Improve Soil Physicochemical Properties Research Articles

Garlic stalk waste and arbuscular mycorrhizae mitigate challenges in continuously monocropping eggplant obstacles by modulating physiochemical properties and fungal community structure.

Continuous vegetable production under plastic tunnels faces challenges like soil degradation, increased soil-borne pathogens, and diminished eggplant yield. These factors collectively threaten the long-term sustainability of food security by diminishing the productivity and resilience of agricultural soils. This research examined the use of raw garlic stalk (RGS) waste and arbuscular mycorrhizal fungi (AMF) as a sustainable solution for these issues in eggplant monoculture. We hypothesized that the combined application of RGS waste and AMF would improve soil physicochemical properties compared to untreated soil in eggplant monoculture. The combined use of RGS and AMF was expected to suppress soil-borne pathogens, increase the abundance of soil beneficial microorganisms and alter fungal community structure. The combined application of RGS and AMF will significantly enhance eggplant yield compared to untreated plots. This study aimed to determine whether AMF and RGS, individually or in combination, can ameliorate the adverse effects of monoculture on eggplant soil. We also investigated whether these treatments could enhance eggplant yield. The experiment was arranged in a completely randomized design with four treatments: AMF, RGS, and a combined treatment of AMF + RGS (ARGS), along with a control. Each treatment was replicated three times, Eggplant seedlings inoculated with AMF and treated with RGS amendments, both individually and combined. The effects on root traits, soil physicochemical properties, soil enzyme activity, and fungal community structure were investigated. RGS amendments and AMF inoculation improved root length, volume, and mycorrhizal colonization. The combined treatment showed the most significant improvement. RGS and AMF application increased soil nutrient availability (N, P, K) and organic matter content. Enzyme activities also increased with RGS and AMF treatments, with the combined application showing the highest activity. Soil electrical conductivity (EC) increased, while soil pH decreased with RGS and AMF amendments. Sequencing revealed a shift in the fungal community structure. Ascomycota abundance decreased, while Basidiomycota abundance increased with RGS and AMF application. The combined treatment reduced the abundance of pathogenic genera (Fusarium) and enriched beneficial taxa (Chaetomium, Coprinellus, Aspergillus). Pearson correlations supported the hypothesis that soil physicochemical properties influence fungal community composition. This study demonstrates the potential of co-applying RGS and AMF in continuous cropping systems. It enhances soil physicochemical properties, reduces soil-borne pathogens, and promotes beneficial microbial communities and eggplant yield. This combined approach offers a sustainable strategy to address the challenges associated with eggplant monoculture under plastic tunnels.

Effect of mixed planting on soil nutrient availability and microbial diversity in the rhizosphere of Parashorea chinensis plantations.

Parashorea chinensis Wang Hsie (Pc) is an endangered tree species endemic to tropical and subtropical China. However, the acidic red soil areas where it is distributed generally face nutrient limitation. The study of the effects of mixed planting on soil biogeochemical processes contributes to the sustainable management and conservation of Pc. We selected pure and mixed stands of Pc and collected its rhizosphere and bulk soil samples to clarify the effect of mixed planting on the soil microbial community and the nutrient status. The results showed that (1) All stands were strongly acidic phosphorus-deficient soils (pH < 4.0, available phosphorus <10.0 mg·kg-1). There was a significant rhizosphere aggregation effect for soil organic C, total and available N and K, microbial biomass, and inorganic P fraction. (2) The mixed planting significantly increased the soil water content, organic C, available nutrients, the activities of β-1,4-glucosidase and urease, and microbial biomass. The inorganic P fractions are more influenced by rhizosphere, while organic P fractions are more influenced by tree species composition. (3) Fungi and their ecological functions are more susceptible to tree species than bacteria are, and have higher community compositional complexity and α-diversity in mixed plantations. And mixed planting can improve network complexity among key microorganisms. (4) The correlation between soil microorganisms and environmental factors was significantly higher in mixed forests than in pure forests. Soil organic C, available N and P, microbial biomass C and N, β-1,4-glucosidase, and stable P fractions were the key environmental factors driving changes in fungal and bacterial communities. In conclusion, the mixed planting patterns are more advantageous than pure plantations in improving soil physicochemical properties, enhancing nutrient effectiveness, and promoting microbial activities and diversity, especially Pc mixed with Eucalyptus grandis × E. urophylla is more conducive to soil improvement and sustainable management, which provides practical references for relocation protection of endangered tree species and species selection and soil fertility management in mixed planting. In addition, the study highlighted the key role of rhizosphere microenvironment in soil nutrient cycling and microbial community structure, which provides new perspectives for a deeper understanding of soil-microbe-plant interaction mechanisms.

Effects of aged biochar additions at different addition ratios on soil greenhouse gas emissions

Biochar addition is effective in reducing soil greenhouse gas (GHG) emissions, but it's essential to evaluate whether aged biochar retains this capability as its properties change over time. However, research comparing the effects of fresh and aged biochar on soil GHG emissions is limited. Moreover, exploring the priming effect of biochar on native soil organic carbon (SOC) mineralization is crucial for revealing the effect mechanism on soil CO2 emission. However, research investigating the priming effects of aged biochar is limited. In this study, the effects of aged biochar addition on soil physicochemical properties, GHG emissions, and global warming potential (GWP) were examined through an incubation experiment with three treatments: (1) soil only (CK), (2) 1 % aged maize straw biochar addition (HBC1) and (3) 4 % aged maize straw biochar addition (HBC4), and then their effects were compared with those of fresh biochar from our previous research. 13C tracer technology was used to assess the priming effect of aged biochar on native SOC mineralization. Results showed that aged biochar improved soil physicochemical properties. Compared to CK, HBC1 and HBC4 reduced CO2 emissions by 28.02 % and 20.15 %, respectively, and reduced N2O emissions by 61.54 % and 66.39 %. HBC4 significantly increased CH4 emission, whereas HBC1 reduced it. HBC1 and HBC4 reduced GWP by 29.01 % and 21.41 %, respectively. Overall, aged biochar demonstrated a greater reduction effect compared to fresh biochar at the 1 % addition ratio. The CO2 reduction is attributed to the negative priming effect of aged biochar on native SOC mineralization. The reduction in N2O emissions is attributed to aged biochar promoting microbial nitrogen fixation and reducing the ratio of denitrification to nitrification. The variation in CH4 emissions reflects differing dominant factors influencing CH4 emission across varying addition ratios. In conclusion, 1 % aged biochar addition demonstrates a more favorable long-term effect on mitigating GHG emissions.

Remediation of multi-metal(loid) contaminated soils using Mn-modified biochar: Mechanistic insights and influencing factors

Mn-modified biochar could impact soil quality and metal(loid) migration in contaminated soils. However, the remediation efficiency, mechanism, and influencing factors of Mn-modified biochar on multi-metal(loid) contaminated soils were largely unknown. In this study, three Mn-modified biochar were prepared by using MnCl2-impregnated rubber, tobacco rod, and coconut shell biochar, respectively. The remediation efficiency of Mn-modified biochar on Pb, As, Cd, Cu, and Zn contaminated soil was also compared. Our data revealed that the addition of Mn-modified biochar increased the effective cation exchange capacity (ECEC), organic matter (OM), alkaline hydrolyzed nitrogen (AHN), and the mobility of the nutrient Zn in the soil. Furthermore, Mn-modified rubber biochar and Mn-modified coconut shell biochar reduced acid extractable or Diethylenetriamine Pentaacetic Acid (DTPA) leached Pb, As, Cd, and Cu However, Mn-modified tobacco rod biochar increased the acid extractable or DTPA leached Pb, Cd, and Cu. The study showed that three Mn-modified biochars could effectively improve soil physicochemical properties and significantly increase soil nutrient activity. Mn-modified rubber and coconut shell biochar can effectively immobilize metal(loid)s and reduce their damage to soil. However, the Mn-modified tobacco rod biochar instead increased the mobility of metal(loid)s. The results indicate that feedstock is an important factor influencing the application of Mn-modified biochar and should be considered in the production.

Biochar and wood vinegar altered the composition of inorganic phosphorus bacteria community in saline-alkali soils and promoted the bioavailability of phosphorus

As an important part of the ecosystem, saline-alkali soils are in urgent need of efficient and environmentally friendly soil conditioners. Biochar and wood vinegar are regarded as organic soil improvement and plant growth regulators to improve soil physicochemical properties and promote crop growth. However, the mechanism of how inorganic phosphorus bacteria increase phosphorus when biochar and wood vinegar applied to saline-alkali soils is not clear. Herein, the present study was designed to investigate the effects of biochar and wood vinegar with different rates on physicochemical properties of saline-alkali soils and inorganic phosphorus bacteria diversities and to discuss the mechanism of biochar and wood vinegar on available phosphorus by pot experiments. The application of biochar and wood vinegar exhibited an effect on the decrease in pH and salt contents and the increase in soil porosity, soil nutrients, and hundred-grain weight of rice. The 600 kg ha−1 biochar and 1800 kg ha−1 wood vinegar group showed the most significant increment in available phosphorus, alkaline phosphatase, acid phosphatase, and neutral phosphatase activities, with the increases of 49.24%, 40.35%, 48%, and 149%, respectively. The 600 kg ha−1 biochar and 1200 kg ha−1 wood vinegar group significantly enhanced microbial biomass phosphorus concentrations by 41.29%. Moreover, biochar and wood vinegar shifted inorganic phosphorus bacteria composition structure and promoted its diversities, more so at a higher rate of wood vinegar application. The dominant species of inorganic phosphorus bacteria were Proteobacteria, Gammaproteobacteria, Alphaproteobacteria, Pseudomonas, and Rhizobium in saline-alkali soils. The Alphaproteobacteria and Hydrogenophaga were the key microorganisms reducing pH and salt contents and increasing available phosphorus contents in saline-alkali soils. In conclusion, the application of biochar and wood vinegar was a useful strategy to improve saline-alkali soils.

Ameliorative effect of poly-γ-glutamic acid biopreparation on coastal saline soil

To investigate the effect of poly-γ-glutamic acid (γ-PGA) biopreparation on ameliorating coastal saline soil, three treatments were established: soil salt washed treatment (CK), soil salt washed with added γ-PGA (PGA), soil salt washed with added γ-PGA biopreparation (PGAB). This study determined the effects of γ-PGA on coastal saline soil by analyzing soil aggregate, soil evaporation, soil vertical water and salt distribution, and soil cation content, soil pH, soil nutrient content and soil microorganism quantity. Results showed that γ-PGA had an ameliorative effect on saline soil, with the PGAB treatment exhibiting the most pronounced ameliorative effect compared to CK. Adding PGAB reduced soil evaporation by 30.45 %, soil salt content by 27.91 %, meanwhile increasing plant height by 33.86 %, plant fresh weight by 98.54 %, soil aggregate diameter by 6.68 times, soil water content by 26.47 % (P < 0.05). Additionally, soil total nitrogen was increased by 50.0 % in PGAB treatment, and available nitrogen and phosphorus contents were increased by 1.68 times and 85.83 % (P < 0.05), respectively. Populations of soil-culturable bacteria and fungi of PGAB treatment increased by 65.96 % and 1.23 times, respectively (P < 0.05). After salt-washing process, adding PGAB improved soil physicochemical properties, which altered the ecological environment of rhizosphere soil and promoted plant growth. The results can provide a practical approach for ameliorating coastal saline soils.

Enhanced Soil Fertility and Carbon Sequestration in Urban Green Spaces through the Application of Fe-Modified Biochar Combined with Plant Growth-Promoting Bacteria.

The soil of urban green spaces is severely degraded due to human activities during urbanization, and it is crucial to investigate effective measures that can restore the ecological functions of the soil. This study investigated the effects of plant growth promoting bacteria (Bacillus clausii) and Fe-modified biochar on soil fertility increases and mechanisms of carbon sequestration. Additionally, the effects on C-cycling-related enzyme activity and the bacterial community were also explored. Six treatments included no biochar or Bacillus clausii suspension added (CK), only Bacillus clausii suspension (BC), only biochar (B), only Fe-modified biochar (FeB), biochar combined with Bacillus clausii (BBC), and Fe-modified biochar combined with Bacillus clausii (FeBBC). Compared with other treatments, the FeBBC treatment significantly decreased soil pH, alleviated soil alkalization, and increased the alkali-hydro nitrogen content in the soil. Compared to the individual application of FeB and BC, the FeBBC treatment significantly improved aggregates' stability and positively improved soil fertility and ecological function. Additionally, compared to the individual application of FeB and BC, the soil organic carbon (SOC), particulate organic carbon (POC), and soil inorganic carbon (SIC) contents for the FeBBC-treated soil increased by 28.46~113.52%, 66.99~434.72%, and 7.34~10.04%, respectively. In the FeBBC treatment, FeB can improve soil physicochemical properties and provide bacterial attachment sites, increase the abundance and diversity of bacterial communities, and promote the uniform distribution of carbon-related bacteria in the soil. Compared to a single ecological restoration method, FeBBC treatment can improve soil fertility and carbon sequestration, providing important reference values for urban green space soil ecological restoration.

Impacts of climate-smart soil and water conservation practices and slope gradient on selected soil chemical properties in Eastern Ethiopia: A case study of the Kulkullessa Sub-watershed, Goro Gutu District

The productivity and sustainability of agricultural systems are heavily influenced by soil fertility and physicochemical properties. This study investigated the effects of climate-smart soil and water conservation (SWC) practices and slope gradient on selected soil physicochemical properties and soil organic carbon stock (SOCS) in the Kulkullessa Sub-Watershed of Goro Gutu District, Eastern Ethiopia. The research focused on farmland conserved by stone bunds (SB), bench terraces (BT), and grass strips (GS) five years post-implementation, across two slope gradients (15-20% and 21-30%). Twenty-four composite soil samples were collected from a depth of 0-20 cm and analyzed at the Haramaya University soil laboratory. Results demonstrated that climate-smart SWC practices significantly improved soil physicochemical properties and SOCS in the study area. Slope gradients also induced considerable variations in these parameters. Conserved farmland and areas with lower slope gradients exhibited higher clay content and lower sand fractions. Bench terraces were associated with lower bulk density (BD) and significantly higher total porosity (p ≤ 0.05). Conserved farmlands showed higher electrical conductivity (EC) and lower pH values, both statistically significant (p ≤ 0.05). Stone bunds were most effective in increasing soil organic matter (SOM) content and total nitrogen (TN). Climate-smart SWC practices also enhanced exchangeable bases in the farmlands. Cation exchange capacity (CEC) was significantly improved (p ≤ 0.05) on farmland conserved by SB and BT. In conclusion, climate-smart SWC practices demonstrated substantial potential for improving agriculturally and environmentally relevant soil physicochemical properties and organic carbon stocks. These findings underscore the importance of such conservation measures in enhancing soil quality and promoting sustainable agriculture in the region.

Straw Retention with Reduced Fertilization Enhances Soil Properties, Crop Yields, and Emergy Sustainability of Wheat-Soybean Rotation.

Cereal + legume rotation is an integrated system that facilitates soil fertility and sustainable agricultural production. However, research on the management compatibility affecting soil physico-chemical properties yields overall agro-ecosystem sustainability, but profitability is lacking, especially under straw retention and potential reductions in fertilizer application. An 11-year field experiment investigated three treatments: no straw retention + traditional mineral fertilization (TNS), straw retention + traditional mineral fertilization (TS), and straw retention + reduced mineral fertilization (DS). Compared with TNS, TS significantly improved soil physico-chemical properties, including macro-aggregates (R > 0.25 mm), porosity, field water capacity (FWC), soil organic carbon (SOC) storage, total nitrogen storage, microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) by 17.3%, 3.2%, 13.0%, 5.5%, 3.2%, 15.5%, and 13.8%, respectively. TS also significantly increased total (wheat + soybean) yields (TYs), economic profits, and emergy sustainability index (ESI) by 15.8%, 25.0%, 3.7 times that of TNS, respectively. Surprisingly, compared with TS, DS further significantly improved R > 0.25 mm, porosity, FWC, SOC storage, MBC, MBN, TY, economic profits, and ESI by 11.4%, 1.5%, 6.1%, 3.0%, 10.6%, 7.2%, 5.7%, 11.1%, and 36.5%, respectively. Overall, retaining straw with reduced fertilization enhances soil properties, yields, and emergy sustainability in wheat-soybean rotation systems.

Characterization and utilization of algal and wheat husk biochar as biofertilizers for sustainable soil amelioration

This study focus on managing agricultural crop residue and algae into soil amelioration. The wheat-husk and algal biochar studied to improve soil physico-chemical properties and their impact on Vigna radiata (Moong) and Pennisetum glaucum (Bajra). Biochar used at various proportions of 4-12 % at an interval of 8, 16 and 24 days. Algal biochar, at a concentration of 12 %, results in shoot lengths of 25.53 cm for Moong and 16.75 cm for Bajra, whereas, wheat husk biochar for the same concentration results in shoot length of 9.52 cm for Moong and 6.95 cm for Bajra after a 24-day growth period. The root and shoot length observed more in wheat husk whereas the algal biochar showed the more plant yield enhancement and degree of induction in both the crops. The algal biomass showed more biochar production efficiency and the proximate and ultimate characterization after adding biochar and increase in soil pH, cation exchange capacity, total organic carbon in Moong. Moreover, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy- Energy Dispersive X-ray spectroscopy and X-Ray Diffraction studied for both before and after biochar addition. Overall, the addition of both biochar has contributed significantly in improving soil health.

Nitrogen application increases the productivity of perennial alpine cultivated grassland by improving soil physicochemical properties and microbial community characteristics

Nitrogen application increases the productivity of perennial alpine cultivated grassland by improving soil physicochemical properties and microbial community characteristics

Radish cover crop and manure alter organic carbon characteristics and improve soil physicochemical properties as well as wolfberry yields

Cover crops are widely used to increase soil organic carbon (SOC) stocks in agroecosystems. However, the effects of cover crops on the labile fractions and chemical composition of SOC, as well as the consequences for fruit yield in manure-applied orchards are still unclear. Here, we conducted two field experiments in an arid area of Northwest China to explore the responses of soil physicochemical properties, SOC characteristics, and wolfberry (Lycium barbarum L.) yield to cover cropping and manure application rate. Decomposed sheep manure was incorporated into the soil at 0, 6660, and 13,320 kg·hm–2 in the absence (wolfberry monocropping) and presence (cover cropping) of forage radish (Raphanus sativus L.). Lower soil bulk density and higher total nitrogen, available nitrogen, available potassium, and dissolved organic carbon contents were observed under cover cropping compared to monocropping (p < 0.05). The contents of SOC and its labile fractions showed the greatest response to cover cropping with medium manure rate, which resulted in the highest wolfberry yield. Solid-state 13C nuclear magnetic resonance analysis identified O-alkyl carbon (26.2–52.4%) as the dominant SOC functional group across all treatments, followed by alkyl carbon (15.9–34.5%) and aromatic carbon (9.7–35.2%). The relative abundance of alkyl carbon trended higher under cover cropping in Yinchuan (by 1.1%) and Zhongning (by 21.3%), whereas manure application rate did not affect the chemical composition of SOC. Structural equation modeling revealed that cover cropping contributed to wolfberry yield in manure-applied fields directly or indirectly by altering SOC composition and improving labile SOC accumulation as well as soil physicochemical properties. Findings of this study are helpful to enhance soil carbon management and wolfberry orchard productivity in arid areas.

Practical Guidelines for Farm Waste Utilization in Sustainable Kale Production

Natural amendments from agricultural waste to improve soil physicochemical properties continuously attract research interest in promoting eco-friendly plant production. The present study evaluated the proper use of sawdust, biochar, and compost made from farm waste for kale production from seedling propagation to field conditions. From the seedling propagation process, the results demonstrate that the most suitable growing medium for kale seedings was 0.5:1:1 v/v of sawdust + biochar + compost, which gave the fastest mean germination times (2.71 days) and the highest seed germination percentage (78.33%). In addition to investigating the selected growing media as the soil amendments at five different rates (0, 6.25, 12.50, 18.75, 25.00, and 31.25 t ha−1), the result reveals that the fresh weight of marketable leaves was significantly highest under the 31.25 t ha−1 treatment. The application rate that yielded the highest gross profit margins was eight times higher than the control. Moreover, in some harvesting periods, the kale leaf yields under the treatment of 31.25 t ha−1 showed higher total chlorophyll and carotenoid contents.

Sheep manure organic fertilizer is an effective strategy to promote strawberry growth by improving soil physicochemical properties and microbiota

The use of organic fertilizers instead of chemical fertilizers can improve soil pH, help to maintain soil health and enable landowners to achieve organic or ecological-status agriculture. Rapeseed cake, sheep manure, and biofungal fertilizer are considered to be effective amendments to improve soil quality. However, there have been few studies on the effects of the three fertilizers on strawberry production, soil physicochemical properties, and inter-root soil microbial community structure. In this study, field experiments were conducted to investigate the differences in strawberry growth, quality, yield, and the structure and diversity of strawberry soil bacterial and fungal communities under four treatments: no organic fertilizer (CK), rapeseed cake organic fertilizer (T1), sheep manure organic fertilizer (T2) and bio-organic fertilizer (algae-optimized bacteria) (T3), the relationship between soil physicochemical properties and soil microbial diversity were analyzed. Our results have shown that these three amendments promoted the growth of strawberry to some extent. The effects of available phosphorus, ammonium nitrogen, sucrase, protease and urease under T2 treatment were significantly increased by 50.62%, 54.14%, 276.50%, 129.47%, 232.61%, and 232.00%, respectively, compared with the control. The soil bacterial and fungi community were the most abundant and diversified under the T2 treatment. Soil physicochemical properties and soil key enzyme activities varied significantly under different fertilizer treatments, with the soil nutrient content and soil carbon and nitrogen metabolizing enzyme activities being highest under T2 treatment. A Pearson correlation analysis showed that soil organic matter was closely related to the diversity of soil microbial communities. A redundancy analysis (RDA) showed that the main variables of the bacterial community included nitrate nitrogen (NN) and rapidly available potassium (RAP), while the main variables of the fungal community included alkaline dissolved nitrogen (ADN) and ammonium nitrogen (AN). Overall, different fertilizers promoted the release and transformation of soil nutrients by affecting the structure and diversity of bacterial and fungal communities in strawberry soils, which was beneficial to the supply of soil nutrients and the improvement of soil quality. The application of sheep manure organic fertilizer had the best soil improvement effect.

Studies on the Effects of Liming Acidic Soil on Improving Soil Physicochemical Properties and Yield of Crops: A Review

Soil acidity is a major constraint to crop production globally by potentially limiting agricultural productivity and causing environmental challenges, especially in temperate and tropical regions of the world where there is high precipitation. The review article summarizes the works of literature and gathers information on the effects of liming on soil's physicochemical properties and the yield of crops. Soil acidity is caused by natural ways, such as the high amount of precipitation that exceeds evapotranspiration that leaches appreciable amounts of exchangeable bases from the soil surface, weathering, and decomposition of organic matter and by human interference (by the use of nitrogen fertilizer mainly ammonia and urea fertilizers). Application of lime improved soil pH and neutralize the effect of toxic elements. Liming directly improves some physicochemical properties of the soil, such as aggregates, density, and porosity as physical properties and reduction of exchangeable acidity, Al saturation, micronutrients (Cu, Fe, Mn, and Zn) in the soil solutions, from exchange complex to the levels required and increasing soil pH, exchangeable cations (Na+, K+, Ca+2, and Mg+2) as chemical properties. Soil aggregation, density, and porosity of soil undergo changes with the application of lime. The long-term lime application resulted in increased soil chemical properties. Lime application contributed to increased crop productivity and crop quality. The effects of liming can be explained by the flocculation and cementing action of Calcium ions in the short term. In the long term, increases in productivity induced by liming, result in increasing soil pH, available phosphorus, cation exchange capacity, basic cations, microbial activity, organic carbon, total nitrogen, and decreasing leaching of nutrients, exchangeable aluminum, and acidity, all favoring the physical and chemical properties of the soil.

Paper mill wastes and biochar improve physiochemical properties and reduce heavy metals leaching risks in podzolic soils

Background: The incorporation of industrial wastes, such as wood ash and paper sludge, as soil amendments is vital for both environmental sustainability and agroecosystem productivity. Herein, we evaluated the effects of wood ash and paper sludge alone and in combination with biochar on the physicochemical properties and heavy metal leaching risks in podzolic soils. Methods: The treatments included limestone (control), wood ash, paper sludge, wood ash+paper sludge, limestone+biochar, wood ash+biochar, paper sludge+biochar and wood ash+paper sludge+biochar, arranged in a 4 × 2 factorial design with three replicates. The Hydrus-1D model was employed to simulate the water movement under these soil amendments using leaching colums. Results: Overall, wood ash, paper sludge and biochar application significantly increased the pH of amended soil compared to control. Paper sludge amended treatments alone or in combination with biochar significantly decreased bulk density (8%–17%) and increased the total porosity (14%–25%). While biochar addition to wood ash and paper sludge significantly reduced the concentrations of Cd (by 6.42%), Co (by 10.95%), Cu (by 11.76%), Pb (by 30%) and Ni (by 3.75%) in the collected leachates. The treatment paper sludge + biochar was found to be the most effective treatment to retain the heavy metals, with maximum plant available water (0.28 cm3 cm−3) and field capacity (0.36 cm3 cm−3) compared to control treatment. The predictions from Hydrus-1D showed that paper mill wastes with biochar has a significant potential to increase the volumetric moisture contents of amended podzolic soil, with the simulated leaching times and saturation levels closely aligning with the measured values. Conclusion: paper sludge + biochar treatment showed improved soil physicochemical properties and displayed lower heavy metals than allowed limits to be used in soil. Further, experiments are needed to assess the effects of papermill waste products on podzolic soil properties under variable field conditions.

Biochar addition promotes soil organic carbon sequestration dominantly contributed by macro-aggregates in agricultural ecosystems of China

Soil aggregates play pivotal roles in soil organic carbon (SOC) preservation and climate change. Biochar has been widely applied in agricultural ecosystems to improve soil physicochemical properties. However, the underlying mechanisms of SOC sequestration by soil aggregation with biochar addition are not well understood at a large scale. Here, we conducted a meta-analysis of 2335 pairwise data from 45 studies to explore how soil aggregation sequestrated SOC after biochar addition in agricultural ecosystems of China. Biochar addition markedly enhanced the proportions of macro-aggregates and aggregate stability, and the production of organic binding agents positively facilitated the formation of macro-aggregates and aggregate stability. Soil aggregate-associated organic carbon (OC) indicated a significantly increasement by biochar addition, which was attributed to direct and indirect inputs of OC from biochar and organic residues, respectively. Biochar stimulated SOC sequestration dominantly contributed by macro-aggregates, and it could be interpreted by a greater improvement in proportions and OC protection of macro-aggregates. Furthermore, the SOC sequestration of soil aggregation with biochar addition was regulated by climate conditions (mean annual temperature and precipitation), biochar attributes (biochar C/N ratio and pH), experimental practices (biochar addition level and duration), and agronomic managements (land type, cropping intensity, fertilization condition, and crop type). Collectively, our synthetic analysis emphasized that biochar promoted the SOC sequestration by improving soil aggregation in agricultural ecosystems of China.

Almond shell-derived biochar decreased toxic metals bioavailability and uptake by tomato and enhanced the antioxidant system and microbial community

The effectiveness of almond shell-derived biochar (ASB) in immobilizing soil heavy metals (HMs) and its impact on soil microbial activity and diversity have not been sufficiently studied. Hence, a pot study was carried out to investigate the effectiveness of ASB addition at 2, 4, and 6 % (w/w) on soil biochemical characteristics and the bioavailability of Cd, Cu, Pb, and Zn to tomato (Solanum lycopersicum L.) plants, as compared to the control (contaminated soil without ASB addition). The addition of ASB promoted plant growth (up to two-fold) and restored the damage to the ultrastructure of chloroplast organelles. In addition, ASB mitigated the adverse effects of HMs toxicity by decreasing oxidative damage, regulating the antioxidant system, improving soil physicochemical properties, and enhancing enzymatic activities. At the phylum level, ASB addition enhanced the relative abundance of Actinobacteriota, Acidobacteriota, and Firmicutes while decreasing the relative abundance of Proteobacteria and Bacteroidota. Furthermore, ASB application increased the relative abundance of several fungal taxa (Ascomycota and Mortierellomycota) while reducing the relative abundance of Basidiomycota in the soil. The ASB-induced improvement in soil properties, microbial community, and diversity led to a significant decrease in the DTPA-extractable HMs down to 41.0 %, 51.0 %, 52.0 %, and 35.0 % for Cd, Cu, Pb, and Zn, respectively, as compared to the control. The highest doses of ASB (ASB6) significantly reduced the metals content by 26.0 % for Cd, 78.0 % for Cu, 38.0 % for Pb, and 20.0 % for Zn in the roots, and 72.0 % for Cd, 67.0 % for Cu, 46.0 % for Pb, and 35.0 % for Zn in the shoots, as compared to the control. The structural equation model predicts that soil pH and organic matter are driving factors in reducing the availability and uptake of HMs. ASB could be used as a sustainable trial for remediation of HMs polluted soils and reducing metal content in edible plants.

Floristic changes and environmental drivers of soil fungi and archaea in different salt-tolerant plant communities in the intertidal habitat of coastal wetlands.

Microorganisms are crucial elements of terrestrial ecosystems, which play significant roles in improving soil physicochemical properties, providing plant growth nutrients, degrading toxic and harmful chemicals, and biogeochemical cycling. Variations in the types and quantities of root exudates among different plants greatly alter soil physicochemical properties and result in variations in the diversity, structure, and function of soil microorganisms. Not much is understood about the differences of soil fungi and archaea communities for different plant communities in coastal wetlands, and their response mechanisms to environmental changes. In this study, fungal and archaea communities in soils of Suaeda salsa, Phragmites australis, and Spartina alterniflora in the intertidal habitat of coastal wetlands were selected for research. Soil fungi and archaea were analyzed for diversity, community structure, and function using high throughput ITS and 16S rRNA gene sequencing. The study revealed significant differences in fungi and archaea's diversity and community structure in the rhizosphere soil of three plant communities. At the same time, there is no significant difference in the functional groups. SOM, TP, AP, MC, EC and SOM, TN, TP, AP, MC, EC are the primary environmental determinants affecting changes in soil fungal and archaeal communities, respectively. Variations in the diversity, community structure, and ecological functions of fungi and archaea can be used as indicators characterizing the impact of external disturbances on the soil environment, providing a theoretical foundation for the effective utilization of soil microbial resources, thereby achieving the goal of environmental protection and health promotion.

Effect of soil and water conservation practices and slope gradient on organic carbon stocks micronutrients: A case study on Kulkullessa sub-watershed, Eastern Ethiopia

Soil degradation in sub-Saharan Africa is a serious problem that causes declines in agricultural productivity linked to hunger and poverty. The study was conducted in the Kulkullessa sub-watershed of Goro Gutu District in Eastern Ethiopia to assess the effects of climate-smart soil and water conservation (SWC) practices and slope gradient on selected physicochemical properties of the soil and the soil’s organic carbon stocks. The farmland conserved by stone bund (SB), bench terrace (BT), and gras strip (GS) five years after construction with two slope gradients (15-20%) and (21-30%) was selected. Twenty-four composite soil samples were collected from a depth of 20 cm and tested in the Haramaya University soil laboratory. The study found that climate-smart SWC practices were very effective on the soil physicochemical properties and soil organic carbon stock (SOCS) of the study area. Similarly, the slope gradient brought considerable variation in soil physicochemical properties and soil organic carbon stock. On farmland that a bench terrace had preserved, the bulk density (BD) value was lower. The recorded value for total porosity on the farmland conserved by BT was also positively higher and significant (p ≤ 0.05). Likewise, the higher mean values for micronutrients and SOCS were recorded on farmlands conserved by SB, BT, and GS in contrast to the values recorded on non-conserved farmland (NCF) in the study area. Based on the study findings, climate-smart soil water and conservation practices have outstanding potential for improving soil physicochemical properties essential for agricultural crop production, climate change adaptation, and strengthening smallholder farmers’ resilience.