Municipal Solid Waste Compost Research Articles

Assessing microplastics contamination and characteristics in organic soil amendments in the Greater Accra Metropolitan Area of Ghana

The study examines the increasing use of organic soil amendments (OSA) due to declining soil fertility and the high cost of synthetic fertilizers, alongside growing concerns about microplastics (MPs) accumulating in soil, which negatively impact soil, crop, and food quality. This research assessed the presence and characteristics of microplastics in Municipal Solid Waste Composts (MSWC) and dry sewage sludge (DSS) within the Greater Accra Metropolitan Area (GAMA) of Ghana. The study analyzed two sources of MSWC (MSWC 1 and MSWC 2) and two sources of DSS (Sludge 1 and Sludge 2), with five samples each, for microplastic concentrations. A reference soil sample, collected from a depth of 0-25 cm, was also tested. The microplastics were extracted using acid digestion (30 % H2O2 at 70 °C), density separation with a ZnCl2 solution, and vacuum filtration. Results revealed that Sludge 1 had the highest concentration of microplastics (4316 ± 968 MPs kg-1), followed by MSWC 1 (3572 ± 1196 MPs kg-1), MSWC 2 (3104 ± 418 MPs kg-1), and Sludge 2 (2024 ± 562 MPs kg-1). The soil sample had the lowest concentration of 232 ± 62 MPs kg-1. Statistical analyses (Kruskal Wallis and Dunn’s multiple comparisons) showed significant differences (p < 0.05) in microplastic concentrations among the samples. The composition of microplastic polymers varied among the samples. The soil sample predominantly contained cellophane (91.67 %) and polyvinyl propionate (8.33 %). MSWC 1 contained urethane alkyd (31.11 %), polyethylene (26.67 %), and polyester (20 %), while MSWC 2 had polyethylene (24.10 %), polyester (20.48 %), cellophane (18.07 %), and polypropylene (15.66 %). Sludge 1 was dominated by polyethylene (35.29 %), polypropylene (30.25 %), cellophane (15.13 %), and urethane alkyd (11.76 %), whereas Sludge 2 mainly contained polyester (42.86 %), cellophane (23.21 %), urethane alkyd (21.43 %), and polyethylene (12.50 %). Microplastics were prevalent in the MSWC and sewage sludge which were obtained from the GAMA, with significantly higher concentrations than those in the soil samples. Further research is needed to develop strategies to mitigate microplastic pollution in OSAs to improve soil health.

Effect of Nitrogen and Municipal Solid Waste Compost on the Physicochemical Properties of a Calcareous Soil Under Wheat Cultivation

ABSTRACT Municipal solid waste (MSW) is an exciting source of organic matter (OM) for agricultural soil. In recent years, the application of MSW compost has received considerable attention. On the other hand, simultaneous use of organic and chemical fertilizers can lead to better plant growth and soil fertility. The main purpose of this study was to evaluate the impact of MSW compost and nitrogen fertilizer (N-fertilizer) on soil physicochemical properties. Treatments consisted of three levels of MSW compost 0, 10, and 20 t ha−1 (C0, C10, and C20), three rates of N-fertilizer 0, 100, and 200 kg ha−1 (N0, N100, and N200). Application of N-fertilizer and MSW compost alone or in combination significantly affected some physical and chemical properties of soil. The addition of N-enriched compost to the soil increases electrical conductivity (EC), N-NO3 − contents (in C20N200 treatment) and available iron (Fe) and zinc (Zn), field capacity (FC) and available water (AW) contents (in C20N100 treatment). While the bulk density (BD) of the soil decreased. Our results show that the use of MSW compost and N-fertilizer is a beneficial option for improving the physicochemical properties of soil, especially physical properties under arid and semi-arid conditions.

EFFECT OF MUNICIPAL SOLID WASTE COMPOST, GYPSUM AND MYCORRHIZA ON METALS CONTENT IN SOIL AND PEANUT GRAIN

Municipal solid waste compost (MSWC) is widely used as an organic soil amendment and fertilizer on agricultural land. However, applying MSWC can cause adverse effects due to the heavy metals contained. This study aimed to determine the heavy metal content of MSWCs in the presence of mycorrhizae and gypsum and their effects on soil and peanut grain. The field experiment was carried out in the split factorial design based on a completely randomized block in three replications as a field trial in 2018 and 2019, in Iran. The main factor includes two levels of gypsum (0 and 150 kg ha-1) and the sub-factors include the presence and absence of Arbuscular mycorrhizal fungi (AMF) and different levels of MSWC at five levels (0, 2, 4, 6, and 8 t ha-1). The findings showed that MSWC significantly increased the concentrations of manganese (Mn), lead (Pb), nickel (Ni), zinc (Zn), cobalt (Co), chromium (Cr), cadmium (Cd), and boron (B) in soil and grains. In addition, Co, Ni, and Zn concentrations in grain increased and Pb, Mn, Ni, and Zn concentrations in soil decreased with AMF application. Gypsum treatment also had no significant effect on metals in both grain and soil.

Priming effect of pigeon pea and wood biochar on carbon mineralization of native soil organic carbon and applied municipal solid waste compost

A laboratory incubation experiment was conducted for 36 days to study the effect of pigeon pea biochar (PPB) and wood biochar (WB) on carbon mineralization of native soil organic carbon (SOC) and municipal solid waste compost (MSWC) applied to soil. The MSWC addition enhanced soil respiration by 2-fold (231 mg C kg-1 soil) over the control (118 mg C kg-1 soil). The PPB addition significantly (P &lt; 0.05) increased cumulative loss of carbon as CO2, whereas WB significantly decreased the cumulative loss of C over control. Addition of PPB at 5% and 10% levels increased SOC mineralization (positive priming) +22.9% and +31.2%, respectively; whereas reduction in SOC mineralization (negative priming) was noticed in WB (5% and 10%) treated soils by -3.1% and -21.7%, respectively. Similarly, WB induced strong negative priming effects (-21.9% and -29.5%), while PPB caused a weak positive priming effect (+3.0% and +11.6%) at 5% and 10% levels on mineralization of added labile carbon substrate (MSWC), respectively. Results indicate the hardwood (Prosopis juliflora) biochar exhibits refractory properties that inhibit mineralization of both native SOC and applied organic compost (MSWC), and thereby it can be used as an amendment to stabilize native and applied organic matter in soil, which may significantly contribute to soil carbon sequestration.

Organic Fraction Municipal Solid Waste Compost and Horse Bean Green Manure Improve Sustainability of a Top-Quality Tobacco Cropping System: The Beneficial Effects on Soil and Plants

Organic Fraction Municipal Solid Waste Compost and Horse Bean Green Manure Improve Sustainability of a Top-Quality Tobacco Cropping System: The Beneficial Effects on Soil and Plants

Photosynthetic Activities, Phytohormones, and Secondary Metabolites Induction in Plants by Prevailing Compost Residue.

Compost residue enriches soil health with the potential to enhance plant metabolism and hormonal balance, but has not yet been studied. A study was performed to determine how prevailing compost residue induces tomato (Solanum lycopersicum 'Scotia') plant morpho-physiology, phytohormones, and secondary metabolites. Plants were grown in soils with a previous history of annual (AN) and biennial (BI) compost amendments. The controls were soil without compost (C) amendment and municipal solid waste compost (MSWC) alone. The MSWC- and AN-plants had similar and significantly (p < 0.05) highest growth and photosynthetic activities compared to the BI- or C-plants. Total phenolics and lipid peroxidase activity were significantly (p < 0.001) high in BI-plants, while hydrogen peroxide and antioxidant capacity were significantly (p < 0.001) high in AN-plants. MSWC-plants recorded the highest cis-abscisic acid, followed by AN-, and then BI- and C-plants. Cis-zeatin, trans-zeatin, and isopentenyladenine ribosides were detected in the MSWC- and AN-plants but not in the BI- or C-plants. Furthermore, gibberellins GA53, GA19, and GA8 were high in the MSWC-plants, but only GA8 was detected in the AN plants and none in the others. Besides, MSWC plants exhibited the highest content of 1-aminocyclopropane-1-carboxylic acid. Conjugated salicylic acid was highest in the BI-plants, while jasmonic acid-isoleucine was highest in MSWC-plants and C plants. In conclusion, prevailing compost chemical residues upregulate plant growth, phytohormones, and metabolic compounds that can potentially increase plant growth and abiotic stress defense. Future work should investigate the flow of these compounds in plants under abiotic stress.

Mulching with Municipal Solid Waste (MSW) Compost Has Beneficial Side Effects on Vineyard Soil Compared to Mulching with Synthetic Films

Municipal solid waste (MSW) compost represents a sustainable alternative to plastic film for mulching in viticulture. This study investigated the effects of MSW compost on vineyard soil properties, specifically focusing on side effects such as soil temperature and microbial decomposition activity, independently from its role in weed control. The experiment was conducted in a vineyard located in the Mediterranean region (Southern Italy), with six different mulching treatments: black polyethylene (PE) film, black and white biodegradable film, three different amounts of MSW compost (8, 15, and 22 kg plant−1), and a control without mulching. Weed growth was monitored to determine the optimal compost application amount. The 15 kg plant−1 treatment was selected for further analyses, as it did not significantly impact weed growth compared to the control. Results indicated that MSW compost mulching maintained lower soil temperatures compared to other treatments (up to 5 °C in the warmest hours) and reduced the amplitude of the thermal wave up to 50% compared to the non-mulched soil and even more compared to black film mulched soil, particularly during the warmest periods. This suggests that MSW compost can mitigate heat stress on plant roots, potentially enhancing plant resilience and preserving crop production also in stressful growing conditions. Microbial decomposition activity, assessed using the tea bag index, was higher in the MSW compost treatment during spring compared to the control, indicating temperature as a key driver for organic matter decomposition, but this effect disappeared during summer. These findings highlight the potential of MSW compost to support sustainable viticulture by reducing reliance on synthetic mulching materials and promoting environmental sustainability through the recycling of organic municipal waste.

Role of compost in assisted phytostabilization via three naturally occurring species on mine-contaminated soil and health risk alleviation for livestock

Phytostabilization emerges as an efficient and enduring remediation technique for heavy metal-contaminated mine soils using plants acclimatized to such circumstances. In this research, the synergistic effects of Marrubium cuneatum, Verbascum speciosum, and Stipa arabica species, alongside municipal solid waste compost (MSWC) amendment at 0, 1, 3, and 5 % rates, were assessed for a six-month pot experiment aimed at remediating naturally polluted soil containing lead (Pb) and cadmium (Cd) and mitigating the health risks associated with these metal exposures for grazing ruminants. Applying compost improved the aboveground biomass of M. cuneatum and V. speciosum and S. arabica by 13, 19, and 18 %, respectively. Also, soil dehydrogenase and urease enzyme activities were enhanced up to 131 and 34 %. Upon MSWC application, all three species uptake Cd and Pb at a significantly lower rate, except in the V. speciosum shoot at 3 and 5 % doses, and bioaccumulation factors were markedly diminished. Compost notably augmented the antioxidant system, leading to a reduction in malondialdehyde content of V. speciosum, M. cuneatum, and S. arabica by 35, 29, and 23 %, respectively, and an elevation in chlorophyll level. Superoxide dismutase, catalase, glutathione peroxidase, and ascorbate peroxidase activities either increased or displayed no significant differences. Risk assessment revealed that MSWC substantially decreased the daily intake of Pb and Cd and their accumulation in animal organs, thereby eliminating limits on meat consumption. Findings affirm the combined efficacy of MSWC and the study species in stabilizing contaminated Pb and Cd soils, diminishing risks to animal feed security and human health.

Response of tomato to innovative organo-mineral fertilizers

Organo-mineral fertilizers (OMFs) with low organic carbon (Corg) content have been associated with higher mineral fraction nutrient use efficiency. However, the extraction of peat, which is typically used in these OMFs, from endangered ecosystems causes long-time stored Corg to mineralize and to be released back into the atmosphere as carbon dioxide (CO2). This study analyzes the replacement of peat in OMFs with biowaste materials. These materials, considered organic byproducts that microorganisms and other living things can decompose through composting and aerobic or anaerobic digestion, offer a viable opportunity. This study investigated three stabilized biowastes—green compost (GC) from pruning residues, municipal solid waste compost (MSWC), and manure-based vermicompost (VC)—as the organic matrices for granular OMFs. These matrices were impregnated with dissolved ammonium sulfate and urea and used to coat diammonium phosphate granules. Each biowaste OMF contained 7.5% Corg, 20% mineral N, and 10% mineral P2O5 (OMF20 − 10). Fertilizers with high nutrient concentrations have the advantage of requiring low application volumes, facilitating their application in the field. Biowaste OMFs were compared with peat OMFs with the same Corg-N-P2O5 concentration. Peat and MSWC were also used to create OMFs containing 7.5% Corg, 10% mineral N, and 5% mineral P2O5 (OMF10 − 5). A 75-day tunnel trial was conducted under semi-controlled conditions using tomato plants (Solanum lycopersicum L.) fertilized to an equivalent of 81 mg N kg−1 soil and 18 mg P kg−1 soil. Controls included no fertilization (N0P0) and mineral N and P fertilization (MFNP). The Soil Plant Analysis Development (SPAD) chlorophyll meter and the BBCH (from German Biologische Bundesanstalt, Bundessortenamt und CHemische Industrie) scale as well as the number of shoots were measured over time, as berry and total aboveground yield, N and P uptakes, and N and P use efficiencies (NUE and PUE, respectively) were calculated at harvest. All treatments outperformed the control N0P0 in most indicators. Peat20 − 10 did not have more berry yield than other OMF20 − 10; however, the higher number of shoots indicated a higher potential yield in the event of prolonging the experiment. At the end of 75 days, VC20 − 10 and MSWC20 − 10 showed similar PUE to peat, suggesting that those materials can be used as replacements. In the case of OMF10 − 5, MSWC10 − 5 had yield and N and P uptakes like peat OMFs, confirming the potential use of MSWC as peat replacement even at different nutrient concentrations. This research provides reassuring evidence of the effectiveness of biowaste OMFs, offering a positive outlook for sustainable agriculture. However, their use is not recommendable for short growing seasons.

Heavy Metal Accumulation in Soil and Plants Using Municipal Solid Waste Compost in Variable pH Conditions

ABSTRACT Municipal solid waste composts (MSWC) are extensively utilized as organic soil conditioners and fertilizers in agricultural fields across many countries. However, the use of MSWC can lead to heavy metal pollution in soil and plants, which may adversely affect plant growth. This study examined the impact of MSWC on the heavy metal content in plants and soil across various pH levels. The experiment was conducted in a pot setting with three replications. The research findings indicated that MSWC application increased the levels of copper (Cu) and zinc (Zn) in soils but had no significant effect on lead (Pb), nickel (Ni), manganese (Mn), and iron (Fe) levels. Additionally, increases were observed in the Cu, Zn, and Fe content in plants, while Pb and Ni content remained unchanged. Cu, Zn, and Fe are essential for plant growth, and their enhancement in both soil and plants is a direct result of their relatively high presence in the MSWC used. The soil-plant transfer coefficients show that the transfer of heavy metals from soil to plants is highest under acidic conditions, indicating that the heavy metal content in MSWC can vary depending on soil pH and application rate. Therefore, it is crucial to carefully analyze and evaluate the heavy metal contents of soil and compost samples before employing MSWC in agricultural fields.

Plastics and plastic-bound toxic metals in municipal solid waste compost from Sri Lanka.

This study examined plastics and toxic metals in municipal solid waste compost from various regions in Sri Lanka. Plastics were extracted using density separation, digested using wet peroxidation, and identified using Fourier Transform Infra-Red Spectroscopy in Attenuated Total Reflection mode. Compost and plastics were acid-digested to quantify total Cd, Cu, Co, Cr, Pb, and Zn concentrations and analyzed for the bioavailable fraction using 0.01M CaCl2. Notably, plastics were highly abundant in most compost samples. The main plastic types detected were polyethylene, polypropylene, and cellophane. However, the average Cd, Cu, Co, Cr, Pb, and Zn levels were 0.727, 60.78, 3.670, 25.44, 18.95, and 130.7mg/kg, respectively, which are well below the recommended levels. Zn was the most bioavailable (2.476mg/kg), and Cd was the least bioavailable (0.053mg/kg) metal associated with compost. The Contamination factor data show that there is considerable enhancement of Cd and Cu, however, Cr, Cu, Co, and Pb are at low contamination levels. Mean geo accumulation index values were 1.39, 1.07, - 1.06, - 0.84, - 0.32, and 0.08 for Cd, Cu, Co, Cr, Pb, and Zn. Therefore, the contamination level of compost samples with Cd and Cu ranges from uncontaminated to contaminated levels, whereas Co, Cr, Pb, and Zn are at uncontaminated levels. Despite no direct metal-plastic correlation, plastics in compost could harm plants, animals, and humans due to ingestion. Hence, reducing plastic and metal contamination in compost is crucial.

A multi-criteria approach to test and evaluate the efficiency of two composting systems under two different climates

ABSTRACT The selection of the appropriate composting system, climate conditions, and duration of the composting process are important parameters for municipal solid waste composting. Therefore, this research aimed to design, test, and evaluate two different static composting systems under two different climate regions, Palestine and India, following a multi-criteria approach. A forced-aeration composting system was designed for use in Palestine, and a naturally aerated one was used in India. Three experiments were conducted, two of them in Palestine and one in India. The operational parameters were controlled and monitored during the composting process, while the physio-chemical and biological parameters were tested to evaluate the compost end quality. The results showed that both systems provide good efficiency toward formation of final compost (39–43 days in Palestine, and 31 days in India), and the average materials’ volume reduction was almost 60%. The physio-chemical analysis showed that most of the parameters comply with the threshold limits specified by the Palestinian Standards Institution (PSI) and Indian Fertilizer Control Order (FCO) except for minor deviations. Both systems provided a high fertility index (4.3, 4.7, and 4.8), and a high clean index (4.6, 5.0, and 4.7). However, the results of the biological parameters showed that all the experiments met PSI, but none of them met FCO, suggesting that the outer edges of the composting system didn’t heat enough to inactivate pathogenic microbes, therefore, developing the system by adding turning option could overcome this shortcoming. It was concluded that the forced aeration system is suitable for Palestine, while the natural aeration system is suitable for India. Implications: Municipal solid waste management is facing technical and financial challenges worldwide due to the increasing generation of solid waste following the population growth. The current improper management of this waste stream through landfilling is adding pressure on the environment as a result of methane emissions and landfill leachate. Therefore, composting of the organic fraction through selection of an appropriate composting system can solve many waste management problems and contribute to environmental sustainability. This research focuses on design, test and evaluate two composting systems in two regions with different climatic conditions, Palestine and India as both are facing waste management problems. The outcome of this research optimized the composting process which can be replicated and scaled up in other countries worldwide with similar climatic conditions.

Bio-chelate assisted leaching for enhanced heavy metal remediation in municipal solid waste compost

Municipal solid waste compost, the circular economy's closed-loop product often contains excessive amounts of toxic heavy metals, leading to market rejection and disposal as waste material. To address this issue, the study develops a novel approach based on: (i) utilizing plant-based biodegradable chelating agent, l-glutamic acid, N,N-diacetic acid (GLDA) to remediate heavy metals from contaminated MSW compost, (ii) comparative assessment of GLDA removal efficiency at optimal conditions with conventional nonbiodegradable chelator EDTA, and (iii) enhanced pre- and post-leaching to evaluate the mobility, toxicity, and bioavailability of heavy metals. The impact of treatment variables, such as GLDA concentration, pH, and retention time, on the removal of heavy metals was investigated. The process was optimized using response surface methodology to achieve the highest removal effectiveness. The findings indicated that under optimal conditions (GLDA concentration of 150 mM, pH of 2.9, retention time for 120 min), the maximum removal efficiencies were as follows: Cd-90.32%, Cu-81.96%, Pb-91.62%, and Zn-80.34%. This process followed a pseudo-second-order kinetic equation. Following GLDA-assisted leaching, the geochemical fractions were studied and the distribution highlighted Cd, Cu, and Pb's potential remobilization in exchangeable fractions, while Zn displayed integration with the compost matrix. GLDA-assisted leaching and subsequent fractions illustrated transformation and stability. Therefore, this process could be a sustainable alternative for industrial applications (agricultural fertilizers and bioenergy) and social benefits (waste reduction, urban landscaping, and carbon sequestration) as it has controlled environmental footprints. Hence, the proposed remediation strategy, chemically assisted leaching, could be a practical option for extracting heavy metals from MSW compost, thereby boosting circular economy.

Quantification and polymeric characterization of microplastics in composts and their accumulation in lettuce

Organic fertilizers have become a vector for the transport of microplastics (MPs), which pose human health concerns through the food chain. This study aimed to quantify and characterize MPs in eight different compost samples of various raw materials and their subsequent translocation to lettuce (Lacuta sativa) grown on contaminated composts. The results revealed that the MP abundance ranged from 3810 to 16530 MP/kg. Municipal solid waste compost (MSWC) had highest abundance (16082 ± 632 MP/kg), followed by leaf compost (LC) and organic compost (OC) (6299 ± 1011 and 3680 ± 419 MP/kg, respectively). MPs of <100 μm in size were most dominant in MSWC and LC. Fragments and fibers were the prevalent shape types, with white/transparent colored MPs being more abundant. Polyethylene (PE), polypropylene (PP) and polyethylene terephthalate (PET) were the dominant polymers. MPs accumulation in the lettuce leaves was greatest in the lettuce plants grown on MSWC, followed by those grown on LC and OC, indicating that MSWC grown lettuce is not suitable for human consumption. The decrease in the growth (leaf length, number of leaves, leaf fresh and weights) and physiological (membrane stability index, relative water contents) parameters of lettuce was in line with the trend of MP accumulations. Hence, it is highly important to regulate the plastic contents in compost because it is a threat to ecosystems and human health.

Formulation of Novel Microbial Consortia for Rapid Composting of Biodegradable Municipal Solid Waste: An Approach in the Circular Economy

Urbanization and rapid industrialization have led to the escalation of municipal solid waste generation and accumulation. Composting is widely recognized as a sustainable solution for solid waste management. However, its long-term investment is considered a disadvantage. The present research study discusses the rapid biotransformation of solid waste into valorized compost. Bacteria were isolated from soil, solid waste, and leachate samples from open dump sites. From the 18 different bacterial consortia created using potential isolates, the five most promising consortia were selected based on concurrent different enzyme production. These selected consortia were incorporated into typical compost bins with Municipal Solid Waste (MSW). Daily monitoring of enzymatic activity, pH, conductivity, bulk density, moisture, and temperature, along with other composting parameters, was conducted. The study’s results demonstrated that consortium No. 5, comprising Bacillus haynesii, Bacillus amyloliquefaciens, and Bacillus safensis, exhibited significant (p&lt;0.05) enzyme activity of cellulase, amylase, lipase and proteinase enzymes during composting compared to the control and other treatment setups. Consortium No. 5 also facilitated rapid and successful composting, as evidenced by significant alterations of composting parameters by exhibiting a shorter average composting time, reducing it from 110±10 days to 20±3 days, showcasing the potential applicability of formulated bacterial consortium as a sustainable and greener approach to the global solid waste problem. The novelty of this study lies in the isolation of local bacterial strains from open dump sites soil, MSW, and MSW leachate samples, which were then utilized in the composting organic fraction of MSW, enhancing the potential for effective waste management.

Synergistic Benefits of Combined Application of Manures and Chemical Fertilizers: Enhancing Growth and Yield of Rice and Wheat

The incorporation of compost and manure with chemical fertilizer has become a key concern to sustain soil fertility. Because the nutrients are continuously depleting from the soil and consequently creating a risk to preserving soil health. Aims: This study assesses the response of different doses of cowdung (CD), municipal solid waste compost (MSWC), oil cake (OC), and poultry manure (PM), incorporated with fertilizers on the growth, yield and protein content of BRRI dhan49 rice and BARI Gom-24. Study Design: RCBD with 8 treatments and 3 replications. Place and Duration of Study: Field experiment and nutrient analysis were carried out at Bangladesh Agricultural University (BAU), Mymensingh. Wheat was grown during the rabi season from October 2018 to March 2019. Again, rice was cultivated during kharif II season from August 2019 to December 2019 on the same field. Then the laboratory analysis was performed till June 2020. Methodology: Eight treatments i.e., T0 Control (no fertilizer), T1 Recommended Fertilizer Dose, T2 (CD + NPK), T3 (MSWC + NPK), T4 (OC + NPK), T5 (PM + N), T6 (MSWC + N), T7: (CD + OC) were accommodated. Data on the growth parameters including grain and straw yields were documented after the harvest of the fully matured crop simultaneously determining the nitrogen (N) and protein content. Results: Adoption of various combinations of compost and manures with fertilizer accorded an increase in yield contributing characters as well as the N and protein content. Integrating MSWC @ 10 t ha-1+N projected the highest grain yield (7.11 t ha-1 in rice; 4.84 t ha-1 in wheat) and straw yield (8.8 t ha-1 in rice; 5.55 t ha-1 in wheat). It also promisingly secured the highest protein content compared to all other treatments. Conclusion: The appliance of MSWC @ 10 t ha-1 with the recommended dose of N may be endorsed for rice and wheat cultivation in the AEZ-9 region and retaining the physicochemical properties of Old Brahmaputra Floodplain soils.

Microplastic Abundance in the Locally Produced Commercial Compost and the Characteristics

Compost is a widely used soil amendment in the agricultural sector in Sri Lanka. Applying compost could improve soil quality, and it is used in reclaiming degraded agricultural lands. However, low grade compost that contains pollutants may have adverse effects on the quality of the agro-ecosystem. Microplastic is a possible contaminant that can be moved into the agro-ecosystem through poor quality compost application. The present study was conducted to assess the microplastic availability and characteristics of locally produced municipal solid waste and agricultural waste compost. Representing commercial scale agricultural and municipal solid waste composting facilities; twenty compost samples with three replicates were obtained for microplastic identification. A combination of methods (manual separation, oxidation digestion plus density separation) was used to separate and detect microplastics from compost samples. This study revealed that; microplastics are present in agricultural and municipal solid waste compost. Municipal solid waste compost contained significantly (p&lt;0.05) higher microplastic than agricultural waste compost (on average 0.63% and 0.033%, respectively). Average amount of soft plastic content in municipal solid waste compost and agricultural waste compost (1321 items/kg and 71 items/kg, respectively) were higher than the hard plastics (388 items/kg and 37 items/kg, respectively). The study confirmed that compost could act as a carrier of microplastics in agricultural ecosystems. It can be recommended that quality standards should be implemented to minimize the microplastic content in compost and the code of practices for municipal solid waste compost production should be updated to control microplastic contamination to safeguard the quality of agro-ecosystems.

Substitution of mineral N fertilizers with organic wastes in two long‐term field experiments: Dynamics and drivers of crop yields

AbstractOrganic wastes (OW) are rich in nutrients, and their recycling into agriculture can substitute chemical fertilizers. The level of substitution (partial with mineral fertilizer or exclusive with only OW), along with the method, amount, and timing of OW application, as well as the crop type, can impact crop productivity. The temporal dynamics of crop productivity after repeated applications of OW remain uncertain. Thus, two French long‐term field experiments (QualiAgro and PROspective, started in 1998 and 2000, respectively) were used to evaluate the effect of repeated OW applications on crop yield dynamics and investigate the potential driving factors affecting crop yields. Six different OW were applied: urban sewage sludge (SLU), green waste and SLU compost (GWS), biowaste compost (BIO), municipal solid waste compost (MSW), farmyard manure (FYM), and composted FYM (FYMC). The OW were applied every 2 years in QualiAgro (~4 t C ha−1) and PROspective (~1.7 t C ha−1). QualiAgro was studied under high and low mineral N conditions, while PROspective was examined with and without mineral N fertilization. The results indicated that at the QualiAgro site, a combination of OW and high mineral N treatments resulted in higher maize and wheat yields compared to the mineral N control, while the combination of OW and low mineral N reached the same maize and wheat yield as the mineral N control after 3 and 6 applications of OW, respectively. At the PROspective site, partially substituting mineral fertilizer with OW maintained maize yields but decreased wheat yields, while full substitution led to a decrease in both maize and wheat yields compared to the mineral N control. Results from the gradient boosting model (GBM) showed that soil total N rather than mineral N input was the primary driver of the relative maize yield, while mineral N fertilizer input was more critical for wheat during the second year. We conclude that the joined use of OW and mineral fertilizers is superior to using OW or mineral fertilizer alone for maintaining high yields and soil fertility. We further suggest that OW full substitution of mineral fertilizer may need to apply OW more frequently to meet the crop demands, and/or to use OW with higher N availability like digestates.

Effects of Biochar and Municipal Solid Waste Compost on Soil Physical Quality and Productivity Index Under Sorghum Cultivation Irrigated with Saline Water

ABSTRACT Amending soil with different materials is gaining acceptance as an effective and inexpensive technique for reclamation of salt-affected soils. The main idea of this study was to investigate the effects of biochar, compost of municipal solid waste and different water salinities level on soil physical quality (SDexter) and soil productivity index (SPI). The treatments were as followed: Control: Soil without biochar or compost and irrigated with tap water, S1: Soil without biochar or compost and irrigated with saline water (EC = 4.5 dS m−1), S2: Soil without biochar or compost and irrigated with saline water (EC = 9 dS m−1), B: Soil amended with 1.5%w/w biochar and irrigated with tap water, B+S1: Soil amended with 1.5%w/w biochar and irrigated with saline water (EC = 4.5 dS m−1), B+S2: Soil amended with 1.5%w/w biochar and irrigated with saline water (EC = 9 dS m−1), C: Soil amended with 1.5%w/w compost and irrigated with tap water, C+S1: Soil amended with 1.5%w/w compost and irrigated with saline water (EC = 4.5 dS m−1), C+S2: Soil amended with 1.5%w/w compost and irrigated with saline water (EC = 9 dS m−1). Soil water characteristic curve (SWCC), Field capacity (FC), Plant wilting point (PWP), Plant available water (PAW), Dexter’s index of soil physical quality (SDexter) and SPI were examined in a greenhouse experiment. The SPI was calculated by integrating the effects of six soil quality indices: plant available water, organic matter (OM), Electrical conductivity (EC), pH, Bulk density (BD) and Root weighting factor (RF) for all treatments were calculated. The results showed that the B treatment had a slightly higher effect on SWCC. The applied B and C treatments caused insignificant increase in PAW relative to the control. In addition, application of biochar or compost to soil significantly increased the SDexter. The application of C treatment had insignificantly higher value of SDexter compared to other treatments. Compared with the control, SPI was significantly higher for the B and C treatments. Overall, the application of biochar/compost minimized the destructive effects of saline irrigation water and improved the quality of the salt-affected fine-textured soil.

Review of the Responses of Various Soil Amendments in Sandy Soils

The primary constraints with sandy soils are low soil organic matter content, poor nutrient availability, heavy losses of applied nutrients and lower water holding capacity. Improving the productivity of sandy soils, particularly in developing countries, could be a viable solution to food insecurity and poverty. Large extent of sandy soil is one of the major constraints for crop production in the Eastern Province of Sri Lanka. Meanwhile, various soil amendments can be applied to improve the performances of cropping systems in sandy soils. Nevertheless, a comprehensive knowledge on which soil amendment would work better across different scales is not well known. To address this knowledge gap, this review was conducted using published literature. Systematic review approach was adopted, and the data were extracted from 65 highly relevant papers. The data were analyzed to calculate the percentage changes on crop yields, soil organic matter and soil carbon, in response to the applications of different soil amendments. The review highlighted the potential of several soil amendments to improve the crop performances in sandy soils. Interestingly, rice straw biochar and the municipal solid waste compost have greatly increased crop yields especially in rice at the rate of 0.9% w/w and 3% w/w in soil weight basis, respectively. Highest improvement in soil organic matter and soil carbon was observed under the applications of compost and spent grain, respectively. Therefore, rice straw biochar and compost could be evaluated to improve the productivity of sandy soils, especially in the Eastern region of Sri Lanka. Although the spent grain was promising, the availability for large scale applications may be limited in Sri Lanka. Testing of these soil amendments would require long-term experiments incorporating different crops and cropping systems. &#x0D; Keywords: Compost, Biochar, Sandy soil, Soil amendments