Municipal Solid Waste Compost Application Research Articles

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.

Effect of Municipal Solid Waste Compost on Yield, Plant Growth and Nutrient Elements in Strawberry Cultivation

In terms of sustainable economic activities, environmental and production costs of plant nutrition material in agricultural production and wastes that harm the environment, humans and living beings are two important problems. This study, which combines these two problems into a common denominator, aimed to obtain plant nutrition input with low environmental and production costs by using the wastes generated during the domestic consumption process in strawberry cultivation. Municipal solid waste compost (MSWC) for plant nutrition input and an Albion strawberry variety as a trial plant were used as research materials. In the study, where the random block trial design method was used, the effects of MSWC on plant growth, fruit quality characteristics and plant nutrient parameters were investigated. According to the results of the study, it was concluded that the examined parameters (number of fruits per plant, fruit weight, fruit taste, macro and micronutrient content in plant leaves) were positively affected according to the rate of use of MSWC. In the parameters evaluated within the scope of the study, 4 tons of MSWC applications in fruit weight, stem number, root length, plant width, leaf area, K and Ca parameters; 1.2 tons of MSWC applications in the number of fruits per plant and TA parameters; all MSWC applications in fruit yield per plant, pH, plant height, N, Mn and Cu parameters; 2 tons of MSWC applications in the TSS parameter and 1, 2 and 4 tons of MSWC applications in P and number of leaves per plant parameters gave better results compared to the control. Research findings support the idea that the use of MSWC as a plant nutrition input will provide both the production of plant nutrition input with low environmental and production costs and the prevention of the harms of waste to the environment, humans and living creatures.

The Influence of Municipal Solid Waste Compost on the Tranformations of Phosphorus Forms in Soil

Searching for a renewable phosphorus (P) source for agricultural soils has become a challenge of particular importance on a global scale. Depletion of the world’s phosphate resources as well as the risk of environmental problems caused by excessive P mobility have placed this topic among the most important environmental issues. The aim of this study was to analyse the transformation of phosphorus forms in municipal solid waste compost (MSWC) at different maturity stages, to assess the effects of their application on soil phosphorus status and to evaluate the suitability of MSWC for agricultural soils as a potential phosphorus source. The application of MSWC to the soil had a positive effect on the content of available P. The content of potentially mobile P forms increased significantly in the soil, primarily after the introduction of immature MSWC and confirmed by the significant correlations with the applied P indicators. However, the results indicate that the MSWC does not pose a serious environmental risk and could become a potential source of P in the soil, although the material used for this purpose should be mature. This study also indicated that the assessment of using compost as a P source should not be based on P total content alone, but should include the content of different P forms and specific P-related indicators, to reflect both the P availability and the potential environmental risks.

Analytical Approach by Sorting of Manure for Farming and Electricity from Municipality Solid Waste

Waste operation and declining soil fertility are the main issues endured by all developing nations, like India. Currently, agrarian application of Municipal Solid Waste (MSW) is one of the most promising and cost effective options for managing solid waste. It's helpful in working current burning issues viz. soil fertility and MSW operation still there's always a implicit trouble because MSW may contain pathogens and poisonous adulterants. Thus important emphasis has been paid to composting of MSW in recent times operation of compost from MSW in agrarian land helps in upgrading the soil’s physico- chemical parcels. Piecemeal from that it also assists in perfecting natural response of cultivated land. Keeping the present situation in mind, this review critically discusses the current script, agrarian application of MSW compost and energy from part of soil microbes and soil microbial response on external solid waste compost operation.

Effect of municipal solid waste compost and NPK fertilizer on growth, yield and protein content of rice (cv. BRRI dhan49)

An experiment was conducted to study the effect of municipal solid waste compost (MSWC) on growth, yield and protein content as well as to know the effect of combined application of MSWC and NPK fertilizers in rice (cv. BRRI dhan49). There were six treatments including- T0 = Control (No fertilizer or no MSWC); T1= 100% Recommended Doses of Fertilizers (RDF) NPK; T2 = (MSWC @ 5 t ha-1+ 75% RDF); T3= (MSWC @ 7. 5t ha-1+ 50% RDF); T4= (MSWC @ 10 t ha-1 + 25% RDF); T5 = (MSWC @ 10 t ha-1). The experiment was laid out in a randomized complete block design (RCBD) with three replications. Our results showed that the integrated application of MSWC and different RDF% had a significant impact on various plant growth and yield parameters including plant height, panicle length, number of effective tillers per hill, number of filled grains per panicle, 1000-grain weight (g), and grain and straw yield of rice. In case of T2 treatment, highest grain yield (5.70 t ha-1), straw yield (7.71 t ha-1) and protein content (5.875%) were obtained. Thus, the result indicated that combined application of MSWC with NPK performed better than the single application of either MSWC or NPK fertilizer.

Changes in Soil Characteristics, Microbial Metabolic Pathways, TCA Cycle Metabolites and Crop Productivity following Frequent Application of Municipal Solid Waste Compost.

The benefit sof municipal solid waste (MSW) compost on soil health and plant productivity are well known, but not its long-term effect on soil microbial and plant metabolic pathways. A 5-year study with annual (AN), biennial (BI) and no (C, control) MSW compost application were carried out to determine the effect on soil properties, microbiome function, and plantgrowth and TCA cycle metabolites profile of green beans (Phaseolus vulgaris), lettuce (Latuca sativa) and beets (Beta vulgaris). MSW compost increased soil nutrients and organic matter leading to a significant (p < 0.05) increase in AN-soil water-holding capacity followed by BI-soil compared to C-soil. Estimated nitrogen release in the AN-soil was ca. 23% and 146% more than in BI-soil and C-soil, respectively. Approximately 44% of bacterial community due to compost. Deltaproteobacteria, Bacteroidetes Bacteroidia, and Chloroflexi Anaerolineae were overrepresented in compost amended soils compared to C-soil. A strong positive association existed between AN-soil and 18 microbial metabolic pathways out of 205. Crop yield in AN-soil were increased by 6-20% compared to the BI-soil, and by 35-717% compared to the C-soil. Plant tricarboxylic acid cycle metabolites were highly (p < 0.001) influenced by compost. Overall, microbiome function and TCA cycle metabolites and crop yield were increased in the AN-soil followed by the BI-soil and markedly less in C-soil. Therefore, MSW compost is a possible solution to increase soil health and plants production in the medium to long term. Future study must investigate rhizosphere metabolic activities.

Does the timing of short-term biowaste compost application affect crop growth and potential nitrate leaching? The case studies of processing tomato and cauliflower under field conditions

The feasibility of municipal solid waste compost (MSWC) as a substitute for mineral nitrogen (N) fertiliser was tested for a spring-summer (i.e., processing tomato) and an autumn-winter (i.e., cauliflower) vegetable crop grown in Mediterranean open field conditions. Two different doses (10 and 20 t dm C ha–1) and two distribution timings for each dose (i.e., early application at about nine months before processing tomato transplanting and five months before cauliflower transplanting: C10_early and C20_early; late application at about one month before processing tomato and cauliflower transplanting: C10_late and C20_late) were compared in a two-year field experiment. An unfertilised control and a 100% mineral N fertilisation (MIN, 200 kg N ha–1 for processing tomato and 150 kg N ha–1 for cauliflower) were added to the experiment. The application of MSWC significantly reduced the aboveground DM accumulation compared to the MIN in both crops, and it was inadequate to ensure a high yield for spring-summer and autumn-winter vegetables. However, the timing of compost application seems to play an essential role in reducing the reduction of crop growth due to compost application. In both tomato and cauliflower, when the MSWC was applied a few months earlier than the transplanting (i.e., in the previous summer in tomato and the previous spring in cauliflower), the DM and yield reduction was less apparent than in soil where compost was applied immediately before transplanting. Despite the lowest N-uptake associated with the MSWC application, the N-NO3 concentration in the soil solution was reduced by MSWC. In addition to the amendment effect, compost use may positively impact lowering N leaching risks in the groundwater. Combining the use of MSWC applied early before the crop season with mineral N fertiliser, it is possible to gain high yield, increase soil organic carbon and reduce groundwater contamination risk both in spring-summer and autumn-winter vegetable crops. Highlights- Biowaste compost decreased the aboveground biomass accumulation and yield in processing tomato and cauliflower. - Biowaste compost alone did not meet the N requirement in processing tomato and cauliflower. - Biowaste compost distribution in the summer before the processing tomato growing season alleviated its depressive effect in reducing DM and yield. - Biowaste compost distribution in the spring before the cauliflower growing season alleviated its depressive effect in reducing DM and yield. - Biowaste compost decreased the N-NO3 concentration in soil solution compared to mineral fertilisation with a positive effect in reducing N leaching risks in the groundwater.

Bioaccumulation of chemical elements in vegetables as influenced by application frequency of municipal solid waste compost

Municipal solid waste (MSW) compost is used to enrich soils by virtue of its bio-physicochemical properties. However, undesirable accumulation of chemical elements can reduce soil quality and cause food safety issues. A 5-yr field study was carried out to investigate the impact of Compost Quality Alliance (CQA)-tested MSW compost application frequency (annual, biennial and no-compost) on soil quality and chemical element accumulation in edible portions of lettuce (Lactuca sativa cv. Grand Rapids), beet (Beta vulgaris cv. Detroit Supreme), carrot (Daucus carota cv. Nantes), and green bean (Phaseolus vulgaris cv. Golden Wax). Analysis of soil showed that chemical elements were highest in annual application followed by biennial, but less in control (no-compost) and fallow soils. Soil background levels of chemical elements influenced the concentrations of iron (Fe) and manganese (Mn) in green bean, aluminum (Al) in green bean and beet, and barium (Ba) in carrot, beet, and lettuce. Cadmium (Cd) concentration in beet, lettuce, and green bean grown in the annual plot was increased by 48%, 52% and 62%, respectively while carrot recorded a 56% increase in the biennial plot compared with no-compost. Bioaccumulation factors were < 1 for all of the essential and non-essential trace elements in all of the plant species, except boron (B) and molybdenum (Mo). However, lettuce showed a higher tendency to accumulate Cd, rubidium (Rb), and strontium (Sr). Overall, the health risk for human consumption is low. Although long-term annual application of compost to vegetables seemed safe for human consumption, it is necessary to continuously monitor potential chemical element accumulation, particularly non-essential trace elements in soils and plants.

Variation in frequency of CQA-tested municipal solid waste compost can alter metabolites in vegetables

The use of compost to enhance plant growth and mineral nutrients composition are extensively studied but not much literature information exists on its influence on plant metabolic profiles. A study was performed to assess a 5-year variable frequency of application of Compost Quality Alliance tested municipal solid waste (MSW) compost effect on metabolic profiles of the edible portions of four different vegetable plants. The plants were lettuce (Latuca sativa cv. Grand Rapids), beets (Beta vulgaris cv. Detroit Supreme), carrot (Daucus carota cv. Nantes) and green beans (Phaseolus vulgaris cv. Golden Wax) grown under a sub-humid continental climate. The treatments were annual, biennial and no (control) applications of the MSW compost. Typically, soil fertility highly increased with the annual application of the MSW compost followed by the biennial application but declined in the control plot. The annually applied MSW compost increased total amino acids in the lettuce, carrot, beets, and green beans by ca. 323%, 109%, 94% and 18% respectively, compared to the control. Overall, total phospholipids were enhanced by the biennially applied MSW compost. Total organic acids in the lettuce, beets, and green beans were altered by the annual and biennial MSW compost applications by ca. 35% and 23%; 6% and 6.4%; and 22% and 65%, respectively compared to the control. A 2-dimension principal component analysis biplot confirmed positive association between the different frequencies of MSW compost application and soil fertility enhancement of plant metabolites. In conclusion, the annual application of MSW compost enhanced amino acids, phospholipids, acylcarnitines, amines and choline but reduced glucose in the lettuce, beets, carrot, and green beans. Further studies to elucidate the mechanisms underpinning such biofortification will be required.

Effect of some additives on heavy metals behavior and phytoavailability in municipal solid waste compost-amended soil

The effect of application of municipal solid waste compost (MSWC) on copper (Cu), lead (Pb) and cadmium (Cd) levels in soil and wheat plant was studied. The effectiveness of complementary remediations including compost washing (three levels), wood ash and sawdust application (each at three levels) was also examined. A completely randomized design pot experiment with medium-textured soil was performed. The diethylenetriaminepentaacetic acid–triethanolamine (DTPA–TEA) extracts of the soil and plant shoots were tested for heavy metal content using atomic absorption. The heavy metal contents of plant showed a definite dependence on extractable heavy metals in differently treated soil. The highest metal uptake by plant was observed in unleached compost-amended soil, followed by leaching, sawdust and wood ash remediations. No significant differences were observed within different levels of leaching and wood ash applications. The highest crop yield was obtained for wood ash amendment (1 wt%). Consequently, wood ash is an appropriate remediation for MSWC-treated soil to reduce heavy metal phytoavailability although monitoring of total heavy metal in soil is necessary for long-term application of MSWC.

INFLUENCE OF MUNICIPAL SOLID WASTE COMPOST ON YIELD OF TOMATO- APPLIED SOLELY AND IN COMBINATION WITH INORGANIC FERTILIZER WHERE NITROGEN IS THE ONLY VARIABLE FACTOR

Municipal solid waste compost (MSWC) is considered as one of the prominent fertilizers that improve soil health and productivity. To evaluate the effects of MSWC on plant growth, an experiment was conducted by using sole MSWC and with a combination of inorganic fertilizer. The sole MSWC was applied at the rate of 0, 5, 10, 15 t ha-1. In case of MSWC with inorganic fertilizer, MSWC was applied equally (5 t ha-1) and phosphorus and potassium fertilizers were applied at 100 and 50 kg ha-1, respectively. Nitrogen was the only variable nutrient. Nitrogen was applied three different doses (25, 50 and 100 kg ha-1) along with control. Tomato (Solanum lycopersicum L.) was grown as experimental plant and maximum yield (72.7±6.3 t ha-1) of tomato was found when sole MSWC was applied at 15 t ha-1 and was significantly higher than other treatments. When MSWC was applied in combination with inorganic fertilizer, the combination 5 t ha-1 MSWC +100 kg N ha-1 +100 kg TSP ha-1 +50 kg MoP ha-1 produced maximum yield (79.0±3.2 t ha-1). So, application of sole MSWC in soil enhanced the productivity of soil and side by side, MSWC in combination with inorganic fertilizer reduced the volume of MSWC application.

Effect of Vermicompost and Municipal Solid Waste Compost on Growth and Yield of Canola under Drought Stress Conditions

ABSTRACT In order to study the effect of municipal solid waste (MSW) compost and vermicompost on morpho-physiological properties and yield of canola under drought stress conditions, an experiment was conducted as factorial arrangement based on randomized complete block design with four replications. Treatments consisted of three levels of water regimes, including: 75% of the field capacity for well-watered and 55% and 35% for moderate and severe stress, respectively, and biofertilizer in five levels, including: nonapplication of biofertilizer (control), application of MSW compost, and vermicompost at 2% and 4% levels. Results showed that interaction of irrigation and biofertilizer had significantly affected on all traits except leaf area ratio and nitrogen percent. The moderate and severe stress significantly reduced all traits compared to normal irrigation. Application of 4% vermicompost was resulted in increased growth, biomass and yield of canola under normal irrigation, moderate and severe drought stress compared to other biofertilizer treatments.

Improvement of Soil Quality Parameters by Municipal Solid Waste Compost Application in Clay-Loam Soil

Organic matter (OM) content of the soils should be improved for sustainable productions. Municipal solid waste compost (MSWC) is an organic material used in several countries to improve soil OM contents. This study was conducted to determine potential use of MSWC as soil amendment. Field experiments were conducted for two years with single MSWC treatments. Experiments were conducted on 18 plots in randomized complete blocks design with 3 replications. Six different MSWC doses (0, 40, 80, 120, 160 and 200 t ha-1) were applied to experimental plots. Compost doses were calculated in dry weight basis, applied to 21 m2 plots and sunflower was sown as the experimental plant of the study. Following the sunflower harvest, disturbed and undisturbed soil samples were taken from the experimental plots and soil samples were subjected to various analyses. Applied MSWC doses significantly increased soil OM contents, electrical conductivity (EC) and cation exchange capacity (CEC), aggregate stability (AS) and saturated hydraulic conductivity (Ksat) and reduced soil bulk density (BD). Effects of MSWC on soil pH were not found to be significant. Effects of MSWC treatments were more remarkable with increasing doses. MSWC treatments increased soil OM contents about 3 folds and increased CEC by about 25%. MSWC treatments significantly increased salt contents of the soils. Such increases were found to be significant at 1% level in the first year and 5% level in the second year. Increasing OM contents also increase soil aggregation, thus reduced bulk density and increased hydraulic conductivity. Correlation analysis revealed significant correlations between OM and AS. Present findings revealed that MSWC positively influenced physical and chemical characteristics of clay-loam soils of arid and arid climates, but salt contents should carefully be monitored in repetitive uses.

Achievability of Municipal Solid Waste Compost for Tea Cultivation with Special Reference to Cadmium

Municipal solid waste compost (MSWC) is quite often used for soil amendment in agricultural crops and yet little is known about its effect on tea (Camellia sinensis L.) cultivation. This study investigates the effect of MSWC application on cadmium (Cd) concentrations in soil, tea plants, and infusions. Different doses of MSWC are added to soil with two Tocklai vegetative (TV) tea clones (TV1 and TV23) for 2 years in pot experiments. Several fractions of Cd in amended soils, biomass yield, and Cd content in different parts of tea plants and in tea infusions are measured. Several indexes related to risk assessment are also calculated. The geo‐accumulation index values of Cd in soil amended with MSWC ranges from −1.74 to 3.12, indicating class 0 (practically uncontaminated) to class 4 (heavily contaminated) contamination level. Average daily intakes (ADI) of Cd through tea infusion produced from tea plant amended with MSWC are 8.9 × 10−6 and 9.2 × 10−6 mg kg−1 per body weight and day for men and women, respectively. These values are much lower than those given in the Joint FAO/WHO Provisional Tolerable Monthly Intake Guideline for Cd. The non‐carcinogenic risk values (also called hazard quotient) for Cd, estimated from the ADI values, are found to be 1.78 × 10−2 and 1.94 × 10−2 mg kg−1 per day for men and women, respectively, suggesting no health hazard. The results suggested the possibility of management of MSW through composting and the feasibility of compost application for tea cultivation.

Biological response of using municipal solid waste compost in agriculture as fertilizer supplement.

Waste management and declining soil fertility are the two main issues experienced by all developing nations, like India. Nowadays, agricultural utilization of Municipal Solid Waste (MSW) is one of the most promising and cost effective options for managing solid waste. It is helpful in solving two current burning issues viz. soil fertility and MSW management. However, there is always a potential threat because MSW may contain pathogens and toxic pollutants. Therefore, much emphasis has been paid to composting of MSW in recent years. Application of compost from MSW in agricultural land helps in ameliorating the soil’s physico-chemical properties. Apart from that it also assists in improving biological response of cultivated land. Keeping the present situation in mind, this review critially discusses the current scenario, agricultural utilization of MSW compost, role of soil microbes and soil microbial response on municipal solid waste compost application.

Effects of municipal solid waste compost, rice-straw compost and mineral fertilisers on biological and chemical properties of a saline soil and yields in a mustard–pearl millet cropping system

We investigated the effects of organic amendments, municipal solid waste compost (MSWC) and rice-straw compost (RSC) with and without mineral fertilisers on biological and chemical properties of a saline soil. Field experiments were conducted for two consecutive years during 2012–14. In the first year, application of 8tha–1 of MSWC+50% of the recommended dose of fertilisers (RDF) resulted in higher microbial biomass carbon (MBC), enzyme activities, soil organic carbon (SOC), available nitrogen (N), phosphorus (P) and potassium (K) than 7tha–1 of RSC+50% RDF, after mustard (Brassica juncea) and pearl millet (Pennisetum glaucum) harvests. Combined use of 8tha–1 of MSWC+50% RDF resulted in 47% and 54% more MBC than the unfertilised control after mustard and pearl millet harvests, respectively. Dehydrogenase activity was significantly higher with 100% RDF than the control after 2 years of the cropping cycle. Among organic amendments, MSWC was superior to RSC in terms of MBC, and activities of dehydrogenase, alkaline phosphatase and urease. SOC was significantly increased under MSWC+50% RDF compared with 100% RDF alone. Significant build-up of soil fertility in terms of available N, P and K was observed with RSC+50% RDF compared with the control. During the second year of the cropping system, soil treated with RSC+50% RDF had 14%, 17% and 9% higher N, P and K than soil treated with 100% RDF, after pearl millet harvest. The magnitude of change in soil electrical conductivity and pH was low during 2012–13; however, soil salinity decreased by 55% and 48% with MSWC+50% RDF and RSC+50% RDF, respectively, relative to the control at 120 days of pearl millet growth in 2013–14. Application of MSWC +50% RDF produced 2.5 and 2.70tha–1 of mustard and pearl millet, and increased grain yield by 19% and 15%, respectively, compared with 100% RDF. Integrated use organic amendments and mineral fertiliser is recommended for promoting biological and chemical properties of saline soil in a mustard–pearl millet cropping system.

Nickel dynamics influenced by municipal solid waste compost application in tea (Camellia sinensis L.): a cup that cheers

Effects of municipal solid waste compost application on tea (Camellia sinensis L.) cultivation (Tocklai Vegetative clone 1 and Tocklai Vegetative clone 23) was studied with respect to biomass yield, soil nickel risk, nickel uptake and transfer to tea infusion. Application of municipal solid waste compost @ 2–6 t ha−1 in soil lowered the risk assessment code of nickel by increasing non-labile nickel pool. Reduced Ni translocation factor from root to stem to leaf led to low nickel accumulation in leaf indicating high nickel tolerance ability of tea. Tea infusions from Tocklai Vegetative clone 1 and Tocklai Vegetative clone 23 with municipal solid waste compost application in soil up to 10 t ha−1 showed leaf nickel contents below permissible limit, i.e., from 0.002 to 1.2 and 0.01 to 1.1 μg L−1, respectively. Municipal solid waste compost could therefore be a valuable alternative for soil amendment subject to non-enhancement of soil nickel storage on long-term use. The one-way analysis of variance along with Duncan’s multiple range tests showed significant differences between pair of treatments. Hierarchical cluster analysis revealed formation of three different groups between the clones and treatments imposed.

The Study of the Effect of some Bio-Fertilizers and Municipal Solid Waste Compost Application as Growing Media on some Growth Indices of Zinnia (Zinnia elegans

The Study of the Effect of some Bio-Fertilizers and Municipal Solid Waste Compost Application as Growing Media on some Growth Indices of Zinnia (Zinnia elegans

Influence of municipal solid waste compost application on heavy metal content in soil.

Municipal solid waste composts (MSWC) are widely used over agricultural lands as organic soil amendment and fertilizer. However, MSWC use may result in various adverse impacts over agricultural lands. Especially, heavy metal contents of MSWC should always be taken into consideration while using in agricultural practices. The present study was conducted to find out heavy metal contents of municipal solid waste compost (MSWC) and to investigate their effects on soils. Experiments were carried out in three replications as field experiments for 2 years. Dry-based MSWC was applied to each plot at the ratios of 0, 40, 80, 120, 160, 200 t ha(-1). Results revealed that heavy metal content of MSWC was within the allowable legal limits. Compost treatments significantly increased Cu, Zn, Ni, Cr, Cd, and Pb content of soils (p < 0.01). Increasing soil heavy metal contents were observed with increasing applied compost doses. Although compost treatments significantly increased soil heavy metal contents, the final contents were still within the allowable legal limits. Results showed that MSWC doses over 10 t ha(-1) may create a heavy metal risk in long term for soils with pH ≥ 7. Therefore, in MSWC use over agricultural lands, heavy metal contents should always be taken into consideration and excessive uses should be avoided.

Carbon and Nitrogen Mineralization and Humus Composition Following Municipal Solid Waste Compost Addition to Laterite Soils under Continuous Cassava Cultivation

A glasshouse incubation experiment was conducted to study the carbon (C) and nitrogen (N) mineralization of municipal solid waste compost (MSWC) added at differential rates to a laterite soil where cassava has been continuously cultivated for the past 10 years. The rate of C mineralization from added substrates increased with increasing rates of addition of MSWC. Available N significantly increased with increase in the rate of application of MSWC. There was a decreasing trend in E465/E665 ratio of humic acid as we increased the rate of application of MSWC from 2.5 to 20 t ha−1. The Cross Polarization Magic Angle Spinning (CPMAS) 13C NMR spectral analysis revealed that there are differences in the rate of humification of added MSWC, and application of MSWC at 15 t ha−1 resulted in least humification with the greatest alkyl C, lowest aromatic C, and greater O-alkyl C content. The decomposition rate (R) was found to be greater for this treatment. The residual C in soil was found to increase over time coincident with greater rates of MSWC application, indicating increased C stabilization, which could improve soil quality.