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Fractionation, characterization and speciation of heavy metals in composts and compost-amended soils
CMA Iwegbue, FN Emuh, NO Isirimah, AC Egun
African Journal of Biotechnology , 2007,
Abstract: Speciation of heavy metals in soils determines the availability for metals for plant uptake and potential for contamination of groundwater following application of composts to agricultural lands. Methods used to characterize heavy metals in solid phase of composts and compost amended soils include physical fractionation and chemical extraction. Chemical extraction schemes are most frequently used approach to fractionate trace metals in soils, sewage sludge and composts. Several variations exist in the sequential extraction procedures. These variations include reagent types, strength, volume and extraction time. A main drawback shared by all sequential extraction schemes is that the procedures themselves are complex and time consuming. This setback has been overcome by the use of ultrasound accelerated extraction which reduce the extraction time for the entire extraction steps to about 90 minutes allowing composting process to be monitored more frequently which help to provide detailed understanding of the partitioning behaviour of heavy metals. Inspite of the variability the sequential extraction schemes, they all aimed at correlating each fraction with the mobility and plant availability of each metal. Several studies have shown that phase association of heavy metal in composts include water-soluble, exchangeable, precipitated as discrete phases, co-precipitate in metal oxides and adsorbed or complexed by organic ligands and residual forms. The phase association and solubility of metals changes over composting time thereby altering metal availability. It is apparent that the positive effects of resulting from compost application far outweigh the negative effect, but more research is needed on a wide range of municipal solid waste compost with more precise determination of the fate of municipal solid waste compost applied trace metals in the environment.
Kinetics of Nitrogen Mineralization in Soils Amended with Compost, Vermicompost and Cattle Manure  [cached]
S. Soodaee Mashaee,N. Aliasgharzade,S.h. Ostan
Journal of Science and Technology of Agriculture and Natural Resources , 2008,
Abstract: Understanding nitrogen mineralization from different organic sources should be a key factor in developing efficient prediction of the need for nitrogen fertilization with minimal negative environmental impact. In order to investigate nitrogen mineralization rate in soils amended with compost, vermicompost and cattle manure, an experiment was done as factorial in a randomized complete block design in three replications. Four treatments (compost, vermicompost, cattle manure and soil alone), two temperature levels (8 and 25 0C) and two moisture levels (50% and 85% FC) were used for the 90 - day incubation study. Ammonium and nitrate were measured by spectrophotometer method. Results indicated that the mixed first-and zero-order kinetics model is the best model for our data. Cattle manure treatment had the highest Nmin at 25 0C (87.78 mgN/kg equal to 14.54% Ntotal) and the least value (23.62 mgN/kg equal to 4.62% Ntotal) was obtained for the compost treatment at 8 0C. N0k (nitrogen availability index) for treatments was in the following order: Cattle manure>Vermicompost >Compost. With increasing the temperature and moisture, N mineralization increased. Also Nmin positively correlated with N0 (r =0.583*), and N0k (r =0.834**).
Optimisation Study on the Production of Anaerobic Digestate Compost for Application on Arable Soils
YA Abdullahi, SS Suleiman, JC Akunna
Bayero Journal of Pure and Applied Sciences , 2011,
Abstract: Organic fraction of municipal solid waste (OFMSW) is a rich substrate for biogas and compost production. Anaerobic Digestate compost (ADC) is an organic fertilizer produced from stabilized residuals of anaerobic digestion of OFMSW. This paper reports the result of studies carried out to optimise the production of ADC from organic fractions of domestic wastes and the effects of ADC amendments on soil quality. In general, ADC amended soils showed greater bioactivity and soil biomass compared to unamended soils. The diversity of soil community structures also increased with increasing ADC amendments with fungal populations showing greater variation than bacteria, suggesting that ADC amendment has greater impact on fungi than bacteria. It was found that seed germination in ADC amended soils increased with dilution and incubation time, suggesting that lower ADC application rates and longer lag periods between soil applications and planting can improve the benefits of ADC as an amendment for arable soil.
Runoff and soil and nutrient losses in semiarid uncultivated fields
Santos, Julio Cesar Neves dos;Palácio, Helba Araújo de Queiroz;Andrade, Eunice Maia de;Meireles, Ana Célia Maia;Araújo Neto, José Ribeiro de;
Revista Ciência Agron?mica , 2011, DOI: 10.1590/S1806-66902011000300030
Abstract: although water erosion is the principle agent responsible for soil degradation, field data on the impacts of erosion, due to high operational costs and measurement difficulties, are scarce, especially in semiarid regions. in this context, the aim of this study was to evaluate runoff and soil and nutrient losses in uncultivated areas in the semiarid region of the state of ceará in brazil. the experiment was conducted in a 20 m2 erosion plot that was uncultivated and populated with herbaceous plants. data were collected during the rainy season from january to may 2009. monthly water losses from overland flow ranged from 3.4 to 168.9 mm, representing 1.8 to 42.3% of the total monthly rainfall for january and april, respectively. soil loss from erosion totaled 2,166.6 kg ha-1. in february, soil losses were 834.3 kg ha-1, corresponding to 38.5% of the total value. the rainfall erosivity index (ei30) was 5,716.4 mj mm ha-1 h-1. the observed high variability of soil losses in individual events was influenced mainly by the antecedent soil water content. although this study used only one year of observations, the findings are important for land use planning, especially in the semiarid region of brazil, where datasets are scarce.
Simultaneous Simulations of Uptake in Plants and Leaching to Groundwater of Cadmium and Lead for Arable Land Amended with Compost or Farmyard Manure  [PDF]
Charlotte N. Legind, Arno Rein, Jeanne Serre, Violaine Brochier, Claire-Sophie Haudin, Philippe Cambier, Sabine Houot, Stefan Trapp
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047002
Abstract: The water budget of soil, the uptake in plants and the leaching to groundwater of cadmium (Cd) and lead (Pb) were simulated simultaneously using a physiological plant uptake model and a tipping buckets water and solute transport model for soil. Simulations were compared to results from a ten-year experimental field study, where four organic amendments were applied every second year. Predicted concentrations slightly decreased (Cd) or stagnated (Pb) in control soils, but increased in amended soils by about 10% (Cd) and 6% to 18% (Pb). Estimated plant uptake was lower in amended plots, due to an increase of Kd (dry soil to water partition coefficient). Predicted concentrations in plants were close to measured levels in plant residues (straw), but higher than measured concentrations in grains. Initially, Pb was mainly predicted to deposit from air into plants (82% in 1998); the next years, uptake from soil became dominating (30% from air in 2006), because of decreasing levels in air. For Cd, predicted uptake from air into plants was negligible (1–5%).
Stabilisation of Pb in Pb Smelting Slag-Contaminated Soil by Compost-Modified Biochars and Their Effects on Maize Plant Growth  [PDF]
Mary B. Ogundiran, Olamide O. Lawal, Sifau A. Adejumo
Journal of Environmental Protection (JEP) , 2015, DOI: 10.4236/jep.2015.68070
Abstract: Compost has been used to stabilise lead (Pb) in soil. However, compost contains a high level of dissolved organic matter (DOM) which may make Pb bioavailable in plant and thereby limiting its effectiveness and application. Addition of biochar to compost can reduce this effect. Rice husk (RH) and Cashew nut shell (CNS) biochars and compost-modified biochars were used in comparison to compost for stabilizing Pb in lead smelting slag (LSS)-contaminated soil (Pb = 18,300 mg/kg) in Nigeria. Efficiency of Pb stabilisation in control and amended soils was assessed using CaCl2 batch leaching experiment and plant performance. In pot experiments, maize plant was grown on the contaminated soil and on soil treated with minimum and optimum doses of the amendments singly and in combination for 6 weeks. Agronomical and chemical parameters of the plants were measured. CaCl2-extractable Pb in the untreated soil was reduced from 60 mg/kg to 0.55 mg/kg in RHB amended soils and non-detectable in other amended soils. RH-biochar/compost increased plant height, number of leaf and leaf area more than the others. Similarly, at minimum rate, it reduced root and shoot Pb by 91% and 86.0% respectively. Compost-modified rice husk biocharstabilised Pb in lead smelting slag contaminated soil reduced Pb plant uptake and improved plant growth. Lead stabilisation through the use of rice husk biochar with compost may be a green method for remediation of lead smelting slag-contaminated soil.
Compost of Different Stability Affects the Molecular Composition and Mineralization of Soil Organic Matter  [PDF]
Bekele Eshetu, Christel Baum, Peter Leinweber
Open Journal of Soil Science (OJSS) , 2013, DOI: 10.4236/ojss.2013.31007

This study investigated the C mineralization and chemical modification of a typical tropical soil amended with regional compost of different stability. Compost samples were produced from coffee pulp and fruit and vegetable waste in a method of small heap composting and the samples were collected in three different phases of composting. Both the fresh waste and compost samples were analyzed for their phytotoxicity. These samples were added to a tropical Nitisol at the rate of 48 t ha?1 and a control was set up without amendment. The CO2-C respired was determined during 98 days of incubation and the incubated samples were taken at the start and end of incubation for molecular-chemical analysis by Pyrolysis-Field Ionization Mass Spectrometry (Py-FIMS). The fresh waste yielded a germination index (GI) < 26% indicating phytotoxicity but this disappeared in all the composts (GI > 100%). The CO2-C respired was best explained by a first order plus linear model. A soil amended with a compost taken at the thermophilic phase attained the lowest overall organic C loss. In general, the Py-FIMS revealed a significant enrichment of stable N-compounds during the incubation in all amended soils compared to the control. Furthermore, among the compost-soil mixtures Py-FIMS indicated significantly higher increases in the proportions of carbohydrates, peptides and phenols/lignin monomers at the expense of fatty acids and sterols in soil amended with composts from the thermophilic phase. Thermal volatilization curves of Py-FIMS indicated enrichments of stable N-compounds and peptides in compost amended soil. This was a result of enhanced decomposition and stabilization of decomposition products by physical protection through association with clay and soil aggregates. In summary, application of compost shortly after reaching the high temperature phase was shown to be more efficient in organic C sequestration in a clay-rich tropical agricultural soil than mature composts.

Effect of Saturated Near Surface on Nitrate and Ammonia Nitrogen Losses in Surface Runoff at the Loess Soil Hillslope  [PDF]
Yu-bin Zhang,Fen-li Zheng,Ning Cao
International Journal of Chemical Engineering , 2010, DOI: 10.1155/2010/398504
Abstract: Water pollution from agricultural fields is a global problem and cause of eutrophication of surface waters. A laboratory study was designed to evaluate the effects of near-surface hydraulic gradients on NO3–N and NH4–N losses in surface runoff from soil boxes at 27% slope undersimulated rainfall of a loess soil hillslope. Experimental treatments included two near-surface hydraulic gradients (free drainage, FD; saturation, SA), three fertilizer application rates (control, no fertilizer input; low, 120?kg N ha-1; high, 240?kg N ha-1), and simulated rainfall of 100?mm h-1 was applied for 70?min. The results showed that saturated near-surface soil moisture had dramatic effects on NO3–N and NH4–N losses and water quality. Under the low fertilizer treatment, average NO3–N concentrations in runoff water of SA averaged 2.2 times greater than that of FD, 1.6 times greater for NH4–N. Under the high fertilizer treatment, NO3–N concentrations in runoff water from SA averaged 5.7 times greater than that of FD, 4.3 times greater for NH4–N. Nitrogen loss formed with NO3–N is dominant during the event, but not NH4–N. Under the SA condition, the total loss of NO3–N from low fertilizer treatment was 34.2 to 42.3% of applied nitrogen, while under the FD treatment that was 3.9 to 6.9%. However, the total loss of NH4–N was less than 1% of applied nitrogen. These results showed that saturated condition could make significant contribution to water quality problems. 1. Introduction Water pollution is a major global problem that amounts for more than 14,000 deaths daily [1]. The national environmental statistic bulletin of China reported that total discharge amount of ammonia nitrogen was 127.0?×?104?t in waste water in 2008 [2]. In the most recent national report on water quality in the United States, 45 percent of assessed stream miles, 47 percent of assessed lake acres, and 32 percent of assessed bay and estuarine square miles were classified as polluted [3]. Phosphorous (P) and nitrogen (N) in runoff from agricultural fields are key components of nonpoint source pollution and can accelerate eutrophication of surface waters [4, 5]. Most mineral forms of nitrogen are quite soluble in water and may be easily lost from soils through leaching and volatilization. In most freshwater (lakes and streams), P is the nutrient that can set off eutrophication, and N is the nutrient most likely to cause eutrophication for saltier waters (estuaries and costal areas) [6]. The transport of agricultural chemicals from the field to groundwater or to surface-water bodies is most commonly
Studies on integrated use of tannery wastewater, municipal solid waste and fly ash amended compost on vegetable growth
Nalawade P.M.,Kamble J.R.,Late A.M.,Solunke K.R.
International Journal of Agriculture Sciences , 2009,
Abstract: The present study is an attempt carried out to explore the possibility of finding the solution to environmentalproblem by eco-friendly technique. Utilization of bacteria, earthworms and its compost for growing crops having muchmore importance in recent years, under concept of sustainable agriculture. In the present investigation tannery wastewater, municipal solid waste and cow dung is being used with the help of bacteria and earthworm for manure preparation.Three different methods are used i.e. pit composting, bacterial composting and vermicomposting for manure preparation,which for vermicomposting Eisenia foetida species and for bacterial composting Azatobactor sp. were used. Forpreparation of compost 2:2:1 proportion of cow dung, municipal solid waste and saw dust is used respectively, followed byspraying tannery waste water. During the present study waste material were analyzed for its chemical characteristicsbefore and after composting. The compost produced from these three different methods was mixed with fly ash generatedin coal based thermal power plant and used for selected vegetable plants i.e., Trigonella fenugrecum (Methi) and Pisumsativum (Watana) to study the growth rate. The polyphenol and chlorophyll content of selected vegetable plants werestudied with comprising the chemical characteristics of soil.
Effect of Variation in Harvest Time on the Uptake of Metals by Barley Plants from Soil Amended with Sludge and Compost  [PDF]
J. Nouri,P. J. Peterson,B. J. Alloway
Journal of Biological Sciences , 2001,
Abstract: Increasing the metal concentrations by amending the sewage sludge increased the metal content in barley leaves. The yield of the 100 % sludge was the lowest and the soil pH was lowered as well. With the increase in time, the metal removal by plants is also increased. Chromium in barley behaved differently to the other metals studied, showing a declination with time. High voltage application of soluble chromium in solution culture resulted in decreased concentration of nitrogen, phosphorous, potassium , copper, iron, magnesium and zinc in barley and produced toxic effects and reduced growth. The metal uptake by plants from sludge amended soil was influenced by time of harvesting and stage of growth.
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