Effect of N‐form on growth and nutrient content of creeping bentgrass 1

Abstract

The primary nitrogen forms utilized by plants are ammonium and nitrate. Although the importance of nutrients other than nitrogen for proper turfgrass growth is well established, the amounts of these nutrients in the plant tissue in relation to the use of different N‐forms has not been clearly documented. This study was conducted under greenhouse conditions to determine the effect of N‐form and cutting regime on growth, macronutrient, and micronutrient content of creeping bentgrass (Agrostis palustris Huds. ‘Penncross'). Treatments consisted of 100% NO3^? (calcium nitrate), 100% NH₄ ⁺ (ammonium sulfate), and a 50:50 ratio of NH₄ ⁺:NO₃ ^?. Half the turfgrass plants were maintained at a height of 1 cm (cut), while the other half of the plants were not cut until the end of the study (uncut). The uncut 50:50 treatment yielded the highest shoot, verdure, and total plant dry matter, while the uncut NO₃ ^? treatment produced the highest root dry matter. The uncut NH₄ ⁺ treatment yielded the least shoot, root, and total plant dry matter. Plants of the uncut NO₃ ^? treatment had greater accumulation of macronutrients in the shoot and root tissue compared to plants of the NH₄ ⁺ treatment. The uncut NO₃ ^? and 50:50 treatments had higher total accumulation of micronutrients compared to the uncut NH₄ ⁺‐treated plants. The cut NO₃ ^? treatment resulted in the highest macronutrient and micronutrient contents in the root tissue in comparison to other cut treatments. The cut treatments had the highest percentage accumulation of nutrients in the verdure tissue, while the uncut treatments had the highest percentage accumulation of nutrients in the shoot tissue.     

Effect of N‐form on macronutrient and micronutrient concentration and uptake of creeping bentgrass 1

Abstract

Nitrogen‐form effect on nutrient uptake and the subsequent concentration of nutrients in turfgrass plant tissue has not been thoroughly investigated. This study evaluated the effects of clipping regime and N‐form on the tissue concentration of macronutrients and micronutrients and macronutrient uptake in ‘Penncross’ creeping bentgrass (Agrostis palustris Huds.). Turfgrass plugs were grown under greenhouse conditions in a modified Hoagland's solution with a combination of three nutrient solutions (100% NO₃ ^?, 100% NH₄ ⁺, and 50:50 ratio of NH₄ ⁺:NO₃ ^?) and two cutting regimes (cut and uncut). Concentrations of macronutrients and micronutrients were determined for shoot, root and verdure. Nutrient uptake was determined weekly. Uncut NO₃ ^?‐treated plants accumulated higher concentrations of K, Ca, Mg, B and Cu in the shoot tissue; P, K, Ca, Mg, B, Cu, Mn and Zn in the root tissue; and P, Ca, Mg, B, Fe and Mn in the verdure compared to uncut NN₄ ⁺‐treated plants. Nitrate uptake was greater with uncut NO₃ ^?‐treated plants than was NH₄ ⁺ absorption with uncut NH₄ ⁺‐treated plants. Plants grown with the uncut 50:50 treatment adsorbed more NH₄ ⁺ than NO₃ ^?. Plants grown with the uncut NO₃ ^? and 50:50 treatments adsorbed higher amounts of P, K, and Ca compared to the NH₄ ⁺ treatment. The cut NO₃ ^?‐treated plants accumulated higher concentrations of K in the shoot tissue; P, Ca, Mg, B, Cu, Fe and Mn in the root tissue; and B in the verdure than did the cut NH₄ ⁺‐treated plants. Cut NO₃ ^?‐treated plants adsorbed less NO₃ ^? than did cut NH₄ ⁺‐treated plants adsorbed NH₄ ⁺. The cut 50:50 treatment adsorbed more NH₄ ⁺ than NO₃ ^?. Plants grown with NO₃ ^? and 50:50 treatments, under both cutting regimes, resulted in higher concentrations of most macro‐ and micronutrients and greater nutrient uptake compared to the NH₄ ⁺‐treated plants.     

The foliar absorption of urea‐N by tall fescue and creeping bentgrass turf

The absorption and assimilation of ¹⁵N‐labeled urea applied to the foliage of tall fescue (Festuca arundinacea Schreb.) and creeping bentgrass (Agrostis palustris Huds.) turf was examined under a controlled environment. Each source of N was dissolved in deionized water to a final concentration of 25 g N liter^‐1 and spray‐applied at a rate of 5 g N m^‐2. Absorption of the fertilizer‐N over a 72 hr period, as measured by ¹⁵N analysis of tissue digests, averaged 55% for the two species. Absorption was also estimated by a washing procedure which measured the urea remaining on the foliage, and by the increase in total N in the plant tissue.

There were no significant differences between the three methods in estimating absorption. Partitioning of the absorbed ¹⁵n between tissues averaged 37% in new leaves, 51% in old leaves and shoot tissue, and 11% in the roots. More than 90% of the absorbed urea‐N was hydrolyzed by 72 hr.     

AB‐DTPA and Mehlich III soil tests unable to predict copper available to creeping bentgrass

Abstract

Copper (Cu) can be toxic to creeping bentgrass (Agrostis palustris ’Penncross') grown in sand‐based systems. Plant analysis is not always a reliable predictor of toxic levels of Cu in these sand‐based systems. Therefore, there is need for soil analysis to detect potentially toxic Cu concentrations in soil. The objective of this research was to determine the effectiveness of AB‐DTPA and Mehlich III soil tests to assess Cu availability to ‘Penncross’ creeping bentgrass grown in calcareous and silica sand/peat media. Samples of sand/ peat were removed from greenhouse pots, air dried, and Cu was analyzed by inductively coupled argon plasma spectrometry (ICAP/IRIS). Correlations were made between extracted Cu and Cu in the shoot and root tissue of the plant. The AB‐DTPA‐extractable Cu was 24% and 42% higher for the calcareous sand at the 400 and 600 mg kg^‐1 Cu treatments, respectively, when compared with Cu extracted from the silica sand. The Mehlich III soil test extracted 25% more Cu at the 400 mg kg^‐1 Cu treatment and 37% more Cu at the 600 mg kg^‐1 Cu treatment from the calcareous as compared to the silica medium. Shoot and root tissue Cu concentrations were higher at all Cu treatment levels for plants grown in silica sand. Although correlations were significant between Cu extracted from both sands by the AB‐DTPA and Mehlich III soil tests and Cu in the shoot and root tissue of plants, these extractants were unsuccessful in determining Cu availability from the two sand medium. This research indicates a need for a soil test which can be effectively used to extract plant‐available Cu from sand‐based systems.     

Foliar Symptomology and Tissue Concentrations of Nutrient‐Deficient Vegetative Strawflower Plants

Abstract

Elemental deficiencies of nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, copper, zinc, or boron (N, P, K, Ca, Mg, S, Fe, Mn, Cu, Zn, or B) were induced in plants of Florabella Pink strawflower [Bracteantha bracteata (Vent.) A. A. Anderberg]. Rooted stem cuttings were planted in 4.87‐L plastic containers and fertilized with a complete modified Hoagland's solution or this solution minus the element that was to be investigated. Plants were harvested for tissue analyses as well as dry weights when initial foliar symptoms were expressed and later under advanced deficiency symptoms. Deficiency symptoms for all treatments were observed within 7 weeks. The most dramatic expression of foliar symptoms occurred with N (chlorotic lower foliage leading to necrotic margins on the mature leaves), Ca (black necrotic spots on the tips of the young leaves), S (uniform chlorosis of young leaves and recently mature leaves), B (thick, leathery, and deformed young leaves), Fe (uniform yellowish‐green chlorosis on the young leaves), and Zn (brownish‐gray necrosis on the tips of the mature leaves). At the initial stage, only Fe‐deficient plants weighed less than the control, whereas K‐, Ca‐, and Mg‐deficient plants had greater dry weights than plants receiving the complete modified Hoagland's solution (control plants). Dry weights of plants treated with solutions not containing N, P, Ca, S, Cu, or Mn were significantly lower when compared with the control plants under an advanced deficiency. Foliar‐tissue concentration data will assist plant‐tissue analysis laboratories in establishing foliar symptom standards for growers.     

The effects of straw return on potassium fertilization rate and time in the rice–wheat rotation

In order to investigate the effects of straw return on potassium (K) fertilizer application rate and time in the rice–wheat rotation, field experiments were conducted at three sites. The results showed that when the K rate was decreased to 70% of the recommended K dosage, crop yields showed no significant decrease. With K fertilization only at rice phase, crop yields showed no marked difference compared with that provided K fertilizer both at wheat and rice seasons. Though the NH₄OAc-extracted K and HNO₃-extracted K differed slightly among the treatments, the soil apparent K balance was negative without K fertilization. With crop straw fully incorporated, the recommended K dosage could be at least reduced by 30% at the experimental sites and the K fertilizer could be applied only at rice phase. A further hypothesis can be made that the best K rate was the amount of K took away by crop grain. In the long run, straw return combined with K fertilization would be an effective method to maintain soil K fertility and productivity.     

Influence of different long-term mineral–organic fertilization on yield,nutrient balance and soil C and N contents of a sandy loess (Haplic Phaeozem) in middle Germany

In a long-term field trial (Halle, Germany, founded in 1949 by K. Schmalfuß, soil type Haplic Phaeozem), the effects of different mineral and organic fertilization on dry matter yields, soil C and N contents and N balances were investigated. Over a period of 60 years, yields increased on average in all cultivated crops (winter and spring cereals, potatoes, sugar beets, silage maize), even without any fertilization. Nitrogen deficiency in unfertilized and PK treatments caused strong decreases in yield (up to 48%) in comparison with the N2PK standard treatment. The effect of omitting K or P supply was smaller (up to 18% and 7% yield reduction, respectively). The highest yields were obtained with high mineral N + PK application and (except winter wheat) with farmyard manure in combination with mineral fertilization. The N balances were negative in all treatments. However, if N immission from the air (40 kg ha^?1 a^?1) was included in the calculation, N balances were negative only in low N treatments. The soil C and N contents increased up to 1975. A considerable decrease has been seen since about 1985. The highest soil C and N contents were observed in the farmyard manure treatments. In addition to fertilization effects, this development of soil properties reflects changes in environmental pollution, climatic changes, as well as shifts in cultivation methods like tillage depths, over recent decades.     

Response of phosphorus fractions to land-use change followed by long-term fertilization in a sub-alpine humid soil of Qinghai–Tibet plateau

Purpose

Identification of phosphorus (P) species is essential to understand the transformation and availability of P in soil. However, P species as affected by land use change along with fertilization has received little attention in a sub-alpine humid soil of Tibet plateau.

Materials and methods

In this study, we investigated the changes in P species using Hedley sequential fractionation and liquid-state ³¹P-NMR spectroscopy in soils under meadow (M) and under cropland with (CF) or without (CNF) long-term fertilization for 26 years in a sub-alpine cold-humid region in Qinghai–Tibet plateau.

Results and discussion

Land-use change and long-term fertilization affected the status and fractions of P. A strong mineralization of organic P (OP) was induced by losing protection of soil organic matter (SOM) and Fe and Al oxides during land-use change and resulted in an increase of orthophosphate (from 56.49 mg kg^?1 in M soils to 130.07 mg kg^?1 in CNF soils) and great decreases of orthophosphate diesters (diester-P, from 23.35 mg kg^?1 in M soils to 10.68 mg kg^?1 in CNF soils) and monoesters (from 336.04 mg kg^?1 in M soils to 73.26 mg kg^?1 in CNF soils). Long-term fertilization boosted P supply but failed to reclaim soil diester-P (from 10.68 mg kg^?1 in CNF soils to 7.79 mg kg^?1 in CF soils). This may be due to the fragile protection from the combination of SOM with diester-P when long-term fertilization had only improved SOM in a slight extent.

Conclusions

These results suggest that SOM plays an important role in the soil P cycling and prevents OP mineralization and losses from soil. It is recommended that optimization of soil nutrient management integrated with SOM was required to improve the P use efficiency for the development of sustainable agriculture.

     

Time of Day Effect on Foliar Nutrient Concentrations in Corn and Soybean

Foliar nutrient concentrations vary during the day. Field research was conducted to quantify and better understand this variation in corn (Zea mays L.) and soybean (Glycine max L. Merr.) with foliar sampling during the vegetative and reproductive stages. Time of day effects occurred inconsistently across nutrients. Nitrogen (N), manganese (Mn), iron (Fe), and zinc (Zn) foliar concentrations were generally high early in the day. Phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S) foliar concentrations varied inconsistently with time of day, while concentrations of boron (B) in both crops and copper (Cu) in corn were not affected. Limiting foliar sampling to after 10:00 AM reduced the variation for soybean but not for corn. Interpretation by Diagnosis and Recommendation Integrated System (DRIS) did not reduce the time of day effect. The variation caused by time of day, along with other causes, affects confidence in interpretation of foliar results suggesting use of the information with either additional foliar sampling or soil testing in making nutrient management decisions.     

Long-term manuring and fertilization influence soil inorganic phosphorus transformation vis-a-vis rice yield in a rice–wheat cropping system

A study on the rice–wheat cropping system was conducted at Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India, to assess the effects of long-term manuring and fertilization on transformation of the inorganic phosphorus (P) fraction in soil after 22 years of the crop cycle. Soil samples were collected after Kharif from seven treated plots having different types of organic amendments like farm yard manure, paddy straw and green manuring with 50% substitution of nitrogen levels in rice crop only. The result showed that the yield trend of rice was maintained due to the buildup of P from various organic inputs. Although cultivation for 22 years without adding any fertilizer caused a significant decrease in almost all the forms of P viz. avail-P, saloid P, iron phosphorus fraction (Fe–P), aluminum phosphorus fraction (Al–P), calcium phosphorus fraction (Ca–P) and total P in control. Partial substitution of inorganic fertilizer N (50%) with organics, however, caused a significant increase in almost all the P fractions in soil over the control. The relative abundance of all the fractions of inorganic P irrespective of treatments was as follows: Fe–P > reductant soluble P fraction > occluded P > Al–P > Ca–P > saloid P. Saloid and Fe–P were the dominating fractions responsible for 92% variation of available P and total P levels, respectively.     

Low soil temperature effects on short-term gross N mineralisation–immobilisation turnover after incorporation of a green manure

The decomposition of Italian ryegrass (Lolium multiflorum L.) was studied over 37 days in an incubation experiment, at constant temperatures of 3, 9 and 15°C. With the use of a ¹⁵N label in the form of (¹⁵NH₄)₂SO₄ and employing the pool dilution principle, the short-term dynamics of the gross N transformation rates were estimated using both the classical analytical equations formulated by Kirkham and Bartholomew (Soil Sci. Soc. Am. Proc., 18 (1954) 33) and the numerical model FLUAZ (Mary et al., Soil Biol. Biochem., 30 (1998) 1963). The assumptions of the pool-dilution method concerning homogeneity of labelling, disturbance of processes upon labelling and reliability of measurements were evaluated. Gross transformation rates calculated with the numerical model FLUAZ were considered superior to those calculated analytically, because with the FLUAZ model data variability could be taken into account, statistical measures corresponding to calculated rates were given, and nitrate immobilisation and nitrification kinetics were considered. The effect of temperature on the C mineralisation and gross N transformation rates was clear, all rates increasing with increasing temperature. Initially, there was high microbial activity in the Italian ryegrass treatment, followed by a decline in the second half of the incubation, reflecting changes in the quality of substrate being decomposed. The Q₁₀ relationship was used to shed light on this effect and a comparison of Q₁₀ values indicated that the breakdown of recalcitrant substances was more limited at low temperature than that of the more easily degradable substances. Decreases in the gross N mineralisation-to-immobilisation ratio with increasing temperature suggested that gross N immobilisation may be more sensitive to low temperatures than gross N mineralisation. That this may be the case was indicated by a positive net mineralisation rate for Italian ryegrass at 3°C, versus a net immobilisation in the short term at 9 and 15°C, as would also normally be expected for a green manure material with a C-to-N ratio above 20 such as the Italian ryegrass used in this study.     

Determination of Optimum Rate and Growth Stage for Foliar‐Applied Phosphorus in Corn

Abstract

Foliar applications of fertilizer phosphorus (P) could improve use efficiency by minimizing soil applications. Nine experiments were conducted in 2002 and 2003 to determine foliar P rates and appropriate growth stages for application. Treatments comprised of 10 factorial combinations of three foliar P application timings and four rates of foliar P. Foliar application times were V4 (collar of fourth leaf visible), V8 (collar of eighth leaf visible), and VT (last branch of the tassel completely visible but silks not yet emerged) corn growth stages. Foliar P rates were 0, 2, 4, and 8 kg ha^?1. Foliar P applied at the VT growth stage improved grain and forage P concentration, which was reflected in increased grain yield in some of the experiments. A foliar P rate of 8 kg ha^?1 improved yield to some extent and forage and grain P concentration more than the smaller rates. The results suggest that foliar P could be used as an efficient P‐management tool in corn when applied at the appropriate growth stage and rate.     

Effects of fertilization with urban and agricultural organic wastes in a field trial – Prokaryotic diversity investigated by pyrosequencing

The impact of different fertilizer treatments on prokaryotic diversity in a Danish urban waste field trial was investigated using tag-encoded amplicon pyrosequencing. The field trial was established in 2003 to investigate the application of urban organic waste as fertilizer in agriculture and to identify the effects on soil quality. The fertilizers (e.g. composted organic household waste, sewage sludge and human urine) contain a large amount of nutrients but possibly also undesirable toxic compounds that may influence the bacterial flora in the soil. A 561 bp fragment of the 16S rRNA gene flanking the V4, V5 and V6 regions, was amplified from each soil sample, tagged and sequenced using pyrosequencing. The major classified bacterial phyla and proteobacterial classes for all treatments were Actinobacteria, Acidobacteria and Betaproteobacteria, while the Crenarchaeota was the most frequent phylum of Archaea. No major changes in the community composition due to different fertilizer treatments were found, demonstrating a high robustness of the soil microbiota. However, some differences were observed e.g. Cyanobacteria were most frequent in the unfertilized soil, in comparison to the soils treated with nitrogen containing fertilizers and Firmicutes had higher occurrence in the soil with the composted household waste compared to all other treatments. Additionally, we used quantitative PCR (qPCR) to quantify specific bacterial groups, and used these numbers to convert the relative abundances of all bacteria obtained by pyrosequencing, to the actual numbers present in one gram of soil. All treatments resulted in a total number of bacteria between 1.99 × 10⁹ and 4.11 × 10⁹ gram⁻¹ soil.     

Potassium and sodium fertilization affects leaf nutrient content and growth of ‘Shawnee’ blackberry

Aluminum (Al) has many detrimental effects on plant growth, and shoots and roots are normally affected differently. A study was conducted to determine differences among sorghum [Sorghum bicolor (L.) Moench] genotypes with broad genetic backgrounds for growth traits of plants grown at 0,200,400,600, and 800 μM Al in nutrient solutions (pH 4.0). Genotypes were categorized into “Al‐sensitive”, “intermediate Al‐tolerant”, “Al‐tolerant”, and SC 283 (an Al‐tolerant standard). As Al increased, shoot and root dry matter (DM), net main axis root length (NMARL), and total root length (TRL) became lower than controls (0 Al). Aluminum toxicity and/or nutrient deficiency symptoms become more severe, and shoot to root DM ratios and specific RL (TRL/root DM) values also changed as Al in solution increased. Root DM had greater changes among genotypes than shoot DM, and NMARL at 400 μM Al, and TRL at 200 μM Al had greater differences among genotypes than root DM, ratings for toxicity and/or deficiency symptoms, and other DM and RL traits. The wide differences among genotypes for NMARL and TRL could be used more effectively to evaluate sorghum genotypes for tolerance to Al toxicity than the other growth traits.     

The influence of spruce on acidity and nutrient content in soils of Northern Taiga dwarf shrub–green moss spruce forests

Presently, among the works considering the influence of forest trees on soil properties, the idea that spruce (Picea abies) promotes the acidification of soils predominates. The aim of this work is to assess the effects of spruce trees of different ages and Kraft classes on the acidity and content of available nutrient compounds in the soils under boreal dwarf shrub–green moss spruce forests by the example of forest soils in the Kola Peninsula. The soils are typical iron-illuvial podzols (Albic Rustic Podzols (Arenic)). Three probable ways of developing soils under spruce forests with the moss–dwarf shrub ground cover are considered. The soils under windfall–soil complexes of flat mesodepressions present the initial status. The acidity of organic soil horizons from the initial stage of mesodepression overgrowth to the formation of adult trees changed nonlinearly: the soil acidity reached its maximum under the 30–40-year-old trees and decreased under the trees older than 100 years. The contents of nitrogen and available nutrients increased. The acidity of the mineral soil horizons under the trees at the ages of 110–135 and 190–220 years was comparable, but higher than that under the 30–40-year-old trees. The differences in the strength and trends of the trees’ effect on the soils are explained by the age of spruce trees and their belonging to different Kraft classes.     

Effect of fertilization history on short-term emission of CO2 and N2O after the application of different N fertilizers – a laboratory study

Increasing organic carbon (OC) stocks in soils reduce atmospheric CO₂, but may also cause enhanced N₂O emissions. The objective of this study was to determine whether there are any differences in N₂O and CO₂ emissions from sandy arable soils with different soil OC and total nitrogen stocks due to the annual application of either farmyard manure (S-FYM) or mineral fertilizer (S-MIN) over 27 years. A laboratory incubation was performed to test the short-term effects of the application of different fertilizers [farmyard manure (FYM), KNO₃ (MIN) and biogas waste (BW)] on N₂O and CO₂ emissions. The CO₂ emission rates indicated that OC availability in the soil was higher after BW application than after FYM application. N₂O emission for 53 days following fertilizer application amounted to 0.01% (MIN), 0.21% (FYM) and 24% (BW) of the total amount of N applied. The high emissions induced by BW were attributed to the combination of a high availability of OC and ammonium in the fermented waste. Fertilization history, which caused higher soil OC stocks in S-FYM, did not influence N₂O emissions. The results suggest that characterization of C and N pools in organic fertilizers is required to assess their impact on N₂O emissions.     

Potassium concentration in leaf‐blades and petioles as affected by potassium fertilization and stage of maturity of cotton

Abstract

Analysis of data obtained from samples collected in the Delta area of Mississippi showed that the potassium concentration of young mature and old mature cotton leaf‐blades correlated better with soil test potassium than did that of the apical immature leaf‐blades.

Results from field studies indicated that the old mature petiole was the most sensitive indicator of the potassium status of the cotton plants. The potassium concentration in both leaf‐blades and petioles decreased with stage of maturity from early square to early half‐grown boll. Potassium concentration did not fluctuate with sampling at different times of the day. The rate of decline of potassium concentration was greater in petioles of mature cotton leaves than in the leaf‐blades. For mature leaves, the potassium concentration of leaf‐blades was highly correlated with that in petioles, but for immature leaves, the correlation was poor. The rate of decline of potassium concentration in both cotton leaf‐blades and petioles was not affected by potassium fertilization but was a function of maturity stage.     

Dynamics of maize straw–derived nitrogen in soil aggregates as affected by fertilization

Journal of Soils and Sediments - The addition of maize residue nitrogen (N) to the soil strongly influences soil N accumulations, but the specific contributions of maize residue N to soil...     

Effects of fertilization with urban and agricultural organic wastes in a field trial – Waste imprint on soil microbial activity

In the past decades a significant change in composition of urban organic waste products has occurred in many first world countries, due to cleaner technologies as well as outsourcing of heavy industries. However, the societal perception of organic urban waste has become increasingly negative, leading to widespread advocacy of incineration. Therefore we established the ‘CRUCIAL’ long-term field trial in 2003, with the rationale that by approaching the known limits for a number of heavy metals below which no profound disturbance should be observed on key soil ecological functions, it should be possible to discern if some of the many unknown components in the composite urban waste as well as agriculturally based fertilizers have measurable impacts. The following treatments were established: human urine, sewage sludge (normal N-level and accelerated level aiming at three times normal N-level), degassed and subsequently composted organic municipal waste (normal and accelerated level), deep litter, cattle slurry, cattle manure (accelerated level), NPK fertilizer, unfertilized but with clover undersown and an unfertilized control. After 4 years the soil organic matter (SOM) C content, basal CO₂ respiration and soil microbial biomass (SMB) C was significantly affected by treatments. All soils having received organic fertilizer had higher SMB C than those with no added fertilizer (unfertilized and unfertilized with clover undersown) and inorganic fertilizer. The treatment effect on qCO2 (CO₂/SMB C) was not significant, but the unfertilized treatments showed the highest values. Treatments with accelerated levels of composted household waste and sewage sludge had the highest number of colony forming heterotrophic bacteria. Sole carbon source utilization in EcoPlates indicated a very robust microbial community in the treatments. Cumulative input of heavy metals was less than that required for reaching the heavy metal ecotoxicological limits, even after accelerated loading with sewage sludge corresponding to approximately 55 years of normal application. This could indicate that it is possible use organic urban waste for an extended period on a given site, without compromising soil functioning as long as ecotoxicological guidelines for heavy metal content are observed.