Effects of the application of heated sewage sludge on soil nutrient supply to plants

Abstract

We previously reported that heating sewage sludge significantly changes the rate of N mineralization. The present study was undertaken to examine the extent to which these changes affect plant growth and nutrient supply after application to different soils. A pot experiment in which komatsuna plants (Brassica campestris L. var. rapa) were grown in a Fluvisol or an Arenosol indicated that the amount of N taken up by the plants increased significantly by heating air-dried sludge at 120°C and decreased significantly by heating at 180°C. Heat-drying of the sludge at 120°C or 180°C also increased the N uptake significantly. These plant responses could be explained by the heat-induced changes in the release of inorganic N from the sludge. In contrast to N, the sludge materials containing Fe as a coagulant immobilized soil soluble P. When the sludge was applied to an Andosol, the N-supplying effects on plant growth were offset by P adsorption onto the sludge and soil. In a successive pot experiment conducted without additional sludge application, it was further suggested that frequent sludge application is required to maintain plant growth. However, it will also lead to the accumulation of sludge components in the soil because less than 40% and 15% of the sludge N and P, respectively, were apparently recovered in two harvests of the plants. In conclusion, heated sludge materials can act as an effective organic N fertilizer provided that they are applied to a suitable soil and that the short-term effects on soil productivity are balanced with the long-term effects on environmental quality.     

Effects of sewage sludge stabilization on fertilizer value and greenhouse gas emissions after soil application

Application of sewage sludge on agricultural land becomes more and more common in many parts of the world in order to recycle the nutrients from the sludge. A range of sewage sludge stabilization techniques are available to make the sludge more stable prior to storage, transportation, and application. These stabilization techniques include dewatering, drying, anaerobic digestion, composting, and reed bed sludge treatment. However, very few studies have investigated the effect of these techniques after the sludge has been applied to agricultural land. The objective of the current study was therefore to investigate the effect of sewage sludge stabilization techniques on the C and N mineralization and gaseous emissions from soil. A soil incubation was conducted to determine the rate of C and N mineralization and N₂O and CH₄ emissions of sewage sludge stabilized using different techniques. Unstabilized sludge released up to 90% of their C content as CO₂, part of which could be caused by release of CO₂ from carbonates. Compared with this, sludge stabilization including anaerobic digestion and drying resulted in a reduction of the C mineralization rate of about 40%. Liming reduced C mineralization with around 29%, while treatment in a reed bed system reduced it by 74%. The current study thus clearly demonstrated that stabilization techniques resulted in sludge that was more stable once they were applied to agricultural land. Stabilization also reduced the N immobilization phase, potentially improving the value of the sludge as a fertilizer. Emissions of CH₄ were also reduced through sludge stabilization and mainly occurred after application of easily degradable sludge types, which is likely to have enhanced the creation of anaerobic microsites. The stabilization processes also decreased emissions of N₂O. The results for both CH₄ and N₂O indicate that the stabilization tends to reduce the chance of developing conditions where these gases could be produced.     

Effects of sewage sludge amendment on soil aggregation

Sewage sludge in doses of 200 and 400 Mg ha⁻¹ (dry weight) were applied in an experimental rehabilitation of a limestone quarry to improve soil physical condition. The effect of this organic waste on soil aggregation and structural stability has been tested measuring aggregate size distribution by dry- and wet-sieving procedures over a period of 28 months. We discuss the influence of the organic components of aggregates on soil structure. The main effect of sewage sludge was to increase aggregate stability to raindrop impact (splash) just after application of the former but one year later this effect decreased notably. Organic matter is distributed in different ways between macro- and microaggregates, and this parameter seems to be responsible for the structure changes observed. Copyright © 1999 John Wiley & Sons, Ltd.     

施用辐照处理的污水污泥对作物产量和土壤氮的影响

A field experiment was conducted to study the feasibility of irradiated and non-irradiated sewage sludge as a fertilizer for the growth of wheat and rice. The irradiated and non-irradiated sewage sludge were applied at rates of 0 (CK), 75, 150, 225 and 300 kg N ha^-1 for wheat, and 0 (CK), 112.5, 225, 337.5 and 450 kg N ha^-1 for rice, respectively. (NH₄)₂SO₄ at a rate of 150 kg N ha^-1 for wheat, and 225 kg N ha^-1 for rice were added to the control treatments. Additionally, 20 kg ¹⁵N ha^-1 in the form of (NH₄)₂SO₄ was added to each treatment for wheat to study the effect of sewage sludge on chemical nitrogen fertilizer recovery. The results showed that the irradiation of sewage sludge by gamma ray at a dosage of 5 kGy increased crop yield by 11%~27% as compared to the non-irradiated treatments. Irradiation stimulated mineralization of organic nitrogen in the sludge and improved seedling growth. It was found that addition of irradiated sludge could reduce the leaching loss of chemical nitrogen fertilizer. Both irradiated and non-irradiated sewage sludge could increase the content of soil total nitrogen. Based on the preliminary results, it was concluded that irradiated sewage sludge could partly substitute for chemical nitrogen fertilizer in crop production.     

Increased phosphorus availability from sewage sludge ashes to maize in a crop rotation with clover

A recycling of Phosphorus (P) from the human food chain is mandatory to secure the future P supply for food production. However, many available recycled P fertilizers from sewage sludge do not have an adequate P bioavailability and, thus, are not suitable for their application in soils with pH >5.5–6.0, unless being combined with efficient mobilization measures. The aim of the study was to test the P mobilization ability of red clover (Trifolium pratense L.) from two thermally recycled P fertilizers for a subsequently grown maize. Two sewage sludge ashes (SSA) were investigated in a pot experiment at soil pH 7.5 with red clover differing in its nitrogen (N) supply (added N fertilizer or biological N₂ fixation (BNF)), followed by maize (Zea maize L.). Shoot dry matter of maize was almost doubled when N supply of previous grown clover was covered by BNF, instead of receiving added N fertilizer. Similarly, shoot P removal of maize following clover with BNF was significantly increased. It is suggested that the P mobilization is related to the BNF, and a proton release of N₂ fixing clover roots led to the measured decrease in soil pH and thereby increased P availability of the tested fertilizers.     

施用生活污泥改良滩涂土壤理化性状的探讨

采用符合土地改良用标准的生活污泥为材料,通过田间小区随机区组试验,研究了生活污泥的不同施用量（0、75、150、300、600 t/hm2）对滩涂土壤部分理化性质的影响。结果表明,施用生活污泥可显著改善滩涂土壤的理化性状。随着污泥施用量的提高,滩涂土壤的容重、密度、pH值逐渐下降,有机质、全氮、全磷、速效氮、速效磷、CEC均呈上升趋势,全钾、速效钾无显著变化。滩涂土壤的细菌、放线菌数量随污泥施用量的提高呈上升趋势。     

Barley growth in response to potassium fertilization of soil with long term application of sewage sludge

Application of sludges to agricultural land depressed plant growth despite its beneficial effects on crop production. Hence it remained to be determined whether sludge application induced any adverse effect on crop nutrition or growth. Thus the growth response of barley on an Andosol to which two kinds of sewage sludge compost had been applied for 17 y was tested in pot experiments with and without application of chemical K fertilizer. The addition of K in the sewage sludge composts resulted in the improvement of plant growth, high dry matter production and increase of total K content both in plant and soil compared to the materials without K application. It was assumed that long term application of sewage sludge requires chemical fertilizer amendment for crop production.     

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。     

Activity of bacteria strains originaited from sewage sludge against some soil fungi

Abstract

The potential biological activity of three bacterial strains against the four phytopathogens was examined. The bacterial strains were originated from sewage sludge water extract and from the humic acid solution obtained from the sewage sludge. The fresh bacteria cultures and filtered culture broth were used. The noncoated sugar beet seeds were coated by soaking for 15 min in the liquid culture of bacteria, then they were sown in the sterilized soil inoculated by one of the following types of soil fungus: Aphanomyces cochlioides L3, Phoma betas PH8, Pythium irregulare PIR4, Rhizoctonia solani Z10-2. The test proved that Bacillus amytoliquefaciens O1 / O3 and Flaviomonas oryzihabitans K1 / K2 showed antifungal activity on the artificial medium, but they were not able to effectively suppress fungal pathogens in the soil. The bacteria did not injure sugar beet roots, so they can be regarded as microorganisms that are not harmful to plants. It may be concluded that these bacteria have the potential to support antifungal activity of the humis acid and the sewage sludge extracts.     

Bioremediation of the soil contaminated with petroleum oil products using sewage sludge

ABSTRACT

The remediation technologies of soils contaminated with petroleum products are developed in two main directions: the first one encompasses searching for new effective bioagents and the other one explores the ways to activate those microorganisms present in the soil that are capable of degrading oil. The objective of this research was to determine if it is possible to increase the effectiveness of biodegradation of petroleum products by using chemical additives. The soil was supplemented with additives: CuSO4, MnSO4, KMnO4, H2O2, 5% and 10% chemical industry plants sludge, 5% and 10% Stock Company ‘Klaipedos vanduo’ (SC‘KV’) municipal wastewater treatment plants sludge. The data suggest that all the additives statistically significantly stimulated the degradation of diesel fuel (F = 12.01; p = .001) and black oil (F = 9.93; p = .001) compared with the control. It was determined that diesel fuel was degraded the fastest in samples with KMnO4, where efficiency of degradation was 90%, and 88% efficency in samples with 10% chemical industry plants sludge. Black oil was degraded the best in samples, where KMnO4 was added: efficiency of degradation was up to 63%. In the samples with 10% of sewage sludge from chemical industry plant degradation efficiency was 62%.     

污泥农用对土壤和作物重金属累积及作物产量的影响

以3 a定位试验为基础,比较3种不同处理的污泥肥料（消化污泥、污泥堆肥及污泥复混肥）农田施用下土壤养分、土壤和作物籽粒中Mn、Cu、Zn、Pb、Cd 5种重金属的积累以及作物产量的变化情况,以阐明污泥农用对土壤及作物的影响。研究表明,3种污泥肥料提高了土壤中氮素和有机质的含量;与空白和普通化肥处理相比,3种污泥肥料增加了土壤中Mn和Cu的含量,而对土壤交换态重金属含量没有显著影响;3种污泥处理均增加了小麦籽粒中Zn的含量;相对普通化肥处理,3种污泥肥料处理对小麦和玉米产量均无显著影响。合理施用污泥肥料可以有效地提高作物产量;污泥肥料施用对土壤重金属有一定累积效应,但短期施用对土壤比较安全。     

Ecological risks of the use of sewage sludge as fertilizer in soil restoration: effects on the soil microarthropod populations

Experimental plots were laid out in a limestone quarry in Girona (Catalonia, Spain) to test the effects of sewage sludge on the soil microarthropod populations. Two different doses of sludge (7·5 per cent and 15 per cent) were applied to fertilize soil that was used to restore a quarry after opencast mining. Mean annual arthropod density increased when sludge was applied, but the 15 per cent dose caused an impoverishment of the community structure and a decrease of the soil oribatid diversity. Julidae (Diplopoda) and large predators of the mite family Parasitidae (Mesostigmata) were the most depressed taxa, whereas some groups depending on the availability or quality of organic matter (such as the immature Coleoptera or the Uropodidae), or on water availability (such as Collembola) were stimulated. Among the oribatids, Punctoribates sp. was the most depressed, whereas the more common little Oppias were significantly favoured. The application of sludge at a dose of 15 per cent must be avoided in order to preserve the soil biodiversity. Copyright © 1999 John Wiley & Sons, Ltd.     

Monitoring the variation of soil quality with sewage sludge application rates in absence of rhizosphere effect

Agricultural soils in semi-arid regions have frequently been degraded due to adverse climatic conditions, organic matter depletion, and poor farming practices. To enhance soil quality, this study examines the reuse of sewage sludge (SS) as an available source of organic matter in a typical Mediterranean sandy-loam soil. Accordingly, we studied the cumulative effect of two annual applications of 40, 80 and 120 tons of sludge per ha on soil quality in absence of vegetation. The dose-dependent improvement of organic matter content was the most significant event that reflected sludge application rates, and consequently influenced other soil properties. Accordingly, soil structural stability increased by 13.3%, 28.8% and 59.4% for treatments SS-40, SS-80 and SS-120 respectively as compared to unamended control. Structural stability improvement was also confirmed by the dose-dependent variation of other edaphic factors including calcium content, the microbial quotient as well as Welt and C:N ratios. These parameters are involved in cementing soil aggregates by cation bridging, the formation of microbial mucilage, and clay-humic complexes. Soil magnetic susceptibility (SMS) was measured in situ as a possible rapid tool to evaluate soil condition. SMS showed significant correlation with sludge dose and stability amelioration testifying to the aggregation role that can play Al₂O₃ and particularly Fe₂O₃ minerals added by the hematite-rich sludge. Besides, analytical results and field observations revealed no trends of soil salinization or acidification by excessive sludge amounts. By avoiding the rhizosphere effect, outcomes could reflect the resilience and intrinsic capacity of the soil to cope with excessive sludge loads.     

Modification of soil porosity after application of sewage sludge

The effect of the application of sewage sludge on soil porosity over 28 months is discussed here. Anaerobic sludges of urban refuse waters were applied on a degraded limestone soil in a mining land by two ways. First, a previous mixture of sludge and soil was carried out; this was then applied to the target land. Second, a direct application of sludge to soil and tilling. Porosity and pore morphology were measured on thin sections prepared from undisturbed soil samples. Data were obtained from backscattered electron images and image-processing computer equipment. The application of sludge induced an increase of both soil fine microporosity (φ<50 μm) and coarse microporosity (φ>50 μm). However, this effect showed transient, since no significant differences were reported in relation to the control plot after one year from application. The incorporation of sludge and developed vegetation modified coarse micropore irregularity and orientation. On the other hand, fine micropore morphology remains unchanged.     

污泥加石灰后作为肥料用于玉米生长中施肥研究

The use of sewage sludge on agricultural land provides an alternative for its disposal. Therefore, the aim of the present study was to evaluate the feasibility of using industrial sewage sludge produced in Pakistan, as an agricultural fertilizer. The agricultural soil amended with 250 g kg^-1 sewage sludge with or without lime treatment was used for the growth of the common local grain crop, maize （Zea maize）. The mobility of the trace and toxic metals in the sludge samples was assessed by applying a modified BCR sequential extraction procedure. The single extraction procedure was comprised of the application of a mild extractant （CaCl2） and water, for the estimation of the proportion of easily soluble metal fractions. To check the precision of the analytical results, the concentrations of trace and toxic metals in every step of the sequential extraction procedure were summed up and compared with total metal concentrations. The plant-available metal contents, as indicated by the deionized water and 0.01 mol L^-1 CaCl2 solution extraction fractions and the exchangeable fraction of the sequential extraction, decreased significantly （P 〈 0.05） with lime application because of the reduced metal availability at a higher pH, except in the cases of Cd and Cu, whose mobility was slightly increased. Sludge amendment enhanced the dry weight yield of maize and the increase was more obvious for the soil with lime treatment. Liming the sewage sludge reduced the trace and toxic metal contents in the grain tissues, except Cu and Cd, which were below the permissible limits of these metals. The present experiment demonstrates that liming was an important factor in facilitating the growth of maize in sludge-amended soil.     

Behaviour of cadmium and nickel in a soil amended with sewage sludge

Various urban and industrial sewage sludges were applied to a soil at two doses (50 and 100 t ha⁻¹ y⁻¹) during eight years in a field experiment. The soil was analysed at two depths (0–30 and 30–60 cm) for extractable cadmium and nickel. In general these trace metal increased with dosage. However, cadmium formed complexes with organic matter and nickel bound to iron and manganese oxides. Hence, the available fractions of these metals constituted a small proportion of the total content. The results obtained show a low risk of contamination due to the available fractions of these metals at sludges dosages of up to 100 t ha⁻¹. Copyright © 2001 John Wiley & Sons, Ltd.     

Initial organic matter transformation of soil amended with composted sewage sludge

 An incubation experiment with composted sewage sludge (CSS) just added to the soil was conducted to determine its initial effects on C decomposition, N nitrification and the transformation of organic matter. CSS was mixed with a sandy loam soil from uncultivated ochric epipedon of a Typic Haploxeralf at rates of 0, 40 and 80 t ha^–1 (dry weight). The data obtained showed that with regard to the unamended soil, both the 40 and the 80 t ha^–1 treatments produced the same result in decreasing respiratory activity, but the addition of increasing amounts of CSS progressively delayed C decomposition. The nitrification index (NI), defined as the relation between nitrate-N and nitrate-N + ammonium-N, increased in correlation with the C mineralization coefficient. Total organic matter decreased after incubation whereas the humic substances increased in relation to the total C mineralized. Received: 28 October 1999     

Effects of N-enriched sewage sludge on soil enzyme activities

Sewage sludge is increasingly used as an organic amendment to soil, especially to soil containing little organic matter. However, little is known about utility of this organic amendment with N-enriched or adjusted C:N ratios in soil. We studied the effects of adding of different doses (0, 100, 200 and 300 t ha⁻¹) and C:N ratios (3:1, 6:1 and 9:1) of sewage sludge on enzyme activities (β-glucosidase, alkaline phosphatase, arylsulphatase and urease) in a clay loam soil at 25 °C and 60% soil water holding capacity. Nitrogen was added in the form of (NH₄)₂ SO₄ solution to the sludge to reduce the C:N ratio from 9:1 to 6:1 and 3:1. The addition of different doses and C:N ratios of the sludge caused a rapid and significant in the enzymatic activities in soils, this increase was specially noticeable in soil treated with high doses of the sludge. In general, enzymatic activities in sludge-amended soils tended to decrease with the incubation time. All activities reached peak values at 30 days incubation and then gradually decreased up to 90 days of incubation. Sewage sludges also the increased available metal (Cu, Ni, Pb and Zn) contents in the soils. However, the presence of available soil metals due to the addition of the sludge at all doses and C:N ratios did negatively affect all enzymatic activities in the soils. This experiment indicated that all doses and C:N ratios of sewage sludge applied to soil would have harmful effects on enzymatic activity. Some heavy metals found in sewage sludge may negatively influence soil enzyme activities during the decomposition of the sludge.     

造纸污泥堆肥对酸性土壤铝污染的影响

通过盆栽试验,研究在砖红壤中施加富含铝盐的造纸污泥堆肥后,土壤－作物体系中的铝毒效应。试验结果表明：盆栽初期,添加造纸污泥堆肥各处理土壤中的总酸溶性铝和总单核铝浓度较CK呈显著上升趋势,并随堆肥用量的增加而增加;随着种植时间推移,各处理（除了CK）总酸溶性铝和总单核铝浓度显著降低,且在盆栽结束时各处理总酸溶性铝浓度均低于原砖红壤中总酸溶性铝浓度;在整个盆栽期间,总单核铝是土壤中活性铝的主要存在形态;添加堆肥的各处理玉米植株的根部和地上部分铝含量均显著小于CK,玉米的生长状况均优于CK,说明在酸性土壤中添加造纸污泥堆肥,能起到很好的肥效作用,且不会对玉米生长形成铝毒效应,其中10%为本试验的最佳配比;另外,土壤理化性质测定结果显示：添加造纸污泥堆肥能有效减缓土壤酸化、增加土壤有机质和有效磷含量,提高土壤质量。