In the context of the circular economy, managing sewage sludge (SS) is vital for resource valorization and sustainability. This study aims to compare the impact of different application methods (two phase mulch, single phase mulch, incorporation) and doses (10, 25, 40 and 50 t/ha) of residual sewage sludge on the quality of sandy-silty soils and the morpho-physiological characteristics of durum wheat (Triticum durum) plants, specifically the Oued El Bared G4 variety. The field experiment was conducted in a hot arid region in northeastern Algeria. Results demonstrated that SS significantly improved soil fertility and wheat performance (p < 0.001). Soil organic matter (OM) and Phosphorus peaked at 1.92% (T2D3) and 258.46ppm (T1D4) respectively, representing a substantial enrichment compared to lower doses. Regarding crop yield, the 1000 grain weight (WTG) reached a maximum of 54.88g with single phase mulch (T2D1), which is 33.8% higher than the two phase application method. Similarly, plant height and leaf surface area (LSA) were maximized under the T2 method (91cm and 37.41 cm2, respectively). While soil pH remained stable, electrical conductivity (EC) increased with dosage, peaking at 1.87 µS/cm (T2D4). This finding suggest that sludge biorecycling in single phase mulch application (T2) at moderate doses optimizes both soil quality and durum wheat yield component in arid region. Future research should focus on the long term cumulative effects of repeated sludge application on soil heavy metal dynamics and groundwater quality in arid environment.

Background: Phosphorus is vital plant nutrient and limiting factor for soil productivity, hence better management of agronomic practices may influence the P availability in soils. The different P fractions plays also role in management of soil productivity. The goal of our study was to evaluate the effect of synthetic fertilizer in combination with organic manures and microbes on phosphorus fractions and system productivity. Methods: The study has planned in split plot design with two pulses based cropping systems and eight nutrient management options role and combination of inorganic fertilizers, organic manure and microbial inoculants. Different phosphorus fractions were determined using stepwise fractionation techniques and soil characteristics were ascertained using normal analytical procedures. Result: The findings showed that the blackgram-mustard (B-M) cropping system outperformed the fallow-chickpea (F-C) cropping system in terms of soil porosity, water-holding capacity and phosphorus fraction. Compared to the initial status of the soil, both systems have better soil qualities. Similar to this, phosphorus fractions improved when 125%, 100% and 75% of the recommended inorganic fertilizer was applied in conjunction with FYM and microbial inoculants, as compared to when inorganic fertilizers were applied only. The system productivity was higher with B-M cropping system and also with 125%, 100% and 75% inorganic fertilizer with FYM and microbial inoculants. Overall, our study suggests that 25% of inorganic fertilizer can be reduced along with FYM and microbial inoculants in B-M cropping systems in semi-arid region.

Phosphorus-solubilizing bacteria regulate soil phosphorus activation mechanisms and impact on available nutrients: a meta-analysis

Soil phosphorus (P) deficiency is an important factor limiting plant growth in the semi-arid Loess Plateau region in China. The topsoils in this area undergo repeated drying–rewetting (DRW) cycles, which can influence soil P availability, a process that may become more pronounced due to climate change. However, little is known about how soil P availability responds to DRW cycles under different land-use types. To investigate this issue, we conducted three 120-day soil culture experiments to investigate the direction and magnitude of soil available P and the responses of its influencing factors to repeated DRW cycles and their frequency and intensity under three typical land-use types (cropland, grassland, and shrubland) in Gansu Province, North-western China. The results showed that the available P concentration of cropland, grassland, and shrubland soils after repeated DRW cycles significantly decreased by 8.9%, 11.5%, and 14.2%, respectively, compared with a constant humidity control. With increasing intensity of the DRW cycles, the available P concentration of grassland and shrubland soils significantly increased by 14.3% and 15.5%, respectively, while in cropland soil P significantly decreased by 10.4%. Compared with low-frequency DRW cycles, high-frequency DRW cycles significantly reduced the available P concentration by 6.4% in grassland soil and increased it by 9.8% in shrubland soil but had no significant effect in cropland soil. Overall, the responses of soil P availability to repeated DRW cycles vary among different land-use types, and the magnitude of the soil P availability response to repeated DRW cycles depended strongly on soil microorganism biomass, phosphatase activity, and the initial soil properties, being more pronounced in grassland and shrubland soils than in cropland soils. It is therefore essential to consider land-use type when studying the effects of DRW on soil P cycling in semi-arid regions, especially in the context of climate change.

Introduction Continuous soil monocropping typically disrupts microecological equilibrium, leading to reduced crop yield and quality degradation, whereas crop rotation often mitigates these issues. However, understanding of the microbial mechanism behind this rotation practice is still limited. Methods A three-year field experiment was conducted comparing tobacco continuous monocropping and tobacco-rice rotation. The bacterial community structure, assembly processes, and functional profiles were analyzed within three tobacco growing periods. Results While most soil physicochemical parameters, such as pH, total phosphorus, and available phosphorus, were not significantly different between the two systems, tobacco monoculture specifically resulted in elevated contents of total nitrogen and alkali-hydrolyzable nitrogen compared to tobacco-rice rotation systems. Although α-diversity also showed no significant differences between systems, bacterial community composition diverged significantly, with Proteobacteria, Acidobacteria, and Actinobacteria dominating. Deterministic processes governed community assembly, with βMNTD and βNTI exhibiting significant correlations with soil available nitrogen, phosphorus, potassium, and pH exclusively in the rotation system-contrasting sharply with the absence of such correlations in monoculture. Tobacco-rice rotation exhibited more complex co-occurrence networks anchored by 22 topological connector taxa than tobacco monocropping. Functionally, the rotation significantly suppressed nitrifying bacteria abundance, whereas monocropping enriched dark sulfide-oxidizing bacteria. Notably, despite the absence of significant overall differences in pathogen abundance between the two cropping systems, a high variation was observed of plant pathogen abundance in the vigorous growth stage of tobacco monocropping, which indicates that certain locations possess a considerably elevated susceptibility to potential disease epidemics. Discussion Compared to continuous monocropping, tobacco-rice rotation caused minimal shifts in soil α-diversity and physicochemical properties. However, our three years field study reveals that it profoundly restructured the composition and interaction networks of the soil bacterial community. This highlights the divergent impacts of cropping systems on the soil microbiome and indicates that the benefit of rotation may stem primarily from its ability to rewire microbial interactions, thereby alleviating continuous cropping obstacles.

Abstract Knowledge concerning the use of solid residues from the distillation of medicinal and aromatic plants (MAP) as amendments-fertilizers for acid soils, instead of their combustion or disposal to the environment, is too limited. The aim of the study was a preliminary evaluation of the use of solid residues from the distillation of selected medicinal and aromatic plants as amendments-fertilizers for acid soils. Specifically, in the perspective of further and extensive investigation, the fertilization capacity of solid residues from the distillation of selected MAP was initially realized and the optimal range of application rates of the residues to acid soils was initially determined. From that point of view, the present study was a preliminary study and lasted for six months. Solid residues from the distillation of hemp ( Cannabis sativa L.), helichrysum ( Helichrysum italicum (Roth) G. Don), lavender ( Lavandula angustifolia Mill.), oregano ( Origanum vulgare L.), rosemary ( Rosmarinus officinalis L.) and sage ( Salvia officinalis L.) were collected from industries of essential oils of northern Greece. Then the residues were added to a strongly to moderately acid soil at 0 (control), 1, 2, 4 and 8% rates (treatments), in three replications and the soil treatments were analyzed for chemical properties and fertility indices. pH significantly increased compared with control upon the addition of all residues at the 2% rate and above. Although pH remained acid in all cases, it increased more than one unit in soils treated with 4% and 8% flower-leaf residues from hemp distillation, making soil’s reaction slightly acidic. Similar results were obtained for electrical conductivity (EC) and the carbon/nitrogen (C/N) ratio. It is worth noting that EC increased six-ten times upon the 8% application of flower-leaf residues, whereas the C/N ratio increased considerably with the 8% addition of lavender and helichrysum residues. Regarding soil available macronutrients, nitrate-nitrogen (NO 3 -N), phosphorus (P) and potassium (K) significantly increased from adequate to high levels compared with control. From the soil available micronutrients, only boron (B), zinc (Zn) and manganese (Mn) consistently affected by the application of residues and significantly increased. It is worth noting the multiple increases of B and Zn in soils treated with 8% residues compared with control, which were somewhat concerning. In almost all treatments, soil available B, Cu and Zn ranged at sufficiency levels, whereas Fe and Mn ranged at high levels. The solid residues from the distillation of the studied MAP, especially the flower-leaf residues, could be used as amendments-fertilizers for acid soils, at application rates between 2 and 4%. Rates lower than 2% are not expected to significantly affect soil properties, whereas rates higher than 4% should be avoided, because of risks of soil salinization, N immobilization and B, Zn and probable Mn phytotoxicities. Graphical Abstract

ABSTRACT Plant species distributions are strongly influenced by soil nutrient availability in tropical forests. Yet, the relative importance of abiotic and biotic factors underlying the composition of pervasive fungal symbionts of plants, arbuscular mycorrhizal fungi (AMF), remains unresolved in lowland tropical forests. Utilizing a long‐term plot network in central Panama with mapped soil properties and tree species distributions, we aimed to understand the relative contribution of soil properties, geographic distance, root traits, and plant species identity in determining AMF community composition. We further asked how plant‐fungal networks vary between sites with contrasting soil phosphorus (P) availability. We sampled fine roots for molecular identification of AMF communities from 140 trees representing 26 species with varied distributions across the soil nutrient availability gradient. We found that plant species identity and soil properties, especially soil P availability and dry‐season moisture deficit, independently structured AMF community composition. Taxonomic turnover and a large number of indicator taxa across a soil P availability gradient provide further evidence for the strong abiotic and biotic structuring of AMF communities. Moreover, a significantly nested plant–AMF network in the low‐P site points to a role of soil nutrient availability in mediating plant–AMF interactions. Our results lay the foundation for future studies to uncover the functional consequences of this symbiosis for plant distributions and ecosystem function in tropical forests.

Organic fertilization improves activities of phosphomonoesters hydrolase in rhizosphere to facilitate phosphorus acquisition in cucumber and accumulates organic phosphorus in soil

Long-term biomass removal in grasslands reduces plant and soil phosphorus, increases carbon:phosphorus stoichiometry, but does not lead to microbial phosphorus limitation

Soil phosphorus fractions drove nitrous oxide emissions: Based on nitrification inhibitor and phosphate-solubilizing bacterium applications.

Organic amendment quality as a driver of soil phosphorus enrichment and crop yield: A global synthesis

Microbial functional shifts drive soil phosphorus transformation under long-term nitrogen and water inputs in a semi-arid grassland

Partial substitution of chemical nitrogen fertilizer with organic manure is more feasible than full substitution for soil phosphorus risk management

Interaction between dissolved organic matter structure diversity and phosphorus forms in phosphogypsum tailings under the influence of fungal microorganisms.

Earthworms enhance soil phosphorus cycling but plant responses differ among earthworm ecological categories: a meta-analysis

Abstract Introduction Soil nutrient management is essential for sustainable agriculture, directly affecting crop productivity and food security. Conventional laboratory-based methods for estimating soil nitrogen (N) and phosphorus (P), although accurate, are time-consuming, labor-intensive, and unsuitable for rapid or large-scale monitoring. Objectives This study aimed to develop an efficient, accurate, and scalable framework for soil nitrogen and phosphorus estimation using hyperspectral imaging integrated with deep learning techniques. Methods A total of 286 soil samples were collected from two agricultural locations in North Dakota during pre-sowing and post-harvest periods, capturing spatio-temporal variability. Laboratory chemical analyses were conducted to quantify soil N and P, and corresponding hyperspectral data were acquired in the visible and near-infrared (VNIR) and short-wave infrared (SWIR) regions. Spectral data were processed and categorized based on laboratory reference values. A convolutional neural network (CNN) model was developed for nutrient prediction, incorporating neural architecture search (NAS) and hyperparameter tuning for model optimization. The framework was evaluated using single-sensor and fused multi-sensor datasets, with spectral augmentation techniques applied to improve model robustness. Results Baseline CNN models achieved prediction accuracies of approximately 0.44, which improved to 0.68 with multi-sensor data fusion and spectral augmentation. Integration of NAS and hyperparameter tuning resulted in an additional 10–15% performance gain, achieving a final prediction accuracy of approximately 0.83 for combined nitrogen and phosphorus classification. NAS-based models showed minimal performance differences between raw and augmented datasets, while computational training time nearly doubled due to increased model search complexity. Applying NAS on raw hyperspectral data provided the most balanced trade-off between computational efficiency and predictive performance. Conclusions The integration of hyperspectral imaging with optimized CNN architectures and NAS enables accurate, scalable, and efficient soil nutrient prediction. This framework addresses spectral variability and environmental noise, offering a robust pathway for real-time soil nutrient monitoring and advancing data-driven precision agriculture.

Abstract Background and aims Arbuscular mycorrhizal fungi (AMF) play an essential role in plant nutrition in both natural and agro-ecosystems. However, how soil nutrient availability simultaneously regulates AMF diversity and contribution to plant nutrition, requires more attention. We hypothesised that the interaction between the availability of key soil macronutrients phosphorus (P) and nitrogen (N) regulates AMF contribution to wheat nutrition and that nutrient availability will simultaneously influence AMF community composition. Methods We tested this using a unique long-term P fertilisation trial, sampling wheat roots across two growing seasons. Expression of wheat mycorrhizal nutrient transporters was quantified by RT-qPCR and AMF communities were characterised by ITS2 metabarcoding. Complementary experiments under controlled conditions examined how the interaction between P and N regulates arbuscular mycorrhizal function in plant nutrition. Results Field-grown wheat showed campaign-specific effects of P fertilisation on AMF colonisation and nutrient transporter expression, which coincided with shifts in plant N status. Controlled experiments confirmed that colonisation depends on the limitation of either P or N, but that the regulation of peri-arbuscular phosphate, ammonium and nitrate transporters depended on the limiting nutrient. AMF communities also responded to soil P availability, with the genus Funneliformis consistently dominating under high P conditions. Conclusions Our findings demonstrate that P and N availability jointly shape root AMF communities and regulate their nutritive function in wheat. The combination of community profiling and mycorrhizal molecular markers provides a valuable approach for understanding the AMF contribution to plant nutrition across agroecosystems, and therefore can be used for optimising agroecological practices.

Objective: To evaluate the effect of the concentration of lignin contained in leaf litter on the mineralization rate and accumulated mineralization in forest soils. Design/methodology/approach: 25 g of soil from the Abies religiosa forest in the Sierra Nevada were incubated with increasing concentrations of leaf litter and branch lignin, with a humidity of 60 % at 35°C. CO2 was recovered in a solution of 0.5 N NaOH and 0.5 N barium chloride, and titrated with 0.5 N H2SO4. A completely randomized experimental design with two factors was used. Mineralization rate and cumulative mineralization were determined. Linear regression analysis and ANOVA were performed with the statistical package SAS OnDemand for Academics. Results: CO2 emissions fit a linear model for lignin and soil levels, with mineralization rates ranging from 12.06 mg day-1 of CO2 to 33.68 mg day-1 of CO2. There are highly significant differences between lignin levels. The Site-Lignin Concentration interaction shows statistical differences. There is a positive and highly significant relationship between soil nitrogen and phosphorus. Limitations on study/implications: It is suggested to consider the climate factor throughout the year as a source of variation in CO2 emissions and its interaction with the quality of the leaf litter, as well as microbial activity. Findings/conclusions: CO2 emissions show a linear and positive trend with lignin concentration. Mineralization rates and accumulated minerali-zation show statistical differences in lignin levels, as well as in total nitrogen content, as well as in the interaction between sites and lignin concentration.

To enhance sustainable soil fertility and efficient phosphorus (P) management, phosphate-solubilizing bacteria (PSB) play a central role in solubilizing soil mineral phosphorus by releasing organic acids and acidifying micro-niches. Thus far, the influence of spatial P heterogeneity on bacterial eco-physiological adaptations to P-limited, alkaline soils remains poorly understood. This study examined how soil edaphic factors vary across major wheat-growing regions, assessing their influence on the abundance and functional properties of culturable PSB. Soil available P was the strongest predictor of culturable bacterial abundance, with a threshold of P &amp;lt; 6.3 mg kg –1 dry soil driving major variations. At low P levels, organic matter played a key role, while at higher P levels, potassium ( K ≥ 123) and pH further shaped bacterial abundance. Low-P soil PSB (L PSB ) secreted elevated levels of organic acids such as malic, succinic, gibberellic and citric acid, but low levels of indole acetic acid. A clear trade-off was observed between P solubilization and growth-related traits: L PSB invested more in acquiring resources (e.g., producing siderophores and organic acids) and less in synthesizing phytohormones. A net house study showed that L PSB contribute to plant growth. Plants with 70% phosphate fertilization (P 70 ) and PSB inoculation reached the yield levels comparable to those with 100% fertilization without the PSB, indicating the potential of PSB to reduce dependency on fertilizers. This was associated with a significant increase in wheat biomass (24.3%), yield (28.53%) and P use efficiency (31.66%) by L PSB inoculation compared to the control P 70 . Our findings emphasize the importance of microbial functional plasticity in enhancing P use efficiency in P-limited soil, offering a basis for developing climate-smart bioformulations to improve sustainable crop productivity.

Phosphorus (P) and zinc (Zn) are essential nutrients required for plant growth and productivity. Phosphorus plays a pivotal role in energy transfer (ATP), nucleic acid synthesis, root development, and grain formation, while zinc is involved in enzyme activation, hormone synthesis, photosynthesis, and seed development. Calcareous soils, which dominate large areas of Iraq and the Middle East, pose significant challenges due to their high calcium carbonate content and alkaline pH. These conditions lead to phosphorus precipitation as insoluble calcium phosphates and zinc immobilization through adsorption or precipitation as carbonates and hydroxides, thereby reducing their availability and causing deficiency symptoms such as slow growth and purpling of leaves in P deficiency, or stunted plants and interveinal chlorosis in Zn deficiency. Nutrient interactions between P and Zn represent an additional challenge; excessive P fertilization often suppresses Zn uptake, while balanced fertilization enhances the utilization of both nutrients. The major processes governing phosphorus include mineralization, immobilization, adsorption–precipitation, and desorption, whereas zinc undergoes mineral weathering, adsorption onto soil minerals, precipitation, organic complexation, and redox reactions, all of which restrict their bioavailability, particularly in calcareous soils. Recent studies from Iraq, the broader Middle East, and global field trials have demonstrated that integrating nanofertilizers, foliar applications, and organic amendments (such as compost and vermicompost) within integrated nutrient management (INM) systems significantly improves the availability of phosphorus and zinc. These practices enhance the productivity of strategic crops such as wheat, barley, and maize. Linking these nutrient management strategies with the United Nations Sustainable Development Goals (SDGs)—particularly SDG 2 (Zero Hunger), SDG 3 (Good Health and Well-being) through zinc biofortification, and SDG 12 (Responsible Consumption and Production)—highlights the strategic importance of sustainable phosphorus and zinc management in calcareous soils.