Asian Soil Research Journal
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Quantification of Microbial Biomass Carbon and Nitrogen in Leaf Litter Amended Soil in Northern Nigeria
No full textA 119-day laboratory incubation study was conducted to evaluate microbial biomass dynamics in soil amended with different leaf litters. The treatments included five leaf litter sources: African mahogany (Khaya senegalensis), Mango (Mangifera indica), Beechwood (Gmelina arborea), Red River Gum (Eucalyptus camaldulensis), and a mixed litter treatment, arranged in a Completely Randomized Design with three replicates. Chemical properties of the leaf litters, including organic carbon, nitrogen, sulfur, potassium, calcium, sodium, magnesium, total soluble polyphenols, and lignin content, were analyzed. Soil microbial biomass carbon (SMBC) and nitrogen (SMBN) were determined using the chloroform fumigation incubation (FI) method.
Among the treatments, Eucalyptus camaldulensis exhibited the highest C:N ratio (33.3), while Gmelina arborea showed the lowest (20.6). Significant differences (p<0.05) were observed across leaf litter types and weeks for soil microbial carbon and nitrogen parameters. Soil amended with Eucalyptus camaldulensis recorded the highest microbial biomass carbon (122.85 mg kg⁻¹), significantly (p<0.05) exceeding the values for mixed leaf litter, control, Gmelina arborea, Khaya senegalensis, and Mangifera indica.
The highest microbial biomass nitrogen values were observed in soils amended with Khaya senegalensis (13.90 mg kg⁻¹) and Mangifera indica (13.25 mg kg⁻¹), with the control treatment yielding the lowest value. Eucalyptus camaldulensis amended soil also had the highest microbial biomass C:N ratio, followed by Mangifera indica, Gmelina arborea, the mixed treatment, and the control. The results suggest that Mangifera indica, Khaya senegalensis, and the mixed leaf litter have a greater potential to enhance soil microbial nitrogen, while Eucalyptus camaldulensis promotes higher carbon activity in the soil
Spatial Variability and Pollution Loads of Selected Heavy Metals in Cocoa Plantation Soils in Cross River State, Nigeria
No full textUnderstanding heavy metal concentrations and their spatial variability is crucial for improved soil health and increased crop productivity. This study assessed heavy metal concentrations and their pollution loads in soils of cocoa plantations in Ikom, Etung and Boki Local Government Areas of Cross River State. Sixty (60) composite soil samples were collected from the area and analyzed Cd, Cr, Pb and Al. The results obtained revealed that Cd was above the maximum permissible limit for soil. Lead had means of 0.011 mg/kg, 0.02 mg/kg and 0.010 mg/kg, Cd had means of 1.53 mg/kg, 1.45 mg/kg and 1.25 mg/kg while Cr was 0.05 mg/kg, 0.03 mg/kg and 0.02 mg/kg Ikom, Etung and Boki respectively. The contamination factor for Cr and Pb was low (CF < 1) while Cd was considerably contaminated (3≤ CF < 6). The results of PLI indicated an unpolluted condition (PLI<1). Apart from Cd, the values of Igeo for Cr, Pb and Al fell in class ‘0’, indicating practically uncontaminated conditions in these areas. The soils of the area are safe for crop production but measures should be taken to reverse the trend of high concentration of Cd in the soils
Soil Organic Carbon Estimation Using NIRS and MIRS Spectroscopy with Machine Learning as a Statistical Tool in the Senegalese Peanut Basin: A Rapid Approach for Sustainable Soil Management
No full textSenegalese agriculture relies heavily on peanut cultivation, but agricultural intensification has led to soil degradation and a decline in fertility. Soil organic carbon (SOC) is a key indicator of soil quality, influencing its structure and fertility. However, conventional SOC analysis methods are costly and time-consuming. Infrared spectroscopy (NIRS and MIRS) offers a fast and non-destructive alternative, allowing SOC estimation based on the soil’s spectral properties.
The study, conducted in the Senegalese Peanut Basin, involved the analysis of 240 soil samples at two depths (0–10 cm and 10–30 cm). Spectra were acquired using NIRS and MIRS, then calibrated with reference measurements obtained through CHNSO analysis. Various spectral preprocessing techniques (SNV, SG, MSC, etc.) and machine learning models (PLSR, SVM, Random Forest, XGBoost) were tested to optimize SOC prediction.
The results show that the SVM and Random Forest models offer the best performance, particularly with NIRS spectra preprocessed using Savitzky-Golay, achieving a coefficient of determination (R²) above 0.8 and an RPD > 2, indicating sufficient accuracy for soil management applications. This study highlights infrared spectroscopy as a promising tool for the rapid and cost-effective mapping of SOC, contributing to improved agricultural soil fertility management
Growth and Yield Response of Mung Bean (Vigna radiata L.) to Different Rates of Phosphorous and Potassium Application
No full textThis study investigated the effects of phosphorus (P) and potassium (K) fertilization rates on the growth, yield attributes, and seed yield of mung bean (Vigna radiata L.) under pre-monsoon and monsoon seasons in Myanmar. Field experiments were conducted using a two-factor randomized complete block design with three replications, comprising four P levels (P0, P20, P40, P60: 0, 20, 40, 60 kg P ha-1) and four K levels (K0, K20, K40, K60: 0, 20, 40, 60 kg K ha-1). Results demonstrated that combined P and K application significantly enhanced mung bean productivity compared to single-nutrient treatments. During the pre-monsoon season, the optimal treatment was 60 kg P ha-1 with 40 kg K ha-1 (P₆₀K₄₀), yielding 1,126.87 kg ha-1, which was statistically comparable to P₆₀K₆₀. In the monsoon season, 60 kg P ha-1 with 40 kg K ha-1 (P₆₀K₄₀) produced the highest yield (1,561.17 kg ha-1), showing no significant difference from P₆₀K₂₀ or P₆₀K₆₀. In both seasons, the combined application of P and K fertilizers significantly enhanced yield and yield components, including pods per plant and seeds per pod. While P₆₀K₄₀ is recommended for pre-monsoon cultivation, reduced K input (P₆₀K₂₀) is sufficient during the monsoon, likely due to increased nutrient solubility under wetter conditions. The findings highlight the combined application of P and K in optimizing mung bean yields compared to the single application. Therefore, to optimize mung bean production, growers should consider the combined application of P and K fertilizers rather than single applications. However, to reach a precise conclusion and recommendation, more research work on mung bean should be conducted in different agro- ecological zones
Analysis and Characteristics of Soils Underlying Open Dumpsites in Akwa Ibom State, Nigeria: Their Agricultural and Environmental Implications
No full textOpen dumpsites are naturally connected to climate change, soil pollution and loss of biodiversity, problems described as triple planetary crisis. Despite this, dumping of wastes in open dumpsites is a common practice in Akwa Ibom State and indeed in most developing parts of the world. This study evaluated the impacts of various dumpsite waste materials on the physicochemical characteristics of the underlying soils in Akwa Ibom State, Nigeria with the aim of determining their agricultural and environmental implications. Nine dumpsites were identified and sampled in Etinan, Uyo and Ikot Ekpene Local Government Areas (LGA) of the State: one each for automechanic, paints processing, and abattoir wastes per LGA. An area believed to have no history of any of the wastes’ contamination was used as the control in each of the LGAs. Wastes samples were collected from the wastes piles while soil samples were collected from predetermined depths (0-20, 20-40 and 40-60) cm underneath the wastes piles and analyzed using standard laboratory procedures. The results had revealed that the continuous dumping of the automechanic, paint-processing, and abattoir wastes over the years have greatly modified the physicochemical characteristics of soils beneath the dumpsites in Akwa Ibom State. The pH, electrical conductivity, organic carbon, exchangeable cations, and nutrient changes showed a direct relationship between waste compositions and soil pollution. Abattoir wastes were found to have enriched the impacted soils with organic matter and basic cations; paints processing wastes were outstanding in causing alkalinity in the impacted soils which can interfere with nutrients uptake. These changes can have serious impact on soil health and the entire ecosystem. As such intervention strategies of sustainable segregation of wastes, controlled disposal, and bioremediation must be done as a matter of urgency to ameliorate the impact already caused by the open dumpsites
Nitrogenous Fertilizer Application Rates and Plucking Intervals on Tea [Camellia sinensis (L.)] in Eastern Africa: Changes in Soil Calcium, Magnesium and Manganese Levels
No full textTea production requires high rainfall areas that cause nutrients depletion through surface run-off, leaching, and removal with crop. This makes application of fertilisers mandatory to replenish the nutrients. However, such applications could cause soil nutrients imbalance. Harvesting frequency cause variations in yields. Despite variations in environmental factors recommended fertilizer use is similar while harvesting frequency varies between 7 to 14 days. Fertilizer use and plucking are major agronomic inputs that may influence crop yields and soil nutrients removal. The objective of this study was to determine the influence of rates of NPKS 25:5:5:5 fertilizer and harvesting intervals on soil calcium, magnesium and manganese levels in Eastern African tea soils. Samples were obtained from fertilizer trials on clone TRFK 6/8 at three, two and three sites in Kenya, Tanzania, and Rwanda, respectively, from a 5 nitrogen rates by 3 harvesting frequency factorial trials replicated three times at each site, at 0-10, 10-20, 20-30, 40-60 cm soil depths. The nutrients were determined using ICPAES. Higher rates of nitrogen fertilizer increased (p≤0.05) soil Mn levels but reduced (p≤0.05) Ca and Mg soil levels. Thus, long term use of nitrogenous fertilizers could cause nutrients imbalance that may make tea production uncertain as these nutrients are not controlled through supplementation. Harvesting frequency did not influence soil Ca, Mg and Mn levels at all sites. The nutrients levels varied (p≤0.05) with location of production. Despite the variations the nutrient levels were still optimal and therefore not constraining tea production. These results suggest need for proper management of these nutrients to ensure continued high tea production
Revitalizing Beneficial Soil Microbes: Why Indigenous Soil Knowledge and Conservation Practices in Africa Still Relevant to Sustainable Farming?
No full textResearch Gap: Against the backdrop of a range of documented Western-centric farming practices and approaches that ignored the relevance of Indigenous soil knowledge (IKS) and Conservation agriculture (CA) in revitalizing and preserving beneficial soil microbes, the study aimed to fill a yawning gap on often overlooked continent’s indigenous base farming strategies which are still essential in restoring and enhancing beneficial soil microbial populations.
Methodology: The study was conducted in Chimanimani district of Zimbabwe. It adopted a constructivist research design incorporating a qualitative approach. The sample consisted of 45 research respondents. A purposive sampling was used to select key informants such as extension officers, ecologists, Western-trained scientists and traditional leaders. Snowball sampling helped to identify additional participants such as small-scale farmers and community elders with relevant insights. The study used semi-structured interviews, observations, and content analysis to establish socio-environmental implications emanated from declining microbial populations in rural communities. The data collected were coded, analyzed thematically, and discussed in light of relevant literature.
Key Findings: The findings revealed that ignoring the significance of ISK and CA in restoring beneficial soil microbes have posed serious socio-environmental implications on humans and soil ecosystems. Most of the challenges emerged, namely water scarcity, climate-induced disasters, degradation, pollution and human-nature conflict continued to destroy soil microbial populations. Thus, the study found that ISK based in conservation practices is still relevant in sustaining African agriculture. However, the study also revealed that Western-centric practices which often overlook the continent’s rich traditions adversely affect sustainability.
Implications: The findings implied that a call for conservation-based practices with a more comprehensive understanding of soil health and sustainability in various agricultural contexts becomes urgent. Additionally, the results also implied that by overlooking ISK and CA, African rural communities continued to live on borrowed time, in which their future becomes uncertain and precarious
Textural Analysis and GIS Mapping of Agricultural Soil Samples from the Karha River Basin, Pune District, Maharashtra, India
No full textUnderstanding soil texture is vital for sustainable agriculture, as it directly affects water retention, nutrient dynamics, and root development. This study aims to assess and map the spatial variability of agricultural soil texture in the Lower Karha River Basin using granulometric analysis and GIS techniques. A total of 48 soil samples were collected using a 10×10 fishnet grid overlay and analyzed using mechanical sieving method for proportion of granule (0.49%–50.42%), sand (25.24%–64.40%), and silt-clay (21.91%–49.94%) fractions. The soils are predominantly sand-rich, with localized zones of finer textures in the southern and lower basin areas. Grain-size statistical parameters were computed to evaluate sedimentological behavior. Mean grain size ranged from –0.73 to 2.20 ϕ, indicating a spectrum from coarse to fine textures. Sorting indices varied between 1.45 ϕ and 2.75 ϕ, classifying most soils as moderately to poorly sorted. Skewness (–0.23 ϕ to 0.83 ϕ) and kurtosis (0.55 ϕ to 1.76 ϕ) values showed diverse asymmetry and peakedness, reflecting heterogeneous depositional environments across the basin. Spatial distribution maps were generated using Inverse Distance Weighting (IDW) in a GIS environment, enabling high-resolution visualization of texture classes and statistical patterns. The results offer critical insights for precision agriculture, informing crop suitability, irrigation scheduling, and localized land-use planning. The study underscores the significance of integrating geostatistical tools with soil texture analysis for effective soil resource management in semi-arid river basins
Evaluation of Selected Salt Tolerant Soybean Genotypes in Southern Saline Soils of Bangladesh
No full textGlobally salinity is one of the most detrimental factors affecting crop growth, development and yield. Understanding crop responses or growth potential and their effectiveness in salinity mitigation is highly important for selecting salinity tolerant crop. Therefore, a research study was undertaken to evaluate the selected soybean genotypes in southern saline soil of Bangladesh. In this study, two selected salt tolerant soybean lines (V1 = Vietkhai and V2 = G 00382), one moderately salt tolerant soybean line (V3 = USDA-15), one salt sensitive soybean variety (V4 = Binasoybean-4) and a standard check (V5 = BARI Soybean-5) were used to know the yield, yield attributes and seed quality parameters of the soybean genotypes in southern saline soils of Bangladesh. The experiments were conducted at two locations of Shatkhira, one is on station (OS), ARS, BARI, Binerpota and another is farmer’s field (FF), Harodda. The experiments in two locations were laid out in RCBD (randomized complete block design) with three replications. During the entire monitoring interval, OS consistently exhibited higher electrical conductivity (EC) over FF. In field condition, the highest seed yield and, germination % of seed, seedling dry weight, seed protein content, oil content of seed, seed vigor index, fatty acid composition of seed and all of the seed quality parameters were found higher from Vietkhai and G 00382 whereas the lowest values were obtained from salt susceptible genotype Binasoybean-4. From the findings of the study, it may be concluded that, soybean genotypes G 00382 and Vietkhai could be recommended as soybean cultivars for southern saline zones of Bangladesh
Effects of Nano Zinc Oxide (n-ZnO) on Soil Physicochemical Properties, Micronutrient Dynamics, and the Growth Performance of Ficus benjamina
No full textBackground: Despite its agronomic promise, the ecological effects of n-ZnO in soil remain underexplored. Soils are complex and dynamic systems, and nanoparticle interactions can influence nutrient cycling, microbial communities, and micronutrient availability, potentially causing imbalances or toxicity.
Aims: The study aims to investigate the impacts of nano zinc oxide (n-ZnO) on soil physicochemical properties, micronutrient dynamics, and the growth performance of Ficus benjamina.
Materials and Method: The study employed a completely randomized design (CRD). Screen house experiment was set up in Institute of Ecology and Environmental Studies, Obafemi Awolowo University, Ile Ife, Nigeria. Ten concentrations of n-ZnO (0, 10, 25, 50, 75, 100, 150, 200, 250, and 300 ppm) were applied to sandy loam soils and allowed to equilibrate for two weeks. Three-week-old Ficus benjamina seedlings were then transplanted into the amended soils, and growth parameters were monitored biweekly over twelve weeks. Post-harvest soil samples were analyzed for pH, electrical conductivity (EC), total nitrogen (TN), organic carbon (OC), available phosphorus (P), moisture content, cation exchange capacity (CEC), and micronutrients (Fe, Mn, Cu, Zn) using standard methods.
Results: Results showed significant dose-dependent effects of n-ZnO on soil chemistry and plant performance. Soil pH declined from 6.5 (control) to 5.3 at 300 ppm, indicating progressive acidification. EC increased from 0.20 dS/m to 1.12 dS/m at the highest dose, suggesting ionic enrichment. TN and OC slightly increased at 10–50 ppm but declined markedly at ≥150 ppm, indicating microbial suppression. Available P peaked at 50 ppm (35 mg/kg) before falling to 7.3 mg/kg at 300 ppm. Moisture retention improved at moderate levels but declined at higher concentrations. CEC and exchangeable bases decreased at high n-ZnO doses, likely due to cation displacement. Micronutrient trends were inconsistent, with elevated Zn causing nutrient imbalances. Ficus benjamina showed improved growth at 10–50 ppm but experienced phytotoxicity and biomass reduction at ≥150 ppm, culminating in plant mortality at 250 ppm.
Conclusion: The study concludes that while moderate n-ZnO levels enhance soil fertility and plant growth, higher concentrations adversely affect soil health, nutrient dynamics and plant performance. The study recommends regulation and threshold-specific application of n-ZnO to avoid ecological toxicity