorus addition has no effect on soil acidity in two tropical plantations

Strong acidity accompanied by low phosphorus (P) availability occurs in tropical soils especially under high nitrogen (N) deposition. Commonly, improved P availability can mitigate soil acidity in tropical natural forests via direct reaction with acidic cations or impacting plant uptake and soil microbial community to indirectly regulate soil cations. However, whether P input can alleviate soil acidity in tropical plantations remains unknown. This study selected two tropical typical plantations (dominated by Acacia auriculiformis and Eucalyptus urophylla, respectively), to investigate the effects of seven years of P addition on soil acidity and the underlying mechanisms. The results showed that P addition did not change soil pH or cation concentrations, suggesting no variations in soil acidity under P addition. Moreover, P addition did not affect acidic cation concentrations within plant tissues, soil microbial community, litterfall input, and fine-root biomass, indicating that P addition did not impact the processes of plant and soil microbes to regulate the dynamics of soil cations to alleviate acidity. However, we found significant increases in soil available P, soil total P, and plant P concentrations, indicating that added P led to P enrichment in soil and plants. In addition, a consistent response of soil acidity in two tropical plantation ecosystems was observed under combined N with P addition. Our findings improve the understanding of the relationships between P availability and soil acidification in tropical forests and highlight the necessity to accurately evaluate the role of P in acidic tropical forest soils.

Field verification of low-level biochar applications as effective ameliorants to mitigate cadmium accumulation into Brassica campestris L from polluted soils

Introduction: Cadmium (Cd) has been recognized as a significant contributor to the pollution of farmland soils in China, and biochars have been reported to be effective in mitigating soil Cd pollution. However, most studies have been conducted in laboratory or greenhouse settings, not at a field scale, and the biochars used have been applied at unrealistically high amounts (&amp;gt;10 t/ha).Methods: In this research, three biochars: rice straw biochar (RSB), pig manure biochar (PMB) and rice husk biochar (RHB) were produced from readily available farm residues. Then the effects at low-level application (1.8 and 3.6 t/ha) on Cd were investigated in a field experiment cropped with rape (Brassica campestris L.).Results: Batch adsorption experiments indicated Cd adsorption capacity of three biochars followed the order of RSB (43.5 mg/g) &amp;gt; PMB (33.3 mg/g) &amp;gt; RHB (24.4 mg/g). Field experiment indicated biochar amendments could slightly change soil pH and cation exchange capacity (CEC); yet led to considerable and significant decreases in extractable Cd concentrations [reductions of: 43%–51% (PMB), 29%–35% (RSB) and 17%–19% (RHB)]. Reduced extractable Cd correlated with lower Cd concentrations in rape plants. PMB and RSB were more effective in decreasing Cd phytoaccumulation into edible parts of rape (&amp;gt;68% reduction) than RHB.Discussion: Low-level application of PMB or RSB could efficiently decrease the phytoaccumulation of Cd from soils into crops. These results demonstrate the reality of biochar-based remediation solutions to contribute to the mitigation of diffuse Cd contamination in farmland. The results also highlight the need to trail biochars in the presence of the soil to be targeted for remediation.

Changes in micronutrient concentrations under minimum tillage and cotton-based crop rotations in irrigated Vertisols

Australian irrigated cotton (Gossypium hirsutum L.) yields are among the highest in the world but may deplete soil nutrient reserves faster than in dryland systems. Little is known about changes in long-term micronutrient (Cu, Fe, Mn, Zn) concentrations in these systems. This study investigated changes in soil micronutrient concentrations over time in two long-term tillage and crop rotation experiments under furrow-irrigated cotton systems and a no-till dryland cropping enterprise. The tillage practices that were investigated were maximum (disc to 0.2 m, chisel ploughing to 0.3 m followed by the construction of beds in 1 m spacings) and minimum (mulching cotton residues, followed by root cutting, incorporation of cotton stalks and bed renovation with a disc-hiller) tillage. Soil samples were analysed for diethylenetriamine penta-acetic acid (DTPA) extractable micronutrients, x-ray fluorescence (XRF) total micronutrients, pH, and soil organic carbon (SOC). Both maximum and minimum tillage influenced topsoil distribution of DTPA-extractable Cu, Zn and Mn, with the greatest changes occurring in Mn concentration. Concentrations of Mn in the topsoil (0–0.15 m) during 2015 were higher than those in the subsoil (0.15–0.6 m) by 74 % with maximum tillage and 159 % with minimum tillage, suggesting greater stratification with the latter (28 mg kg−1 in topsoil vs 11 mg kg−1 in subsoil). Including wheat (Triticum aestivum L.) and maize (Zea mays L.) in cotton rotations increased DTPA-extractable Mn concentration. DTPA-extractable Mn was positively correlated with SOC in two experiments (P < 0.01) and DTPA Fe and pH were negatively correlated (P < 0.01). DTPA Zn concentrations under minimum-till cotton systems were stable over 18 years. DTPA Zn concentrations measured at 0.02 m increments suggested that soil below the fertiliser band depth (< 0.04 m) was potentially responsive to Zn application. Sampling in smaller depth increments in the topsoil (0.02 m increments in 0–0.1 m depth) more accurately identified micronutrient stratification and may improve management decisions when sowing. Our results indicated that managing soil pH and SOC in alkaline Vertisols under irrigated cotton systems was a more practical approach to address micronutrient availability than soil application of micronutrients. Future research should consider the implications of current agronomic practices in cotton production, such as the method and timing of nitrogen application as it influences changes in soil pH, which may impact micronutrient availability at critical crop growth stages.

Differential responses and mechanistic controls of soil phosphorus transformation in Eucalyptus plantations with N fertilization and introduced N2 -fixing tree species.

Introducing N2 -fixing tree species into Eucalyptus plantations could replace nitrogen (N) fertilization to maintain high levels of N consumption and productivity. However, N enrichment may exacerbate phosphorus (P) limitation as Eucalyptus robusta Smith is extensively planted in P-poor tropical and subtropical soils. We conducted a field experiment in a pure plantation of Eucalyptus urophylla × grandis to investigate the impacts of N fertilization and introduced an N2 -fixing tree of Dalbergia odorifera T. Chen on soil P transformation. Nitrogen fertilization significantly enhanced soil occluded P pool and reduced the other P pools due to acidification-induced pH-sensitive geochemical processes, lowering Eucalyptus leaf P concentration with higher N:P ratio. By contrast, introduced N2 -fixing tree species did not change soil pH, labile inorganic P pool, and Eucalyptus leaf N:P ratio, even enhanced organic P pools and reduced occluded P pool probably due to altering microbial community composition particularly stimulating arbuscular mycorrhiza fungal abundance. Our results revealed differential responses and mechanistic controls of soil P transformation in Eucalyptus plantations with N fertilization and introduced N2 -fixing tree species. The dissolution of occluded P pool along with organic P accumulation observed in the mixed plantations may represent a promising future to better manage soil P availability.

Fungal diversity and community composition responses to the reintroduction of fire in a non-managed Mediterranean shrubland ecosystem

BackgroundMore than a decade of fire suppression has changed the structure of fire-adapted shrubland ecosystems in Spain's National Parks, which are now at extreme risk of uncontrolled wildfires. Prescribed burning can mitigate the risk of wildfires by reducing the fuel load but prescribed burning may also alter the soil properties and reduce microbial and fungal activity, causing changes in the availability of nutrients deep in the soil layer. Although fungal communities are a vital part of post-fire restoration, some fire effects remain unclear. To examine the short-term effects of prescribed burning on soil fungal communities in Doñana Biological Reserve (SW Spain), we collected soil samples pre-burn and 1 day, 6 and 12 months post-burn from burned plots to perform physicochemical and metabarcode DNA analyses. ResultsPrescribed burning had no significant effect on the total fungal operational taxonomic unit richness and abundance. However, changes in soil pH, nitrogen and potassium content post-burn affected fungal community composition. Small non-significant changes in pH and phosphorous affected the composition of ectomycorrhizal fungi. ConclusionsThe ectomycorrhizal fungal community appears to be resilient to the effects of low-to moderate-intensity fires and saprotrophic taxa may benefit from this kind of fire. This finding revealed that prescribed burning is a potentially valuable management tool for reducing fire hazards in shrublands that has little effect on the total richness and abundance of fungal communities.

Differential soil acidification caused by parent materials and land‐use changes in the Pearl River Delta region

AbstractSoil acidification occurs widely across the world, which has been partly attributed to land‐use change. However, measureable effect of land‐use change as well as parent materials on soil acidification remains poorly understood. Here, a typical area with intensive land‐use change in the Pearl River Delta of China was chosen for this study. Topsoil (0–20 cm) and subsoil (20–40 cm) samples (n = 169) under different land uses (paddy fields, vegetable lands and orchards) and parent materials (granite and alluvial sediment) were collected in 2020. Soil pH, exchangeable base cations, exchangeable acidity and pH buffering capacity were measured to evaluate the status of soil acidification. The change of soil pH over the last 15 years was evaluated via comparing with historical data (n = 329) in 2005. The results showed a higher exchangeable acidity and lower pH buffering capacity and exchangeable base cations of soils derived from granite compared with soils derived from alluvial sediment in 2020. In the last 15 years, significant soil acidification under different parent materials was observed under vegetable lands and orchards but not paddy fields. Faster pH decline was found under land‐use change from paddy fields compared with the unchanged vegetable lands or orchards. Furthermore, stronger acidification under the same land‐use change was observed for soils derived from granite compared with soils derived from alluvial sediment. These results indicate that land‐use change induced soil acidification is dependent on parent materials. This study implies that cropping management such as suitable rotation operation may slow soil acidification, and measures including straw returning may ameliorate acidified soils.

Constraints on the spatial variations of soil carbon fractions in a mangrove forest in Southeast China

Mangroves, carbon-rich ecosystems, store significant amounts of carbon in the soil to mitigate climate change. For better mangrove carbon management, the spatial distributions and driving factors of distinct soil carbon fractions, notably soil inorganic carbon (IC) and labile carbon, require clarification. Here, we quantified variations in the soil carbon fractions (total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC), permanganate-oxidizable carbon (POC), and IC) with landward distance and soil depth, and identified the means by which edaphic and biotic factors affect soil carbon fractions in a mangrove forest in Southeast China. Average TOC, IC, POC, DOC, and MBC densities were 15.22 kg/m3, 1.39 kg/m3, 4.23 kg/m3, 43.49 g/m3, and 63.25 g/m3, respectively. Soil total nitrogen was the most important factor affecting TOC, POC, and MBC. Soil IC was found to be controlled by pH, and plant biomass was the main factor explaining soil DOC variation. Except for MBC, landward distance was negatively correlated with organic carbon fractions and positively correlated with IC via soil nutrients, pH, bulk density, and plant biomass. Soil depth directly or indirectly altered soil carbon fractions via soil nutrients, pH, clay, and salinity, resulting in negative relationships with TOC, POC, and MBC and a positive relationship with IC. Collectively, our results indicate that future changes in soil total nitrogen content and pH are likely to impact carbon storage in mangroves, and that the conservation of landward mangroves is important with respect to their high labile carbon contents.

Physico-Chemical Properties of Wetland Soils Affected by Crude Oil Spillage in Niger Delta Area, Nigeria

Loss of soil fertility through loss of soil organic matter, leaching of nutrients, loss of the nutrient-laden topsoil, changes in soil-pH, reduction in cation exchange capacity, salinization, water logging and other forms of soil degradation are major problems associated with agricultural productivity in the oil producing areas of Nigeria. This analysis investigated some selected physico-chemical properties of wetland soils affected by crude oil spillage in Bodo city in the Niger Delta region of Nigeria. Field reconnaissance survey using a handheld Geographic Positioning system (GPS) and survey technique involving random sampling, was used in siting soil profile pits. The unpolluted samples were collected 50 meters away from the polluted site but in the same geographic region and was used as control site. Soil samples were collected based on degree of horizon differentiation and analyzed using routine and special analytical techniques. Soil data were subjected to analysis of variance using Genstat program. Result shows that soil physical properties of the polluted site: moisture content, soil bulk density, and soil texture were highly significant (p=0.01 and 0.05) when compared to the unpolluted site while some chemical soil properties analysed especially soil pH, organic matter, carbon-nitrogen ratio, available phosphorus were affected by crude oil spillage. Results from this study affirm that crude oil can have detrimental effect on soil physico-chemical properties, which implies low soil fertility and thereby affect crop production and increase food insecurity within the study site. Further studies involving more edaphic properties, biotoxic metals and their bioaccessibility in crops growing on waterside affected by crude oil spill will surely enhance knowledge and management of the these highly industrially influenced soils. Also, international and national oil and gas companies should carry out their activities with international best practice.

Lead dissociation and redistribution properties of actual contaminated farmland soil after long-term EKAPR treatment.

Electrokinetic-assisted phytoremediation (EKAPR) is a potential technology much affected by the metal species and accessibility to plant roots. In this study, Pb-contaminated red soil was remediated with Sedum plumbizincicola to investigate the changes in soil pH, available nutrients, dissociation and redistribution of Pb under a long-term periodic reversal direct-current electric field. This approach could effectively activate soil P, K, organic matter (OM)and Pb, without significant soil acidification; the effect was positively correlated with applied voltage. Soil Pb can be continuously dissociated, migrated, and tended to accumulate in the middle region. The maximum Pb removal rate in the anodic section of the EKAPR system was 21.4%, and the aggregation rate in middle regions was 14.4%, higher than the available Pb content of the original soil. The Pb desorption in aqueous solution increased significantly with increasing voltage, irrespective of the solution pH. At a voltage of 20V, the Pb cumulative desorption content reached 91.1mgkg-1 (pH = 7), which was 2.7 times than that without electric field (33.2mgkg-1). Compared to original soil (2.80mgkg-1) and the control (14.54mgkg-1), the available Pb in the anode section of EKAPR system (20.66mgkg-1) increased by 637.9% and 42.1%, respectively. These results indicated that except for the indirect influence of soil pH changes, electrodynamics can directly promote the bioavailability and dissociation of Pb at the soil-water interface. This finding provides a new perspective for further studies on the mechanism of Pb speciation evolution and accumulation changes using EKAPR.

Effects of Biochar and Banana Peel Application on Ulam Raja (Cosmos caudatus) Growth

Excessive consumption of chemical fertilizers in recent years have increased throughout the world, causing serious environmental problems. This research can minimize the usage of chemical fertilizers and reduce the waste management. Hence, the aim of this study is to determine the effects of biochar and banana peel application on growth performance of Cosmos caudatus. The plants were treated by 100 g biochar, 100 g banana peel, the mixture of 50 g biochar and 50 g banana peel and control with five replications as treatments. The research was conducted by using Randomized Complete Block Design (RCBD). The data was analysed by using Analysis of Variance (ANOVA), Statistical Package for the Social Sciences (SPSS) and the differences between treatments mean were compared using Tukey test with significant level (P≤0.05). The growth parameters measured were shoot length, root length, soil pH and number of leaves. The results suggested that the shoot length and number of leaves for all the treatments were significantly higher compared to the control. All the treatments also showed a significantly higher root length compared to the control except 100 g banana peel treatment. There were no significant changes in soil pH for all the treatments. Hence, the study showed that biochar and banana peel gave significant effects on Cosmos caudatus growth.

Investigation of Factors Influencing on Ammonia Emission from Soils in Agricultural Land

Objectives : Major factors affecting ammonia emission from the soil and strategies to reduce ammonia emission were investigated through literature surveys.Methods : An academic search was conducted using keywords such as agriculture, ammonia, and fine dust, and the effects of soil characteristics on ammonia emission were summarized for each factor.Results and Discussion : Emissions of ammonia into the atmosphere can reduce economic returns for a farmer and negatively impact the atmospheric environment by acting as a precursor to PM2.5 formations. It is reported that agriculture accounts for 78% of the total ammonia emission sources in Korea. Ammonia emission from the soil is affected by the type of ammonia fertilizer, soil moisture, pH, temperature, cation exchange capacity, organic matter, and soil texture. An increase in soil moisture increases ammonia emissions. As soil pH increases, ammonia emissions increase, noticeably above 7.5. An increase in soil temperature increases the rate of hydrolysis of urea and the rate of conversion to ammonia gas, resulting in increased ammonia emissions. Soils with high cation exchange capacity adsorb ammonium to reduce ammonia emissions. Soils with a high clay content and soil organic matter content are more buffered to changes in soil pH, reducing ammonia emissions.Conclusion : Based on understanding the mechanisms and causes of ammonia emission from the soil, it is possible to establish soil and environmental management to reduce ammonia emissions into the atmosphere.