Effects of municipal solid waste compost amendments on soil enzyme activities and bacterial genetic diversity

Municipal solid waste (MSW) composts have been used to maintain the long-term productivity of agroecosystems and to protect the soil environment from overcropping, changes in climatic conditions and inadequate management; they also have the additional benefit of reducing waste disposal costs. Since MSW may contain heavy metals and other toxic compounds, amendments cannot only influence soil fertility, but may also affect the composition and activity of soil microorganisms. The effects of MSW compost and mineral N amendments in a 6-year field trial on some physical-chemical properties, enzyme activities and bacterial genetic diversity of cropped plots (Beta vulgaris-Triticum turgidum rotation) and uncropped plots were investigated. The compost was added at the recommended and twice the recommended dosage (12, 24 t ha⁻¹). Amendments of cropped plots with MSW compost increased the contents of organic C from 13.3 to 15.0 g kg⁻¹ soil and total N from 1.55 to 1.65 g kg⁻¹ soil. There were significant increases in dehydrogenase (9.6%), β-glucosidase (13.5%), urease (15.4%), nitrate reductase (21.4%) and phosphatase (9.7%) activities. A significant reduction in protease activity (from 3.6 to 2.8 U g⁻¹ soil) was measured when a double dose of compost was added to the cropped plots. No dosage effect was detected for the other enzymes. Changes in the microbial community, as a consequence of MSW amendment, were minimal as determined using denaturing gradient gel electrophoresis, rDNA internal spacer analysis and amplified ribosomal DNA restriction analysis of bacteria, archaea, actinomycetes, and ammonia oxidizers. This indicates that there was no significant variation in the overall bacterial communities nor in selected taxonomic groups deemed to be essential for soil fertility.     

Long-term suppression of Pythium ultimum in arid soil using fresh and composted municipal wastes

 The effect of addition of municipal solid waste (MSW) at different degrees of stabilisation on the biological properties of an arid soil was studied 24 months after application. This included effects on the indigenous soil microflora and soil enzyme activities in the presence and absence of Pythium ultimum. The addition of organic waste (fresh or composted) reduced populations of culturable bacteria and fungi and disease symptoms caused by P. ultimum, and resulted in heavier plants with longer and more extensively branched roots. Addition of organic waste increased the population size of culturable bacteria and fungi, while enzymatic activity of the soil was higher in soil amended with organic matter than in non-amended soil. Populations of biological control agents, such as Trichoderma and fluorescent pseudomonads, were larger in soil amended with organic matter. The addition of urban waste could therefore be a suitable technique with which to restore soil quality by stimulating biological control against plant pathogens such as P. ultimum. Received: 3 May 1999     

Agricultural and ecological aspects of a sandy soil as affected by the application of municipal solid waste composts

We present the results of a plot experiment in which the changes in physical, chemical and physico-chemical properties of a sandy soil were examined after amending the soil with two different composts produced from municipal solid wastes. Triticale (X Triticosecale), cultivated in a 3-y monoculture, was used as a test plant. Both composts differed in their concentrations of heavy metals. Composts were applied non-recurrently in the spring before sowing, at the rates of 18, 36, and 72 t dry matter ha⁻¹. The plots without fertilization, and those fertilized annually with mineral nitrogen (N), phosphorous (P), and potassium (K) were used as controls. Soil samples were collected 1 month after compost application, as well as each year after harvesting. Application of both composts improved soil physical properties, associated with increasing content of organic carbon (OC). Statistically significant increases of total porosity, field water capacity and amounts of plant-available water were found only in the short time after compost application. Despite the fact that soil OC content decreased with time, a C:N ratio clearly increased in the third year after compost application, which was explained by a depletion of N reserve. Both composts caused a large increase of plant-available P, K, and magnesium (Mg), which was observed during the entire period of the experiment. Beneficial changes were also observed in soil humic substances composition. These were confirmed by increased humic acids content and humic/fulvic acid ratios. Soil cation exchange capacity and base saturation increased in all plots amended with composts. This effect was still observed 1 year after compost application, while in the third year it remained significant only at the highest compost rates. Compost originating from industrial areas, even if applied in low amounts, caused a significant increase in total concentration of soil heavy metals. This fact did not result, however, in any substantial changes in soil quality with regard to heavy metals content.     

Effect of the addition of municipal solid-waste compost on microbial biomass and enzyme activities in soil

Summary Changes in the content of C, N, P, and S in the soil biomass and in phosphatase, urease, protease, deaminase, and arylsulphatase activity, induced by amendment with municipal solid-waste compost, were determined in a clay loam soil during 1 year of incubation at 25° and 35°C.In the unenriched soil (control) decreasing trends in biomass C, biomass N, and biomass S were observed at both temperatures. In the enriched soil, these values increased, reaching a maximum after 1 month. Biomass P, probably due to a slower process of P immobilization, showed different trends. Alkaline phosphomonoesterase, phosphodiesterase, and deaminase activity remained constant after reaching maximum values (3–5 months). Arylsulphatase, urease, and protease activity tended to return to baseline after reaching a maximum (2–3 months).Atrazine, though applied at a dose that was 10 times higher than the recommended field rate, did not modify the chemical and biochemical properties of either the control or the enriched soil.Significant positive and negative correlations between changes in biomass values and changes in enzyme activity were found. The negative correlations are attributed to the delay in the enzymatic response compared with the changes in microbial biomass.     

Effect of enriched municipal solid waste compost application on soil available macronutrients in the rice field

Abstract

A study was conducted in the Department of Environmental Sciences, Tamil Nadu Agricultural University, Coimbatore, India, to transform the normal compost into bioactive compost, which has multiple benefits to the crop system. The key players in this transformation process were Azotobacter sp., Pseudomonas sp., Phosphobacteria sp. and the waste materials like poultry litter and spent wash. This enrichment process increases both the quality and nutrient content of the municipal solid waste compost significantly. A study was carried out to evaluate the effect of application of different levels of enriched municipal solid waste compost on the availability of the macronutrient content to the rice field soil. The effect of enriched compost on soil available nutrients was significant. The soil ammonium nitrogen and soil nitrate nitrogen content was found to be high in the plots where the enriched compost was applied along with inorganic fertilizer with the values of 38.87 mg kg^?1 and 32.87 mg kg^?1, respectively. In addition, the availability decreased towards crop growth. The soil available P and K were also increased with enriched compost application to about 22.46 kg ha^?1 and 647 kg ha^?1 compared with control values of 19.44 kg ha^?1 and 518 kg ha^?1, respectively. Both phosphorus and potassium content decreased towards advancement of crop growth.     

Soil moisture pre-treatment effects on enzyme activities as indicators of heavy metal-contaminated and reclaimed soils

Heavy metal contamination can inhibit soil functions but it is often difficult to determine the degree of pollution or when soil reclamation is complete. Enzyme assays offer potential as indicators of biological functioning of soils. However, antecedent water content of soil samples may affect the outcome of biological measurements. In Mediterranean regions, for much of the year ‘field moist’ surface soil can have water content similar to that of air-dry samples. The objectives of this study were to: (1) determine the sensitivity of a range of enzyme assays to detect the degree of pollution from a heavy metal mine spill; (2) evaluate rewetting field-dry soil as a pre-treatment for enzyme assays; and (3) test multivariate analysis for improving discrimination between polluted, reclaimed and non-polluted soils. The Aznalcóllar mining effluent spill provided a unique opportunity to address these objectives. This accident released toxic, heavy metal-contaminated (As, Bi, Cd, Cu, Pb, Tl, Zn…) and acid tailings into the Guadiamar watershed (SW Spain) in 1998, severely affecting the riparian zone along more than 4000 ha. Contaminated soils were collected from the highly polluted upper watershed and less polluted lower watershed along with reclaimed soil at both sites. Enzyme activities (phosphatases, arylsulfatase, β-glucosidase, urease and dehydrogenase) were assessed on both field-moist samples and soils rewetted to 80% of water-holding capacity and then incubated at 21 °C for 7 d prior to the assay. The reclaimed soils had higher activities than polluted soils but, typically, 1.5-3 times lower levels of activity than the non-polluted soil. Regardless of the moisture pre-treatment, all enzymes showed significant effects due to pollution, with urease and β-glucosidase showing the greatest discrimination between degrees of contamination. In general, rewetting field-dried soils increased activities on non-polluted and reclaimed soils which improved discrimination with polluted soils. Another method to increase the potential of soil enzyme activities to detect soil contamination could be to combine them in multivariate analysis, which provides a more holistic representation of the biochemical and microbial functionality of a soil.     

Assessing solid waste compost application as a practical approach for salt-affected soil reclamation

Abstract

A short-term pot experiment was made to evaluate the effectiveness of municipal solid waste compost amendment on salt-affected soil. Hordeum maritimum plants were cultivated in pots filled with a clay-loam soil containing 0 or 40 t ha^?1 of compost and irrigated with tap water at 0 or 4 g l^?1 NaCl. Soil properties and heavy metal (Zn^{2 +}, Pb^{2 +}, Cd^{2 +}) accumulation were investigated. Municipal solid waste compost application significantly increased the soil contents of carbon, nitrogen and potassium under both non-saline and saline conditions. Soil heavy metal concentrations increased substantially too, but the recorded values were below the toxicity limits. Interestingly, plants subjected to the salt–compost interaction were more vigorous, compared with those grown on non-amended soil. Altogether, our data indicate that short-term utilization of municipal solid waste compost at 40 t ha^?1 may be of potential interest in the perspective of the rehabilitation of salt-affected soils. Yet, it must be stressed that the present findings are preliminary and need to be further evaluated under field conditions before practical recommendations can be inferred.     

复合污染土壤中土霉素的吸附行为及其对土壤重金属解吸影响的研究

参考经济合作与发展组织(OECD)化学品试验导则No.106,采用批量平衡试验的方法,探讨了土霉素(Oxytetracycline,OTC)在3种土壤中的吸附解吸特性,并考察了土霉素外加量对土壤中4种代表性重金属元素(铜、锌、铅、镉)解吸量的影响。试验设置的土霉素初始浓度为0.01、0.1、1.0、5.0、10.0、25.0、50.0、100、200和400 mg L-1。结果表明:(1)存在一个土霉素特征浓度,高于或低于该浓度值时土霉素的吸附性质有所差异,且高低两个浓度范围内的数据均能用Freundlich模型与Langmuir模型较好地拟合;(2)当土霉素浓度在0~25 mg L-1之间时,能在土壤表面与重金属发生竞争吸附,且重金属解吸量随土霉素浓度的增加而增加;当土霉素浓度在25~100 mg L-1之间时,部分游离态重金属以与土霉素的络合物形式重新固定于土壤表面,土壤重金属的解吸量随土霉素浓度增加而减少;土霉素浓度高于100 mg L-1时,体系p H相对于对照有明显下降,土壤重金属的解吸量与土霉素浓度又呈正相关。     

Effect of composting on extractability and relative availability of heavy metals present in Calcutta municipal solid waste

How composting affects heavy metal content is largely unknown. Accordingly, we investigate the total content of six heavy metals, Cd/Zn ratio and the Zn-equiv, the relative availability and fractionation study to assess the suitability of compost derived out of those for environmental concerns. During composting, total metal content increased but their RA decreased. As a result of composting bioavailable form of metals also decreased. High significant correlations between different forms of heavy metals content and degree of humification were found for all the elements. Composting increases humic acid content than fulvic acid. This transformation is mainly responsible to serve as binding agent for metal thereby moderating the rapid metal mobilization.     

施用玉米秸秆堆肥对盆栽芥菜土壤酶活性和微生物的影响

研究了施用玉米秸秆堆肥对盆栽芥菜土壤微生物和土壤酶活性的影响。结果表明,与对照和单施无机肥相比,施用堆肥能够提高芥菜生物量,增加根际土壤细菌、放线菌和真菌的数量,各处理微生物数量均在收获期达到最大值;同时,施用堆肥能够显著提高芥菜根际土壤脲酶、蔗糖酶、过氧化氢酶和纤维素酶的活性。各土壤酶在芥菜的生长期内变化趋势不同,脲酶活性在收获期达到最高;化肥与堆肥配施蔗糖酶活性在整个生长期内较稳定,其他处理均在收获期最低;过氧化氢酶活性在前期比较稳定,收获期有较大幅度下降;纤维素酶活性在旺长期较高,而苗期和收获期较低。相关性分析表明,部分土壤酶活性之间呈显著或极显著正相关;酶活性与土壤微生物数量之间呈显著或极显著正相关,表明土壤酶活性与微生物能够较好地反映土壤肥力水平。     

城市固体废弃物堆肥与化肥对不同土壤植物生长的影响研究

温室盆栽试验研究城市固体废弃物堆肥与化肥对不同土壤黑麦草生长的影响,结果表明,堆肥和化肥可明显增加黑麦草干物质产量,阳春和大安2种土壤处理C50干物质产量分别比对照增加39.53%和109.38%,而NPK处理则分别增产267.44%和406.25%。堆肥与化肥配施处理(NPK C25对阳春和NPK C50对大安)产量最高。堆肥处理明显增加土壤pH、有机碳、土壤有效态磷、钾、铁、锰、锌和铜含量。     

Combination effects of heavy metals and fluoranthene on soil bacteria

The effects of (1) Cd, Cu, Zn, and fluoranthene (FLA), separately applied, and (2) combinations of one of these heavy metals with FLA on the growth of bacteria were studied in agar plate experiments. The bacteria were extracted from A horizons of a Eutric Regosol and a Calcic Chernozem. Significant reductions of bacterial counts were observed for both soils at concentrations > 1.0 mg Cd l^–1, 0.5 mg Cu l^–1, and 0.5 mg Zn l^–1, respectively. Additions of FLA up to 100 mg l^–1 did not result in increasing reductions of bacterial growth in the Regosol. Only 0.5, 2, and 100 mg FLA l^–1 caused significant reductions of 22–27%. Bacterial counts were not affected by 0.2 mg FLA l^–1. Low concentrations of heavy metals which were not affective when added separately were found to reduce bacterial growth when applied in combination with 0.2 mg FLA l^–1. At higher levels of heavy metals up to 2.5 mg l^–1, addition of FLA also increased the toxicity of the metals. It is assumed that the enhancement of toxicity by FLA is due to an alteration of the permeability of bacterial cell membranes. Received: 19 July 1996     

Incorporation of heavy metals by the mud snail,Cipangopaludina chinensis malleata Reeve,in submerged paddy soil treated with composted sewage sludge

Summary The biomass of newborn snails was higher in paddy soil without rice plants than in the soil with rice plants. There was an inverse correlation between shell width and concentratins of Zn and Cu in snail flesh. The Zn and Cu concentrations in snail flesh were extremely high compared with those in the paddy soil surrounding the snails, possibly because snails ingest sludge, one of the main components of the composts. These results suggest that this type of snail may be used to eliminate Zn and Cu from paddy soil when composted sewage sludge has been applied.     

Carbon and nitrogen mineralization of non-composted and composted municipal solid waste in sandy soils

A sterilized, but undecomposed, organic by-product of municipal waste processing was incubated in sandy soils to compare C and N mineralization with mature municipal waste compost. Waste products were added to two soils at rates of 17.9, 35.8, 71.6, and dry weight and incubated at for 90 d. Every 30 d, nitrate and ammonium concentrations were analyzed and C mineralization was measured as total CO₂-C evolved and added total organic C. Carbon mineralization of the undecomposed waste decreased over time, was directly related to application rate and soil nutrient status, and was significantly higher than C mineralization of the compost, in which C evolution was relatively unaffected across time, soils, and application rates. Carbon mineralization, measured as percentage C added by the wastes, also indicated no differences between composted waste treatments. However, mineralization as a percentage of C added in the undecomposed waste treatments was inversely related to application rate in the more productive soil, and no rate differences were observed in the highly degraded soil. Total inorganic N concentrations were much higher in the compost- and un-amended soils than in undecomposed waste treatments. Significant N immobilization occurred in all undecomposed waste treatments. Because C mineralization of the undecomposed waste was dependant on soil nutrient status and led to significant immobilization of N, this material appears to be best suited for highly degraded soils low in organic matter where restoration of vegetation adapted to nutrient poor soils is desired.     

Saline water and municipal solid waste compost application on tomato crop: Effects on plant and soil

A field experiment was conducted in Southern Italy to evaluate the effects of different water quality and fertilizers on yield performance of tomato crop. In mineral nitrogen (N) fertilizer and irrigation with fresh water (Electrical Conductivity, EC, = 0.9 dS m^?1) (FWF); mineral N fertilizer and irrigation with saline water (EC = 6.0 dS m^?1) (SWF); municipal solid waste (MSW) compost and irrigation with fresh water (EC = 0.9 dS m^?1) (FWC); MSW compost and irrigation with saline water (EC = 6.0 dS m^?1) (SWC). At harvest, weight and number of fruits and refractometric index (°Brix) were measured, total and marketable yield and dry matter of fruit were calculated. The results indicated that MSW compost, applied as amendment, could substitute the mineral fertilizer. In fact, in the treatments based on compost application, the tomato average marketable yield increased by 9% compared with treatments with mineral fertilizer. The marketable yield in the SWF and SWC treatments (with an average soil EC in two years to about 3.5 dS m^?1) decreased respectively of 20 and 10%, in respect to fresh water treatments. At the end of the experiment, application of compost significantly decreased the sodium absorption rate (SAR) of SWC treatment in respect of SWF (?29.9%). Significant differences were observed among the four treatments both on soil solution cations either exchangeable cations. In particular compost application increased the calcium (Ca) and potassium (K) contents in saturated soil paste respect to the SWF ones (31.4% and 59.5%, respectively). At the same time saturated soil paste sodium (Na) in SWC treatment recorded a decrease of 17.4% compared to SWF.     

重金属对土壤微生物酶活性的影响

本文通过含有不同浓度的铜、铅、砷、镉 4种重金属的大豆、小麦盆栽试验 ,采用气相色谱方法测定土壤微生物酶活性 .结果表明 :低浓度的重金属能够提高固氮酶和反硝化酶的活性 ,而高浓度的重金属对上述二种酶有强烈的抑制作用     

Effect of metal contamination on microbial enzymatic activity in soil

Anthropogenic metal contamination is a pervasive problem in many urban or industrial areas. The interaction of metals with native soil communities is an important area of research as scientists strive to understand effects of long-term metal contamination on soil properties. Measurements of free soil enzyme activities can serve as useful indicators of microbial metabolic potential. The goals of this study are to determine extracellular soil enzymatic activities with respect to corresponding metal concentrations within a site of long-term contamination. These data are examined to understand relationships between extracellular soil enzyme activities and persistent metal loads in situ. Here we present such results from a rare research opportunity at an un-remediated, urban brownfield in Jersey City, NJ, USA. The soils of the site developed over the last 150 years through the dumping of urban fill from New York City as well as industrial rail use. The site was abandoned and fenced in the late 1960s, and within it, there is a mapped gradient of metal concentration in the soils, including As, Pb, Cr, Cu, Zn, and V. We measured soil enzymatic potential (alkaline phosphatase, cellobiohydrolase, and l-leucine-amino-peptidase) across four plots within the site and at an uncontaminated reference site that is of the same successional age and geographic influence. We found the highest enzymatic activities for all three activities measured at the site with the greatest soil metal loads and a particularly strong relationship among enzyme activity and the metals V and Cr. Our results differ from many experimental studies that show decreased soil enzyme activity in soils experimentally treated with metals. The results may indicate the effects of long-term adaptation of soil communities within these metal contaminated soils.     

Cover crop and tillage effects on soil enzyme activities following tomato

Increasing numbers of vegetable growers are adopting conservation tillage practices and including cover crops into crop rotations. The practice helps to increase or maintain an adequate level of soil organic matter and improves vegetable yields. The effects of the practices, however, on enzyme activities in southeastern soils of the United States have not been well documented. Thus, the objectives of the study were to investigate the effects of cover crops and two tillage systems on soil enzyme activity profiles following tomato and to establish relationships between enzyme activities and soil organic carbon (C) and nitrogen (N). The cover crops planted late in fall 2005 included black oat (Avena strigosa), crimson clover (Trifolium incarnatum L.), or crimson clover–black oat mixed. A weed control (no cover crop) was also included. Early in spring 2006, the plots were disk plowed and incorporated into soil (conventional tillage) or mowed and left on the soil surface (no-till). Broiler litter as source of N fertilizer was applied at a rate of 4.6 Mg ha⁻¹, triple super phosphate at 79.0 kg P ha⁻¹, and potassium chloride at 100 kg K ha⁻¹ were also applied according to soil testing recommendations. Tomato seedlings were transplanted and grown for 60 days on a Marvyn sandy loam soil (fine-loamy, kaolinitic, thermic Typic Kanhapludults). Ninety-six core soil samples were collected at incremental depths (0–5, 5–10, and 10–15 cm) and passed through a 2-mm sieve and kept moist to study arylamidase (EC 3.4.11.2), l-asparaginase (EC 3.5.1.1), l-glutaminase (EC 3.5.1.2), and urease (EC 3.5.1.5) activities. Tillage systems affected only l-glutaminase activity in soil while cover crops affected activities of all the enzymes studied with the exception of urease. The research clearly demonstrated that in till and no-till systems, l-asparaginase activity is greater (P ≤ 0.05) in plots preceded by crimson clover than in those preceded by black oat or their mixture. Activity of the enzyme decreased from 11.7 mg NH₄⁺–N kg⁻¹ 2 h⁻¹ at 0–5 cm depth to 8.73 mg NH₄⁺–N kg⁻¹ 2 h⁻¹ at 5–10 cm and 10–15 cm depths in the no-till crimson clover plots. Arylamidase activity significantly correlated with soil organic C (r = 0.699**) and soil organic N (r = 0.764***). Amidohydrolases activities significantly correlated with soil organic N but only urease significantly correlated with soil organic C (r = 0.481*). These results indicated that incorporation of cover crops into rotations may increase enzyme activities in soils.     

长期肥料试验对土壤和水稻微量元素及重金属含量的影响

长期肥料试验会影响土壤中微量元素和重金属状况以及作物对微量元素和重金属的吸收。本文研究了长期的不同施肥处理对土壤、糙米中微量元素Cu、Zn、Fe、Mn和重金属Pb、Cd含量的影响,结果表明:经17a连续施用猪粪及秸秆还田显著增加了土壤Cu、Zn和Cd全量,而土壤Fe、Mn和Pb全量在不同施肥处理间没有显著差异;施肥增加了土壤有效态Cu、Zn和Fe含量,其中施用猪粪及秸秆还田的3个处理显著增加了土壤有效态Cu、Zn和Cd含量,而土壤有效态Pb含量在不同施肥处理间没有显著差异。不同处理糙米Cu、Zn、Fe、Mn和Pb含量变化较小或没有显著性差异,而在3个施猪粪和秸秆还田处理中,糙米Cd含量均超过国家食品卫生标准(>0.2 mg kg-1)。水稻地上部吸收积累Cu、Zn、Fe、Mn、Pb和Cd总量与其地上部生物量呈正相关,土壤Cu、Zn、Cd有效态与全量含量呈极显著相关关系,而糙米中的镉含量与土壤镉含量有较好的相关关系。长期施用畜粪导致土壤Cd污染问题应引起高度重视。     

山东棕壤重金属污染土壤酶活性的预警研究

本文研究了重金属Cu2+、Cr3+、Pb2+污染对山东棕壤土壤过氧化氢酶、脲酶、磷酸酶、蔗糖酶活性的效应;提出了山东棕壤重金属Cu2+、Cr3+、Pb2+污染,土壤酶的预警指标和预警阈值。结果表明,在本试验条件下,Cu2+污染可以过氧化氢酶为预警指标,由相应的回归方程计算出国家土壤环境质量标准Cu2+的临界浓度的预警阈值:一级土壤为9.36%,二级土壤为11.57%;Cr3+污染可以脲酶为预警指标,其预警阈值:一级土壤为11.94%,二级土壤为15.12%;Pb2+污染可以蔗糖酶为预警指标,其预警阈值:一级土壤为1.50%,二级土壤为3.42%。