Sains Tanah - Journal of Soil Science and Agroclimatology
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Evaluating the efficacy of bacterial-assisted phytoremediation using maize (Zea mays L.) to uptake heavy metals from fly ash
Full text linkThe agricultural sector faces dual challenges of declining soil fertility and unsustainable waste accumulation. This study examines the synergistic effects of fly ash (FA) and plant growth-promoting bacteria (PGPB) on the growth and physiological performance of maize (Zea mays L.) under controlled (potted) conditions. FA, a coal combustion by-product rich in essential minerals, was applied at varying doses (1–4 t ha-1) to assess its potential as a soil amendment with a bacterial strain (BSNK7) inoculated to enhance nutrient uptake and mitigate stress. Results showed a significant increase in fresh and dry biomass, leaf area, and chlorophyll content in treated plants. The combined application of 1 t ha-1 FA in conjunction with PGPB significantly increased fresh biomass by 1.57%, dry biomass by 0.94%, leaf area by 2.21%, and higher chlorophyll content compared to control (FA 0 t ha-1 and without bacteria). In contrast, FA 4 t ha-1, when applied without bacterial inoculation, resulted in reduced fresh biomass by 19.94% and dry biomass by 17.39%, respectively, compared to the control (FA 0 t ha-1 and without bacteria) which indicates the creation of toxicity at elevated doses. These findings suggest that the integrated use of low-dose FA and PGPB can sustainably enhance maize growth while minimizing environmental risks. The Application of appropriate doses of FA with PGPB can increase crop productivity and soil health simultaneously. Further field-based studies are recommended to validate scalability, optimize application rates, and assess the long-term impacts on soil health impacts
The relationship between soil properties in pedogenesis dynamics: A study of pedons on slopes and basins
Full text linkSoil formation and weathering are essential processes influencing natural fertility, yet the combined role of particle size distribution, texture, and organic carbon content at the profile scale remains understudied. Earlier research has focused chiefly on soil properties at the landform or regional scale, without examining interhorizon variations, leading to a limited understanding of their interactions in pedogenesis under different environments. This study compared the physical and chemical characteristics of soils in two contrasting pedons, Jatinangor (slope) and Tanjungsari (depression), both located in Sumedang Regency, West Java, Indonesia, with similar soil-forming factors. A descriptive-comparative method was employed using horizon-based sampling, laboratory analysis, and Principal Component Analysis (PCA) to reveal relationships and dominant factors. Results indicated that clay fractions dominated the JTN (Jatinangor) pedon with a clay texture due to intensive weathering under well-drained conditions. In contrast, the TJN (Tanjungsari) pedon was dominated by silt fractions resulting from fine material deposition under waterlogged conditions. Organic carbon content was lower in JTN due to leaching on slopes, whereas higher accumulation occurred in TJN due to depression settings. PCA identified sand fraction as the main discriminating factor, while fine fractions (silt and clay) were positively associated with organic carbon. These findings highlight that integrated analysis of these variables at the pedon scale provides a sensitive indicator of pedogenesis, weathering, and soil fertility
Relationship model of land biophysical properties and their influence on Arabica coffee production in Bandung Regency, Indonesia by using the PCR method
Full text linkCoffee is an essential agricultural commodity that significantly contributes to Indonesia's foreign exchange revenue. Arabica coffee (Coffea arabica L.), generally grown in highland areas at elevations between 1,000 to 2,000 m above sea level, exhibits persistently low productivity within the country. A primary factor influencing this low yield is the biophysical condition of the land. This study aims to examine the impact of land biophysical characteristics on Arabica coffee productivity and to investigate the interrelationships among those biophysical factors. This study was conducted in Bandung Regency, West Java Province, Indonesia. This study utilized 60 data sets encompassing 22 land biophysical parameters and one plant parameter, specifically coffee productivity. The data collection utilized a survey approach. Land biophysical data were collected through field observations and laboratory analyses, whereas coffee productivity data were obtained through farmer interviews. The principal component regression (PCR) method, incorporating principal component analysis (PCA) and multiple regression, was employed for statistical analysis. The findings indicated 7 principal components (PC) with a data representation level of 75.8%. PC1 comprises primary components consisting of sand content, clay content, exchangeable Mg, Ca, and Na, with a representation level of 18.6%. PC2 consists of exchangeable K and potential K2O, while PC3 consists of total N, organic C, altitude, and slope. These components are the most significant factors influencing Arabica coffee production. The application of K and N fertilizers along with organic materials is expected to increase Arabica coffee production
Distribution of humic substances in sieved aggregates of soil under contrasting land use
Full text linkSoil quality indicators that control aggregate stability need o be extensively investigated so as to maintain our soils. Humified carbon (HC), humified acid carbon (HAC), and aggregate-associated fulvic acid carbon (FAC) in forest soils, cocoa plantations, five-year fallow, and five-year continuous cultivated soils were studied. Samples of soil were collected at 0-15 cm topsoil in order to measure the amount of humic materials in both the wet sieved and dry sieved aggregates. Findings revealed a significant input of land use on values of HC, HAC, and FAC occluded in sieved soil aggregates. The HC and FAC were preferentially stored in micro aggregate fractions less than 0.25 mm, while the HAC was greater in macro aggregates 2-1 mm and 1-0.5 mm. Concentration of HC was 18.8 g kg-1 in dry sieved and 17.2 g kg-1 in wet sieved micro aggregates less than 0.25 mm. The HC increased significantly (p<0.05) under a 5-year fallow. The HAC was stored in macro aggregates larger than 1 mm, whereas the HC and FAC fractions were occluded in micro aggregates > 1.0 mm. Continuous cropping decreased MWD of water-stable aggregates by 55%, while bulk density increased by 18%. The correlation coefficient between HC and MWD was significant (r = 0.811, p < 0.01), revealing the positive role of HC in aggregate stability. This study will help in understanding soil management strategies that will raise the accumulation of HC and HAC in macro-aggregates, thereby protecting the soil mass from structural degradation
Chemical modification of biochar’s functional groups enhances phosphate and arsenite adsorption
Full text linkAnionic arsenic (As) species and phosphate often show similar behavior in soils. Bioavailability of these anionic species has a significant implication for crop production and soil health. Biochar (BC) is considered an effective amendment for managing these anionic species. This study aims to evaluate how surface-modified biochars influence phosphate and arsenite adsorption. Biochars with a range of functionalities were produced using mineral doping, and chemical oxidation with hydrogen peroxide. These biochars were then characterized using different chemical techniques, including FTIR. Next, a phosphorus adsorption study was conducted with fresh, mineral-doped and chemically oxidized biochars. A desorption study was also conducted to understand the strength of sorption. Moreover, an adsorption study was carried out using three different biochars fresh, oxidized, and doped in interaction with As. Our results showed that chemical oxidation increased oxygen-containing functional groups while mineral impregnation decreased their presence, resulting in a reduction in cation exchange capacity. As a result, phosphate adsorption was significantly higher with mineral- doped biochar (2.5 mg g-1 biochar) than in fresh biochar (2.2 mg g-1 biochar) treatment. The strength of binding was higher for positively charged biochars. Similar to phosphate, the As adsorption was also higher in the doped biochar (~0.50 mg g-1 biochar) than oxidized biochar (0.20 mg g-1biochar). Surprisingly, the As adsorption was higher in the oxidized BC than fresh BC possibly due to its co-adsorption with cations. Altogether, our results suggest that biochar with positive surfaces could strongly bind negatively charged ions from aqueous solutions and soils
Applications of synthetic microbial communities platform through plant growth-promoting traits to enhance ecological functions in sustainable agriculture
Full text linkSynthetic microbial communities (SynCom) present a promising strategy for sustainably enhancing agricultural productivity and ecological resilience. This review critically discusses recent advancements in applying SynCom within agricultural ecosystems and highlights their practical benefits for economic sustainability. Plant growth-promoting (PGP) traits are essential for developing SynCom, as they enhance plant growth, increase nutrient uptake, improve stress tolerance, and support resistance to pathogens. SynCom demonstrates significant effectiveness as a biofertilizer, substantially improving soil health and crop yields through enhanced nutrient cycling and bioavailability. Its role as a biopesticide is also significant, as it offers an eco-friendly approach to insect pest management. The integration of SynCom into agricultural practices has proven to enhance plant disease resistance, significantly contributing to crop resilience. Moreover, SynCom plays a vital role in maintaining soil fertility, promoting carbon sequestration, and mitigating the impacts of climate change. Its applications extend to environmental remediation, where it effectively degrades hazardous pollutants in agricultural soils and efficiently processes lignocellulosic biomass, supporting sustainable biomass utilization. SynCom offers considerable advantages but also faces challenges, including community stability, environmental adaptability, and regulatory concerns. Future research efforts aim to address these limitations and enhance SynCom's efficacy regarding long-term agricultural sustainability. Our review provides valuable insights for policymakers, practitioners, and researchers to construct SynCom-based strategies that promote plant growth, enhance sustainable agriculture, and support environmental conservation
Improving coffee soil health using compost made from sugarcane leaves, coffee pulp, and Gliricidia sp.
Full text linkAgricultural waste management remains a critical environmental concern, necessitating sustainable approaches to transform organic residues into valuable resources. Among these, composting offers an effective solution by converting biomass into nutrient-rich soil amendments and reducing the burden of waste disposal. This study aims to investigate the potential of combined agricultural waste composting for producing high-quality compost and enhancing soil properties in a coffee plantation. Eight composting treatments and three replications were formulated: P1: Saccharum officinarum leaves (100%), P2: Coffee pulp (100%), P3: Gliricidia sp. leaves (100%), P4: Saccharum officinarum leaves (50%) + Coffee pulp (25%) + Gliricidia sp. leaves (25%), P5: Coffee pulp (50%) + Saccharum officinarum leaves (25%) + Gliricidia sp. leaves (25%), P6: Gliricidia sp. leaves (50%) + Coffee pulp (25%) + Saccharum officinarum leaves (25%), P7: Coffee pulp (50%) + Saccharum officinarum leaves (50%), and P8: Coffee pulp (50%) + Gliricidia sp. leaves (50%). The findings indicated that the compost mixtures containing Gliricidia sp. leaves and coffee pulp yielded a C:N ratio of less than 25, signifying that the compost was mature. The application of compost resulted in an overall increase in soil pH, organic carbon, and total nitrogen, while also ameliorating soil structure through reduced bulk density and enhanced porosity, particularly at a depth of 30–60 cm. These results provide valuable insights for farmers and agricultural policymakers in developing sustainable waste management strategies that effectively address agricultural waste disposal challenges while improving soil fertility and promoting more environmentally friendly coffee production systems
Differential herbicide persistence and shifts in soil bacterial communities in Alfisol and Inceptisol
Full text linkWeeds significantly reduce crop yields and promote herbicide use, accounting for 80% of agricultural pesticides. However, herbicide persistence and toxicity adversely affect soil microbial communities, impacting soil health and productivity. This study compared the effects of organic (Vinegar-weed-care: acetic acid) and chemical herbicides (PrimextraGold: Atrazine + S-metolachlor; Imazapyr: Isopropyl amine) on soil bacteria in Alfisol and Inceptisol from Ibadan, Nigeria. Soils were analysed for physical properties and microbial DNA, and herbicide degradation was tracked using GC-MS at 0, 4, 8, and 12 weeks. Alfisol exhibited higher fertility with pH 6.2, organic carbon 3.9 g kg-1, nitrogen 0.7 g kg-1, and phosphorus 25.9 mg kg-1, compared to Inceptisol (pH 5.5, organic carbon 1.9 g kg-1, nitrogen 0.6 g kg-1, phosphorus 20.8 mg kg-1). Herbicide persistence was greater in Alfisol: metolachlor (84.94%) and Imazapyr (61.00%) vs. Inceptisol (52.55% and 50.15%, respectively). Organic herbicide metabolites also persisted more in Alfisol (35.13%) than in Inceptisol (28.00%). In non-sterile Alfisol, biodegradation of PrimextraGold and Imazapyr was lower (43.46% and 10.30%) than in sterile soils (53.97% and 16.17%), while the organic herbicide biodegraded more in non-sterile (23.49%) than in sterile (17.08%). In non-sterile Inceptisol, Imazapyr degraded less (8.94%–31.72%) than in sterile (29.49%–34.75%), but atrazine degraded more in non-sterile (61.96%–68.17%). Organic acetamide degraded better in non-sterile Inceptisol (23.42%–90.5%) than in sterile (12.47%–30.7%). Chemical herbicides reduced Candidatus Udaeobacter, Pedosphaera, and Chthoniobacter in Alfisol, while organic herbicides enhanced them in both soils. These findings highlight the ecological benefits of soil-friendly organic herbicides
Modeling the activity ratio of soil potassium using machine learning approach
Full text linkThe potassium (K) Quantity-Intensity (Q-I) relationship results in important parameters, including the activity ratio of potassium at equilibrium (AReK), which indicates potassium availability in soil. Experiments to observe soil Q-I K relationship parameters are often complex, time-consuming, and do not include environmental variables. This research aims to model AReK using a machine learning (ML) approach. ML models applied are Random Forest (RF), Cubist, and Support Vector Machine (SVM) as the primary approaches, with Multiple Linear Regression (MLR) serving as a baseline. The dataset was derived from sixty-one observation points in Brebes, Central Java. The predictors were pH, organic carbon, clay, cation exchange capacity (CEC), exchangeable cations (Exc-Ca, Mg, K, Na), water soluble K, available K, K saturation, potential K, non-exchangeable K (NE-K), elevation, and slope. The response variable was the AReK. Variable selection was performed using Pearson correlation to eliminate highly correlated predictors and reduce multicollinearity. Exactly 75% of the data was utilized as the training set and 25% as the test set. Three metrics, i.e., MAE, RMSE, and R², were used in model evaluation. The results showed that the Cubist model could predict AReK with high accuracy (R2=0.9437) and low RMSE (0.5701) and MAE (0.3514). Based on the Cubist model, Exc-K, Exc-Mg, CEC, and Exc-Ca were the most important variables for predicting AReK. This model can be employed to support site-specific fertilizer recommendation strategies. To improve the performance of the model, it is necessary to add other predictor variables (e.g., soil physical properties, clay minerals, rainfall, temperature and soil moisture)
Soil nutrient improvement with organic amendments: a basis for lemon orchard management
Full text linkLemon trees require the nutrients they extract from the soil. This research aims to analyze the impact of organic matter application on enhancing soil nutrient availability and improving soil chemical properties using a pot-scale incubation experiment. This study used a completely randomized design with eight treatments and four replications. The pot treatment used 10 kg of air-dry soil per pot mixed with an organic matter dosage of 30 tons ha-1 and was observed at 2, 4, 8 weeks after applications. The treatment consisted of P1 (topsoil, control), P2 (subsoil, control), P3 (topsoil + compost), P4 (subsoil + compost), P5 (topsoil + cow manure), P6 (subsoil + cow manure), P7 (topsoil + goat manure), and P8 (subsoil + goat manure). The results indicated that compost and manure fertilizer had a significant effect in increasing soil chemical properties (pH, organic carbon content, cation exchange capacity, total-N, available-P, and exchangeable-K), with topsoil treatment having the highest value compared to the subsoil treatment, almost at all parameters. The topsoil treatment + 30 tons ha⁻¹ cow manure significantly increased the N-total by 44.44% at 8 and 12 WAA on the control treatment. The topsoil treatment + goat manure 30 tons ha-1 significantly increased P-available by 13.63 - 29.74% and exchangeable-K by 40.61 - 62.88% at 4, 8, and 12 WAA against the control treatment. Based on these findings, the best fertilizer method of topsoil treatment + 30 tons ha⁻¹ of manure is recommended to increase the soil fertility of the lemon tree soil