Soil Nutrient Status Research Articles

Rhizosphere as a hotspot for microbial necromass deposition into the soil carbon pool

Abstract Microbial leftovers, known as necromass, are key players in storing carbon in the soil around plant roots (i.e. rhizosphere), a zone characterized by high‐efficiency microbial anabolism. Yet, the extent and mechanisms through which the rhizosphere contributes to soil organic carbon (SOC) via microbial necromass, especially under changing environments remain unclear. We aimed to evaluate the contributions of microbial necromass to SOC and influencing factors from the rhizosphere perspective. We collected the rhizosphere and bulk soil from 39 alpine coniferous forest sites on the eastern Tibetan Plateau to assess the extent of microbial necromass contribution to SOC in the rhizosphere from a dynamic perspective by calculating the ratio of increased amino sugars (AS) to increased SOC in the rhizosphere relative to that in bulk soil (RAS/SOC). We also collected climate data and determined nutrient concentrations and microbial physiological traits in rhizosphere soil to elucidate the factors affecting RAS/SOC. The results showed that across all sampling sites, the average concentrations of SOC‐normalized AS in the rhizosphere were significantly higher than those in the bulk soil. Furthermore, the average RAS/SOC was greater than 1, indicating a faster microbial necromass accumulation than SOC accumulation in the rhizosphere. These results implied that the rhizosphere sustains a greater capacity for microbial necromass contribution to the SOC pool than the bulk soil does. Soil nutrient availability was the primary factor affecting RAS/SOC, and precipitation indirectly affected microbial anabolism and RAS/SOC by changing soil nutrient status. Additionally, with increasing rhizosphere soil nutrient availability, microbial carbon‐use efficiency and growth rate increased but the biomass‐specific enzyme activity declined, indicating that microorganisms tended to exhibit high‐yield strategies with increasing soil nutrient availability. Synthesis. Our findings underpin the vital effect of microbial necromass in SOC accumulation from the rhizosphere perspective and offer valuable insights into mechanisms underlying microbial C metabolic processes in rhizosphere SOC accumulation under changing environments.

Association between Soil and Plant Nutrients in Pomegranate Productivity in Northern Karnataka, India

Pomegranate productivity and quality necessitate the optimum nutrient supply and for this, soil nutrient status and leaf nutrient concentration are very much required. Concerning this, a survey study was conducted to analyse the soil and plant nutrient status of 150 pomegranate orchards of northern Karnataka. Soil pH, EC, OC, available nutrients (K, P, S, Fe, Mn, Zn and Cu), exchangeable calcium and magnesium, and corresponding leaf nutrient concentrations were analysed in orchards. The high yielding orchards with yield greater than mean productivity of Karnataka (11.71 t ha-1) were further categorized as category 1 (12.32-13.61 t ha-1), category 2 (14.32-22.64 t ha-1) and category 3 (22.84-25.63 t ha-1). The availability of soil nutrients viz., K, S, and Mn content were higher in category- 3 HYO whereas, available N, exchangeable Ca & Mg and Cu content were higher in category 1. Similarly, total P, K, S & Fe content in pomegranate leaf was higher in category 3 while leaf N, Ca, Mg & Cu content were found high in category 1 and category 2. These can be the basis for the application of the optimum dose of fertilizers.

Nutrient Uptake and Soil Nutrient Status as Influenced by Drip Fertigation Levels and Schedules in Broccoli

The experiment was carried out to study the effect of fertigation levels and schedules on growth and yield of broccoli (Brassica oleracea var italica) during the rabi season of 2021-22 involving 4 levels of fertilizer (75, 100 and 125 % RDF) along with one control (100 % RDF) through soil application and three fertigation scheduling (S1, S2 and S3) with three replications. The result of study revealed that higher fertigation of broccoli with balanced nutrition; better water and nutrient utilization gave significantly higher plant growth and yield and good quality of broccoli. In general, pooled mean revealed that application of 125 % RDF with fertigation schedule S2 :15 % NPK at transplanting to plant establishment, 1-10 DAT, 50 % NPK at curd initiation stage,11-35 DAT and 35 % NPK at curd development stage, 36-60 DAT recorded maximum NPK uptake in plant (kg/ha) and available NPK in soil (kg/ha).

Effect of fertigation scheduling and doses of NPK on growth, yield and quality of cherry tomato (Solanum lycopersicum L. var. cerasiforme) under protected condition

This study investigated the impact of different fertigation schedules on cherry tomato (Solanum lycopersicum var. cerasiforme) cultivation in a controlled environment at TNAU, Coimbatore, India. A Completely Randomized Design with nine treatments and three replications was used, incorporating various combinations of soil application and fertigation with water-soluble fertilizers at 25%, 50%, 75%, and 100% of the recommended dose of fertilizer (RDF). Critical parameters such as growth, phenological traits, yield, fruit quality, soil nutrient status, and plant nutrient uptake were evaluated. Statistical analyses, including ANOVA, path coefficient analysis, and principal component analysis (PCA), were performed to assess treatment effects and identify relationships between variables. The results consistently demonstrated that fertigation with water-soluble fertilizers at 100% RDF (T3) yielded the best outcomes for most parameters, followed by 75% RDF fertigation (T4) and a combination of 25% soil application and 75% fertigation (T7). Significant improvements in plant growth, yield and fruit quality were observed with optimized fertigation compared to traditional soil application methods. T3 (100% RDF through fertigation) resulted in the highest plant height (263.95 cm), number of primary branches (15), leaf area (316.77 cm²) and dry matter production (96.85 kg/plant). Yield attributes such as fruits per plant (326.50), fruit weight (3.73 g), and total yield (23.95 t/ha) were also highest in T3. Path coefficient analysis indicated strong positive correlations between growth and yield parameters. PCA showed that the first principal component accounted for 85.9 % of the total variation. These findings highlight the potential for fertigation to improve resource use efficiency and productivity in cherry tomato cultivation.

Organic matter accumulation encouraged K-strategy bacteria increase and metabolism variation in karst vegetation restoration

Vegetation restoration plays a critical role in terrestrial carbon sink increase, especially in subtropic Southwest China which has been the hotspot of vegetation restoration areas in recent decades. However, the variations in microbial community diversity resulting from this intervention remain unclear, and further research is needed to elucidate the complex interactions between microorganisms and soil nutrient elements. Soil samples were collected from three vegetation restoration stages in a karst rocky desertification (KRD) valley of Southwest China, which were named dry cropland (CL), 3–8 years grassland (WL), and afforestation land that recovered more than 20 years (AL), to investigate the soil nutrient and bacterial diversity variation during vegetation restoration course. The soil organic carbon (SOC) and total nitrogen (TN) contents are significantly higher in the afforestation land soil compared to the cropland and grassland soils, while the available nutrient contents decrease during the vegetation restoration course. The soil dominant bacteria genus shifts from R-strategy bacteria in cropland to K-strategy bacteria in afforestation land, and the relative abundances of R-strategy genera remain similar in the grassland and cropland soil. The dual-relative bacteria network evaluates from simple correlation net to very complex ones during the vegetation restoration, of which the core influenced factor alters from available nutrients to organic matter. The results of this study suggest that it will take a relatively longer period for the soil nutrient conditions and bacterial community to recover fully, although vegetation restoration could reduce the impacts of agricultural activities. This study refers to the ecological preservation and restoration strategies under the global climate change background, elucidating the nutrient metabolism variation induced by the accordance variation of organic matter accumulation and soil bacterial life strategy during the ecosystem restoration course.

Soil microbial community composition by crop type under rotation diversification

BackgroundCrop rotation is an important agricultural practice that often affects the metabolic processes of soil microorganisms through the composition and combination of crops, thereby altering nutrient cycling and supply to the soil. Although the benefits of crop rotation have been extensively discussed, the effects and mechanisms of different crop combinations on the soil microbial community structure in specific environments still need to be analyzed in detail.Materials and methodsIn this study, six crop rotation systems were selected, for which the spring crops were mainly tobacco or gramineous crops: AT (asparagus lettuce and tobacco rotation), BT (broad bean and tobacco rotation), OT (oilseed rape and tobacco rotation), AM (asparagus lettuce and maize rotation), BM (broad bean and maize rotation), and OR (oilseed rape and rice rotation). All crops had been cultivated for > 10 years. Soil samples were collected when the rotation was completed in spring, after which the soil properties, composition, and functions of bacterial and fungal communities were analyzed.ResultsThe results indicate that spring cultivated crops play a more dominant role in the crop rotation systems than do autumn cultivated crops. Crop rotation systems with the same spring crops have similar soil properties and microbial community compositions. pH and AK are the most important factors driving microbial community changes, and bacteria are more sensitive to environmental responses than fungi. Rotation using tobacco systems led to soil acidification and a decrease in microbial diversity, while the number of biomarkers and taxonomic indicator species differed between rotation patterns. Symbiotic network analysis revealed that the network complexity of OT and BM was the highest, and that the network density of tobacco systems was lower than that of gramineous systems.ConclusionsDifferent crop rotation combinations influence both soil microbial communities and soil nutrient conditions. The spring crops in the crop rotation systems had stronger dominating effects, and the soil bacteria were more sensitive than the fungi were to environmental changes. The tobacco rotation system can cause soil acidification and thereby affect soil sustainability, while the complexity of soil microbial networks is lower than that of gramineous systems. These results provide a reference for future sustainable applications of rotation crop systems.

Improving maize yield and drought tolerance in field conditions through activated biochar application

Amidst depleting water resources, rising crop water needs, changing climates, and soil fertility decline from inorganic modifications of soil, the need for sustainable agricultural solutions has been more pressing. The experimental work aimed to inspect the potential of organically activated biochar in improving soil physicochemical and nutrient status as well as improving biochemical and physiological processes, and optimizing yield-related attributes under optimal and deficit irrigation conditions. Biochar enhances soil structure, water retention, and nutrient availability, while improving plant nutrient uptake and drought resilience. The field experiment with maize crop was conducted in Hardaas Pur (32°38.37’N, 74°9.00’E), Gujrat, Pakistan. The experiment involved the use of DK-9108, DK-6321, and Sarhaab maize hybrid seeds, with five moisture levels of evapotranspiration (100% ETC, 80% ETC, 70% ETC, 60% ETC, and 50% ETC) maintained throughout the crop seasons. Furthermore, activated biochar was applied at three levels: 0 tons/ha (no biochar), 5 tons per hectare, and 10 tons per hectare. The study’s findings revealed significant improvements in soil organic matter, bulk density, nutrient profile and total porosity with biochar supplementation in soil. Maize plants grown under lower levels of ETC in biochar supplemented soil had enhanced membrane stability index (1.6 times higher) increased protein content (1.4 times higher), reduced malondialdehyde levels (0.7 times lower), improved antioxidant enzyme activity (1.3 times more SOD and POD activity, and 1.2 times more CAT activity), improved relative growth (1.05 times more) and enhanced yield parameters (26% more grain and stover yield, 16% more 1000-seed weight, 29% more total seed weight, 33% more apparent water productivity) than control. Additionally, among the two biochar application levels tested, the 5 tons/ha dose demonstrated superior efficiency compared to the 10 tons/ha biochar dose.

Rubber-Based Agroforestry Ecosystems Enhance Soil Enzyme Activity but Exacerbate Microbial Nutrient Limitations

Agroforestry ecosystems are an efficient strategy for enhancing soil nutrient conditions and sustainable agricultural development. Soil extracellular enzymes (EEAs) are important drivers of biogeochemical processes. However, changes in EEAs and chemometrics in rubber-based agroforestry systems and their mechanisms of action are still not fully understood. Distribution of EEAs, enzymatic stoichiometry, and microbial nutrient limitation characteristics of rubber plantations under seven planting patterns (RM, rubber monoculture system; AOM, Hevea brasiliensis-Alpinia oxyphylla Miq; PAR, Hevea brasiliensis-Pandanus amaryllifolius Roxb; AKH, Hevea brasiliensis-Alpinia katsumadai Hayata; CAA, Hevea brasiliensis-Coffea Arabica; CCA, Hevea brasiliensis-Cinnamomum cassia (L.) D. Don, and TCA, Hevea brasiliensis-Theobroma Cacao) were analyzed to investigate the metabolic limitations of microorganisms and to identify the primary determinants that restrict nutrient limitation. Compared with rubber monoculture systems, agroforestry ecosystems show increased carbon (C)-acquiring enzyme (EEAC), nitrogen (N)-acquiring enzyme (EEAN), and phosphorus (P)-acquiring enzyme (EEAP) activities. The ecoenzymatic stoichiometry model demonstrated that all seven plantation patterns experienced C and N limitation. Compared to the rubber monoculture system, all agroforestry systems exacerbated the microbial limitations of C and N by reducing the vector angle and increasing vector length. P limitation was not detected in any plantation pattern. In agroforestry systems, progression from herbs to shrubs to trees through intercropping results in a reduction in soil microbial nutrient constraints. This is primarily because of the accumulation of litter and root biomass in tree-based systems, which enhances the soil nutrient content (e.g., soil organic carbon, total nitrogen, total phosphorus, and ammonium nitrogen) and accessibility. Conversely, as soil depth increased, microbial nutrient limitations tended to become more pronounced. Partial least squares path modelling (PLS-PM) indicated that nutrient ratios and soil total nutrient content were the most important factors influencing microbial C limitation (−0.46 and 0.40) and N limitation (−0.30 and −0.42). This study presented novel evidence regarding the constraints and drivers of soil microbial metabolism in rubber agroforestry systems. Considering the constraints of soil nutrients and microbial metabolism, intercropping of rubber trees with arboreal species is recommended over that of herbaceous species to better suit the soil environment of rubber plantation areas on Hainan Island.

Impacts of nitrogen (N), phosphorus (P), and potassium (K) fertilizers on maize yields, nutrient use efficiency, and soil nutrient balance: Insights from a long-term diverse NPK omission experiment in the North China Plain

Context or problemSoil nutrient deficiency is one of the significant challenges in grain production, particularly nitrogen (N), phosphorus (P), and potassium (K). These deficiencies not only reduce crop yields but also cause associated environmental issues, such as soil structure deterioration and ecosystem services diminution. ObjectivesThis research aimed to investigate the long-term effects of NPK fertilizers on soil nutrient properties and maize phenology, further on the grain yield, and to evaluate the nutrient use efficiency and soil nutrient balance under different fertilization managements. MethodsA long-term field experiment was initiated in 1990 in a summer maize field in the North China Plain, including five fertilizer treatments: CK (control), NP, NK, PK, and NPK. The soil nutrient properties, maize yields, crop nutrient uptake amount, nutrient recovery efficiency (NRE), nutrient harvest index (NHI), and soil nutrient balance were annually evaluated from 2005 to 2022. ResultsSignificant improvements in maize yields were found under NPK (9081 kg ha−1), NP (6426 kg ha−1), and PK (2668 kg ha−1) compared with CK (1809 kg ha−1) and NK (1656 kg ha−1). The yield increase was mainly attributed to: (1) enhancing in soil nutrient properties, such as soil organic carbon, soil total N (TN), available N (AN), total P (TP), available P (AP), and available K (AK), and (2) the shortened vegetative period, leading to greater sunshine hours (SH) and accumulative growing degree days (GDD) during the reproductive period. Furthermore, a random forest analysis quantified their importance to grain yield, showing that the edaphic factors (mainly SOC, TN, AK, AN, TP, AP, C:N, and N:P) explained a much greater proportion of yield variation compared with phenological factors (mainly GDD during tasseling and physiological maturity stages, and SH during tasseling stage). Additionally, the significantly higher response ratio of both N and P to NRE and NHI implied that N and P fertilizers having a more pronounced impact on improving nutrient use efficiency than K fertilizer. In terms of soil nutrient balance, a most relative soil nutrient balance was detected under NPK treatment, avoiding either substantial nutrient depletion or accumulation under any nutrient deficiency conditions. ConclusionsSoil deficiencies in N and P had more severe impacts on maize yields and nutrient use efficiency compared with K deficiency. Additionally, a balanced NPK fertilizer regime effectively managed soil nutrient balance. Implications or significanceThese findings elucidate the roles of N, P, and K fertilizers in maize production and soil nutrient conditions from a long-term field experiment, which could provide valuable insights for optimizing fertilization management strategies.

Effects of Compost Application of Green Waste on Soil Properties: A Meta-Analysis

Objective: With the accelerating urbanization process, the garden area is gradually expanding, and the production of green waste is also increasing. Composting green waste can not only reduce environmental pollution caused by incineration and landfill and improve the utilization efficiency of resources but also improve the soil and increase soil productivity. The study aims to investigate the comprehensive impact of green waste compost (GWC) application on soil nutrient conditions. Through comprehensive data analysis, the impact of compost application of green waste on soil properties was revealed as a reference for compost application and fertilizer reduction. Methods: Based on meta-analysis, we quantitatively investigated the response of soil properties to the application of green waste, collected published experimental data, and integrated 25 domestic and international literature to analyze the effects of different soil properties on soil nutrients. Literature was used to analyze the impact of different application rates of GWC on the physicochemical properties of soils with varying pH levels. The results were compared to control conditions with no GWC application. Results: The application of significantly improved soil quality by reducing soil bulk density and increasing the levels of soil organic matter, organic carbon, total nitrogen, available phosphorus, available potassium, and dehydrogenase activity. The increases in available potassium and soil organic carbon were consistently significant across all subgroups. However, the effects on available phosphorus and organic matter varied in significance depending on initial soil pH. Soil bulk density was influenced by the GWC content, while dehydrogenase activity showed significant effects only when initial soil pH was ≥8. Total nitrogen levels were significantly impacted by GWC application in soil with an initial pH of <8 and at GWC contents of ≥50%. Conclusion: The application of green waste compost demonstrates a positive effect on soil improvement. This study provides a comprehensive database that supports the use of GWC in enhancing soil quality and reducing the need for chemical fertilizers.

Characteristics and Drivers of Soil Carbon, Nitrogen, and Phosphorus Ecological Stoichiometry at the Heavy Degradation Stage of the Alpine Meadow

An in-depth understanding of the soil nutrient status and balance relationship can help the effective recovery and management of alpine degraded meadows. In order to study the balance relationship among soil carbon, nitrogen, and phosphorus nutrients during the heavy degradation stage of meadows, field sampling and investigation, indoor analysis, and mathematical statistics were used to explore the characteristics and driving factors of changes in soil carbon, nitrogen, and phosphorus content, storage, and ecological stoichiometry during the heavy degradation stage of alpine meadows in the Sanjiangyuan region. The results showed that in the heavy degradation stage, miscellaneous grass plants occupied absolute dominance, soil C∶N∶P was approximately 32.83∶3.87∶0.67, and there was certain nitrogen limitation. The coefficients of variation of soil carbon, nitrogen, and phosphorus content were in the following order： organic carbon （1.09） > total nitrogen （0.63） > total phosphorus （0.29）. The organic carbon content and the carbon and nitrogen ratio showed a significant linear decreasing trend with the increase in the grassland degradation index （GDI）, while the total phosphorus content and organic carbon storage showed a significant non-linear change, in which the total phosphorus content showed a significant gentle U-shaped distribution, and the organic carbon storage decreased more gently at the beginning of the heavy degradation stage and then decreased sharply when the GDI was 57.9. The results of Mantel correlation analysis showed that the soil carbon to nitrogen ratio, carbon to phosphorus ratio, and nitrogen to phosphorus ratio showed significant correlation with organic carbon content and storage and total nitrogen storage. The results of structural equation modeling indicated that soil water content had direct effects as well as indirect through vegetation factors, soil carbon, nitrogen, and phosphorus ecological stoichiometry ratios, and soil water content and vegetation factors （height, cover, and biomass） were key environmental factors affecting soil ecological stoichiometry. The research results can provide scientific basis and practical guidance for the restoration of heavily degraded grassland in alpine meadows.

Effect of Wastewater Irrigation on Yield, Water Productivity and Economics of Sunflower and Toria Crop

Water scarcity is one of the most important issue affecting the global economy and human livelihoods. Climate change, rapid population growth, freshwater pollution and depletion are among the factors exacerbating the situation. Although not yet fully exploited, wastewater reclamation and reuse are considered potential mechanisms to mitigate the challenge. To evaluate the impact of wastewater on yield, economics, soil nutrient status, seed oil content and water productivity, a two-year experiment at farmers field in Angul, Odisha was taken up. The sunflower yield was found significantly higher with wastewater irrigation (10%) which was mainly contributed by higher head diameter (15.3 cm), no. of achenes per head (467) and 100 achene weight (69g). Similarly, toria crop irrigated with wastewater had higher yield by 11% resulting from higher siliquae per plant (179), no of seeds per siliqua (12.1) and test weight (4.6) compared to freshwater irrigation. Besides this soil nutrients and oil content was higher in wastewater irrigated toria and sunflower crop than freshwater crops. Benefit cost ratio was higher in wastewater irrigated sunflower (3.9) and toria (2.0) crop compared to freshwater irrigated crops (3.0 and 1.4 respectively for sunflower and toria). Water productivity under wastewater irrigation in sunflower (0.38 kg/m3) and toria (0.21 kg/m3) was higher than freshwater irrigated crops by 10-12%. The findings of the present study suggest that wastewater can be used as a source of irrigation for oilseed crop in Angul Odisha where water scarcity is acute during rabi season.

Nitrogen and phosphorus additions affect fruiting of ectomycorrhizal fungi in a temperate hardwood forest

The functioning of mycorrhizal symbioses is tied to soil nutrient status, suggesting that nutrient availability should influence the reproduction of mycorrhizal fungi. To quantify the effects of nitrogen (N) and phosphorus (P) availability on ectomycorrhizal fungal fruiting, we collected >4000 epigeous sporocarps representing 19 families during the course of a season in a full factorial NxP addition experiment in six replicate forest stands. Nutrient effects on fruiting shifted as the season progressed, with early fruiting species responding more to P and late-fruiting species responding more to N. The composition of species fruiting in young successional forests differed more with nutrient addition than in mature forests. Sporocarp abundance and species richness were suppressed by N addition. This work shows that N and P availability affect ectomycorrhizal fungal fruiting, with these effects taking place within a context defined by stand age and the progression of fruiting across the season.

Effect of Organic Nutrient Sources on Economics, Soil Micro Nutrient Status and Microbial Growth of Ragi under Guni Method of Cultivation

A field experiment was conducted during the kharif-2019 at the farmers field of Mylandahalli in Chikkaballapura distict of Karnataka, to study the effect of organic nutrient sources on soil micro nutrient status, microbial count and economics of finger millet under guni method. The trial was framed out in randomized blocked design with twelve treatments reproduced thrice. The results of different organic nutrient sources were showed that supplement of sericulture waste compost (SWC) @ 50% N eq. + Enriched biodigested liquid manure (EBDLM) @ 50% N eq. ha-1 + panchagavya (PG) spray @ 3% (T9) had a significant effect on micro nutrient status in soil and their values were statistically higher than all the other treatments. The findings of study reported that supplement of sericulture waste compost (SWC) @ 50% N eq. + Enriched biodigested liquid manure (EBDLM) @ 50% N eq. ha-1 + panchagavya (PG) spray @ 3% (T9) recorded significantly higher Diethylenetriamine pentaacetic acid (DTPA) extractable iron, zinc, manganese and copper in soil. Likewise, the same treatment had recorded significantly superior in population of bacteria (49.96 colony forming units (CFU) x 106 g-1), fungi (27.36 CFU x 103 g-1) and actinomycetes (14.44 CFU x 103 g-1) were noticed compared to others and found to be highest economic returns during cropping period of kharif 2019.

Studies on the effect of nitrogen, phosphorous and potassium on soil nutrient status of seed tuber production derived from apical rooted cuttings of potato (Solanum tuberosum L.) var. Kufri Badshah under central Telangana region

Studies on the effect of nitrogen, phosphorous and potassium on soil nutrient status of seed tuber production derived from apical rooted cuttings of potato (Solanum tuberosum L.) var. Kufri Badshah under central Telangana region

Deciphering soil environmental regulation on reassembly of the soil bacterial community during wetland restoration

Soil bacteria are vital to regulate biogeochemical processes in wetlands, however, little is known about the patterns and mechanisms of soil bacterial re-organization during wetland restoration. Here, we used a space-for-time substitution approach and examined the ecological processes that drive soil bacterial assembly from cultivated to restored to natural wetlands. Results showed a decrease of soil bacterial α diversity and increase of bacterial community similarity and bacterial interaction (cooperation vs. competition) with years of restoration, which was dominantly influenced by deterministic processes. Identified bacterial keystone taxa (e.g. Variibacter, Acidibacter) with nutrient metabolism capacity exerted strong positive effect on bacterial interaction. Furthermore, changes of soil water condition and nutrient status showed dominantly direct positive effects on soil bacterial reassembly, while falling soil pH significantly promoted bacterial reassembly by increasing keystone taxa and bacterial interaction during wetland restoration. Overall, findings highlighted the crucial role of environmental filtering and its pathway in influencing keystone bacterial taxa that promotes the reassembly of bacterial community during wetland restoration. Our work thus provides a new crucial and timely insight for improving the management of soil bacterial community assembly within the plethora of current and future wetland restoration projects.

Phosphorus availability influences disease-suppressive soil microbiome through plant-microbe interactions.

Soil nutrient status and soil-borne diseases are pivotal factors impacting modern intensive agricultural production. The interplay among plants, soil microbiome, and nutrient regimes in agroecosystems is essential for developing effective disease management. However, the influence of nutrient availability on soil-borne disease suppression and associated plant-microbe interactions remains to be fully explored. This study aims to elucidate the mechanistic understanding of nutrient impacts on disease suppression, using phosphorous as a target nutrient. A 6-year field trial involving monocropping of tomatoes with varied fertilizer manipulations demonstrated that phosphorus availability is a key factor driving the control of bacterial wilt disease caused by Ralstonia solanacearum. Subsequent greenhouse experiments were then conducted to delve into the underlying mechanisms of this phenomenon by varying phosphorus availability for tomatoes challenged with the pathogen. Results showed that the alleviation of phosphorus stress promoted the disease-suppressive capacity of the rhizosphere microbiome, but not that of the bulk soil microbiome. This appears to be an extension of the plant trade-off between investment in disease defense mechanisms versus phosphorus acquisition. Adequate phosphorus levels were associated with elevated secretion of root metabolites such as L-tryptophan, methoxyindoleacetic acid, O-phosphorylethanolamine, or mangiferin, increasing the relative density of microbial biocontrol populations such as Chryseobacterium in the rhizosphere. On the other hand, phosphorus deficiency triggered an alternate defense strategy, via root metabolites like blumenol A or quercetin to form symbiosis with arbuscular mycorrhizal fungi, which facilitated phosphorus acquisition as well. Overall, our study shows how phosphorus availability can influence the disease suppression capability of the soil microbiome through plant-microbial interactions. These findings highlight the importance of optimizing nutrient regimes to enhance disease suppression, facilitating targeted crop management and boosting agricultural productivity. Video Abstract.

Effect of Integrated Nutrient Management on Soil Nutrient Status in Garlic (Allium sativum L.)

An experiment was conducted during rabi season, 2021 to investigate the effect of integrated nutrient management on soil nutrient status in garlic. The study was structured around eighteen treatments with combinations of inorganic fertilizers, biofertilizers and organic manures like Jeevamrit and Beejamrit. The treatment T12 [(75 % RDF + 40 kg Sulphur/ha + Azotobacter + Phosphate Solubilizing Bacteria + FYM (25t/ha)] resulted in minimum soil pH (6.82) and electrical conductivity (0.181 dSm-1) as well as highest organic carbon (0.86 %), available Nitrogen (258.84 kg ha-1), Phosphorus (26.72 kg ha-1) contents. Further, the treatment T17 [(100 % RDF + FYM (25t/ha)] recorded maximum available Potassium (180.35 kg ha-1) and treatment T16 [(100 % RDF + 40 kg S/ha + FYM) recorded highest S (44.98 kg ha-1) contents. Thus, it can be concluded that integration of inorganic fertilizers with biofertilizers and organic manures helps in improving the soil nutrient status.

Estimation of Nutrient Uptake and Available Nutrient Status of Rabi Safflower Through Soil Test Crop Response in Rainfed Ecosystem

Background: Adoption of SSNM is directly affected by cost of fertilizer. Soil test crop response (STCR) concept attribute to contribution of soil and targeted yield level for fertilizer recommendation for a selected crop. This approach is also known as prescription based fertilizer recommendations. It is specific type of soil, climatic condition and specific location. Nutrient requirement is differ for different crops. The available soil nutrients efficient used and added to those available soil nutrients through fertilizers is different for different type of soil geography under a particular set of climatic conditions. Methods: A research experiment was carried out during rabi 2017-18, 2018-19 and 2019-20 at Research Farm of Agronomy, Dr. P.D.K.V, Akola (Maharashtra). Fertilizers were applied based on uptake pattern of crop, target yield levels and soil test values. The experiment was laid out in FRBD-Factorial randomized block design with two factors. Total 15 treatment combinations were formed which replication 4 times. Result: Significantly greater uptake of nitrogen (62.76, 74.67 and 81.89 kg ha-1), phosphorus (19.15, 24.32 and 29.38 kg ha-1), potassium (80.32, 92.14 and 99.18 kg ha-1), sulphur (18.46, 24.10 and 26.03 kg ha-1) and zinc (493.97, 571.01 and 620.91 g ha-1) recorded in treatment where crop supplied with farm yard manure @ 5 t ha-1 than rest of treatments during 2017-18, 2018-19 and 2019-20, respectively. A similar trend was observed in respect of soil nutrient status such as available N, P2O5, K2O, S and Zn. Application of fertilizers through soil test crop response equation with zinc sulphate @ 25 kg ha-1 and Sulphur @ 10 kg ha-1 registered maximum total uptake of nitrogen (66.89, 78.99 and 90.06 kg ha-1), phosphorus (20.78, 25.31 and 31.96 kg ha-1), potassium (86.05, 97.99 and 109.09 kg ha-1), sulphur (20.27, 26.39 and 29.80 kg ha-1) and zinc (537.78, 618.06 and 696.21 g ha-1) than rest of nutrient management treatments during three years of field experiment, respectively. The same trend was observed with respect to available N, P2O5, K2O, S and Zn under respective treatment during three years of experimentation.

Different seasons and vegetation cover more than fire control nutrient stoichiometry and biological activities in Mediterranean soils

Mediterranean soils are affected by degradation phenomena, exacerbated by anthropic disturbance. These ecosystems are affected by peculiar climatic conditions, characteristic vegetation and frequent fire that with the anthropic activities can compromise soil nutrient status. Studies concerning the nutrients stoichiometry in Mediterranean area are scarce, therefore the present research aim to fill the gap about the effect of seasonal variations, vegetation cover and fire occurrences on soil nutrient balance and microbial biomass and activity. The sampling was performed inside the Vesuvius National Park across 24 sites during two seasons (Fall and Spring), under trees and shrubs and in burned and unburned areas. Soils were characterized for carbon (C), nitrogen (N), phosphorous (P) and potassium (K) concentrations, for bacterial and fungal biomass (Eub and Fungi) and for microbial activities (respiration, hydrolase: HA, dehydrogenase: DHA, β-glucosidase: β-glu and urease: U). The results showed that, both in Fall and Spring, high C:N (18.7), C:P (130) and N:P (6.74) ratios were observed in soils under trees. Both in soils under trees and shrubs, low eubacterial biomass (trees: 90.2 ng g−1 w.w.; shrubs: 44.4 ng g−1 w.w.), respiration (trees: 0.24 mg CO2 g−1 d.w. min−1; shrubs: 0.14 mg CO2 g−1 d.w. min−1) and hydrolase (trees: 37.0 mmol FDA g−1 d.w. min−1; shrubs: 11.9 mmol FDA g−1 d.w. min−1) activities were observed in Spring. Fire effect was evident only in Fall where low values of eubacterial biomass (667 ng g−1 w.w.) and respiration activity (0.60 mg CO2 g−1 d.w. min−1) were observed in burnt soils. In conclusion, the seasonal variations and the vegetation cover appeared the main environmental factors that affect nutrient stoichiometry and microbial biomass and activity in Mediterranean soils. It is necessary to monitor Mediterranean soils during different seasons and encourage the growth of native vegetation to enhance nutrient cycling and maintain soil health.