Aug 2026· New forests· Vol 57· 0 citations· 87 references
Abstract
This study evaluated the effects of sewage sludge composted (SSC, mixed with sugarcane bagasse at 1:1 ratio) and microbial biopromoters on soil fertility and early growth of Astronium fraxinifolium, a native tree with high recovery potential in the Brazilian Cerrado. In a randomized block design (2 × 4 factorial), treatments consisted of two SSC levels (with and without 23 g pot⁻¹ of chemically characterized, environmentally safe compost) and four inoculation treatments (control; Bacillus subtilis - BS; Rhizophagus clarus - RhC; and BS + RhC) with five replicates in 6-L pots. After 150 days, growth, root morphology, gas exchange, and soil properties were evaluated. SSC improved soil fertility (reduced aluminum, increased P, sum of bases, base saturation, and essential micronutrients Fe, Mn, Zn) without inducing heavy metal toxicity, increasing plant height. The SSC + RhC interaction significantly promoted shoot and root biomass, stem diameter, and root surface area/volume. Seedling Quality Index (SQI) was highest under SSC + RhC and SSC + BS. Furthermore, SSC and inoculants significantly enhanced gas exchange parameters, translating into substantially higher photosynthetic performance. Overall, combining this specific SSC rate with biopromoters, particularly Rh. clarus, effectively improved soil chemical properties and seedling vigor. While limited to nursery conditions, these findings demonstrate that this approach successfully promotes high-quality seedlings, establishing a promising baseline for future long-term field validation and dose-response trials in degraded lands.
Sewage sludge is widely explored as an organic nutrient source, but its ecological effects on soil microbial communities remain context dependent. This study evaluated the effects of sewage sludge and NPK fertilizers on soil microbial populations associated with kale (Brassica oleracea L. cv. ‘GM Dari’) and spinach (Spinacia oleracea L. cv. ‘Shalimar Green’). A two-season field experiment (rabi and kharif) was conducted at the Experimental Farm, Wadura Campus, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, using a randomized complete block design with nine treatment combinations and three replications. Results showed that sewage sludge amendments significantly increased the abundance and diversity of soil microorganisms compared to control and solely chemical fertilizer treatments. Rhizospheric soils of kale and spinach contained Flavobacterium, Bacillus, and Alcaligenes species, while fungal genera such as Aspergillus, Trichoderma, Mucor, and Paecilomyces were predominant in sludge-amended soils. The highest bacterial counts (39.30 × 10x CFU g-1 for kale and 39.25 × 10x CFU g-1 for spinach) and fungal counts (16.70 × 10t CFU g-1 for kale and 16.39 × 10t CFU g-1 for spinach) were recorded under 100% sewage sludge, followed closely by the combined treatment of 75% sludge + 25% NPK, whereas the control plots exhibited the lowest microbial abundance. The findings demonstrate that sewage sludge effectively enhances soil microbial activity and diversity, improving soil biological fertility. Partial substitution of mineral fertilizers with sludge (75% sludge + 25% NPK) appears optimal for maintaining microbial health and supporting sustainable vegetable production in the Kashmir Valley.
Sabia Zafar, K. Hussain, Sameer Farooq et al.· Journal of the Indian Societ...· 0 citations
Aerobic composting of cattle manure is often limited by slow humification and long duration. This study evaluated a staged inoculation strategy using phase-specific microbial consortia to enhance composting efficiency. Cow manure and rice straw were composted under four treatments: no inoculant (W), staged commercial EM inoculant (EM), single initial composite inoculant (TF), and staged targeted consortia (YF). The YF treatment achieved the longest thermophilic phase (11 days, peak 62.87 °C), the highest humic substances (122.02 g/kg) and humic acid (92.32 g/kg), and the highest total nitrogen (19.20 g/kg) with a seed germination index of 90.63%. Pot experiments using the resulting composts on pakchoi showed that the YF-derived organic fertilizer (YFP) significantly improved soil available nitrogen, phosphorus, and potassium, increased plant height and root length, enhanced chlorophyll content, and reduced superoxide dismutase activity compared to other treatments. Staged inoculation with targeted consortia effectively modulated microbial community succession, promoting lignocellulose degradation and humus synthesis. These findings demonstrate that phase-synchronized microbial management is a promising strategy to accelerate composting, improve product maturity, and enhance agronomic performance, supporting sustainable agricultural waste recycling.
Huan-Yao Li, Weimin Zeng, Jin Huang et al.· Frontiers in microbiomes· 0 citations
This study evaluated the agronomic potential and environmental impact of a macrophyte-based fertilizer (OMF) in maize cultivation. OMF was previously characterized in accordance with regulatory standards and applied to sandy loam and clayey soils at six rates (0, 2, 4, 6, 8, and 10 g dm⁻³). The experimental design also included a mineral fertilizer (MF) control receiving N, P, and K amounts equivalent to the 10 g dm⁻³ application, arranged in a randomized block design. After 45 days in greenhouse conditions, maize biomass and total nutrient accumulation, soil macronutrient concentrations, and the activities of arylsulfatase, β-glucosidase, and acid phosphatase were quantified. Basal soil respiration (BSR) and nutrient leaching were also evaluated through laboratoy-based analyses. OMF increased BSR, with CO₂ release in sandy loam and clayey soils highest under OMF (11.5; 10.7 mg g⁻¹), moderate under sludge compost (7.06; 7.51 mg g⁻¹), and lowest in unfertilized soil (2.34; 3.40 mg g⁻¹). OMF also promoted linear increases in soil P, K, Ca, Mg, and S, as well as in maize biomass and total N, P, and K accumulation. However, the highest OMF dose achieved only 20–31% of MF biomass. Moreover, organic fertilizers consistently reduced NO₃⁻-N, NH₄⁺-N, and K⁺ leaching compared with MF. In sandy soil, NO₃⁻-N leaching decreased by 31.2% and 38.5%, NH₄⁺-N by 45.6% and 37.4%, and K⁺ by 71.3% and 24.3% under SSC and OMF, respectively. In clayey soil, reductions reached 44.6% and 46.4% for NO₃⁻-N, 24.0% and 20.9% for NH₄⁺-N, and 35.9% and 15.7% for K⁺ under SSC and OMF, respectively. OMF offers environmental advantages by decreasing NO₃⁻-N leaching and supplying a slow-release K⁺ source, although it remains less effective than mineral fertilizer in promoting maize growth.
Paulo Sergio Costa Trindade, Andre Luiz de Freitas Espinoza, J. H. S. da Luz et al.· Journal of soil science and...· 0 citations
Sandy soils are characterized by low organic matter content, weak nutrient retention, and limited water-holding capacity, which restrict crop productivity in arid and semi-arid regions. This study evaluated the individual and combined effects of biochar, Azolla pinnata, and eggshell powder on soil properties and the productivity of common bean (Phaseolus vulgaris L.) grown in sandy soil. Field experiments were conducted during two consecutive growing seasons (2021–2022) at the Ismailia Agricultural Research Station, Egypt, using a randomized complete block design with eight treatments and three replicates. Soil chemical properties, photosynthetic pigments, vegetative growth, biomass accumulation, and yield parameters were evaluated. The combined application of biochar, Azolla, and eggshell powder significantly improved soil fertility compared with the control treatment. Soil organic matter increased to 0.70%, while available nitrogen, phosphorus, and potassium reached 51.10, 6.67, and 200 mg kg⁻¹, respectively. The integrated treatment also enhanced chlorophyll content, plant growth, biomass production, and seed yield across both seasons. Correlation analysis indicated strong positive relationships between soil organic matter, nutrient availability, and crop productivity. These results demonstrate that the integrated application of biochar, Azolla pinnata, and eggshell powder can effectively improve soil fertility and enhance the productivity of Phaseolus vulgaris in sandy soil systems.
D. M. Khalifa, A. Alrashidi, Ammar Al-Farga et al.· Scientific Reports· 0 citations
It is suggested that Bacillus strains possess PGP properties under metal stress conditions, indicating their potential for application in the remediation of metal-contaminated soils and enhancement of plant growth.
Aisha Bibi, S. Alam, A. Naz et al.· Plant and Soil· 0 citations
Wastewater sludge can improve soil fertility and support resource recycling, but potential heavy metal accumulation limits its agricultural application. In this study, we evaluated the effects of anaerobically digested wastewater sludge, applied alone or in combination with the purple non-sulfur bacterium (Rhodopseudomonas palustris), on two green manure crops, Sesbania cannabina and Glycine max. A 90-day pot experiment was conducted with five treatments: control, sludge at 10 and 20 t/ha, and each sludge level combined with R. palustris. Soil physicochemical properties, plant biomass production, and heavy metal concentrations in soil and plant tissues were analyzed. Sludge application increased soil total carbon, total nitrogen, and available phosphorus, while co-application with R. palustris further enhanced phosphorus availability. The greatest biomass production response was observed in G. max under 20 t/ha sludge plus R. palustris, with a 78% increase after 90 days. However, heavy metal concentrations and plant uptake generally increased with sludge dosage, particularly for Ni and Cr. These results indicate that sludge–PNSB application may improve soil fertility and biomass production, but heavy metal risks require careful evaluation.
Ping-Yuan Yang, Chun-Han Ko, Bo-Xiang Lee et al.· Agronomy· 0 citations