Inorganic Soil Research Articles

Geotechnical analysis of potential landslides on slopes in the Rimbo Panjang area of Padang City and mitigation

The Lambung Bukik area of Padang City is a relocation area for the flash flood disaster in Batu Busuk Padang on 24 July 2012. This research analyzes the potential for slope failure in the Rimbo Panjang area, where many residents’ houses are built on steep slopes. Geotechnical analysis was carried out to determine the soil characteristics in the Rimbo Panjang area, which was taken at four locations. The results of the classification show that the soil in the Rimbo Panjang area is inorganic silt - high plasticity (MH). The plasticity index value is 2.5 – 10.4%, indicating that the soil has low swelling potential. The activity value in inorganic silt soil is meager, namely in the range of 0.1 – 0.99, which is the mineral kaolinite and illite activity value. The activity values agree with the XRD test results, where the soil contains kaolinite and illite minerals with low swelling properties. The low swelling characteristic causes the slopes to have a low landslide potential. The safety factor value of the slopes is in the range of 1.79 – 2.71 > 1.5, so the slope can be said to be stable.

Potential of clay‐rich waste and industrial by‐products as effective inorganic soil amendments to enhance soil physical properties

AbstractClay minerals play a crucial role in regulating the structure and functions of soils because of their chemical nature and their interactions with other soil constituents. In this context, a key objective of the research described in this article was to assess the extent to which the addition of various types of recycled clay‐rich materials to soils prone to crusting and erosion increase their clay content and improve their physical properties. Excavated soil (ExS), considered waste under European Union law, and quarry sludge (QS), an industrial by‐product of the washing process in mining operations, were used as soil amendments. ExS is dominated by swelling clay mineralogy such as interstratified illite‐smectite, whereas QS contains high level of non‐swelling clay minerals such as kaolinite and illite, and a low level of interstratified illite‐smectite. Lysimeters were filled with topsoil (0–30 cm) from an agricultural field. Treatments where the soil was amended with these materials were compared with a control without amendment. Lettuce was cultivated for three growing seasons. After 250‐days, the aggregate stability and water retention of the topsoil were measured. The equivalent pore‐size distribution (PSD), derived from the soil water retention curve, was analysed to predict soil water and aeration status. The application of QS to the topsoil enhanced soil structure without compromising lettuce productivity compared with the control and other treatments. However, amending topsoil with ExS decreased the stability because of the abundance of swelling clay minerals. Soil water retention at saturation increased from 27% in the control to 42% and 36% with ExS and QS amendments, respectively. At a pressure head >15,000 cm (residual pores <0.2 μm), water retention rose from 6% in the control to 19% with ExS and 14% with QS. The application of the clay‐rich material increased small pores compared with larger ones. This led to a minor increase in porosity responsible for water movement, aeration and root growth. This observation highlights the limitations of clay application benefits, which depend on the quantity and mineralogy of the clay and the presence of other binding agents. Further research is needed to investigate the combined effects of organic matter and clay‐rich materials on improving the soil structure and optimizing the pore size distribution for multiple functions.

The Influence of Lime Variations on the Unconfined Compressive Strength of Inorganic Clay Soil Stabilized with a Combination of Nickel Slag and Aluminum Hydroxide

Soil stabilization is a ground improvement technique aimed at enhancing the strength and bearing capacity of soil, particularly in road construction projects. The combination of multiple stabilization materials allows for achieving better improvements in soil bearing capacity. The use of industrial waste materials offers an eco-friendly solution while repurposing materials that are typically discarded. This study focuses on the engineering application of adding limestone as a natural pozzolanic material. The research involves laboratory testing to measure the unconfined compressive strength (UCS) of stabilized clay soil samples. The addition of stabilization materials is based on weight ratios, where the ratio of nickel slag to aluminum hydroxide is 1,5, and limestone is added in varying proportions of 2%, 4%, and 6%. The curing of the test specimens is carried out over periods of 3, 7, 14, and 28 days to examine the influence of curing time on the improvement of soil UCS values. The results indicate that the addition of nickel slag and aluminum hydroxide significantly enhances the soil’s UCS. Furthermore, variations in limestone content show that increasing its concentration up to 6% yields optimal results in improving soil strength. This study concludes that the combination of waste materials and limestone can effectively enhance the mechanical characteristics of soil, providing a sustainable and environmentally friendly solution for soil stabilization in various infrastructure projects.

The Comparative Study on the Influence of Inorganic Soil Amendment on the Growth and Leaching Analysis of the Brassica Family

Research on the positive effects of inorganic soil amendments in the agricultural sector has been steadily increasing to demonstrate their impact on plant development and the reduction of leaching. In this study, kaolin, metakaolin, zeolite, and perlite, which operate as inorganic soil amendments, were mixed with soil to determine their effectiveness in promoting Brassica growth and reducing the leaching of nitrite and nitrate. Seven alternative treatments; control standard (SS), control low (SL), 3g kaolin (3gK), 3g metakaolin (3gM), 3g zeolite (3gz), 5g of zeolite (5gZ), and 5g of perlite (5gP), were chosen to assess their effectiveness in the growth and reducing leaching in Brassica family (mustard green and kale). All the experiments were conducted in a greenhouse. According to the statistical analysis one-way ANOVA by comparing the mean, zeolite amended soil showed a higher significance difference in mustard green and kale growth analysis at harvest 1 and harvest 2 compared to other treatments. Kaolin, metakaolin, and perlite also showed slightly greater significance differences in mustard green and kale growth compared to the standard and low NPK treatments. In the leaching investigation, kaolin, metakaolin, zeolite, and perlite exhibited the lowest concentration of nitrate and nitrate compared to both standard NPK and low NPK. As demonstrated by the findings, inorganic soil amendments show the potential to improve the growth of mustard green and kale which also reduces the concentration of nitrate and nitrite, especially when using zeolite.

Characteristic of PM2.5 concentration and source apportionment during winter in Seosan, Korea

Seosan is a concentrated industrial complex in the midwestern region of Korea. A study was conducted from December 2020 to January 2021, measuring PM2.5 and chemical components in Seosan using online instruments every hour. The concentration of PM2.5 during the winter season was 31.4±17.8 μg/m3, exceeding the national ambient air quality standard of Korea. The mass fraction of organic matter, elemental carbon, three major ions, five minor ions, crustal elements, and trace elements in PM2.5 accounted for 24.5%, 4.36%, 32.0%, 2.82%, 4.11%, and 5.17% of the total PM2.5 mass concentration, respectively. Source identification was conducted using positive matrix factorization modeling, revealing eight sources of PM2.5: Secondary inorganic aerosol (SIA), vehicle exhaust, industry, coal combustion, biomass burning/incinerator, oil combustion, soil, and aged sea salt. Source contributions varied during high pollution episodes (HPE), with SIA dominating in HPE1 and soil and aged sea salt in HPE2. The potential source contribution function and conditional probability function were utilized to estimate the potential local and regional emission areas for the identified sources. In Seosan, vehicle exhaust and biomass burning/incinerator were primarily influenced by local sources. SIA, industry, and oil combustion sources were significantly affected by short-range transport from eastern China. Soil and aged sea salt, which exhibited high contributions during HPE2, were associated with long-range transport from Inner Mongolia. Coal combustion was attributed to both local sources, particularly large industrial complexes near Seosan, and long-range transport from Northeast China and Inner Mongolia.Graphical

Phosphorus lability in a Ferralsol as affected by land-use change in the Brazilian Cerrado

ABSTRACT Low availability of phosphorus (P) is a constraint to agricultural development in tropical soils, owing to the high fixation of P in the soil matrix. Land-use change can modify soil P dynamics. This study aimed to evaluate the effects of land-use change on P fractions in a Ferralsol under different systems of use and management. Inorganic (Pi) and organic soil P (Po) fractions were assessed by sequential fractionation using H2O, NaHCO3, NaOH, hot concentrated HCl and H2SO4-H2O2 as extractants. The systems in the study were as follows: pasture (PAST), no-tillage system (NT), organic cultivation (ORG) with 2, 6, 8 and 10 years of organic management, and conventional continuous cropping tillage (CT). A native Cerrado forest (F) area was used as reference. In general, Po forms predominated over Pi, with exception of the CT soil, where Pi represented 41% of the total P. On average, conversion of F into the CT system reduced levels of Po in the soil by up to 72%. The soil P resilience index showed that P inputs in the CT and NT systems were insufficient at recovering P availability after the land-use change. On the other hand, the most recent ORG systems demonstrated the greatest efficiency at restoring the equilibrium of the soil P state. The hypothesis that less intensive agricultural systems increase the soil labile P pool, enhancing available P levels, was confirmed. Agricultural systems that used organic inputs and reduced soil disturbance were found to be more efficient at recovering and maintaining soil P availability.

The Process of Soil Carbon Sequestration in Different Ecological Zones of Qingtu Lake in the Arid-Semi-Arid Region of Western China.

As a vital component of the global carbon pool, soils in arid and semi-arid regions play a significant role in carbon sequestration. In the context of global warming, increasing temperatures and moisture levels promote the transformation of barren land into wetlands, enhancing carbon sinks. However, the overdevelopment of oases and excessive extraction of groundwater lead to the opposite effect, reducing carbon sequestration. This study examines two soil types-meadow soil (MS) and swamp soil (SS)-from Qingtu Lake, an arid lake in western China. It analyzes the sources of soil inorganic carbon, the composition and origin of dissolved organic matter (DOM), and the relationships between microbes, soil organic carbon (SOC), soil inorganic carbon (SIC), mineral composition, and soil texture. The results indicate that inorganic carbon in the study area consists of both primary carbonate minerals and secondary pedogenic carbonates. The DOM primarily consists of two components, both identified as terrestrial humic substances. In meadow soils, bacterial activity drives the weathering of plagioclase, which releases Ca2+ necessary for the formation of pedogenic carbonates. Plagioclase also provides colonization sites for microbes and, along with microbial activity, participates in the soil carbon cycle. Within the soil community, bacteria appear to play a more critical role than fungi. In contrast, microbial contributions to the carbon cycle in swamp soils are weaker, with minerals predominantly interacting with organic carbon to form mineral-associated organic matter, thus promoting the soil carbon cycle. These findings have important implications for understanding soil carbon sinks under different micro-ecological conditions in arid and semi-arid regions. Through targeted human intervention, it is possible to enhance carbon sequestration in these areas, contributing to the mitigation of global climate change.

Implementation of integrated nutrient management (MIN) on small agricultural properties: case studies in Mozambique

Integrated nutrient management is a sustainable approach that combines nutrient management practices to improve soil fertility and agricultural productivity while minimising environmental impacts. This article reviews the implementation of integrated nutrient management on small holder farms, focusing on case studies globally and in Mozambique. Integrated nutrient management integrates the use of organic and inorganic fertilisers, crop rotation and soil cover to optimise nutrient efficiency and preserve soil health. Case studies show that, globally, integrated nutrient management can increase productivity and sustainability, while in Mozambique, practices such as green manuring and nutrient recycling have shown significant benefits. However, implementation faces challenges such as technical complexity, initial costs and the need for institutional support. Future prospects include strengthening public policies, adopting innovative technologies and adapting to climate change. Integrated nutrient management offers a promising path to transform small-scale agriculture, promoting food security and ecological resilience. Through a commitment to innovation and local adaptation, integrated nutrient management can become a standard agricultural practice, empowering farmers and contributing to global sustainability.

Relationships and determinants of adoption of sustainable land management technologies in Eastern and Southern Highlands of Ethiopia

Degraded land is a major danger to agricultural productivity and food security in Ethiopia. Sustainable land management technologies (SLMTs), through targeted interventions, have been applied to address this problem. Notwithstanding some of the known agricultural and environmental benefits connected with the adoption of some SLMTs, the adoption rate remains below expectations. Therefore, this study aims to analyze the relationships and determinants of the adoption of SLMTs in eastern and southern Ethiopia. Data were collected from 384 sampled households selected using multi-stage sampling techniques. Descriptive statistics and multivariate probit (MVP) model were used to analyze data. Estimated results of MVP revealed that the adoption of SLMTs is positively and significantly influenced by education level, livestock, membership in a social group, extension contacts, access to SLM information, training, credit, land tenure, and slope, while age, farm distance, and the number of active family members due to youth migration abroad had negative effects. The widely adopted SLMTs on farmlands were inorganic fertilizer (49.5%), soil bunds (48.4%), bench terraces (47.2%), intercropping (46.1%), and manure (38%). This study concluded that farmers invested a blend of SLMTs, some of which complemented and others substituted for one another. Therefore, policy-makers and planners should focus on fortifying human and local institutions’ capacity to implement SLM and consider SLM technology interdependencies before communicating with farmers.

Morphological and physiological plasticity of tomato in response to Azolla fern, a novel organic fertilizer of environmentally friendliness

Tomatoes are highly valued vegetable crops due to their excellent nutritional content. However, production remained low due to an incorrect combination of organic and inorganic soil nutrition. A pot experiment was conducted under shaded conditions with Azolla and inorganic nitrogen fertilization to determine the morphological and physiological plasticity of tomatoes. The study used a factorial combination of four levels of Azolla (0, 25, 50, and 75 g per pot) and four levels of nitrogen (0, 0.23, 0.46, and 0.69 g per pot) in a complete randomized design with three replications. We collected data on chlorophyll content (Chl a, Chl b, TChl), photosynthetic rate, water use efficiency, transpiration rate, stomata number, branch number (primary and secondary), plant height, leaf area, stomata conductance, relative water content, and number of leaves. Analysis of variance was employed to analyze the data, and the means were separated using the least significant differences test at a 5 % significance level. The results showed that primary and secondary branches, stomata number, transpiration rate, and water use efficiency were highly plastic due to the higher nitrogen levels and Azolla alone. The interaction effect of Azolla and nitrogen had a significant influence on chlorophyll content, photosynthesis rate, stomatal conductance, relative water content, number of leaves, plant height, and leaf area. It can be concluded that a balanced combination of organic and inorganic fertilizers remains essential for optimal tomato growth and physiology, emphasizing that the exclusive use of organic farming methods may not be the ideal solution.

The effects of some common inorganic soil components on the pyrolytic analysis of plastics

Plastics and microplastics are major hazards for the environment and human health. Plastic materials in the sedimentary record are a marker for modern anthropogenic activity. One environmental reservoir of plastics and microplastics is soil. One method to detect the presence of plastics in soil, and to thereby recognise the presence of its hazards, is pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). Yet soils are multicomponent mixtures and any analytical artefacts generated will reduce our ability to monitor the presence of plastics. We have studied the Py-GC-MS responses for the polymers polyethylene (PE), polypropylene (PP), polystyrene (PS) and poly(vinyl chloride) (PVC), in the presence of individual phyllosilicate (kaolinite, illite and montmorillonite) and iron oxyhydroxide/oxide (goethite and magnetite) minerals that may be present in soil. Our data show the distinctive polymer fingerprint becomes obscured when analysed with minerals. We have isolated the effects of some potential inorganic soil components so that responses from complex matrices can be deconvolved. The mineral-assisted aromatisation of compounds affects the diagnostic signals of the original polymer, particularly for those polymers (PE and PP) which have a large aliphatic hydrocarbon signature when analysed alone. Iron oxyhydroxide/oxide are shown to have a greater effect on the data than phyllosilicates. Our results will help guide future interpretations of Py-GC-MS data obtained when monitoring soils for plastic contamination. Py-GC-MS is most commonly applied as a qualitative method, yet detailed quantitation of the organic-inorganic reactions we have described, albeit analytically complex, would represent a useful future study.

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.

Precise method to measure fungal and bacterial necromass using high pressure liquid chromatography with fluorescence detector adjusted to inorganic, organic and peat soils

Soil organic matter is the dominant pool of carbon (C) in terrestrial ecosystems. Recent advances in understanding of the mechanisms of C stabilization in the soil emphasize microbes as the main drivers. Special attention is placed on the accumulation of bacterial and fungal necromasses. This calls for development of fast and reliable methods to estimate microbial necromass in a various type of soils, including peat soils. Here we provide precise method to measure fungal and bacterial necromasses with high-pressure liquid chromatography-fluorescence detector (HPLC-FLD) and its comparison with gas chromatography method. Purity of the chromatographic peaks was confirmed with mass spectrometry. The HPLC-FLD method provides reliable results for mineral, organic and highly organic peat soils.

From lava to leaf: Physiological responses and trace element mobility in Tilia cordata L. trees grown in volcanic ash amended urban soil

This study investigates the potential of utilizing volcanic ash (VA), classified as special waste, as an inorganic soil amendment to enhance tree growth and resilience in urban areas near volcanic regions. Lime trees were transplanted into pots filled with urban soil (Cnt) or amended with 10 % VA. Tree’s physiological traits were monitored over the growing season. Notably, VA-treated trees showed improved net CO2 assimilation (Pn) and stomatal conductance (gs) during the leaf senescent stage. The analysis of ash, and Cnt and VA soils, showed low concentrations of trace elements. In addition, trace element accumulation in the leaves of VA trees was not observed. In summer, during a 12-day drought stress test, VA-stressed trees exhibited enhanced water absorption, reduced lipid peroxidation, and higher Pn and gs values in the initial days compared to control-stressed trees. Importantly, the VA also promoted a 33 % larger tree root system, potentially enhancing drought resilience. This could offer an important advantage for trees, especially during the tree's critical establishment phase. Thus, VA could be a promising amendment for urban soils to bolster tree tolerance to drought.

Production and profitability of mint (Mentha x piperita L.) with organic and inorganic soil covers

La menta piperita es una planta medicinal, su cultivo es considerado un interesante rubro de renta, sin embargo, es susceptible al déficit hídrico, siendo ésta la causa principal de los bajos rendimientos de este cultivo en parcelas sin sistema de riego. Con el objetivo de evaluar parámetros productivos y económicos del cultivo de menta piperita con coberturas orgánicas e inorgánicas de suelo que ayuden reducir el déficit hídrico, se llevó a cabo esta investigación en un diseño completamente al azar, compuesto por cinco tratamientos (suelo sin cobertura, mulching negro, mulching blanco, cascarilla de arroz y pasto pacholí) y cuatro repeticiones, totalizando 20 unidades experimentales. Las variables evaluadas fueron: longitud de brotes basales, cantidad de brotes basales y brotes laterales, rendimiento de masa fresca y seca. Adicionalmente, se analizó la rentabilidad de cada tipo de cobertura. Todas las medias fueron sometidas al análisis de varianza (ANAVA) y comparadas por el Test de Tukey al 5%. En cuanto a la longitud de brotes basales, los mejores resultados fueron con la utilización de mulching negro, seguido por el mulching blanco y pasto pacholí; la mayor cantidad de brotes laterales con 16,45 con el mulching blanco, en cambio en la cantidad de brotes basales fue el testigo que presentó una mayor cantidad con 4,15. El mulching blanco presentó mayor rendimiento que el testigo para la masa fresca y masa seca con 1.544 kg ha-1 y 628 kg ha-1, respectivamente. Al analizar la rentabilidad en la masa fresca de la menta piperita, la utilización del mulching blanco fue más factible, mientras que en masa seca se observó una rentabilidad negativa para todos los tratamientos.

Cross-talk between antioxidant production and secondary metabolite biosynthesis under combined effects of ozone stress and nitrogen amendments: A case study of lemongrass

The present experiment was done to study the interactive effects of soil nitrogen (N) amendments and elevated ozone (O3) (N–O3) on a medicinal plant, lemongrass [Cymbopogon flexuosus (Steud.) (Wats.)]. The experiment used two doses of inorganic soil nitrogen (N1, recommended and N2, 1.5-times recommended dose) in open-top chambers under ambient and elevated (ambient + 15 ppb and ambient + 30 ppb) O3 conditions. To analyze various characteristics, samples were collected at 45 and 90 days after transplantation (DAT). Additionally, at 110 days after transplantation (DAT), the metabolite contents of the leaves and essential oils were analyzed. The present study aims to investigate the mechanistic approach involving the crosstalk between antioxidant production and secondary metabolite biosynthesis in lemongrass upon N–O3 interactions. The present experiment showed that N amendments can be an efficient measure to manage O3 injury in plants, along with ensuring a balance between primary and secondary metabolic pathways, thus sustaining the plant defense and production of bioactive compounds, simultaneously. Under N–O3, not only the Halliwell asada pathway was stimulated resulting in the increased activities and concentrations of antioxidant pools; the shikimate, phenylpropanoid and mevalonic acid pathways were also invigorated, producing more number and contents of secondary metabolites (SMs), compared with plants that were not treated with N doses. This study suggests that soil nitrogen amendments will improve the therapeutic qualities of lemongrass, along with the strengthening of its antioxidant machinery, upon exposure to O3 stress.

Mitigating water pollution by nitrogen fertilizers through amending ammonium sorption in an acid soil using Calciprill and sodium silicate

Use of nitrogen (N) fertilizers is gaining popularity to meet crop nutrient requirement for sustaining the food security of the increasing global population. However, improper management of N fertilizers in acid soils causes leaching and surface runoff because of excessive rainfalls and poor N retention in the tropics in particular. This results in N pollution in water bodies (also known as eutrophication), which degrades water quality to the detriment of aquatic ecosystems near farms. Thus, there is a need for using inorganic soil amendments such as Calciprill and sodium silicate to improve soil N adsorption because of the alkalinity and ability of these amendments to retain N for mitigating excessive N contamination in water bodies. To this end, this N sorption study was conducted to determine the effects of Calciprill and sodium silicate on ammonium (NH4+) adsorption and desorption in an acid soil (Bekenu series, Typic Paleudults). The soil was co-applied with different rates of Calciprill (80 %, 90 %, and 100 % Ca saturations) and sodium silicate (90, 105, 120, 135, and 150 kg ha−1), followed by the NH4+ adsorption capacity determination through the additions of NH4+ isonormal solutions at the five concentrations (0, 25, 50, 75, and 100 mg L−1) to establish a linear relationship between the amount of NH4+ absorbed (qe) and the amount of NH4+ left in the solution (Ce) after 24 h of equilibration. Apart from the soil only without any amendment (C0S0), there were another two additional treatments where the soil was added with Calciprill (100 % Ca saturation) (C3) and sodium silicate only (150 kg ha−1) (S5) to determine their respectively effects on N sorption. The collected data were fitted to the Langmuir and Freundlich isotherms. Thereafter, NH4+ desorption was determined using the same soil samples added with 2 mol dm−3. Compared with the soil without any amendment (C0S0), the Calcirpill alone (C3) and the combined use of Calciprill and sodium silicate significantly increased NH4+ adsorption at the NH4+ addition of 250 mg L̶1, suggesting that Calciprill is the amendment which dominantly increases NH4+ adsorption and the effects of amendments are more pronounced at the lower soil NH4+ concentration. The results also revealed that the NH4+ adsorption in the soils following the co-application of Calciprill and sodium silicate followed the assumption of Freundlich isotherm. Regardless of the NH4+ concentration used, the effects of Calciprill and sodium silicate on the NH4+ desorption remain unclear, which could be because of the ability of sodium silicate to stabilize the soil structure. This stabilization reaction might have impeded the dissolution of Calciprill and temporarily fixed the absorbed NH4+. These findings suggest that it is possible to use the amendments to amend NH4+ sorption in Bekenu series for mitigating NH4+ leaching and runoff to prevent eutrophication.

The effects of microalgae use as a biofertilizer on soil and plant before and after its anaerobic (co-)digestion with food waste

The increase in food waste generation has resulted in significant challenges for its sustainable management. Anaerobic digestion coupled with microalgae-based ponds for digestate treatment can be used as a low-cost eco-friendly technology approach. In this case, microalgal biomass harvested from the ponds may be valorized into bioenergy (biogas) and soil conditioner and/or biofertilizers. The aim of the present study was to evaluate the microalgal biomass produced from a food waste digestate treatment ponds as agricultural fertilizer. For this purpose, microalgal biomass was tested before and after anaerobic digestion and co-digestion with food waste, exploring its potential for valorization. The inorganic fertilizer urea and soil with no fertilization were also used as treatments. The experimental design consisted of applying the treatments in pots cultivated with hybrid grass Brachiaria cv. Sabiá and distributed in randomized blocks in a controlled greenhouse. Microalgal biomass was mainly composed by Scenedesmus sp.. The assessed parameters showed comparable results on plant growth (i.e. number of tillers, fresh and dry matter and Chlorophyll content index) for fresh and digested microalgal biomass and inorganic fertilizer. Furthermore, it was observed that fresh microalgae provided the highest Phosphorus content in the leaf (21 %). Additionally, there were increases of 9 % in Nitrogen and 12 % in organic matter in the soil after applying digested microalgae compared to the control group without any fertilization. Finally, experimental data obtained suggests that microalgae-based biofertilizer holds the potential to replace inorganic fertilizer as a nutrient source. Moreover, it contributes to the valorization of by-products from organic waste treatment.

Modeling with the controlling effects of inorganic fertilizers, earthworm population and soil fertility on agricultural crop production

Modeling with the controlling effects of inorganic fertilizers, earthworm population and soil fertility on agricultural crop production

Estimation of Groundwater Residence Time Using Radiocarbon and Stable Isotope Ratio in Dissolved Inorganic Carbon and Soil CO2

AbstractEstimation of residence time of groundwater, particularly in regions with inadequate surface waters are very important for formulating sustainable groundwater management policies. We developed a technique for extracting dissolved inorganic carbon (DIC) quantitatively from water for measuring its 14C contents and presented the analytical details here. We also measured stable carbon isotope ratio (δ13C) in soil CO2 and groundwater DIC to correct the groundwater 14C ages. In addition, 14C in soil CO2 were measured for making necessary correction in the initial activity of the recharging water. The corrected 14C contents in the groundwater samples were used to estimate their residence times employing Lumped Parameter Models (LPM), a set of mathematical models to account for the processes that take place during transport from the recharge to the sampling spots. We present a case study focused on the calculation of radiocarbon ages and residence times for a groundwater sample collected from the campus of Physical Research Laboratory in Ahmedabad, Gujarat, India. The study also includes estimations of groundwater residence times using previously measured 14C ages of groundwater samples from Gujarat, India. Various factors controlling the groundwater ages in the LPM and their applicability are discussed.