Journal of the Indian Society of Soil Science
Journal of the Indian Society of Soil Science is the periodical brought out quarterly since 1953 (March, June, September and December) and it covers all aspects of soil study. The Society organizes seminars, symposia, conferences, meeting etc. enables members of ISSS and others to interact and disseminate knowledge on soil and land. Annual Convention of the Society is held regularly. This Society has celebrated its Golden Jubilee in 1984, Diamond Jubilee in 1994 and Platinum Jubilee in 2009. EDITORIAL BOARD Subscription Information for Print Version
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Nitrogen and Phosphorus Mineralization Pattern and Microbial Count in Phosphate Rich Organic Manure (PROM) Amended Soil
Comparative Assessment of Integrated Fertilization Approaches on Finger Millet Quality and Soil Properties in North-Western Himalayas
Climate change induced soil degradation and progressive nutrient depletion are emerging as critical constraints for global food security, particularly in hill agroecosystems. In this context, integrated nutrient management (INM) offers a holistic and ecologically sustainable strategy to improve crop productivity and soil fertility. Therefore, a field experiment was laid out during kharif 2024 (one year) on finger millet as the test crop to evaluate the effect of INM practices on primary macronutrients’ content, uptake and soil chemical properties. The study included nine nutrient management practices (T1: FYM @ 5 t ha-1, T2: N40P20K0 + FYM @ 5 t ha-1, T3: N40P20K20 + FYM @ 5 t ha-1, T4: N60P30K20 + FYM @ 5 t ha-1, T5: N40P20K0 + FYM @ 5 t ha-1 + Azospirillum, T6: N40P20K20 + FYM @ 5 t ha-1 + Azospirillum, T7: N60P30K20 + FYM @ 5 t ha-1 + Azospirillum, T8: natural farming practices, T9: organic farming practices) which were replicated thrice in a randomized block design. The results revealed that conjoint application of N60P30K20 + 5/ t/ ha-1 FYM + Azospirillum (T7) recorded the highest content of nitrogen (N) (1.34%), phosphorus (P) (0.27%) and potassium (K) in grains and total uptake of N, P and K (55.66, 11.31 and 94.78 kg ha-1, respectively) by finger millet. Further, similar treatment recorded maximum soil available P (29.58 kg ha-1). Subsequently, organic practices (T9) significantly improved bulk density. Correlation analysis revealed significant and positive relationship between N, P and K uptake with available N and P, while available K showed nonsignificant relationship. Soil pH exhibited a significant negative correlation with nutrient uptake. Overall, the findings emphasize that combined use of fertilizers, FYM and Azospirillum is an effective strategy for enhancing nutrient uptake and productivity of finger millet under hill conditions.
Agronomic Performance of Tomato to Calcium and Magnesium Sulphate Amendments under Alluvial Plains of Punjab
Punjab region’s crop productivity potential and soil health has been compromised through the continual NPK and imbalance secondary nutrients application. Decreased application of secondary and micronutrients have resulted in severe nutritional deficiencies in crop and soil, and therefore, lowered the overall crop productivity. For investigation, open field experiments were conducted during 2022-23 and 2023-24 under randomized block design (RBD) at research farm, UIAS to evaluate the tomato growth performance and nutrients uptake to varying levels of CaSO4 (75 and 150 kg) and MgSO4 (50 and 100 kg) amended with NPK sources (Urea, SSP and MOP). Nine treatments with three replications comprised of varying Ca and Mg levels along with NPK sources have been selected and tested for two years. Results showed that the Ca and Mg based treatments showed high vigor in improving the crop growth and improved the soil nutrients pool. T5 (100% RDN NPK + Mg @ 100 kg ha-1) showed its supremacy over the other treatments with maximum plant height of 199.73 cm at maturity, fruit/plant (27.64 and 28.51 kg), yield/plant (2.64 and 2.99 kg) and fruit yield/100 m2 (1056.96 and 1081.29 kg). Similar treatment (T5) significantly improved the leaf and fruit NPK content over the sole NPK based treatment. Data on leaf and fruit Ca and Mg content revealed that maximum leaf Ca (2.27 and 2.29%) in T4, fruit Ca (2.16 and 2.18%) in T3, leaf Mg (1.26 and 1.29%) and fruit Mg (0.41 and 0.45%) was recorded under T7 treatment. Moreover, T7 treatment also showed its potential with highest Ca and Mg accumulation of 491.42 and 253.98 ppm in soil in respective years. Therefore, the study identified the T5 and T7 treatments as potent returning higher crop production and quality indices and also restored the soil with balanced Ca: Mg ratios along with other nutrients.
Unraveling the CO2–Microbe Nexus: A Conceptual Framework for Nitrogen Fixation Efficiency in Legume–Rhizobium Systems
Elevated atmospheric CO2, a principal driver of anthropogenic climate change, imposes emerging constraints on symbiotic nitrogen fixation (SNF), particularly within legume–Rhizobium systems. This study critically assesses the impact of CO2 enrichment on nitrogen fixation efficiency (NFER) in Rhizobium spp., a microbial process essential for sustainable crop productivity. Literature search across Scopus and ScienceDirect identified 2,066 peer-reviewed articles, of which 39 met rigorous inclusion criteria focused on plant–microbe interactions under elevated CO2 conditions. To mechanistically synthesize current understanding, we propose a conceptual framework defining NFER as a function of three core parameters: nodule formation and development rate (N), symbiotic connection efficiency (S), and genetic expression and regulation (G). Evidence from the reviewed studies indicates that elevated CO2 can reduce nodulation efficiency by up to 30%, disrupt symbiotic signaling pathways, and impair transcriptional regulation critical for effective nitrogen fixation. These interlinked perturbations contribute to a systemic decline in NFER, threatening agroecosystem resilience and global food security under projected climate scenarios. This synthesis highlights key vulnerabilities in legume–Rhizobium symbioses and delineates strategic knowledge gaps, providing a foundation for targeted quantitative research into microbial adaptation under atmospheric CO2 enrichment.
Effect of Potassium Fertilization on Quality of Potato (Solanum tuberosum L.)
A screen house was conducted to evaluate the effect of applied potassium (K) (0 and 60 kg K2O ha-1) on potato quality parameters planted on 30 different surface (0-15 cm) soils. The field experiments including five levels of K (0, 15, 30, 45, 60 and 90 kg K2O ha-1) were also conducted at four field sites to validate the results obtained from the pot study. Tuber yield, uptake and quality parameters include tuber size, reducing sugars content, tuber color and specific gravity were studied. The results from pot study showed that the tuber yield and uptake increased significantly with addition of 60 kg K2O ha-1 in one-third and one-fourth of the 30 soils whereas tuber size did not show significant increase with the K application of 60 kg K2O ha-1 compared to no K. The reducing sugar content of tubers also showed inconsistent significant decrease with K application. The one-third samples showed negative impact of applied K on the reducing sugars. The reducing sugar weakly but significantly correlated with tuber K uptake (R2=0.141). Tubers received K application were significantly lighter (L) in colour compared with tubers without K. The inconsistent significant effect of K application on specific gravity in all soils were reported. In field experiments, similar inconsistent response of K on plant indices and quality parameters were measured. The results suggest that K addition in soils with low, medium and high exchangeable K causes negative influence on crop yield and its quality.
Effect of Organic Manures and Fertilizers on Potassium Fractions in Coastal Saline Soil under Rice
A field experiment was carried out with no manure, farmyard manure, Glyricidia sepium, Sesbania aculeata, Thespesia populnea, no fertilizers, the recommended dose of fertilizers, Konkan Annapurna briquettes, and urea-diammonium phosphate briquettes in coastal saline soils of Maharashtra during kharif season 2023 to examine how different nutrient management practices influence the availability of potassium with rice as test crop. Results indicated that the maximum (100.33 mg kg-1) water-soluble K+ was observed with treatment receiving recommended dose of fertilizers + 10 t Glyricidia ha-1 at tillering stage, however, the highest exchangeable K+ (579 mg kg-1) was recorded with the integration of Glyricidia and Konkan Annapurna briquettes @ 170 kg ha-1 at panicle initiation stage. The significantly highest non-exchangeable K+ (1056 mg kg-1) was observed at harvest stage with Urea-Diammonium Briquettes (UB-DAP) which was placed without manure. There was significantly higher lattice K+ (9117.00 mg kg-1) with UB-DAP @ 170 kg ha-1 along with Thespesia @10 t ha-1 during harvest stage. The data showed that the water-soluble and exchangeable K got declined from tillering stage to harvest stage and the available K was low during tillering and panicle initiation but increased at harvest of the crop. Non-exchangeable K increased from tillering to harvest stage, however, lattice K and total K were declined from tillering to harvest stage. The sequence of K+ fractions followed the order as: total K+ > lattice K+ > non-exchangeable K+ > exchangeable K+ > water-soluble K+. The combination of Gliricidia sepium and Sesbania aculeata with chemical fertilizers was effective in sustaining the elevated potassium levels and reducing the decline of reserve soil K, particularly in the early and mid-growth phases of rice crop in saline coastal soils.
Influence of Organics and Inorganics on Microbial Population and Enzyme Activities in the Rhizosphere of Kiwifruit (Actinidia deliciosa) in Western Himalayas
Very limited information is available on how different nutrient management practices influence soil microbial populations and enzyme activities (dehydrogenase and acid phosphatase), especially in the lower Himalayan soils of India. To address this gap, we evaluated three nutrient management approaches—Subhash Palekar’s Natural Farming System (SPNFS), an Organic Farming-Based System (OFBS), and a Chemical Fertilizer- Based System (CFBS) using six-year old kiwifruit (Actinidia deliciosa cv. Allison) as test crop at Dr. Y.S. Parmar University of Horticulture and Forestry, Solan, Himachal Pradesh during 2018–19 and 2019–20. Here three nutrient management systems were tested to assess the changes in soil microbial populations and enzyme activities in the surface (0–15 cm) and sub-surface soil (15-30 cm) soil layers. The SPNFS-based treatment having 30 L Jeevaamrit, 3 kg Ghana Jeevaamrit, and 40 kg FYM per vine, recorded the highest biological activity (pooled analysis) and had bacterial, fungal, and actinomycetes populations of 200 × 105, 25 × 10³, and 22 × 10³ cfu g-¹ soil, respectively. Correspondingly, dehydrogenase activity increased to 35.8 μg TPF g-¹ h-¹ and acid phosphatase activity reached to 119.8 μg PNP g-¹ h-¹. The treatment having 100% recommended dose of N through vermicompost + poultry manure on 50:50 basis + 40 kg FYM resulted in bacterial, fungal and actinomycetes populations to the tune of 166 × 105, 19 × 10³ and 13 × 10³ cfu g-¹ soil, respectively, along with dehydrogenase activity of 34.6 μg TPF g-¹ h-¹ and acid phosphatase activity of 116.5 μg PNP g-¹ h-¹, wherein lowest values were observed in T1 (800 g N, 600 g P2O5, 800 g K2O and 40 kg FYM. There was a strong positive association between acid phosphatase activity and bacterial population (r=0.934**), fungal population (r=0.807**), and actinomycetes population (r=0.786**). Acid phosphatase activity was highly correlated with dehydrogenase activity (r=0.894**), suggesting that improved microbial abundance directly enhances the soil enzymatic activity in the rhizosphere of kiwifruit.
Fertilizer Prescriptions Equation for Targeted Yield in Onion under Integrated Plant Nutrient Management System in an Inceptisol
A field experiment was conducted on onion under soil test crop response correlation studies in Varanasi region of Utter Pradesh during rabi 2024-25. Multiple regressions have been calibrated for predicting onion yield through soil and fertilizer nutrients and their interactions. The models were found to have a high and significant predictability value. Using the data, fertilizer adjustment equations have also been developed for prescribing optimum fertilizer doses for attaining different yield targets. Soil test data, bulb yield and NPK uptake by onion were used for achieving four important basic parameters, viz., nutrients required (NR) to produce one quintal of onion bulb contribution of nutrients from fertilizers (% CF), contribution of nutrients from soil (% CS) and contribution of nutrients from organic matter-FYM (% COM). It was found that 0.35, 0.10 and 0.25 kg of N, P2O5 and K2O, respectively were required for producing one quintal onion bulb yield. The per cent contribution of nutrients from soil, fertilizer and FYM were 27.70, 62.37 and 22.08 for N; 12.76, 46.36 and 31.98 for P2O5 and 7.72, 4.80 and 6.79 for K2O, respectively. By using these basic parameters, ready reckoner of fertilizer doses was prepared for varying soil test values and desired bulb yield targets of onion using NPK alone and NPK with FYM.
Behaviour of Biochar as an Amendment for Soil Physico-chemical and Biological Properties in Acidic Soil of West Bengal
A 60-days laboratory incubation study was carried out after applying bamboo biomass-derived biochar to an acidic soil of West Bengal. The results showed that the application of 5, 10, 15, and 20 g kg-1 of soil (w/ w basis) of bamboo biochar significantly affected the physical (particle density, porosity, water holding capacity) and chemical (pH, EC) properties of the soil as well as the enzymatic activities (dehydrogenase, acid phosphatase, and cellulase). As the amount of biochar increased, an increase trend in pH was observed. In comparison to treatments B15 (BioC @ 15 g kg-1 of soil), B10 (BioC @ 10 g kg-1 of soil), B5 (BioC @ 5 g kg-1 of soil), and B0 (control), the EC of soil for B20 (applied BioC @ 20 g kg-1 of soil) was 19.67, 36.06, 46.62, and 52.45% higher, respectively. For every incubation period, a decrease in particle density was followed by an increase in the amount of biochar applied. Following incubation, treatment B20 had the maximum porosity (46.74%), which was statistically higher than all other treatments. For every incubation phase, raising the WHC was followed by raising the biochar levels. In comparison to all other treatment levels B5, B10, and B15, treatment B0 had the lowest dehydrogenase activity in the soil. According to our findings, adding biochar as an amendment to acidic soil promoted a healthy physical, chemical, and biological environment, all of which improved the soil’s quality.
In-depth Insights into Zinc Desorption Kinetics from Inceptisols Using Mathematical Models
Four mathematical models viz. simple Elovich, two-constant rate, parabolic diffusion and parabolic double diffusion adequately described zinc desorption kinetics by DTPA from 10 selected Inceptisols from two watersheds of Gaya district, Bihar, for extraction periods from 0.083 h to 48 h and were evaluated for determination of rate constants of the respective models. The mean values of initial Zn desorption rate constant ‘a’ (two-constant rate), ‘αs’ (simple Elovich), diffusion rate constant ‘kp’ (parabolic diffusion), first diffusion rate constant ‘k/ p’ and second diffusion rate constant ‘k//p’ (parabolic double diffusion) were 10.82×10-2 (mg kg-1s-1) b, 96.46×10-4 (mg Zn kg-1 s-1), 1.17×10-3 (mg kg-1)-0.5, 2.67×10-3 (mg kg-1)-0.5 and 0.73×10-3 (mg kg-1)-0.5, respectively. The mean values of desorption rate coefficient ‘b’ (two-constant rate) and zinc desorption constant ‘βs’ (simple Elovich) were 0.19 (mg Zn kg-1 s-1) and 15.92 (mg Zn kg-1 s-1), respectively. The desorption rate for all the soils included an initial short-term fast reaction followed by a long-term slower continuing reaction. Soil sample S8, having highest values of rate constants ‘ab’ (twoconstant rate); ‘kp’, ‘k/ p’, ‘k//p’ and higher value of rate constant ‘αs’ (associated with lowest value of zinc desorption constant ‘βs’) indicated highest rate of Zn desorption, among the studied soils. Correlation coefficients between rate constants and soil properties revealed oxalate extractable Fe (Feo), representing poorly crystalline or amorphous iron oxides, to be the most important soil factor controlling Zn desorption from the Inceptisols under investigation. The data generated from this study might be crucial for informed decisions towards optimizing nutrient management and reduced environmental impact.
Spatial Variability of Soil Physicochemical Properties in the Mid-Central Table Land Zone of Odisha: A Geostatistical Approach
Soil is a dynamic body exhibiting spatial variability both at micro- and macro-levels. Spatial distribution maps of various physicochemical soil properties, generated using geostatistical tools, are considered more effective for soil management than traditional methods. The objectives of the present study were to assess the spatial variability of different physiochemical properties of soil viz., sand (%), silt (%), clay (%), water holding capacity (WHC) (%), bulk density (BD) (Mg m-3), pH, and electrical conductivity (EC) (dS m-1) of Tangi-Choudwar block situated in the Mid-Central Table Land of Odisha, India and prepare spatial variability map for the region. Total of 193 soil samples were collected from sampling grids spaced 200 meters apart, from a depth of 0 to 15 cm using a GPS device to record the coordinates. Statistical and geostatistical analyses were performed to characterize the spatial distribution of soil physicochemical properties using various kriging models. The results revealed considerable variability among the properties, particularly for sand, silt, clay, and water holding capacity (WHC), with coefficients of variation (CV) of 143, 47.53, 75.82, and 61.04%, respectively. In Semivariogram analysis properties namely, sand, WHC, pH, and EC fitted well with the Gaussian model Instead, the variability of silt, clay and BD were well explained by exponential and spherical models. Apart from water holding capacity (WHC), all properties exhibited moderate spatial dependence, with nugget-to-sill ratios ranging from 29 to 70%. The regionspecific soil maps will be beneficial to both farmers and policymakers, as they will facilitate the adoption of precision agriculture through site-specific nutrient management and ensure the efficient allocation and application of inputs.
Geostatistical Estimation and Mapping of Surface Soil Properties using Ordinary Kriging Approach in the Middle Indo-Gangetic Plains of India
The point measurement of common soil properties and their use in fertilizer predictions over an area in India has often backfired due to large existent spatial variability. Mapping of soil properties with acknowledge of its spatial variability has widespread applications in environmental modelling, precision farming and sustainable agriculture. Hence a study was carried out in the middle Indo Gangetic plain zone of India to map the spatial variability of some important soil properties that are used in fertilizer predictions. A total of 280 surface soil samples from the plough layer (0–15 cm depth) were collected and analyzed for pH, electrical conductivity, organic carbon, available P, available K, sand, silt and clay. The values of these properties ranged from 5.12 to 9.20, 0.01 to 1.71 dS m-1, 1.2 to 8.70 g kg-1, 8.27 to 24 kg ha-1, 114.9 to 277.8 kg ha-1, 19.0 to 58.0%, 13.7 to 56.0 % and 12.5 to 52.5%, respectively following non-normal distribution for electrical conductivity and normal distribution for rest of the parameters. The coefficient of variation was highest for organic carbon (43.7%) and lowest for soil pH (0.15%), suggesting that use of arithmetic mean and standard deviation would serve as a poor estimator of these parameters for unknown locations. Geostatistics revealed that Gaussian model best fitted the experimental semi-variogram for pH and sand content; exponential model for organic carbon, available P, available K, silt and clay content and spherical model for electrical conductivity. The nugget/sill ratio indicated that all the studied soil properties were strongly spatially dependent except pH and sand content, which were moderately spatially dependent. Cross validation statistics showed that the surface soil maps prepared by ordinary kriging were robust and would sever much better when predicating values of the soil parameters in unsampled locations, often need in modelling at the landscape scale, and could serve as a primary guide for identifying management zones for precision farming and region-specific nutrient management and designing future soil sampling strategies in the intensively cultivated soils of the middle Indo Gangetic plains of eastern India.
A large proportion of soils of agroecosystems of India are degraded and depleted of their soil organic carbon (SOC) stock. Soils of arid and semi-arid regions have a relatively higher soil inorganic C (SIC) content. Whereas SOC content decreases with plowing, crop residues removal or burning and intensive grazing, SIC stock is vulnerable to acidification by use of nitrogenous fertilizers. Thus, degraded and depleted soils of India have a large soil C deficit and a high soil C sink capacity. Land use and agricultural practices which enhance SOC content are conservation agriculture, residue retention, elimination of in-field burning of residues, controlled grazing and use of organic amendments. Increasing SOC content in the root zone has a positive impact on crop yield and increase in over all agronomic productivity, and sequestering C through sustainable soil management can be a solution to climate change mitigation. However, gain in SIC content may have a little if any impact on crop yield. Farmers can be incentivized for enhancing soil C stock through payments for ecosystem services (PESs) at the rate of US $50 per credit (INR ~4600) or an appropriate social value of soil C. There is a strong need for Soil Health Act at district, state and national level. The Bharat Soil Protection Policy (BSPP) being developed by ICAR is a useful start in promoting carbon farming and recarbonization of soils of India.
Honorary Members of the Indian Society of Soil Science
Honorary Members & Fellows of the Indian Society of Soil Science
Effect of Sulfur and Zinc on Soil Health Parameters and Yield of Rice (Oryza sativa L.) in Alluvium of Prayagraj, India
Assessment of Soil Moisture Extraction Pattern under Deficit Irrigation of Wheat Crop for Varanasi Region, Uttar Pradesh
Soil Fertility and Mineralogy of the Litchi-supporting Soil of Muzaffarpur District, Bihar
Distribution Pattern of Micronutrients in Relation to Soil Properties in Pipli and Thanesar Blocks of Kurukshetra
A detailed study of spatial variations in soil fertility is essential for implementing precise and sustainable nutrient management practices. The present study was carried out soil micronutrients status of Pipli and Thanesar blocks of Kurukshetra district, Haryana using geographic information system (GIS) and global positioning system (GPS). A total of 220 geo-referenced soil samples were collected from a depth of 0–15 cm across 110 villages, and the data was analysed and mapped using GIS tools (ArcGIS 10.2). The soils in both blocks were found to be neutral to alkaline in reaction and non-saline in nature. The mean concentrations of available micronutrients in the Pipli block were 1.79 mg kg-1 for Zn, 8.49 mg kg-1 for Fe, 1.34 mg kg-1 for Mn, and 3.51 mg kg-1 for Cu. Corresponding values in the Thanesar block were 1.90 mg kg-1 (Zn), 7.67 mg kg-1 (Fe), 1.04 mg kg-1 (Mn), and 3.39 mg kg-1 (Cu). While the levels of manganese were consistently sufficient across all samples, other micronutrients exhibited spatial variability. No significant correlation was observed between the availability of these micronutrients and soil pH or electrical conductivity. These findings underscore the importance of localized soil fertility assessments for precision nutrient management strategies.
Assessment of Mycorrhizal Inoculant Effect on Sorghum Growth Performance and Soil Physical Properties in Andosol
Arbuscular mycorrhizal fungi (AMF) play a vital role in enhancing plant growth and soil health through symbiotic nutrient exchange. This study evaluated the effects of vesicular-arbuscular mycorrhizal (VAM) inoculation on the growth and physiological responses of Sorghum bicolor (L.) Moench under controlled greenhouse conditions at Tokai University, Japan, from August to September 2025. A completely randomized design with three treatments comprising commercial AMF inoculum, sterilized inoculum, and non-inoculated control was applied to plants grown in sterilized Andosol soil mixed with vermiculite. Growth parameters, including plant height, stem diameter, chlorophyll content, and soil electrical conductivity (EC) were measured weekly. Biomass traits and soil bulk density were assessed at harvest. Microscopic analysis confirmed AMF colonization through the presence of hyphae, spores, and vesicles. Data were analyzed using ANOVA and Tukey’s test at a 5% significance level. Results showed no significant differences in early vegetative traits; sterilized inoculum slightly enhanced plant height, reaching 61.5 cm, representing a ~4.8% increase compared to the non-inoculated treatment (58.7 cm). Root biomass was also higher under sterilized inoculum, with fresh root weight reaching 12.1 g, approximately 27% greater than the non-inoculated treatment (9.5 g). Soil EC remained low and stable (0.062–0.086 dS m-1), while bulk density was significantly lower in the non-inoculated treatment (0.290 g cm-3) compared with inoculated treatments (0.650–0.652 g cm-3). These findings suggest that while physiological responses were initially uniform, specific treatments influenced vertical growth and soil structure, highlighting the potential of AMF in sustainable sorghum cultivation.
Seed Inoculation of Rhizobium sp. and Plant Growth Promoting Rhizobacteria in Mungbean Influenced the Dynamics of Mineral N in Soil during Succeeding Wheat
of nitrogen fixing and returning carbon input in soil. Inoculation of legumes with Rhizobium sp. and plant growth promoting rhizobacteria (PGPR) is recommended for improving biological nitrogen fixation (BNF), yields and enhancing soil fertility. This study aimed to examine the effect of microbial inoculation in mungbean on yields and mineral N release behavior during succeeding wheat in a field study conducted for 2 years in a sandy loam soil of terai region, Pantnagar, Udham Singh Nagar, Uttarakhand, India. Microbial inoculation treatments in mungbean consisted of individual and conjoint use of Rhizobium sp. and PGPR and an uninoculated control. The succeeding wheat crop was raised with 3 N levels of 50, 75 and 100% recommended dose of fertilizers (RDF). Results revealed that mineral nitrogen (NH4 +–N + NO3 ––N) and NH4 +–N in the soil decreased with increasing crop age under all the treatments, however, NO3 ––N in soil increased with crop age. The reduction in soil mineral N at different intervals varied with different treatments, being minimum under Rhizobium sp.+ PGPR and maximum under RDF at 148 days. This treatment was followed by Rhizobium in reduction of soil mineral N content. The mineral N content increased due to combined inoculation of Rhizobium sp. + PGPR by 41.3, 46.1, 62.9, 67.3 and 72.5% higher than no inoculation and 14.8, 16.8, 21.3, 23.7 and 26.3% than PGPR alone inoculation treatments at 28, 58, 88, 118 and 148 days after sowing (DAS), respectively. NH4 +–N content in soil also indicated similar pattern registering maximum content with Rhizobium sp. + PGPR and minimum with uninoculated control at similar observational intervals. The NO3 ––N in soil increased with crop age. Treatment of Rhizobium sp. alone and Rhizobium sp. + PGPR were statistically comparable and recorded significantly more NO3 ––N in soil than the uninoculated control, PGPR alone and RDF treatments. It could be concluded that application of diazotrophic bacteria Rhizobium sp., alone or in combination with PGPR in preceding mungbean crop had positive impact on soil mineral N content and grain yields of succeeding wheat, irrespective of fertilizer N levels.
Release Kinetics and 16S rRNA Gene Sequencing of Zinc Solubilizing Bacteria Screened from Zinc Deficient Paddy Soils of Northeast Region of India
Low solubility of insoluble zinc (Zn) complexes and low fertilizer Zn use efficiency owing to a range of soil conditions results in Zn deficiency in paddy soils, which also limits rice productivity. In the present study, prospective Zn-solubilizing bacteria (ZSB) were screened from Zn-deficient paddy soils of northeast (NE) India to assess their ability to solubilize insoluble Zn compounds. Thirteen isolates of ZSB were retrieved following the qualitative assay for clear halo zone formation and Zn solubilization index (ZSI) in modified Pikovskaya’s agar plates containing ZnO (0.12%) and Zn3(PO4)2.2H2O (0.22%) separately. Quantitative release of diethylene triamine penta-acetic acid-extracted (DTPA)-Zn, pH change, and Zn release kinetics were evaluated for the isolates in liquid medium using ZnO following 40 days of incubation. 16S rRNA gene amplification and sequence analysis were used to identify ZSB isolates with a high capacity to solubilize ZnO. The isolates were identified as Bacillus subtilis, Pseudomonas putida, Pseudomonas aeruginosa, Paraburkholderia tropica and Bacillus circulans. The isolate Bacillus subtilis ZSBK95 showed the largest clear halo zone (38 mm), with a ZSI of 4.22 and a cumulative release of DTPA-Zn (205.56 μg mL-1 in the medium containing ZnO. Similarly, the higher initial mineralization rate (7.75 μg mL-1 day-1) was observed for Bacillus subtilis ZSBK95. A significant (p<0.05) drop in pH (5.07- 6.10) from the initial value (pH 7.0) was observed in all the ZSB isolates during the incubation period, along with corresponding release of DTPA-Zn, which was reflected as a strong negative correlation (-0.838, n=56, p≤0.01) between pH drop and Zn solubilization. The results indicated that the five identified ZSB isolates have high potential for application as biofertilizers in Zn-deficient paddy soils.
Distribution of Potassium Fractions in Soils under Different Land Uses in Coastal Region of Raigad District, Maharashtra
The distribution of different potassium fractions in nine typical pedons, associated with different land uses (grassland, paddy, fallow land) in the coastal region of Raigad district, Maharashtra were studied. The soils were clay loam to silt loam in texture and their pH varied from 5.05 to 6.60 electrical conductivity from 0.15 and 20.10 dS m–1. The surface horizon of grassland had higher organic carbon (> 20 g kg–1) than the paddy-growing soil and in general, soil organic carbon showed positive correlation with lattice and total K, but was inversely related to exchangeable K. Fallow land showed higher water-soluble, exchangeable and available K in the surface horizon than the cultivated soils. Soil pH had inverse relationship with lattice and total K, while it was positively related to available K. Clay content was inversely related to nonexchangeable, lattice, and total K, whereas, silt content had a negative association with water-soluble, available K, but a positive relationship with lattice K. In contrast, sand content had a strong positive relationship with water-soluble and available K. Water-soluble potassium showed a strong positive correlation with all K-forms barring lattice K. Exchangeable K and available K had significant positive relationship with available K and non-exchangeable K. There was a positive correlation between nonexchangeable and total K, lattice and total K. Amongst the different K fractions, total K followed by lattice K, was highest in all the land uses. In paddy field, the order for K fractions was as total K > lattice K > available K > non-exchangeable K > exchangeable K > water-soluble K while the order for other fractions differed in soils of grassland and fallow land.
Eco-Friendly Induction of Systemic Resistance against Insect Pests and Diseases in Vegetables Using Neem-Enriched Organics and Inoculation of Beneficial Soil Microbes
The overuse of agrochemicals, along with intensive irrigation, has led to an escalation in insect pests and disease infestations in vegetable crops, causing significant economic losses and environmental and health hazards. In contrast, neem-added organic manure enriched with plant growth-promoting micro-organisms (PGPMs) has proven to be an effective organic amendment for organic vegetable production, improving soil quality and strengthening plants’ natural defence against insect pests and diseases. A long-term experiment was conducted from 2019-20 to 2023-24 at the College of Agriculture, Sumerpur-Pali, to examine the impact of six different combinations of chemical fertilizers and neem-added organic manures, along with plant growth-promoting microorganisms, on the induction of systemic resistance in various vegetable crops. The results showed that replacing chemical fertilizers by neem-added organic manure, in presence of PGPMs, significantly enhanced the plants’ ability to defend themselves and reduced insect pests and disease damage in comparison to chemical fertilizers across various vegetables by 75.51% in potatoes, 67.40% in onions, 71.81% in radishes, 65.47% in tomatoes, 63.80% in brinjal, and 64.57% in okra. These findings highlight the vital role of neem-added compost and beneficial soil microbes in inducing systemic resistance, reducing the need for agrochemicals, and improving food safety.
Unravelling the Key Drivers of Soil Organic Carbon (SOC)Dynamics: A Comprehensive Review and Meta-Analysis
Soil organic carbon (SOC) is a vital component of soil and plays a dynamic role in the soil ecosystem, including soil health, agriculture, and climate change. Despite extensive regional-level studies on individual drivers, research lacks an integrated cause-and-effect relationship and identification of universal patterns. This review aims to prepare a relationship model of SOC drivers, depth-dependent variability, and management techniques. For this review, 2100 articles were identified using Google Scholar and ScienceDirect. After screening, 110 papers were selected for detailed review. Furthermore, to examine SOC variability in different ecosystems, data on SOC depth profiles were collected from previous studies and analysed using SPSS and Microsoft Excel. The results show that SOC maintains a positive relationship with rainfall, clay content, soil management, and organic farming, and a negative relationship with temperature, intensive agriculture, erosion, and soil pH. Meta-analysis reveals SOC decreases with depth, and grasslands contain higher SOC followed by forests and croplands. Collectively, the review suggests a need for better strategies and approaches to maintain soil health, increase food security, and address climate challenges.
Unravelling the Key Drivers of Soil Organic Carbon (SOC) Dynamics: A Comprehensive Review and Meta-Analysis
Soil Organic Carbon Stocks and Spatial Variability in Urban Green Spaces: Insights from the Kalyan–Dombivli Municipal Corporation, Mumbai Metropolitan Region, India
within the Kalyan–Dombivli Municipal Corporation (KDMC) in the Mumbai Metropolitan Region, India. A total of 102 composite soil samples were collected from 30 ward groups representing residential, agricultural, and mixed land-use zones at two depths (0–15 cm and 15–30 cm). Laboratory and geospatial analyses quantified SOC distribution, depth-wise variation, and land-use influence. Results revealed high mean SOC concentrations (≈10.9%) and substantial average carbon stocks (~404 t C ha-1 within 0–30 cm). Surface soils exhibited slightly higher SOC than sub-surface layers, though the latter contributed nearly half of the total carbon pool, indicating deep carbon stabilization. Spatial mapping identified distinct carbon “hotspots” (>450 t C ha-1) in vegetated residential and institutional areas such as Kala Lake and Titwala, whereas disturbed and compacted peri-urban zones recorded lower stocks (<250 t C ha-1). Despite moderate variation across land-use categories, sustained vegetation cover emerged as the dominant factor influencing SOC accumulation. These findings underscore that tropical urban soils, when managed ecologically, function as effective carbon sinks comparable to natural ecosystems. The study provides a scientific foundation for integrating soil carbon management into municipal climate strategies, emphasizing the role of urban green spaces in carbon neutrality, climate adaptation, and sustainable city planning.
Soil Health Dynamics in Urban Forests versus Wasteland Soils: A Physico-Chemical Perspective from Subtropical Region of Chhattisgarh, India
Urbanization and land degradation significantly influence soil physicochemical characteristics and nutrient dynamics in subtropical ecosystems. This study comparatively evaluated soil health in urban forest soils (UFS) and wasteland soils (WLS) of Bilaspur, Chhattisgarh, India, analyzing soil colour, texture, bulk density (BD), moisture content (MC), nitrogen (N), carbon (C), hydrogen (H), and sulfur (S). Urban forest soils were generally darker (dark brown to dark grey) with finer textures (silt loam to clay), whereas wastelands exhibited lighter colours and coarser textures. Bulk density ranged from 1.45–1.60 g cm-3 in UFS and 1.10–1.28 g cm-3 in UFS. Moisture content varied from 7.6–15.2% in WLS and 18.0–31.5% in UFS. Carbon and nitrogen ranged between 0.58–1.45% and 0.046–0.138% in WLS, compared to 1.05– 1.68% and 0.204–0.408% in UFS, respectively. Pearson correlation analysis showed significant negative relationships (p < 0.05) between BD and nutrient parameters, with stronger associations in urban forest soils (e.g., BD–C r ≈ –0.76). Moisture exhibited strong positive correlations with carbon and nitrogen (r ≈ 0.86), indicating tight nutrient–water coupling under forest cover. Wasteland soils displayed comparatively weaker inter-parameter associations and greater variability. Multivariate scatterplot matrix analysis further confirmed stronger structural coherence and biogeochemical integration in urban forest soils compared to wastelands. Overall, the findings highlight the regulatory role of vegetation cover in maintaining soil structural stability and nutrient interdependence in the subtropical urban ecosystem of Bilaspur. The study underscores the ecological importance of conserving and restoring urban forest patches to enhance soil health resilience in rapidly expanding cities of central India.
Comparative Evaluation of Different Soil and Water Conservation Practices on Key Soil Physicochemical Properties along Slope Positions in the Belichamena Sub-Watershed, Central Ethiopia
Soil erosion remains one of the most critical environmental challenges in Ethiopia. Despite the implementation of soil and water conservation (SWC) measures over the past two to three decades to curb and reverse this issue, erosion continues to affect many parts of the country, including the Ameka district. This study investigates the impact of soil and water conservation (SWC) practices on selected soil physicochemical properties across different slope positions in the Belichamena sub-watershed, Central Ethiopia. The study area encompassed both conserved and non-conserved cultivated lands situated along upper, middle, and lower slope positions. A total of 27 composite soil samples were collected and analyzed for parameters such as soil texture, moisture content, bulk density (BD), pH, soil organic carbon (SOC), soil organic matter (SOM), total nitrogen (TN), available phosphorus (AP), and electrical conductivity (EC), using standard laboratory procedures. To evaluate the impact of SWC interventions and slope position, statistical analysis was conducted using SPSS software version 26. The findings indicated that soils within bunds supported with desho grass (Pennisetum pedicellatum) exhibited higher levels of clay, moisture content, pH, SOC, SOM, TN, available phosphorus, and EC compared to adjacent bunds without desho grass and non-conserved plots. Conversely, higher bulk density, silt, and sand contents were observed in the non-conserved areas. Most soil properties showed statistically significant variation (p < 0.05) due to both conservation practices and slope position, except for silt, sand, and bulk density. Results indicated that SWC practices significantly enhanced soil fertility, particularly in lower slope positions, where greater accumulation of organic matter and nutrients was observed. Comparatively, non-conserved areas exhibited poorer soil structure and reduced nutrient levels. These results confirm that SWC practices are highly effective in mitigating soil erosion and enhancing soil quality in the Belichamena sub-watershed, thereby promoting sustainable agricultural productivity.