Effect of sewage sludge and its biochar on chemical properties of two calcareous soils and maize shoot yield

Little information is available regarding the effect of sewage sludge biochar on soil properties and crop yield. Thus, our objective was to evaluate the effect of sewage sludge (S) and its biochar (B) on maize shoot yield, nutrients and heavy metals uptake in two calcareous soils. The amendments were applied at the rates of 0, 10, 20 and 40 Mg ha^?1. Moreover, NK treatment was included to compare the effects of S and B with conventional fertilization. At harvest time, plant shoots and soil samples were collected for yield, nutrients uptake and chemical analyses. The highest shoot dry matter was obtained in the S treatment. The B application in the clay loam and loam soils resulted in 5.2% increment and 17.7% decrement of shoot dry matter relative to the control, respectively. Shoot dry matter in the NK treatment was significantly higher than in the control. B application decreased Fe, Zn, Mn, Cu and Pb uptake by maize shoot. DTPA-extractable Pb in B-amended soils was lower than in control, while an inverse trend was obtained for available Fe, Zn, Mn and Cu. Biochar application at the rate of 7.3 Mg ha^?1 might be suggested for maize cultivation in clay loam soils.     

Self-purification of agrosoddy-podzolic sandy loamy soils fertilized with sewage sludge

Sandy loamy agrosoddy-podzolic soils and plants growing on them were studied. The soils had been treated with sewage sludge from the Lyubertsy aeration station applied as organic fertilizer for 5–10 years before 1990. Initially, these soils were used for cultivating vegetables and fodder crops. The content and mobility of heavy metal compounds increased in the plow horizons of studied soils under the influence of sewage sludge. The concentrations of Cd and Zn exceeded the tentative permissible concentrations (TPC) for these elements by 8–16 and 2–4 times, respectively. The contaminated layer was found at the depths within 30–50 cm, which attests to a low migration rate of heavy metals added to the studied soils with sewage sludge (SS) 25 years ago. The concentration of Cd exceeded the maximum permissible concentration (MPC) of this element in all vegetable and fodder crops cultivated on the studied soils. The content of heavy metals in plants differed by three–five times in dependence on the capacity of particular plants to accumulate them. The period of soil self-purification from heavy metals was found to depend on the soil contamination level and element mobility, as well as on the element removal with harvested crops and with soil water flows. The maximal time of achieving the normal level of Cd concentration was estimated as 288 years for maximally contaminated soils; the corresponding values for Cu and Zn were estimated as 74 and 64 years, respectively.     

Effect of sewage sludge on nodulation and N2−fixation in alfalfa grown on calcareous loamy soils

The influence of different rates of sludge applications to calcareous loamy soils of Saudi Arabia, on nodulation and symbiotic N₂?fixation in alfalfa plants (Medicago sativa L.) was studied in a pot experiment. The effect of heavy metals accumulation in soil due to continuous irrigation of the test soil with sewage water was also investigated. Application of up to 80 g sludge per pot enhanced nodulation, nitrogenase activity, dry matter yield and N-contents of alfalfa plants growing in loamy soils either previously irrigated with sewage water or well water. However, sludge applied at the rate of 160–200 g pot^?1 inhibited the nodulation, N accumulation and dry matter yield of alfalfa. The response of alfalfa to sludge was dependent on the rhizobial strain used. Our results also showed that accumulation of heavy metals due to continuous irrigation of a calcareous sandy loam soil with sewage water, for more than 10 years, didn't inhibit N₂?fixation in alfalfa plants, but enhanced it. Microelements in alfalfa plants increased with increase in the rate of sludge application. Although high rates of sludge application affected nodulation and N₂?fixation of alfalfa, dry matter and the nitrogen contents of the plants were not highly affected. Therefore, the inhibitory effect of high rates of sludge was most probably due to the toxic effect of heavy metals on the microsymbiont rather than on the plants.     

Effect of freezing and thawing processes on some physical properties of saline–sodic soils mixed with sewage sludge or fly ash

Dispersion of saline–sodic soils was rather difficult to leach. Therefore, negative effects of freeze–thaw on soil physical properties should be reduced by inexpensive and practical methods. This study investigates the effect of freeze–thaw cycles (3, 6, and 9) on wet aggregate stability, bulk density, and permeability coefficient in three soils with different electrical conductivity and exchangeable sodium percentage levels (soil I: 5.30 dS m⁻¹, 47.51%; soil II: 42.80 dS m⁻¹, 55.45%; soil III: 36.30 dS m⁻¹, 59.34%) which consist of different proportions of sewage sludge and fly ash by volume (10%, 20%, and 30%). The experiment was conducted under laboratory conditions using disturbed and non-cropped soil samples mixed with sewage sludge and fly ash. Soils mixed with sewage sludge produced higher aggregate stability and permeability coefficients and lower bulk density values as compared to the soils mixed with fly ash. Sewage sludge added with a rate of 30% eliminated the negative effects of freeze–thaw processes on wet aggregate stability. Freeze–thaw processes did not affect the bulk density of the soils II and III, which were mixed with sewage sludge. However, fly ash addition decreased the bulk density of these soils very significantly after nine freeze–thaw cycles. Addition of sewage sludge or fly ash with rates of 20% and 30% significantly increased the permeability coefficients in soil I after nine freeze–thaw cycles. Results indicated that addition of sewage sludge and/or fly ash to saline–sodic soils could be alternative way for reducing negative effects of freezing–thawing on soil wet aggregate stability, bulk density, and permeability coefficient.     

连续施用无害化污泥对沙质潮土土壤肥力和微生物学性质的影响

以小麦-玉米轮作体系下的沙质潮土为研究对象,选用经无害化处理后的城市污泥产物,通过2013~2015年田间定位试验,研究了不同城市污泥施用量对土壤肥力的影响,以期为城市污泥资源化利用提供理论基础和技术依据。设置单施化肥(CK)、CK+污泥15 t·hm~(-2)(CS1)、CK+污泥30 t·hm~(-2)(CS2)和CK+污泥45 t·hm~(-2)(CS3)共4个处理。主要研究结果如下:(1)连续定位试验结果表明,同一施用量污泥处理的土壤p H值随施用时间的增加呈下降趋势;土壤有机质(SOM)和养分含量如全氮(TN)、有效磷(AP)和速效钾(AK)随施用时间的增长呈上升趋势;(2)与CK比较,在2015年玉米季施用污泥各处理的土壤p H值显著降低了0.34~0.83个单位(P0.05),且与污泥施用量呈反比,以高施量污泥45 t·hm~(-2)下降最多;土壤SOM、TN、AP和AK分别显著提高了52.1%~166.9%、77.3%~177.8%、215.7%~486.3%和167.2%~379.0%(P0.05),且与污泥施用量呈正比,以高施量污泥45 t·hm~(-2)效果最显著;(3)试验所用污泥施用量范围内不会造成土壤和植物籽粒重金属污染,能够保持土壤环境健康;(4)与CK比较,施用污泥各处理土壤微生物量碳(MBC)、氮(MBN)含量均显著提高(P0.05),且与污泥施用量呈正比,并且季节不同也显著影响土壤MBC、MBN含量(P0.05);施用污泥能够显著提高土壤MBC/MBN(P0.05),说明施用污泥能够改变土壤微生物群落组成;(5)施用污泥,尤其是高施量污泥45 t·hm~(-2),在保证土壤和植物籽粒质量安全下,其土壤培肥效果最优。     

Effect of the addition of sewage sludge as a fertilizer on a sandy vineyard soil

Purpose

The application of sludge from wastewater in agriculture has increased in recent years, and it is therefore important to assess the effect that such treatment has on both the soil and the plant. The aim of the study described here was to ascertain whether there is a variation in the properties of the soil and to determine if this addition has an impact on the plant.

Materials and methods

The area of investigation was close to the municipality of Villarrubia de los Ojos (Ciudad Real). In this work, six samples were taken from the surface horizon in the studied plot at a depth of 35 cm. A further three samples were taken: (i) a surface horizon of a soil close to the area under investigation but without treatment (control sample), (ii) a sample of sludge from the wastewater treatment plant and (iii) a sample of the mixture used by farmers as fertilizer. Laboratory tests were conducted in accordance with the SCS-USDA (1972) guidelines. Trace element samples were analysed by X-ray fluorescence spectrophotometry (Philips PW 2404).

Results and discussion

The parcel of land studied is dominated by a sandy texture (88.3 % sand), and a decrease in pH was observed in areas in which the mixture (manure + sludge) was added (pH?=?8.0) compared to areas in which fertilizer was not applied (pH?=?8.5). It was observed that the addition of the compound led to an increase in the electrical conductivity of the soil. The trace elements can be organized into two groups based on the results obtained in this study. One group contains the trace elements that were only present in the rows that were treated with the fertilizer. The other group of trace elements was mobilized throughout the whole plot.

Conclusions

The application of sewage sludge on agricultural soils can be very useful as an organic amendment because it produces an increase in soil organic matter. However, sewage sludge must be applied with caution due to the changes in soil chemical properties (for example, pH and E.C.). The use of this type of waste for prolonged periods of time can cause problems of contamination in the soil.

     

碱稳定污泥污水对土壤可提取有机碳和铜的影响

An incubation experiment was conducted to evaluate the potential for water contamination with sludge-derived organic substances and copper following land application of alkaline-stabilised sewage sludge. Two contrasting sludge-amended soils were studied. Both soils were previously treated with urban and ruralalkaline biosolids separately at sludge application rates of 0, 30 and 120 t ha^-1 fresh product. The air-driedsoil/sludge mixtures were wetted with distilled water, maintained at 40 % of water-holding capacity and equilibrated for three weeks at 4 ℃ before extraction. Subsamples were extracted with either distilled wateror 0.5 mol L^-1 K₂SO₄ solution. The concentrations of organic C in the aqueous and chemical extracts were determined directly with a total organic carbon (TOC) analyser. The concentrations of Cu in the twoextracts were also determined by atomic absorption spectrophotometry The relationship between the two extractable organic C fractions was examined, together with that between extractable organic C concentration and extractable Cu concentration. Application of alkaline biosolids increased the concentrations of soil mobile organic substances and Cu. The results are discussed in terms of a possible increase in the potential for leaching of sludge-derived organics and Cu in the sludge-amended soils.     

Nutrition of drip irrigated corn by phosphorus under sandy calcareous soils

Phosphorus (P) is an essential nutrient for the higher plants and has low mobility and availability in soils. Good fertilization management for this nutrient may be lead to increasing its availability. A field experiment in a split plot design was conducted out during the 2003 and 2004 summer growing seasons to study the effect of frequency of P fertigation and different forms of P fertilizers on uptake of P by corn plant as well as yield production. The high frequency of P fertigation increased P uptake significantly (p < 0.05) by 12 and 19% in the first and second season respectively. Phosphoric acids (PA) followed by urea phosphate (UP) gave the highest significant biological yield (25.67 and 24.5 ton/ ha). From the results of this study, it may be recommended that in sandy calcareous soils P must be added every three days using acid forms.     

Influence of pyrolysis temperature on chemical and physical properties of biochar from sewage sludge

The use of sewage sludge biochar (SSB) for agro-environmental purposes has been increasing. However, due to the strong influence of pyrolysis temperatures on its production, there is great variation in its final properties. In this regard, efforts to generate relationships among many correlated SSB properties may help to understand this influence. This study sought to evaluate the effect of pyrolysis temperature on agro-environmental physicochemical properties of SSB. Biochars from sewage sludge (SS) were produced at 300, 400 and 500°C and their physicochemical properties were evaluated in comparison to SS samples. The increase in pyrolysis temperature decreased C, N, and H contents and the H/C atomic ratio, while increasing the C/N ratio. The pyrolysis process increased pH values, the surface area and pore volume and enriched the SSB with macro and micronutrients. Considering all variables together, the biochar produced at 300°C was that which showed the greatest nutrients availability, such as N total, S, NO₃^?, NH₄⁺, Ca²⁺ and Mg²⁺. Conversely, SSB produced at 500°C showed higher recalcitrant organic matter and alkalinity, important properties for C sequestration and the correction of acidic soils. The combined application of SSB produced at lower and higher pyrolysis temperatures should be furthered studied.     

Mutagenic potential of municipal sewage sludge amended soils

This study was conducted to measure the mutagenic potential of municipal sewage sludge amended soil. Two separate sludge samples were collected from one municipal wastewater treatment plant and applied to undisturbed soil lysimeters over a 9 mo interval. Soil and sludge samples were collected for approximately 2 yr following sludge application. Samples were solvent extracted using methylene chloride and methanol, and the bacterial mutagenicity of the resulting residue determined using the Salmonella/microsome assay. The maximum specific activity of the sludge amended soil was 416 net revertants per 10 mg of residue induced by the methanol fraction extracted from the Weswood soil collected 154 d following the first sludge application. In the Padina sand, the maximum specific activity was 320 net revertants per 10 mg of residue induced by the methanol fraction extracted from the sample collected 154 d following the first sludge application. The specific activity of the sludge amended soil was observed to decrease slowly with time. For both the Padina and the Weswood soils, mutagenic organic chemicals were detected in soil samples collected 510 d following the second sludge application. For the Weswood soil, the mutagenic activity per unit weight of soil with metabolic activation of the samples collected 510 d after the final sludge application was decreased by 15 and 76% for the methylene chloride and methanol fractions, respectively, when compared to the maximum weighted activity observed 56 d after the final sludge application. The results indicate that municipal sewage sludges may contain organic mutagens which are persistent in the soil.     

长期施用堆肥对小麦根际及非根际土壤化学性质的影响

Compost of different rates was applied to artificial field plots of a low humic andosol at National Agriculture Research Center (NARC)of Japan for 15 or 28 years,and their effects on the chemical properties of wheat rhizosphere soil and nonrhizosphere soil were measured.Contiuous application of compost for 28 years resulted in raise of soil C,N,P,pH and exchangeable based.The building up of compost for 28 years resulted in raise of soil C,N,P,pH and exchangeale bases,The building up of organic matter in the soil occureed slowly.A residual effect of the compost on soil chemical properties was still present after 13 years of no application,but this effect was weaker in comparison with that of the continuous application treatments.In the rhizosphere soil,NaHCO3-extracted P and exchangeable Ca were higher than those in the bulk soil.The removal of free organic acid slightly affected the soil pH,especially,the rhizosphere soil pH.The raise of soil pH may result from the increase of exchangeable base by the application of compost.     

Effect of sewage sludge application on cotton yield and contamination of soils and plant leaves

Abstract

In a two‐year field experiment, dry sewage sludge was applied to fields plots at rates of 0,26,42,58, or 77 tons ha^‐1 year^‐1 on a clay loam soil (calcixerrolic xerochrept), well drained with a pH value of 8.15. Cotton was the cultivated plant (Gossypiumhirsutum variety korina). Sequential extraction was used to separate the different forms of the metals (exchangeable, organically bound, carbonates and residual) in the soil‐sludge mixtures. Cotton yield increased in the second year of experimentation compared with the control treatment (without fertilization and no application of sewage sludge). Most of the metals studied [cadmium (Cd), zinc (Zn), copper (Cu), and nickel (Ni)] were found in the organically bound, carbonate or residual forms. From the elements in the soil fractions, only Zn in the residual form was correlated with the Zn content of cotton leaves. The diethylenetriaminepentaacetic acid (DTPA) extraction of the plant‐available levels of the elements showed only for Cd a simple linear correlation, between concentration in soils and cotton leaves.     

Assessment of chemical composition of plants cultivated on two different soils amended with sewage sludge compost using MANOVA

Abstract

Application of organic fertilizers may replenish soil organic matter, improve soil fertility and increase plant yield and its quality. This research deals with the effects of soil amendment with sewage sludge compost (SSC) on the chemical composition of plants (white mustard, triticale and white lupine) cultivated on two contrasting soils (light vs. medium). A 3-year pot experiment was conducted and SSC at the rate of 6?Mg ha^?1 was applied to the soils.The study clearly demonstrated that SSC as an organic fertilizer had a minor influence on the modification of the chemical composition of shoots and grain cultivated in crop rotation plants and it was more evident in medium soil. The statistically confirmed effect was mainfested in higher c ontents of N and P in grain of plants in the 2^nd and 3^rd year of the experiment.     

伊朗一些石灰性土壤中锌解吸动态研究

Desorption of zinc (Zn) from soil is an important factor governing Zn concentration in the soil solution and Zn availability to plants. Batch experiments were performed to study the kinetics of Zn desorption by diethylenetriaminepentaacetic acid (DTPA) from 15 calcareous soil samples taken from Golestan Province in northern Iran. Soils were equilibrated with 0.005 mol L-1 DTPA solutions for 0.25 to 192 h. The results showed that the extraction process consisted of rapid extraction in the first 2 h followed by much slower extraction for the remainder of the experiment. Desorption kinetic data was fitted to pseudo-first-order kinetic model. The experimental data were found to deviate from the straight line of the pseudo-first-order plots after 2 h. The model of two first-order reactions was fitted to the kinetic data and allowed to distinguish two pools for Zn: a labile fraction (Q1 ), quickly extracted with a rate constant k1 , and a slowly labile fraction (Q2 ), more slowly extracted with a rate constant k2 . The applicability of pseudo-second-order model in describing the kinetic data of Zn desorption was also evaluated.     

施用污泥后石灰性土壤中铜、锌、镉的植物有效性

The toxicity of trace elements (TEs), such as copper (Cu), zinc (Zn), and cadmium (Cd), often restrict land application of sewage sludge (SS) and there was little information about soil-plant transfer of TEs in SS from field experiments in China. In this study pot and field experiments were carried out for 2 years to investigate the phytoavailability of TEs in calcareous soils amended with SS. The results of the pot experiment showed that the phytoavailability of Zn and Cu in the SS was equal to 53.4%-80.9% and 54.8%-91.1% of corresponding water-soluble metal salts, respectively. The results from the field experiment showed that the contents of total Zn, Cu, and Cd in the soils increased linearly with SS application rates. With increasing SS application rates, the contents of Zn and Cu in the wheat grains initially increased and then reached a plateau, while there was no significant change of Cd content in the maize grains. The bioconcentration factors of the metals in the grains of wheat and maize were found to be in the order of Zn > Cu > Cd, but for the straw the order was Cd > Cu > Zn. It was also found that wheat grains could accumulate more metals compared with maize grains. The results will be helpful in developing the critical loads of sewage sludge applied to calcareous soils.     

Effect of aging process on the fractionation of heavy metals in some calcareous soils of Iran

This study was conducted to investigate the effect of time on lead (Pb), zinc (Zn), cadmium (Cd) and copper (Cu) availability in some calcareous soils of Iran. Heavy metals were added to soils at the rate of 500 mg kg^? 1 of Pb, Zn, and Cu and 8 mg kg^? 1 of Cd as chloride. The samples were incubated for 3 h, 1, 3, 7, 14, 21, and 28 days at 25 °C and constant moisture. After incubation, metals in amended and control soils were fractionated by the sequential extraction procedure. There were changes in the proportional distribution of heavy metals in all five studied soils during 28 days of incubation with spiked heavy metals. In general the proportions of heavy metals associated with the most weakly bound fraction (EXCH) tended to decrease, with corresponding increases in the other five more strongly binding fractions during the incubation. The distribution of added heavy metals into different solid phase fractions appears to be consisted of two phases involving the initial rapid retention followed by a slow continuous retention. Three kinetic equations were used to fit the experimental data. The parabolic equation fits well the data used in this work. The transformation rate of EXCH fraction for soils was estimated by parabolic equation for above incubation periods. There were differences in the rates at which redistribution took place between soils and heavy metals. The constant b in parabolic equation was defined as the transformation rate, which were in the order Cu > Zn ≥ Pb ? Cd. The higher proportions of EXCH fraction of spiked Cd in these calcareous soils indicates its higher potential of downward leaching and runoff transport especially at the early stage of pollution.     

Heavy metals in mine soils amended with sewage sludge

In order to reclaim a clay quarry, a topsoil material was mixed with gravelly spoil at different ratios and with various rates of sewage sludge. The influence of three spoil/topsoil ratios (1:1, 2:1 and 3:1) and three sludge rates (40, 80 and 120 t ha⁻¹) on chemical properties of the resulting material was investigated, with emphasis on heavy metal (Fe, Cu, Mn, Ni and Zn) contents. The mixtures topsoil/spoil/sludge were water saturated and incubated for 15 or 30 days in a chamber under controlled conditions. The incubated samples were analysed for pH, total carbon and nitrogen, and total, available, exchangeable and soluble heavy metals. The addition of spoil to the topsoil increased the volume of material available, by utilizing an inert material unsuitable by itself to grow plants. The addition of sewage sludge repaired the disadvantages of the spoil, increasing the pH and the organic matter contents. The total heavy metal contents in the mixtures followed the sequence Fe>>Mn>>Zn, Cu>Ni. All except Cu were within the ranges allowed for agricultural lands. The available heavy metals constituted a small fraction of total contents and decrease with time due to complexation and immobilization processes. The exchangeable and soluble fractions were almost negligible; only small amounts of Mn, Zn and Cu were detected. Therefore, the risk of contamination by heavy metals is insignificant in the conditions investigated. Copyright © 1999 John Wiley & Sons, Ltd.     

Evaluating effects of sewage sludge and household compost on soil physical,chemical and microbiological properties

Recycling of organic wastes within agriculture may help maintain soil fertility via effects on physical, chemical and biological properties. Efficient use, however, requires an individual assessment of waste products, and effects should be compared with natural variations due to climate and soil type. An 11-month incubation experiment was conducted between April 1998 and March 1999, in which a sandy loam without or with anerobically digested sewage sludge (4.2 t dry matter (DM) ha⁻¹) or household compost (17 t DM ha⁻¹) was incubated under constant laboratory conditions at 10 °C, as well as in the field. The following properties were monitored: wet-stability of soil aggregates, clay dispersibility, hot-water extractable carbohydrates, resin-extractable P_i, inorganic N, biomass C and N, PLFA profiles, FDA hydrolysis activity, β-glucosidase activity and CO₂ evolution. In general, effects of waste amendment were positive, but moderate compared to the dynamics observed in unamended soil, and mainly occurred in the first several weeks after amendment. The temporal dynamics of inorganic N, FDA hydrolysis activity, biomass C and PLFA composition appeared to be faster under the fluctuating climatic conditions in the field. To evaluate accumulated effects of repeated waste applications, soil was also sampled from a field trial, in which the sewage sludge and household compost had been applied at the same rates as in the incubation study for three consecutive years. Sampling took place after the final harvest, i.e. 5 months after the final waste application. Compost amendment had increased potentially mineralizable N by a factor of 1.8, and sludge amendment had increased the amount of resin-extractable P_i by a factor of 1.6. However, there were no accumulated effects of waste amendment on the fraction of soil in wet-stable aggregates, or on the microbiological properties tested, which supported the observation from the incubation study that effects of organic wastes were transient.     

The effect of drying on chemical properties of some Papua New Guinea soils

Abstract

Cation exchange capacity increased with both air drying (25°C) and oven drying (105°C). The initial value of exchange acidity at field moisture determines whether exchange acidity increases or decreases after drying. Exchangeable bases, particularly calcium, increase with oven drying.     

Effects of termites on the physical and chemical properties of the acid sandy soils of southern Nigeria

Abstract

This study was aimed at characterizing the effects of the activity of termites of the genus Nasutitermes on the physico‐chemical properties of the acid sandy soils of southern Nigeria. Selected morphological properties of the termite mounds were measured in the field. Outside portions of the termite mound and surface (0–15 cm) soil were collected and analyzed for some physical and chemical properties. Results obtained showed a density of 112 mounds ha^‐1 with average height of 0.85 m. There were significantly higher proportions of clay, silt, and organic carbon, and higher pH, exchangeable potassium (K), calcium (Ca), magnesium (Mg), available phosphorus (P), effective cation exchange capacity and base saturation in the mounds of the Nasutitermes than in the surrounding topsoil. Mounds of Nasutitermes termites, if returned to the soil, could improve the properties of the soil in areas where termites occur in large numbers.