Soil pH Research Articles

The impact of water hyacinth biochar on maize growth and soil properties: The influence of pyrolysis temperature

AbstractIntroductionOptions for managing water hyacinths (WHs) include converting the biomass into biochar for soil amendment. However, less has been known about the impact of WH‐based biochar developed in varying pyrolysis temperatures on plant growth and soil qualities.Materials and MethodsA pot experiment was undertaken in a factorial combination of WH biochars (WHBs) developed at three temperatures (350°C, 550°C and 750°C) and two application rates (5 and 20 t ha−1), plus a control without biochar. Maize was grown as a test crop for 2 months under natural conditions.ResultsOur study showed that applying WHB developed between 350°C and 750°C at 20 t ha−1 increased maize shoot and root dry biomass by 47.7% to 17.6% and 78.4% to 54.1%, respectively. Nevertheless, raising the biochar pyrolysis temperature decreased maize growth, whereas increasing the application rate displayed a positive effect. The application of WHB generated at 350°C and 550°C at 20 t ha−1 resulted in significant improvements in soil total nitrogen (17.9% to 25%), cation exchange capacity (27.3% to 20.2%), and ammonium‐nitrogen (60.7% to 59.6%), respectively, over the control. Additionally, applying WHB produced from 350°C to 750°C at 20 t ha−1 enhanced soil carbon by 38.5%–56.3%, compared to the control. Conversely, applying biochar produced at 750°C resulted in higher soil pH (6.3 ± 0.103), electrical conductivity (0.23 ± 0.01 dS m−1) and available phosphorus (21.8 ± 2.53 mg kg−1).ConclusionWHBs developed at temperatures of 350°C and 550°C with an application rate of 20 t ha−1 were found to be optimal for growing maize and improving soil characteristics. Our study concludes that pyrolysis temperature significantly governs the effectiveness of biochar produced from a specific biomass source.

Mixture Effect of Rock Phosphate and Triple Superphosphate on Maize Yield in Acid Soils of Côte d'Ivoire

Aims: Determine the optimum rock phosphate (RP) / Triple superphosphate (TSP) ratio for improved maize yield Study Design: The experimental design was of random blocks with 3 replications. Place and Duration of Study: The study was carried out in central Cote d'Ivoire, in a savannah area over 3 consecutive years 2019, 2020 and 2021. Methodology: Eight treatments were tested: control T0, T0r (100 Kg urea ha-1 + 200 Kg NPK ha-1), T1 (300 Kg RP ha-1), T2 (270Kg RP ha-1 + 19,6 Kg TSP ha-1), T3 (240 Kg RP + 39,2 Kg TSP ha-1 ), T4 (180 Kg RP ha-1 + 78,4 Kg TSP ha-1), T5 (60 Kg RP ha-1 + 156,8 Kg TSP ha-1 ), T6 (196 Kg TSP ha-1 ). For maintenance, 200 Kg NPK ha-1 and 100 Kg urea ha-1 were added to all treatments except control. After harvest, yields were calculated, pH levels were measured at the beginning, after three months and at the end of the trial. Results: the effect of the RP/TSP combination was effective in the second year. Ratio T3 obtained the best yield (5.71 t ha-1) and was more efficient than the treatment used for maize extension in Côte d'Ivoire (T0r). At the same time, the soil pH has become neutral, contributing to an improvement in soil fertility due to the gradual bioavailability of phosphorus from the solubilized phosphate rock. Conclusion: Mixing RP and TSP in proportions of T3 (240 Kg RP + 39,2 Kg TSP ha-1) is effective in improving maize yields.

Effects of thinning and ground cover plants on soil bacterial community composition and diversity in Picea asperata plantations within giant panda habitats

Abstract Forest thinning and ground cover plant management play crucial roles in habitat enhancement, yet their effects on soil microbiota remain poorly understood. This study examines their impact on soil properties and bacterial communities in artificial spruce forests (Picea asperata) within China’s Huangtuliang ecological corridor, a crucial habitat for giant pandas. Thinning significantly alters soil pH and total phosphorus (TP) levels, with minimal changes observed in total nitrogen (TN), microbial biomass carbon (MBC) and nitrogen (MBN). The combined effect of thinning and ground cover presence increases soil organic carbon (SOC) to 65.47 g/kg, contrasting with its absence. Thinning enhances the abundance of Proteobacteria, Acidobacteria and Chloroflexi while reducing Actinobacteria. Conversely, ground cover removal decreases Proteobacteria and Bacteroidetes but increases Chloroflexi, Verrucomicrobia and Rokubacteria. These changes lead to reduced bacterial community diversity, as indicated by a lower Shannon diversity index and distinct community composition differences demonstrated through beta-diversity analysis. Soil pH, TP and MBN are crucial in maintaining bacterial community structure, with pH and TP exhibiting the strongest correlations. Network analysis confirms the significant influence of TP and pH on bacterial genera across various phyla. This study reveals the role of stochastic processes in high-elevation, low-temperature ecological corridors (R2 = 0.817), with thinning’s impact varying depending on the ground cover presence, thus enhancing effects post-removal by reducing dispersal limitation (migration rate, m = 0.96). These findings highlight the ecological implications of habitat management in sensitive ecosystems and advance our understanding of microbial dynamics in critical habitats.

Karakteristik Fisika dan Kimia pada Tanah Ultisol di Lahan Perkebunan Karet di Desa Gunung Kupang Provinsi Kalimantan Selatan

Soil properties are the inherent characteristics of soil bodies in different locations that are influenced by factors such as mineral composition, structure, texture, and organic content. Soil has characteristics that affect the growth of the plants that are cultivated. This study aims to determine the physical and chemical characteristics of Ultisol soil at a depth of 0-50 cm on rubber plantation land in Cempaka District, Banjarbaru City. This research was conducted in the laboratory of ULM Soil Department. The land used was in Gunung Kupang, Cempaka Village, Cempaka District, Banjarbaru City, South Kalimantan Province. The research method used in this study is an exploratory descriptive method whose implementation is carried out directly at the research site and continued with soil sampling as material for analysis in the laboratory. Soil sampling was purposefully determined in 10 minipits in rubber plantations with two sides of observation at five depths, namely 0-10 cm, 10-20 cm, 20-30 cm, 30-40 cm, and 40-50 cm. Thus, all observations amounted to 100 samples. The data analysis used is presented in graphical form and analyzed descriptively. The results of this study show that increasing soil depth causes changes in soil physical characteristics. Physical characteristics of soil texture values affect the value of bulk density, particle density,and soil moisture content. The phenomenon of changes in physical characteristics ultimately affects the chemical characteristics of C-organic, soil pH, N-total, P-total and K-total values.

Spatial distribution of the ethnomedicinal plant Aglaonema simplex at the Sakaerat Environmental Research Station, Northeastern Thailand

Abstract. O-thong N, Tasen W, Marod D, Thinkampheang S, Phumphuang W. 2024. Spatial distribution of the ethnomedicinal plant Aglaonema simplex at the Sakaerat Environmental Research Station, Northeastern Thailand. Biodiversitas 25: 3043-3050. Aglaonema simplex Blume (Araceae) is an evergreen herbaceous plant used ornamentally and in traditional medicine. Although the usefulness of this plant has been widely studied and reported, its ecology remains poorly understood. In this study, we examined the effects of various environmental factors on the spatial distribution of A. simplex in a Dry Evergreen Forest (DEF) at the Sakaerat Environmental Research Station (SERS) in Northeastern Thailand. All individual plants were counted; their positions were recorded within a 16-ha Forest Dynamics Plot (FDP), and their distribution pattern was analyzed using Ripley's K function. The spatial distribution of A. simplex was determined using a generalized linear model that incorporated plant density and topographic and edaphic variables within the 16-ha study plot. We found a total of 11,232 A. simplex individuals with a density of 702 individuals ha-1, with a clumped distribution pattern. The modeling results showed that the spatial distribution of A. simplex was positively influenced by soil clay content, soil pH, exchangeable magnesium, and adult tree density; it was negatively influenced by sapling density and rocky outcrops. These findings contribute to the broader understanding of the ecological niche of A. simplex. They can be used to design integrated land management approaches that balance ecological conservation with economic development goals.

Soil chemical responses to fertilization, with or without a cover crop, in an olive orchard in southwestern Buenos Aires (Argentina)

Our objective was to study the effect of fertilization on soil chemical traits on an olive orchard (artificially irrigated), considering areas with or without a cover crop, in southwestern Buenos Aires, Argentina, during the period 2020/2021. Fertilization treatments were (1) organic manure applied to the soil near the tree trunk; inorganic fertilization applied to the (2) soil or (3) to the leaves of Olea europaea L. trees; and (4) unfertilized control. Seeding of Vicia benghalensis L. and Avena sativa L. around subplots (one per each of the four studied treatments) constituted the areas with a cover crop. Subplots which were not seeded corresponded to the control areas. Soil pH was lower (p<0.05) under organic and inorganic soil fertilization. In areas without a cover crop in April 2021, soil nitrate concentrations were greater (p<0.05) under organic soil fertilization than in the control. At 0-20 cm soil depth, P concentrations were greater (p<0.05) under organic and inorganic soil fertilizations than in the other treatments. The greatest (p<0.05) K concentrations were found in the organic fertilization treatment. Organic soil fertilization on areas without a cover crop showed greater values for the soil chemical studied traits.

Planting halophytes increases the rhizosphere ecosystem multifunctionality via reducing soil salinity

Soil salinization poses a significant global challenge, exerting adverse effects on both agriculture and ecosystems. Planting halophytes has the potential ability to improve saline-alkali land and enhance ecosystem multifunctionality (EMF). However, it remains unclear which halophytes are effective in improving saline-alkali land and what impact they have on the rhizosphere microbial communities and EMF. In this study, we evaluated the Na+ absorption capability of five halophytes (Grubovia dasyphylla, Halogeton glomeratus, Suaeda salsa, Bassia scoparia, and Reaumuria songarica) and assessed their rhizosphere microbial communities and EMF. The results showed that S. salsa possessed the highest shoot (3.13 mmol g−1) and root (0.92 mmol g−1) Na+ content, and its soil Na+ absorption, along with B. scoparia, was significantly higher than that of other plants. The soil pH, salinity, and Na+ content of the halophyte rhizospheres decreased by 6.21%, 23.49%, and 64.29%, respectively, when compared to the bulk soil. Extracellular enzymes in the halophyte rhizosphere soil, including α-glucosidase, β-glucosidase, β-1,4-N-acetyl-glucosaminidase, neutral phosphatase, and alkaline phosphatase, increased by 70.1%, 78.4%, 38.5%, 79.1%, and 64.9%, respectively. Furthermore, the halophyte rhizosphere exhibited higher network complexity of bacteria and fungi and EMF than bulk soil. The relative abundance of the dominant phyla Proteobacteria, Firmicutes, and Ascomycota in the halophyte rhizosphere soil increased by 9.4%, 8.3%, and 22.25%, respectively, and showed higher microbial network complexity compared to the bulk soil. Additionally, keystone taxa, including Muricauda, Nocardioides, and Pontibacter, were identified with notable effects on EMF. This study confirmed that euhalophytes are the best choice for saline-alkali land restoration. These findings provided a theoretical basis for the sustainable use of saline-alkali cultivated land.

Impact of moisture on the degradation and priming effects of poly(lactic acid) microplastic

AbstractThe degradation of biodegradable microplastics (MPs) can either stimulate or inhibit the decomposition of soil organic carbon (SOC), but the factors influencing these phenomena remain unclear. In this study, we used the 13C natural abundance to differentiate between carbon dioxide (CO2) arising from the mineralization of SOC and poly(lactic acid) (PLA) MP under varying soil water holding capacity (WHC) in alkaline and acidic soils. We also quantified the incorporation of soil‐ or PLA‐derived carbon (C) into phospholipid fatty acid (PLFA)‐distinguishable microbial groups. An increase in soil moisture did not significantly affect PLA MP degradation in alkaline soil, but significantly increased PLA degradability in acidic soil. In particular, the percentages of PLA‐derived C incorporated into PLFA‐distinguishable gram‐negative and gram‐positive bacteria were 14%–63% and 5%–33%, respectively, in all the treatments. The presence of PLA MP induced positive priming effects from 0 to 20 d in all the treatments but subsequently induced negative priming effects under some conditions. The total priming effects induced by PLA MP were significantly greater in alkaline soil with ≥70% WHC (37–43 mg C kg−1 soil) than in this soil with 50% WHC (8.6 mg C kg−1 soil). The total priming effect was 72–78 mg C kg−1 soil in acidic soil with ≤70% WHC, but a negative priming effect was observed in this soil with 90% WHC (−56 mg C kg−1 soil). In alkaline soil, the dissolved organic carbon content was positively correlated with the priming effect, but a negative relationship was observed between the priming effect and the amount of soil‐derived C incorporated into gram‐negative bacteria and fungi. In acidic soil, a positive correlation was found between the priming effect and the soil nitrate content. In summary, our findings indicate that 0.4%–2.8% of PLA MP was degraded in soils after 2 months, and that the intensity and direction of the priming effect induced by PLA MP are regulated by soil moisture and pH, but further exploration is needed to elucidate the microbial mechanisms underlying these effects.

Soil Solution Properties of Tropical Soils and Brachiaria Growth as Affected by Humic Acid Concentration

The soil solution is the compartment where plants uptake nutrients and this phase is in equilibrium with the soil solid phase. Changes in nutrient content and availability in the soil solution can vary among soil types in response to humic acid concentrations, thereby affecting Brachiaria growth. However, there are no studies demonstrating these effects of humic acid application on different soil types and how they affect Brachiaria growth. Thus, the aim of this study was to evaluate the effects of humic acid concentrations (0, 5, 10, 25, and 60 mg kg−1 carbon-humic acid) on Brachiaria brizantha growth and soil solution properties of contrasting tropical soils. Plants were grown for 35 days in greenhouse conditions in pots containing Sandy Entisol, Clayey (Red Oxisol), and Medium Texture (Red-Yellow Oxisol). Soil solution was assessed for pH, electrical conductivity (EC), carbon, and nutrient content. Shoot and root dry matter, as well as macro and micronutrients accumulation in the shoot, were determined. In a soil type-dependent effect, pH, EC, and concentrations of nutrients in solutions changed in response to carbon-humic acid concentration. In the less-buffered soils, Sandy Entisol and Red-Yellow Oxisol, the addition of 30–40 mg kg−1 carbon-humic acid increased root proliferation by 76–89%, while Brachiaria biomass produced in all soils increased by approximately 30%. Levels of carbon in solution were high (>580 mg L−1) and varied depending on the investigated soil type. Though solution carbon contents did not appear to be a driving factor controlling the positive effects of humic acid concentrations on Brachiaria dry matter, there was a direct relationship between other properties and nutrient content in the soil solution, and Brachiaria dry matter production.

Global analysis of spatio-temporal variation in mineral nutritional quality of pepper (Capsicum spp.) fruit and its regulatory variables: A meta-analysis

Pepper (Capsicum spp.) is an important fruit vegetable worldwide, and it is a rich dietary source of minerals for human being. Yet, the spatio-temporal distribution of pepper fruit mineral composition and the factors influencing such variations at global scale remain unknown. A global meta-analysis of 140 publications providing 649, 562, 690, 811 datapoints was conducted to quantify and evaluate the nutritional quality, comprising potassium (K), magnesium (Mg), iron (Fe) and zinc (Zn), of pepper fruits and its influencing variables. The analysis showed that the global average of K, Mg, Fe and Zn content in pepper fruits was 20–25 g kg−1, 1–1.5 g kg−1, 80–100 mg kg−1, and 20–40 mg kg−1, respectively. There had been a downward trend in pepper fruit nutritional quality over the last decade, especially for Fe and Zn. And, the concentration of all these four nutrients were at lower levels in less developed regions, especially in Africa. Our results showed that the vegetable “green pepper” contains more K, Mg, Fe and Zn than the “hot pepper” used as spice. The concentration of K, Mg, Fe and Zn were increased with fruit yield but that of Fe and Zn were decreased with increase in single fruit weight. Nutritional quality was optimal at mean annual temperature of 10 ℃ − 20 ℃, and was adversely affected when mean annual precipitation was < 500 mm. Pepper fruits produced at pH 6.5–7.5 had higher fruit K concentration while acidic soils (pH<6.5) favored higher Fe and Zn concentrations. The higher soil organic matter (SOM) generally improved the nutritional quality of the pepper. Our results suggest that systematic selection of superior varieties and soil amelioration (adjusting pH and SOM) of the soil-crop system are needed to achieve higher nutritional quality of pepper fruit.

PENGEMBANGAN PERANGKAT MULTI SENSOR UNTUK PRECISION FARMING MONITORING MEDIA TANAM

The development of a multi-sensor device and the implementation of a data transmission system to a database for predicting plant suitability parameters are the focus of this paper. This technology enables accurate and continuous data collection for agricultural condition monitoring. The study utilizes a DHT22 sensor for air temperature and humidity, a pH sensor for soil pH, a soil moisture sensor for soil moisture, a rain gauge sensor for rainfall, and a raindrop sensor for rain detection. The data from these sensors are managed by an ESP32 microcontroller and transmitted to a Firebase database. The multi-sensor device was functionally tested and compared with valid reference sensor readings. The results show that all the multi-sensor devices and the recording system in the Firebase database functioned well. The average measurement error for the DHT22 temperature sensor was 1.15°C, with 2.9% for humidity, 0.72% for the pH sensor, and the soil moisture sensor showed 100% accuracy. This system can be applied as a parameter for predicting the suitability of plant types with soil and environmental conditions.

Microbial fertilizers improve soil quality and crop yield in coastal saline soils by regulating soil bacterial and fungal community structure

Salinization is a global problem affecting agricultural productivity and sustainability. The application of exogenous microbial fertilizer harbors great potential for improving saline-alkali soil conditions and increasing land productivity. Yet the responses to microbial fertilizer application rate in terms of rhizosphere soil biochemical characteristics, soil microbial community, and crop yield and their interrelationships and underlying mechanisms are still unclear. Here, we studied changes to rhizosphere soil-related variables, soil enzyme activity (catalase, sucrase, urease), microbial community diversity, and sweet sorghum (Sorghum bicolor (L.) Moench) yield under four fertilization concentration levels (0, 0.12, 0.24, and 0.36 kg m−2) in a saline-alkali ecosystem (Shandong, China). Our results showed that the best improvement effect on soil when the microbial fertilizer was applied at a rate of 0.24 kg m−2. Compared with the control (sweet sorghum + no fertilizer), it significantly increased soil organic carbon (21.50 %), available phosphorus (26.14 %), available potassium (36.30 %), and soil urease (38.46 %), while significantly reducing soil pH (2.21 %) and EC (12.04 %). Meanwhile, the yield of sweet sorghum was increased by 24.19 %. This is mainly because microbial fertilizers enhanced the diversity and the network complexity of bacterial and fungal communities, and influenced catalase (CAT), urease (UE), and sucrase (SC), thereby facilitating nutrient release in the soil, enhancing soil fertility, and indirectly influencing sweet sorghum productivity. Among them, Gemmatimonadota and Verrucomicrobiota may be the key microbial factors affecting sweet sorghum yield, while available potassium, soil urease and available phosphorus are the main soil factors. These findings provide valuable theoretical insights for preserving the health of coastal saline-alkali soils and meeting the agricultural demand for increased yield per unit of land area.

Assessment of nematode and microbial diversity and screening of entomopathogens in revegetated post-coal-mining land in Kutai Kartanegara District, East Kalimantan, Indonesia

Abstract. Sopialena, Rosfiansyah, Suryadi A. 2024. Assessment of nematode and microbial diversity and screening of entomopathogens in revegetated post-coal-mining land in Kutai Kartanegara District, East Kalimantan, Indonesia. Biodiversitas 25: 2921-2930. Post-coal-mining management should strive toward site revegetation. The success of such revegetation efforts is largely determined by the soil's fertility status, which encompasses physical, chemical, and biological components. Biological fertility is indicated by the presence and abundance of soil microbes and nematodes. The objective of this study was to identify the diversity of nematodes and soil microbes in ex-coal-mining land revegetated with oil palm in Kutai Kartanegara District (East Kalimantan, Indonesia), to screen for entomopathogenic nematodes and microbes, and to analyze their relationships with the chemical fertility status of the land. As a control, non-mining land was also investigated. The results showed that microbial diversity and density (including fungi and bacteria) in the ex-coal-mining area were significantly lower compared to the control. Additionally, a decrease in microbial diversity and density was found in deeper soil layers of both post-mining and non-mining lands. In contrast, soil nematodes were more abundant in post-mining land, both in terms of diversity and density, and were also more plentiful in the deeper soil layers. Among the nematodes and microbes studied, only Heterorhabditis and Steinernema (nematodes), Trichoderma (fungi), and Bacillaceae (bacteria) were identified as entomopathogens, causing death in Tenebrio molitor L. larvae. Overall, soil fertility in ex-coal-mining land was observed to be lower, characterized by decreased soil pH, basic saturation, Soil Organic Carbon (SOC), and nutrient content, which contributed to a reduced microbial community compared to non-mining land.

Effect of biochar and iron ore tailing waste amendments on cadmium bioavailability in a soil and peanut seedling system.

Biochar and iron ore tailing waste have been widely separately applied for remediation of various contaminants, but the remediation effect of their combination on cadmium (Cd) pollution is unclear. In this study, the peanut biochar (BC), thermally activated iron ore tailing waste (TS), and the products of the co-pyrolysis of peanut shell and iron ore tailing waste (TSBC) were prepared for stabilizing Cd and reducing its bio-accessibility in soil and peanut seedling system. Present amendments enhanced soil pH, cation exchange capacity, electrical conductivity, and organic carbon content. The application of BC, TS, and TSBC led to decreases in acid-extractable Cd proportion of 2.2-8.81%, 2.43-7.20%, and 7.84-11.57%, respectively, and increases in the residual Cd proportion of 3.48-8.33%, 3.27-11.50%, and 9.02-13.45%, respectively. There were no significant differences in Cd accumulation in peanut roots due to three amendments treatments, especially at low Cd concentrations (i.e., Cd concentration of 0, 1, and 2mg·kg-1), and with a relatively small reduction (2.16-9.05%) in root Cd accumulation under the high Cd treatments of 5 and 10mg·kg-1. The Cd concentrations in seedling roots were significantly positively related to the acid-extractable Cd fraction, with a Pearson correlation coefficient of r = 0.999. The maximum toxicity mitigating effects were found in TSBC treatment, with increases in the ranges of 9.80-17.58% for fresh weight, 5.59-14.99% for dry weight, 5.16-10.17% for plant height, 5.96-10.34% for root length, 5.43-21.67% for chlorophyll a content, 17.17-71.28% for chlorophyll b content, and 13.11-39.60% for carotenoid content in peanut seedlings. Therefore, TSBC is a promising amendment for minimizing Cd contamination in peanut crops and utilizing industrial solid waste materials efficiently.

Dynamic interplay of silica-coated iron oxide nanocomposite on soil-plant system to mitigate Cd toxicity in rice

The utilization of nanotechnology based ameliorative strategies has emerged as an effective method to reduce the potential toxicity of environmental stressors on crops. However, there is limited information available regarding the interaction of silica-coated iron oxide nanocomposite (Fe3O4@SiO2, NCs) with plants under abiotic stress. Therefore, the objective of this study was to investigate the effects of different doses of silica-coated iron oxide nanocomposite (NCs) in mitigating Cd phytotoxicity in rice. The results revealed that Cd-contaminated soil inhibited plant growth, reduced physiological attributes, and induced ultrastructural changes in stressed plants. The presence of Cd in the soil also reduced rhizospheric soil pH and soil enzyme activities while increased Cd bioavailability and its uptake in plants. However, the foliar application of silica coated iron oxide NCs stimulated plant biomass production, chlorophyll biosynthesis, and antioxidant capacity. The application of NCs significantly decreased the activities of lipid peroxidation markers (MDA, EL and LOX) and reduced levels of reactive oxygen species (ROS) accumulation (•OH, O2·− and H2O2) in stressed plants. Additionally, NCs application influenced Cd accumulation in different tissues, potentially through modifying chemical profile of root exudates (amino/organic acids), which facilitated Cd precipitation through chelation and its sequestration in vacuoles via modulating the expression of metal transporters. Furthermore, the application of NCs indirectly regulated Cd fractionation, solubility, mobility and Cd enrichment in the rhizosphere. This study demonstrated the effective mitigation of Cd toxicity in rice plants by applying silica-coated iron oxide NCs. The results provided valuable insights into nanotechnology-based approaches for improving plant stress tolerance and offer promising strategies for sustainable agricultural practices.

Spodosol development and soil organic carbon distribution along a lithosequence in perhumid coastal temperate rainforest

AbstractA dense concentration of old‐growth forest and a wet, cold climate promote mineral weathering and leaching in coastal temperate rainforest soils. Our objective was to assess soil development and soil organic carbon (SOC) distribution across 18 soil profiles in remote, upland terrain of southeast Alaska where pedon data are sparse. We made soil morphological observations, collected samples, and completed laboratory analyses to measure SOC content, pH, and particle size distribution. The survey of upland backslope soils included north‐ and south‐facing hillslopes derived from three lithologies (slate, metavolcanic, and phyllite). The soils across all sites were very gravelly (51.8 ± 20.4% coarse fragments), acidic (mineral soil pH 4.85 ± 0.45), and moderately deep (96.56 ± 37.80 cm); thin, broken E horizons were underlain by thick, carbon‐rich spodic horizons. Soil development was relatively consistent as demonstrated by the Profile Development Index with values from 15 to 26 and Podzolization Index values spanning 8 to 14. A mean pedon SOC stock of 198.02 ± 81.42 Mg C ha−1 (n = 18) was calculated using data collected for all upland organic and mineral soils from our work. The accumulation of SOC was similar among soils formed from contrasting lithologies with averages of 182 ± 15.70 Mg C ha−1 for slate, 188 ± 53.80 Mg C ha−1 for metavolcanic, and 218 ± 124 Mg C ha−1 for phyllite. Our work contributes to soil morphological observations, laboratory data, and SOC stock estimates required to better constrain and model pedogenic processes and SOC stock in remote forests where data sets are limited.

Pengaruh Pupuk Cair terhadap pH, Fe-larut, dan C-organik di Tanah Sulfat Masam Desa Danda Jaya

One of the challenges of acid sulfate soil is the high Fe content in the soil, thus effective processing is needed to address its toxicity. The purpose of this study was to determine the changes in soil pH, Fe solubility, and organic-C from liquid fertilizer in acid sulfate soil in Danda Jaya Village, as well as to determine the relationship between soluble Fe and soil pH, organic-C and soil pH, and soluble-Fe. This research was structured using a descriptive method by comparing the application of liquid fertilizer with a control. The study was conducted in the Chemistry, Physics, and Biology Laboratory of the Soil Department, Faculty of Agriculture, Lambung Mangkurat University. The results of the study showed that the application of liquid fertilizer was able to increase pH and organic-C and decrease Fe solubility. Additionally, there was a correlation between soluble-Fe and pH with a coefficient of -0,95, a correlation between organic-C and pH with a coefficient of 0,91, and a correlation between organic-C and soluble-Fe with a coefficient of -0.89. Furthermore, the equation for the relationships was soil pH = -0.002 soluble-Fe + 5.958, Soil pH = 0.30 organic-C + 4,43, and soluble Fe = -154.92 organic-C + 830.15.

Controlling exposure to As and Cd from rice via irrigation management

Irrigation management controls biogeochemical cycles in rice production. Under flooded paddy conditions, arsenic becomes plant-available as iron-reducing conditions ensue, while oxic conditions lead to increased plant availability of Cd in acidic soils. Because Cd enters rice through Mn transporters, we hypothesized that irrigation resulting in intermediate redox could simultaneously limit both As and Cd in rice grain due to As retention in soil and Mn competition for Cd uptake. In a 2 year field study, we used 6 irrigation managements that varied in extent and frequency of inundation, and we observed strong effects of irrigation management on porewater chemistry, soil redox potentials, plant As and Cd concentrations, plant nutrient concentrations, and methane emissions. Plant As decreased with drier irrigation management, but in the grain this effect was stronger for organic As than for inorganic As. Grain organic As, but not inorganic As, was strongly and positively correlated with cumulative methane emissions. Conversely, plant Cd increased under more aerobic irrigation management and grain Cd was negatively correlated with porewater Mn. A hazard index approach showed that in the tested soil with low levels of As and Cd (5.4 and 0.072 mg/kg, respectively), irrigation management could not simultaneously decrease grain As and Cd. Many soil properties, such as reducible As, available Cd, soil pH, available S, and soil organic matter should be considered when attempting to optimize irrigation management when the goal is decreasing the risk of As and Cd in rice grain.

Assessing Land Suitability for Lamtoro (Leucaena leucocephala) in Reclaimed Mining Lands of Sanggau Regency, West Kalimantan

This study evaluates the suitability of reclaimed zircon mining land in Sanggau Regency, West Kalimantan for cultivating Lamtoro (Leucaena leucocephala), a versatile plant used for forage and as a biomass energy source. Utilizing the weight factor matching method, we analyzed a range of land characteristics including soil texture, drainage, pH, and organic carbon content, as well as environmental factors such as temperature and rainfall. Initial assessments categorized the land as marginally suitable due to suboptimal drainage and soil texture. However, our research suggests that through strategic interventions—specifically improving soil texture using topsoil and enhancing drainage systems—the suitability of the land can be significantly upgraded. Detailed analysis shows that with these modifications, the land shifts from a marginal to a highly suitable rating for Lamtoro cultivation. The successful adaptation of Lamtoro in these reclaimed areas not only supports agricultural viability but also aids in the ecological restoration of post-mining landscapes, contributing to the achievement of sustainable development goals. This study underscores the potential of targeted land management strategies in transforming degraded mining areas into productive agricultural lands, providing a blueprint for similar reclamation efforts globally.

Efficacy of various amendments for immobilization of potentially toxic elements in wastewater contaminated soils

Farmers are using municipal wastewater either treated or untreated for irrigation because of limited fresh water resources. Wastewater extensively used for irrigation purposes is enriched with many nutrients. The reuse of wastewater is imposing a negative impact on human health and the ecosystem. It is a need of the day to identify and assess issues of the reuse of wastewater. In the current experiment, impact of organic/inorganic amendments was studied to mitigate the toxic effects of pollutants present in wastewater. Soil was brought from the site having consistent use of wastewater and different treatments were applied as per plan. The experiment has 28 treatments with 04 replications. Nine different amendments were used at 3 varying levels. Incubation time of 30 days was given after the addition of all treatments. The results of the study showed the application of FYM @ 5.0% w/w soil reduced soil pH (7.44), EC (2.16 dS m−1), SAR (8.14), lead (8.48 mg kg−1), cadmium (1.14 mg kg−1), nickel (10.55 mg kg−1) and arsenic (2.03 mg kg−1) when compared with control and other treatments. Usage of compost and horse waste followed FYM. On the basis of this study, it is recommended that wastewater can be used for irrigation purpose after treating with FYM preferably and compost in general.