Urban Waste Compost Research Articles

English

In the production of quality plant, it is important to consider the growing substrate since it provides plants with very important physical and chemical characteristics of the soil. Many organic materials of vegetal or animal origin have been used in mixtures of substrates for plant production. This study evaluated the development, quality and physiological components of Conilon coffee plants as a function of substrates containing organic materials of different origins. The experiment was carried out in a greenhouse, in a randomized block design with five treatments: T-Control treatment with 100% of soil and the other treatments with 85% of soil and 15% of organic matter derived from urban waste compost, mature cattle manure, dairy residue, and tannery sludge. Development, quality and physiological characteristics of plants were evaluated. All sources of organic matter favored the development of the Conilon coffee plants in relation to the plant receiving no organic matter in the substrate. Dehydrated tanning sludge in the proportion of 15% provided inferior plant performance compared with treatments with the other organic sources and a greater production of flavonoids. The treatments T-Compound, T-Dairy, and T-Manure provided better results than the other treatments for most of the evaluated characteristics, and can be recommended as components of substrates in the production of Conilon coffee plants. Key words: Coffea canephora, alternate substrate, sustainability, Dickson quality index, multiplex.

Soil chemical properties and nutrients in maize fertilized with urban waste compost1

ABSTRACT Urban waste compost has a potential to be used as an organic fertilizer in agriculture, but field studies are required to define the recommendable rates for crops. This study aimed at evaluating the effect of fertilization with urban waste compost on the soil chemical properties, yield, nutrient and heavy metal contents, in maize leaves and grains. The field experiment was carried out in a randomized complete block design, with seven treatments and four replications. The treatments consisted of six urban waste compost doses (0 Mg ha-1, 5 Mg ha-1, 10 Mg ha-1, 20 Mg ha-1, 30 Mg ha-1 and 40 Mg ha-1), applied in the planting furrow, plus an additional control treatment, with NPK mineral fertilization and no waste compost application. Fertilization with up to 40 Mg ha-1 of urban waste compost improves soil fertility. Fertilization with urban waste compost increases grain yield and the N, P and K contents in leaf tissue and maize grains, without inducing plant contamination with heavy metals. The application of 30 Mg ha-1 of urban waste compost can replace mineral fertilization in maize cultivation.

Modeling Copper and Cadmium Mobility in an Albeluvisol Amended with Urban Waste Composts

Core Ideas Mobility of Cu and Cd in compost‐amended soil was estimated using HYDRUS‐2D. Cu and Cd mobility was controlled by sorption in the tilled layer. Different sorption estimations were used to model trace metal leaching. EDTA/CaCl2 extracts ratio gave reliable Kd estimates for Cu but not for Cd. Most of the Cu and Cd mass remained in the tilled layer. Two experimental plots amended with a co‐compost of sewage sludge and green wastes (SGW) or with a municipal solid waste compost (MSW) were compared with a control plot without organic amendment (CONT) in terms of trace metals mobility. These plots were equipped with wick lysimeters, time‐domain reflectometry probes and tensiometers for 6 yr (2004–2010). Different soil structures due to tillage and compost incorporation were identified in the tilled layers and reproduced in HYDRUS‐2D for simulating water, Cu, and Cd transport. Two sorption estimation approaches were used, either assuming equilibrium between CaCl2 and ethylenediaminetetraacetic acid (EDTA) extractable metals (Kd‐1) or using equations based on pedotransfer functions assuming nonlinear sorption for Cu (Kf) and linear sorption for Cd (Kd‐2). Lysimeter data on Cu leaching were successfully reproduced with the Kd‐1 approach for the SGW and CONT plots (model efficiency coefficient ESGW = 0.97, ECONT = 0.95), while the MSW plot showed better fitting with the Kf approach (EMSW = 0.77), which could be explained by the less stable organic matter of the MSW compost because it takes into account organic matter components (dissolved organic C and soil organic matter). The Cd leaching was reproduced with the Kd‐2 approach for the two amended plots (ESGW = 0.12, EMSW = 0.80), while CONT simulation overestimated leaching. The percentage of measured Cu and Cd leached in reference to input mass was 0.6 and 2.7%, respectively, in the SGW plot compared with 5% for both metals in the MSW plot. Trace metal mobility appeared to be limited in the tilled layer by sorption to organic matter.

Long-term amendment of four different compost types on a loamy silt Cambisol: impact on soil organic matter, nutrients and yields

ABSTRACTThis study investigated the long-term effects of different composts (urban organic waste compost (OWC), green waste compost (GWC), cattle manure compost (MC) and sewage sludge compost (SSC)) compared to mineral fertilisation on a loamy silt Cambisol, after a 7-year start-up period. The compost application rate was 175 kg N ha−1, with 80 kg mineral N ha−1 and without. Soil characteristics (soil organic carbon (SOC), carbon-to-nitrogen (C/N) ratio and soil pH), nutrients (nitrogen (N), phosphorous (P) and potassium (K)) and crop yields were investigated between 1998 and 2012. SOC concentrations were increased by compost applications, being highest in the SSC treatments, as for soil pH. N contents were significantly higher with compost amendments compared to mineral fertilisation. The highest calcium-acetate-lactate (CAL)-extractable P concentrations were measured in the SSC treatments, and the highest CAL-extractable K concentrations in the MC treatments. Yields after compost amendment for winter barley and spring wheat were similar to 40 kg mineral N ha−1 alone, whereas maize had comparable yields to 80 kg mineral N ha−1 alone. We conclude that compost amendment improves soil quality, but that the overall carbon (C) and N cycling merits more detailed investigation.

Urban waste composts enhance OC and N stocks after long-term amendment but do not alter organic matter composition

Organic matter (OM) amendments, originating from waste materials, could be used to enhance soil organic carbon (SOC) storage and fertility of cropland soils. However, there is a limited understanding about the long-term effect of different urban waste compost amendments on soil organic matter (SOM) formation processes and their impact on SOC storage. Accordingly, the long-term effects of different OM amendments on the amount and composition of particulate and mineral associated SOM were investigated. Surface soils were sampled from a Luvisol under cropping rotation, which received biannually 0.4kg organic carbonm−2 in form of three different urban composts or cattle manure for a period of 15 years.Despite similar C input, different urban waste compost amendments resulted in contrasting C storage. While there were no C stock changes for municipal solid waste compost amended soils, composts from organic waste and green waste and sewage sludge increased SOC stocks in a similar range as conventional farmyard manure. In bulk soils, SOC stocks were increased by approximately 30%, in occluded particulate OM<20μm by 155% (organic waste compost) and 71% (green waste and sewage sludge compost). Carbon storage in clay fractions showed approximately 20% higher values in all treatments. Organic matter amendments result in C–N coupling as for N proportional stock increases were recorded. The high variability of the composition of different amendment types was reflected in the particulate OM fractions but not in the highly uniform composition of the mineral-associated OM. Bulk soil wettability was not affected by the amendments, as only POM fractions showed increased hydrophobicity, but not clay fractions. Clay fractions showed high alkyl/O-alkyl and low C/N ratios, characteristic for microbial material. The OM composition in the clay fraction is determined by the microbial residues that are independent in their composition from the input material. The increased C storage in the clay fractions of the soil amended with organic wastes and green waste and sewage sludge compost and farmyard manure might be promoted by a better microbial use efficiency leading to C sequestration as microbial compounds.

CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; emission and structural characteristics of two calcareous soils amended with municipal solid waste and plant residue

Abstract. This investigation examines the effect of different amendments on selected soil physical and biological properties over a 24-month period in two cropland fields. Urban municipal solid waste (MSW) compost and alfalfa residue (AR) were used as different organic amendments at the rates of 0 (control), 10 and 30 Mg ha−1 to a clay loam soil and a loamy sand soil in a semiarid region. Results showed that the soil improvement was controlled by the application rate and decomposability of amendments and soil type. The addition of organic amendments to the soils improved aggregate stability and consequently enhanced total porosity, especially macropore fraction. The increased soil organic carbon (SOC) and total porosity values as compared to the control treatment were greater in the loamy sand soil than in the clay loam soil. Moreover, compared to the microbial respiration of control plots, the application of MSW resulted in higher values of microbial respiration in the clay loam soil than in the loamy sand soil, whereas the reverse was found for AR. Linear and power functions were provided for the relationships between microbial respiration and SOC in the loamy sand and clay loam soils, respectively. Also, CO2 emission was stimulated significantly as power functions of the total porosity and the ratio of macroporosity to microporosity. However, the soil microbial respiration and carbon storage improved aggregate stability and pore size distribution, and as a response, soil porosity, especially the macropore fraction, controlled CO2 flux.

Modeling water and isoproturon dynamics in a heterogeneous soil profile under different urban waste compost applications

Compost amendments and tillage practices can modify soil structure and create heterogeneities at the local scale. Tillage affects soil physical properties and consequently water and solute transport in soil, while compost addition to soil influences pesticide sorption and degradation processes. Based on the long-term field experiment QualiAgro (a INRA–Veolia partnership), a modeling study was carried out using HYDRUS-2D to evaluate how two different compost types combined with the presence of heterogeneities due to tillage affect water and isoproturon dynamics in soil compared to a control plot. A municipal solid waste compost (MSW) and a co-compost of sewage sludge and green wastes (SGW) have been applied to experimental plots. In each plot, wick lysimeters, TDR probes, and tensiometers were installed to monitor water and solute dynamics. In the plowed layer, four zones differing in their structure were identified: compacted clods, non-compacted soil, interfurrows, and the plow pan. From 2004 to 2010, the unamended control (CONT) plot had the largest cumulative water outflow (1388mm) compared to the MSW plot (962mm) and SGW plot (979mm). After calibration, the model was able to describe cumulative water outflow for the whole 2004–2010 period with a model efficiency value of 0.99 for all three plots. The CONT plot had the largest isoproturon cumulated leaching (21.31μg) while similar cumulated isoproturon leaching was measured in the SGW (0.663μg) and MSW (0.245μg) plots. The model was able to simulate isoproturon leaching patterns except for the large preferential flow events that were observed in the MSW and CONT plots. The timing of these preferential flow events could be reproduced by the model but not their magnitude. Modeling results indicate that spatial and temporal variations in pesticide degradation rate due to tillage and compost application play a major role in the dynamics of isoproturon leaching. Both types of compost were found to reduce isoproturon leaching on the 6year duration of the experiment.

The impact of organic amendments on soil hydrology, structure and microbial respiration in semiarid lands

Few studies have considered the effect of organic amendments on soil microbial activity and its contributions to hydraulic conductivity under field conditions in semiarid region soils with different textures and degrees of aggregate stability. This study was performed to investigate the relationship between selected soil properties and hydraulic conductivity in response to different types and application rates of organic amendments. For this purpose, urban municipal solid waste (MSW) compost and alfalfa residue (AR) were applied at different rates of 0 (control), 10Mgha−1 and 30Mgha−1 to clay loam and loamy sand soils under field conditions. Results show that after two years, MSW-treated soils had lower soil organic carbon (SOC) compared to those treated with AR due to higher CO2 emissions from the soils treated with MSW. Higher microbial respiration and mineralization quotient (qmC) in the MSW-treated soils resulted in higher levels of water stable aggregates (WSA>0.25mm) and more macro-pore fraction, leading to greater hydraulic conductivity, with larger increases at the higher rate of application (i.e. 30Mgha−1). Relative to the control treatment, the application of MSW caused greater increases in microbial respiration in the clay loam soil than in the loamy sand soil, whereas the reverse was found for AR. Apart from soil texture, aggregate size was found to play an important role in controlling the carbon stock and microbial respiration of soils and consequently hydraulic conductivity. The macro-pore fraction was more sensitive than the micro-pore fraction to the application of organic amendments. Correlation analysis indicated that during the reclamation process higher levels of microbial respiration, SOC, water stable aggregates and macro-pore fraction were associated with greater soil hydraulic conductivity.

Modelling the long-term effect of urban waste compost applications on carbon and nitrogen dynamics in temperate cropland

The recycling in agriculture of Exogenous Organic Matter (EOM) issued from organic waste treatment is a promising way to restore soil organic matter (SOM) content in intensively managed soils. EOM applications to crop fields may also be used as substitute to synthetic fertilisers. The CERES-EGC mechanistic model was used to simulate the effects of repeated applications of urban waste composts and manure over 13 years on both soil carbon (C) and nitrogen (N) dynamics in the soil–crop–water–air system of the long-term field experiment QualiAgro. Several EOMs were considered: a farmyard manure, FYM; a municipal solid waste compost, MSW; a bio-waste compost, BIO; a co-compost of green waste and sewage sludge, GWS. Each EOM application brought the equivalent of 220–400 kg N ha−1. The sub-model NCSOIL was parameterised from C and N mineralisation kinetics of EOMs measured during incubations of soil–EOM mixtures in controlled conditions. The simulation correctly reproduced the experimental kinetics. When transposing these parameters into the CERES-EGC model, C storage at the field scale was well simulated, together with crop N uptake and yields, as well as soil mineral N contents despite a slight overestimation. The GWS compost generated the highest C storage over the 13 y-period and MSW the lowest with 65% and 36% of the Exogenous Organic Carbon (EOC) applied incorporated into the soil organic C, respectively. The GWS and MSW had the highest potential of N loss because of high mineral N content and a high potential of N mineralisation, respectively in contrast to FYM and BIO. MSW had also the highest apparent N use efficiency (48.8%) thanks to a high potential of mineralisation (76.3% of organic N applied). The achieved CERES-EGC parameterisation offers promising prospects for predicting the effects of a larger panel of EOMs, and for further using this soil–plant–water–atmosphere model to manage EOM application practices at the regional scale in compliance with crop production and environmental aims.

Effects of humic acid, compost and phosphorus on growth characteristics of basil herb and concentration of micro elements in plant and soil

Organic matters are important soil components which have considerable effects on phytoavailability of nutrients and improvement of soil physical, chemical and biological properties. The increasing demand for medicinal plants necessitates extensive research on them for sustainable agricultural development. In order to assess the effects of different levels of humic acid, compost and phosphorus (P) on growth traits and some micronutrients’ uptake by basil medicinal plant (Ocimum basiilicum L.) a factorial experiment was conducted in 2011 using a completely randomized design with three replications. Treatments consisted of three levels of humic acid (0, 10 and 20 mg/kg of soil; H1, H2 and H3, respectively), three levels of urban waste compost (0, 5 and 10 ton/ha; C1, C2 and C3, respectively) and three levels of P (0, 10 and 20 mg/kg of soil, as triple super phosphate, P1, P2 and P3, respectively). After harvesting the plants, parameters such as dry weight of aerial parts, number of lateral branches, plant height and concentration and uptake of Fe, Mn, Cu and Zn in aerial parts were measured. Results showed that the effects of humic acid (at H2 and H3 levels) and compost (at C2 and C3 levels) were significant on height, number of lateral branches and shoot dry weight, as compared to control; but these two levels did not have significant difference. Interaction of humic acid and compost, along with P, on plant height, number of lateral branches and dry weight of shoots was not significant. Application of humic acid and compost increased significantly the concentration of Fe, Mn, Zn and Cu in plant shoots, and availability of Fe, Mn, Zn and Cu in soil was increased with the application of organic fertilizers. Interaction of humic acid and compost on concentration of Fe, Mn, Zn and Cu in plant and soil was significant. In interaction of humic acid and compost with P, the application of P reduced concentration of Fe, Mn, Zn and Cu in plant and their availability in soil. But, study of these interactions showed that application of organic fertilizers can somehow improve the negative effects of P on availability of these elements, and therefore, application of these fertilizers is recommended for improving soil chemical conditions and enhancement of growth traits of basil plant.

Agricultural waste utilisation strategies and demand for urban waste compost: Evidence from smallholder farmers in Ethiopia

The use of agricultural waste for soil amendment is limited in developing countries. Competition between fuel and feed is the major cause for the insufficient application of agricultural waste on cropland. The aims of this study were therefore (i) to investigate variation in agricultural waste allocation between groups of farmers with different livelihood strategies and link this allocation with the nutrient balances of their production systems, (ii) to identify farm characteristics that influence utilisation of agricultural waste for soil amendment, and (iii) to assess demand for urban waste compost. A total of 220 farmers were selected randomly and interviewed using standardised semi-structured questionnaires. Four groups of farmers, namely (i) field crop farmers, (ii) vegetable producers, (iii) ornamental-plant growers, and (iv) farmers practising mixed farming, were identified using categorical principal component and two-step cluster analyses. Field crop farmers produced the largest quantity of agricultural waste, but they allocated 80% of manure to fuel and 85% of crop residues to feed. Only <10% of manure and crop residues were applied on soils. Farmers also sold manure and crop residues, and this generated 5–10% of their annual income. Vegetable and ornamental-plant growers allocated over 40% of manure and crop residues to soil amendment. Hence, nutrient balances were less negative in vegetable production systems. Education, farm size, land tenure and access to extension services were the variables that impeded allocation of agricultural waste to soil amendment. Replacement of fuel and feed through sustainable means is a viable option for soil fertility management. Urban waste compost should also be used as alternative option for soil amendment. Our results showed variation in compost demand between farmers. Education, landownership, experience with compost and access to extension services explained variation in compost demand. We also demonstrated that labour availability should be used to estimate compost demand beside cash.

Depletion of Pentachlorophenol Contamination in an Agricultural Soil Treated with Byssochlamys nivea, Scopulariopsis brumptii and Urban Waste Compost: A Laboratory Microcosm Study

Pentachlorophenol (PCP) has been used worldwide as a wood treatment agent and biocide. Its toxicity and extensive use have placed it among the most hazardous environmental pollutants. The response of a PCP-contaminated agricultural soil to the addition of solid urban waste compost and two exogenous Ascomycota fungal strains Byssochlamys nivea and Scopulariopsis brumptii was evaluated. The experiments were conducted in soil microcosms incubated for 28 days at 25 °C and 60 % moisture content. The depletion of PCP and the changes in biochemical soil properties (i.e. microbial biomass, soil respiration, dehydrogenase and fluorescein diacetate hydrolysis activities) were detected. The addition of PCP severely depressed some of the tested biochemical properties such as microbial biomass, dehydrogenase and fluorescein diacetate hydrolysis activities. By contrast, compost limited the negative effect of PCP on the dehydrogenase activity and soil respiration. When compost and fungal strains were contemporary present, a synergistic effect was observed with a reduction of more than 95 % of the extractable PCP after 28 days of incubation. No differences in PCP depletion resulted when fungi or compost were individually used. Our results indicate that many processes (i.e. microbial degradation and sorption to organic matter) likely occurred when PCP was added to the soil. The compost and the fungal strains, B. nivea and S. brumptii, showed good capability to tolerate and degrade PCP so that they could be successfully used in synergistic effect to treat PCP polluted soils.

The combination of compost addition and arbuscular mycorrhizal inoculation produced positive and synergistic effects on the phytomanagement of a semiarid mine tailing

A field experiment was carried out to assess the effectiveness of combining mycorrhizal inoculation with a native AM fungus (Glomus sp.) and the addition of an urban organic waste compost (OWC) applied at two rates (0.5 and 2.0% (w:w)), with regard to promoting the establishment of Anthyllis cytisoides L. seedlings in a heavy metal polluted mine tailing, as well as stimulating soil microbial functions. The results showed that the combined use of the highest dose of OWC and AM inoculation significantly increased shoot biomass – by 64% – compared to the control value. However, the separate use of each treatment had no effect on the shoot biomass of this shrub species. At the 2% rate, OWC enhanced root colonisation by the introduced fungus as well as soil nutrient content and soil dehydrogenase and ß-glucosidase activities. The combined treatment increased the uptake of Zn and Mn in shoots, although only Zn reached excessive or potentially toxic levels. This study demonstrates that the combination of organic amendment and an AM fungus is a suitable tool for the phytomanagement of degraded mine tailings, although its effectiveness is dependent on the dose of the amendment.

Effects of nano iron oxide powder and urban solid waste compost coated sulfur on chemical properties of a saline-sodic soil

The main limiting factors in saline -sodic soils are high amounts of salts, low soil organic matter (SOM) and low availability of macro and micro-nutrients. The effect of different amounts of nano iron oxide powder and urban solid waste compost coated sulfur (USWCS) on the chemical properties of a saline-sodic soil was investigated. The experiment was conducted using a randomized complete block design with factorial arrangement and three replications, in a farm near Qom city. Treatments used in this study included USWCS (0 and 15 ton/ha) and nano iron oxide powder (0 and 20 mg/kg); treatments were applied to treated plots of 4 m 2 and sunflower seeds were sown. The results show that 20 mg/kg of nano-iron oxide, significantly (P<0.05) increased electrical conductivity of saturation extract (ECe), availabil ity of nutrient elements (5.26, 30, 18.18% for phosphorous (P), iron (Fe), and copper (Cu), respectively) in soil, while nitrogen (N), pH and sodium adsorption ratio (SAR) in soil decreased significantly (P < 0.05). Fifteen (15) tons/ha of USWCS significantly increased soil ECe (6.1%), micro and macro-nutrients amounts (8.3, 21.1, 46.6, 45. 5, and 14.9% for N, P, Fe, Cu, and Manganese (Mn) respectively), but significantly (P < 005) decreased the soil pH and SAR, compared to the control. The combined effect of 20 mg/kg of nano iron oxide and 15 ton/ha of USWCS increased micro-nutrient availability, but decreased soil pH and SAR significantly. It was concluded that the combined application of USWCS and nano iron oxide increased the availability of nutrients in saline-sodic soil.

PLONY I CHEMIZM ROŚLIN WIELOWARIANTOWEGO DOŚWIADCZENIA NA MODELOWYM ZŁOŻU ODPADÓW PALENISKOWYCH ENERGETYKI WĘGLOWEJ. CZĘŚĆ II (LATA 2012 – 2013)

Reclamation efficiency of composts produced from the mixture of municipal waste (Radiowo and ZUSOK), urban green waste composts (Complex), housing estate lawn mowing waste (plants) and sewage sludge, as well as mineral fertilizer (NPK – without the use of any organic fertilizer), was assessed in a model experiment on an ash soil. The experiment was launched in 2005 and continued until the end of 2013. Crops were collected and subjected to the analysis in 2005, 2006 and between 2011 and 2012. In the period between 2007 and 2010 no agrotechnical treatments were carried out, with the experiment being limited to mere observation of the natural (spontaneous) succession of plants. Reclamation doses of composts and sewage sludge were measured quantitatively, therefore they differed in the content of dry matter as well as in the contents of organic substances and minerals in the dry matter. The largest aggregated dry matter yield of plants (2005–2013) was reported in the Complex variant, and similarly, in the Radiowo and plant variants, whereas the ZUSOK variant reported the lowest aggregated dry matter field of plants. The yield-forming efficiency of NPK fertilizer was lower than in the case of compost and sludge variants. However, the field-forming efficiency of sewage sludge was lower than its fertilization potential as it was unstable and difficult to mix with the experimental soil. The results showed the yield-forming potential of plants on the experimental coal combustion waste deposits fertilized with composts and sewage sludge as well as the examples of the sites where sewage sludge could be used for the biological reclamation of landfills and spoil tips.

Changes in a Rhodic Hapludox under no-tillage and urban waste compost in the northwest of Rio Grande do Sul, Brazil

The use of urban waste compost as nutrient source in agriculture has been a subject of investigation in Brazil and elsewhere, although the effects on soil physical and chemical properties and processes are still poorly known. The aim of this study was to evaluate the effect of application of urban waste compost and mineral fertilizer on soil aggregate stability and organic carbon and total nitrogen content of a Rhodic Hapludox under no-tillage in the northwestern region of Rio Grande do Sul, Brazil, in the 2009/2010 and 2010/2011 growing seasons. The experiment was arranged in a 2 × 6 (seasons and fertilization) factorial in a randomized complete block design with four replications. The factor time consisted of two growing seasons (sunflower in 2009/10 and maize in 2010/11) and the factor fertilization of five rates of urban waste compost (0, 25, 50, 75 and 100 m³ ha-1), and mineral fertilizer. Soil samples were collected from the 0.0-0.10 m layer to determine aggregate stability (mean weight and geometric diameter), soil organic carbon (SOC) and total nitrogen (TN). Rates of up to 75 m³ ha-1 of urban waste compost, after two years of application to no-tillage maize and sunflower, improved aggregation compared to mineral fertilization in a Rhodic Hapludox. After the second crop, the SOC and TN contents increased linearly with the levels of urban waste compost.

Impact of long-term organic residue recycling in agriculture on soil solution composition and trace metal leaching in soils

Recycling composted organic residues in agriculture can reduce the need of mineral fertilizers and improve the physicochemical and biological properties of cultivated soils. However, some trace elements may accumulate in soils following repeated applications and impact other compartments of the agrosystems. This study aims at evaluating the long-term impact of such practices on the composition of soil leaching water, especially on trace metal concentrations. The field experiment QualiAgro started in 1998 on typical loess Luvisol of the Paris Basin, with a maize–wheat crop succession and five modalities: spreading of three different urban waste composts, farmyard manure (FYM), and no organic amendment (CTR). Inputs of trace metals have been close to regulatory limits, but supplies of organic matter and nitrogen overpassed common practices. Soil solutions were collected from wick lysimeters at 45 and 100cm in one plot for each modality, during two drainage periods after the last spreading. Despite wide temporal variations, a significant effect of treatments on major solutes appears at 45cm: DOC, Ca, K, Mg, Na, nitrate, sulphate and chloride concentrations were higher in most amended plots compared to CTR. Cu concentrations were also significantly higher in leachates of amended plots compared to CTR, whereas no clear effect emerged for Zn. The influence of amendments on solute concentrations appeared weaker at 1m than at 45cm, but still significant and positive for major anions and DOC. Average concentrations of Cu and Zn at 1m depth lied in the ranges [2.5; 3.8] and [2.5; 10.5μg/L], respectively, with values slightly higher for plots amended with sewage sludge compost or FYM than for CTR. However, leaching of both metals was less than 1% of their respective inputs through organic amendments. For Cd, most values were <0.05μg/L. So, metals added through spreading of compost or manure during 14years may have increased metal concentrations in leachates of amended plots, in spite of increased soil organic matter, factor of metal retention. Indeed, DOC, also increased by amendments, favours the mobility of Cu; whereas pH variations, depending on treatments, influence negatively the solubility of Zn. Generic adsorption functions of these variables partly explain the variations of trace metal concentrations and helped to unravel the numerous processes induced by regular amendments with organic waste products.

Modeling the effect of soil structure on water flow and isoproturon dynamics in an agricultural field receiving repeated urban waste compost application

Transport processes in soils are strongly affected by heterogeneity of soil hydraulic properties. Tillage practices and compost amendments can modify soil structure and create heterogeneity at the local scale within agricultural fields. The long-term field experiment QualiAgro (INRA–Veolia partnership 1998–2013) explores the impact of heterogeneity in soil structure created by tillage practices and compost application on transport processes. A modeling study was performed to evaluate how the presence of heterogeneity due to soil tillage and compost application affects water flow and pesticide dynamics in soil during a long-term period. The study was done on a plot receiving a co-compost of green wastes and sewage sludge (SGW) applied once every 2years since 1998. The plot was cultivated with a biannual rotation of winter wheat–maize (except 1year of barley) and a four-furrow moldboard plow was used for tillage. In each plot, wick lysimeter outflow and TDR probe data were collected at different depths from 2004, while tensiometer measurements were also conducted during 2007/2008. Isoproturon concentration was measured in lysimeter outflow since 2004. Detailed profile description was used to locate different soil structures in the profile, which was then implemented in the HYDRUS-2D model. Four zones were identified in the plowed layer: compacted clods with no visible macropores (Δ), non-compacted soil with visible macroporosity (Γ), interfurrows created by moldboard plowing containing crop residues and applied compost (IF), and the plow pan (PP) created by plowing repeatedly to the same depth. Isoproturon retention and degradation parameters were estimated from laboratory batch sorption and incubation experiments, respectively, for each structure independently. Water retention parameters were estimated from pressure plate laboratory measurements and hydraulic conductivity parameters were obtained from field tension infiltrometer experiments. Soil hydraulic properties were optimized on one calibration year (2007/08) using pressure head, water content and lysimeter outflow data, and then tested on the whole 2004/2010 period. Lysimeter outflow and water content dynamics in the soil profile were correctly described for the whole period (model efficiency coefficient: 0.99) after some correction of LAI estimates for wheat (2005/06) and barley (2006/07). Using laboratory-measured degradation rates and assuming degradation only in the liquid phase caused large overestimation of simulated isoproturon losses in lysimeter outflow. A proper order of magnitude of isoproturon losses was obtained after considering that degradation occurred in solid (sorbed) phase at a rate 75% of that in liquid phase. Isoproturon concentrations were found to be highly sensitive to degradation rates. Neither the laboratory-measured isoproturon fate parameters nor the independently-derived soil hydraulic parameters could describe the actual multiannual field dynamics of water and isoproturon without calibration. However, once calibrated on a limited period of time (9months), HYDRUS-2D was able to simulate the whole 6-year time series with good accuracy.

Selection of Plant Species–Organic Amendment Combinations to Assure Plant Establishment and Soil Microbial Function Recovery in the Phytostabilization of a Metal-Contaminated Soil

A mesocosm experiment was established to evaluate the effect of two organic wastes: fermented sugar beet residue (SBR) and urban waste compost on the stimulation of plant growth, phytoaccumulation of heavy metals (HM) and soil biological quality and their possible use in phytostabilization tasks with native (Piptatherum miliaceum, Retama sphaerocarpa, Bituminaria bituminosa, Coronilla juncea and Anthyllis cytisoides) and non-native (Lolium perenne) plants in a heavy metal-contaminated semiarid soil. Except R. sphaerocarpa, SBR increased the contents of shoot N, P and K and shoot biomass of all plants. The percentage of mycorrhizal colonization was not affected by the organic amendments. The highest increase in dehydrogenase and β-glucosidase activities was recorded in SBR-amended P. miliaceum. SBR decreased toxic levels of HM in shoot of P. miliaceum, mainly decreasing Fe and Pb uptake to plants. This study pointed out that the SBR was the most effective amendment for enhancing the plant performance and for improving soil quality. The combination of SBR and P. miliaceum can be regarded the most effective strategy for being employed in phytostabilization projects of this contaminated site.

Effect of Soil Conditioners on Cation Ratio of Soil Structural Stability, Structural Stability Indicators in a Sodic Soil, and on Dry Weight of Maize

The relative effects of Na + and K + on soil structural stability due to application of some conditioners in sodic soils are not clearly defined by the existing literature. In this research, a completely randomized design experiment was performed to quantify the effect of some conditioners on physical properties in a loamy sodic soil. Five treatments included no conditioner as a control, urban solid waste compost (MC), Vermi-compose (VC), poultry manure (PM), and gypsum powder (G). The amount of each soil amendment was 10 ton/ha and each treatment consisted of 3 replications. The most important structural stability indicators including air capacity (AC), water dispersible clay (WDC), the slope of the retention curve at the inflection point (S gi index), and mean weight diameter of aggregates (MWD) were measured. The results showed that compared with the control, soil conditioners improved soil structural stability indicators significantly (P<0.05). Due to application of studied conditioners, the values of AC, WDC, S gi index, and MWD increased. In addition, it was demonstrated that there was a negative and significant correlation between CROSS and SAR and structural stability indicators. By increasing SAR and Cation Ratio of Soil Structural Stability WDC, S gi index, AC, and MWD values were decreased and as a result of these processes and improvement the physical condition of seedbeds, the dry weight of maize was increased.