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1.
During aerobic composting of animal manure, microbial activity within the mixture generates heat and metabolic by-products that inactivate zoonotic pathogens. Although it is recognized that the type and level of microbial activity will vary with the nutrient availability of different compost ingredients, the degree to which these changes could impact pathogen inactivation is of interest. Towards that goal, the purpose of this study was to determine inactivation of Escherichia coli O157:H7 and Listeria monocytogenes in compost laboratory-scale bioreactor systems formulated to different initial carbon:nitrogen (C:N) ratios with cow manure, straw, and cottonseed meal. The C:N ratio did not significantly affect the time to inactivation of Listeria monocytogenes. In contrast, Escherichia coli O157:H7 survived for significantly (P < 0.05) longer periods of time in 40:1 C:N systems than in 30:1 or 20:1 systems even though the cumulative heat exposures were statistically similar in the systems. An increase of pH values to 8 to 9 occurred initially for 40:1 C:N systems, whereas the pH of the 20:1 and 30:1 systems initially declined to 5.5 to 6 before increasing to 8 to 9 after 2 days of composting.  相似文献   

2.
During animal waste agricultural applications, the major concern is pathogen spreading, which may contaminate surface water and groundwater. Among the pathogenic microorganisms found in animal waste, Salmonella typhimurium and Escherichia coli O157:H7 are of particular concern. When transported in sub‐surface agricultural soil, S. typhimurium and E. coli O157:H7 are captured at the air–water–sediment interfaces through physical interactions. Because in situ colloids contribute to the formation of air–water–sediment, their mobilization affects the transport of S. typhimurium and E. coli O157:H7. The impact of irrigation rates on in situ colloid mobilization and S. typhimurium and E. coli O157:H7 transport was investigated in intact soil columns collected from an agricultural site in Gadsden County of Florida, USA. The columns were irrigated with sterilized nano‐pure deionized water to mobilize the colloids in the soil by stepwise increases in flow rate. For each flow rate, after colloids were mobilized and steady state was reached, S. typhimurium and E. coli O157:H7 were introduced. The cumulative amount of released in situ colloids increased linearly with the irrigation rates (R2 = 0.986–0.996) and transport of the bacteria was enhanced after colloid mobilization. Interactions of the bacteria with the sediments and the air‐water interface were characterized: these played an important role in controlling S. typhimurium and E. coli O157:H7 retention in soil.  相似文献   

3.
The population dynamics of Salmonella enterica var. Typhimurium MAE 110 gfp, Escherichia coli O157:H7 gfp, and Pseudomonas fluorescens 32 gfp were investigated in their introduction to cattle excrements and subsequent entering the soil, plants of cress (Lepidium sativum L.), and migration through the gastroenteric tract of French snails (Helix pomatia L.). The survival of these bacteria in the excrements and soil was investigated at cyclically changing (day-night, 25–15 °C) and constant (18 °C) temperatures. The cyclically changing temperature adversely affected the survival of E. coli O157:H7 gfp, and P. fluorescens but did not influence S. enterica var. Typhimurium. All the bacteria and, especially, the analogues of enteropathogens showed high survival in the cattle and snail excrements, soil, and on the plants under the gradual decrease in their population. On the cress plants grown in a mixture of cattle excrements and soil, an increase in the number of the introduced bacteria was observed.  相似文献   

4.

Purpose

The Escherichia coli (E. coli) O157:H7 survival dynamics in original and pH-modified agricultural soils were investigated to determinate how E. coli O157:H7 survival responded to the pH values of different soils, identify the relationships between E. coli O157:H7 survival time (t d ) and soil properties, and assess the potential pathogen contamination after soil pH changed.

Materials and methods

The six soil samples were collected from different provinces of China, and 18 pH-modified soil samples were obtained from original soils by treating the original soils with direct electric current. The E. coli O157:H7 cells were inoculated into 24 soils and incubated at soil moisture of ?33 kPa and 25 °C. The soils were sampled for determining the numbers of E. coli O157:H7 at given time intervals over the incubation. The effects of soil pH change and other properties on the t d values were analyzed.

Results and discussion

The t d values in the test soils were between 7.1—24.7 days. Results indicate that soil pH, texture, and free Fe2O3 (Fed) were the most important factors impacting the t d values in the test soils. Further, the response of E. coli O157:H7 survival to pH change varied with different soils. In the acidic soils (shorter t d values), the t d values decreased as the pH decreased and Fed increased, while in the neutral or alkaline soils (pH?≥?6.45, longer t d values), the t d values did not change significantly with pH.

Conclusions

The changes of amorphous and free sesquioxides induced by pH change might strengthen the response of E. coli O157:H7 survival to soil pH. Closer attention should be paid to E. coli O157:H7 long survival in soils and its potential environmental contamination risk.  相似文献   

5.
During disease outbreaks, composting has been used to safely dispose of carcasses and infectious solid manure. However, optimized methods have not been established to use liquid manure (> 80% water content, WC) from dairies as the substrate for mortality composting. In April of 2007, a 3×2 factorial study was conducted in wooden compost bins (240 × 240 × 140 cm) lined with 0.5 mm plastic to a height of 50 cm. Three levels (LO, 95 kg; MED, 236 kg; HI, 606 kg wet wt.) of liquid manure (91% WC) were applied to barley straw containing a single calf mortality (avg. wt 130 kg). Compost temperature and carcass degradation were evaluated in each bin over 52 d. As an indication of compost efficiency, viability of 4 types of weed seeds (wild buckwheat, Polygonium convolvulus L, BW; dandelion, Taraxacum officinale, DL; stinkweed, Thlaspi arvense L., SW; and wild oat, Avena fatua, WO) was determined from seeds retained at the laboratory (Control) or from those placed in sealed nylon bags (50 μm pore size) embedded at 3 locations in each bin. Initial C: N ratios ranged from 58:1 (HI) to 68:1 (LO), while initial WC was 64, 52 and 42% for the HI, MED and LO treatments, respectively. Rate of compost heating and peak temperature (58.6 vs. 46.5°C) was increased (P < 0.05) for HI as compared to LO. Rate of temperature decline was lower (P < 0.05) and calf decomposition was visibly superior for HI as compared to LO. Viability of WO was eliminated by all compost treatments, but that of BW increased (P < 0.05) in MED and LO as compared to Control. Although HI did not eliminate BW viability, this treatment showed the the most promise for incorporating liquid manure as a substrate in contained mortality compost.  相似文献   

6.
Escherichia coli O157:H7 contaminated wastes such as animal manures and abattoir wastes, may be applied directly onto vegetation, the soil surface, or injected deep into the soil. Our aim was to determine the influence of method of waste application to land on E. coli O157:H7 survival. Bovine slurry and ovine stomach contents containing E. coli O157:H7 were applied to the surface vegetation or sub-surface injected at 25 cm below the soil surface. E. coli O157 survived but did not proliferate on grassland vegetation for up to 6 weeks and in the underlying soil for 8 weeks. Our results suggest that sub-surface injection of organic wastes into soil may reduce the risk of pathogen persistence in the environment.  相似文献   

7.
Boxwood blight, caused by Calonectria pseudonaviculata, is a devastating fungal disease of Buxus spp., first observed in the United States in 2011. Due to the persistent nature of the produced microsclerotia, concern arose over the potential for compost to serve as a disease vector. Previous work demonstrated that C. pseudonaviculata is very stable at mesophilic temperatures, however, no previous work has evaluated C. pseudonaviculata during composting. Our objective was to evaluate the survival of C. pseudonaviculata microsclerotia after being composted for 24, 48, and 72?h at temperatures of 40, 50, and 60?°C. Composting was performed using a newly created bioreactor system, allowing for precise control of the composting process. In conjunction with the composting evaluations, the same temperature/time combinations were evaluated in incubators. While the pathogen survived 40?°C through 72?h in an incubator, compost survival was minimal, with only some survival observed at 24?h at the same temperature. We were able to determine that exposure to temperatures ≥50?°C for 24?h or longer, and that exposure in a composting system for 48?h or longer at 40?°C would kill the microsclerotia.  相似文献   

8.
The purpose of this work was to study the viability of the composting of goat (Capra aegagrus hircus) manure (GM) and rabbit (Oryctolagus cuniculus) manure (RM) and to evaluate the quality of the compost obtained. For this, a mixture of these manures was prepared at a goat/rabbit ratio of 44:56 (fresh-weight basis) and 50:50 (dry-weight basis). The mixture was composted by the Rutgers static pile composting system, with forced aeration and controlled temperature. Throughout the composting process, the temperature was monitored and physicochemical, chemical, and biological parameters were evaluated. The temperature evolution showed the suitable development of the composting process, with thermophilic values (>40 °C) maintained for more than 90 days. The finished compost had stabilized and humified organic matter. However, the pH (9.4) and the salinity (EC of 13.4 dS/m) could limit its potential agricultural use.  相似文献   

9.
Effects of composting manure on viability of Giardia cysts (GC) and Cryptosporidium cysts (CO) were determined in a two-year study with manure from feedlot cattle bedded on barley straw or woodchips. Each year, manure was deposited in 8 m × 2.5 m × 2 m windrows (one per bedding type) on a sheltered concrete pad. On day 0, porous bags containing 100 g of feces from confirmed Giardia- and Cryptosporidium-positive cattle (9 bags per retrieval day in Year 1; 3 per day in Year 2) were implanted in the windrows. Replicate bags were placed on the concrete pads as uncomposted controls. Windrow temperature and water content were measured and compost was turned mechanically twice each week. Fecal bags were retrieved and subsampled for enumerations of total and viable cysts and cysts after 1, 2, 3, 7, 10, 17, 24 and 31 days in 1998 and after 1, 2, 3, 7, 9, 16, 23, 30, 42, 56, 70 and 98 days in 1999. Windrow temperatures (TEMP) exceeded 55°C during the fourth week of composting, and remained above 50°C for 4 wk thereafter in 1999. Bedding material did not affect overall mean temperature in either year, but TEMP was higher with straw than with woodchip from day 10 to day 17 in 1998 (P < 0.05) and on day 16 and day 42 in 1999 (P < 0.10). In 1998, moisture content decreased from 62.2 to 43.2% during composting of woodchip manure and from 67.3 to 39.3% during composting of straw manure. In 1999, moisture content decreased from 61.0 to 31.8% for woodchip and from 64.5 to 28.6% for straw compost. Percentage of viable CO declined gradually over the 31 days in 1998. The following year revealed a rapid decline in viability of GC and CO once compost temperature exceeded 55°C and viabilities of GC and CO were reduced to zero after 42 days (straw compost) and after 56 days (woodchip compost). Exposure of CO and GC to temperatures > 55°C for a period of 15 days appears to be an effective method of inactivating Giardia cysts and Cryptosporidium cysts in feedlot manure.  相似文献   

10.
Abstract

Loss‐on‐ignition (LOI) is a simple method for determining ash content, and by reciprocation, organic matter content of compost and manure. However, reported ignition temperatures and heating times for LOI measurements vary widely, and this brings into question the accuracy of one specific combination of ignition temperature and heating time over another. This study examined the effect of 42 temperature‐heating time combinations (six ignition temperatures from 400 to 650°C in 50°C increments by seven heating times of 1, 2, 8, 12, 16, 20, and 24‐h) on the ash content of a finished compost and a fresh manure. The experiment included the 550°C for 2‐h method recommended in Test Methods for Evaluation of Compost and Composting. The magnitude of the decrease in ash content due to increase in temperature was not consistent across all heating times. For example, after a 1‐h heating time for compost, ash content was 75.7% at 400°C and 67.5% at 650°C, compared to 69.6% at 400°C and 66.8% at 650°C after 24‐h. Irrespective of heating time, an ignition temperature of 400°C overestimated ash content for both compost and manure compared to the TMECC method. The TMECC method with its moderate temperature and short heating time requirement could reduce energy costs without affecting ash content results.  相似文献   

11.
Compost water extracts (compost teas) are gaining popularity among organic growers, largely because of their disease suppressive activity when applied to foliage or soil. Production methods often include addition of supplemental constituents, particularly molasses, to stimulate plant-beneficial microbial populations. We have found that molasses amendments also favor regrowth of human pathogenic bacteria, raising public health concerns about potential contamination of treated crops, particularly produce intended for fresh consumption. Using disease outbreak strains marked with green fluorescent protein (GFP) and spontaneous antibiotic-resistance, we found that regrowth of Salmonella enterica serovar Thompson and Escherichia coli O157:H7 was positively correlated with molasses concentration. For Salmonella, regrowth was also dependent on the type of starter compost material used. Salmonella populations increased from 1 at time 0 to over 1000 CFU ml?1 in dairy manure compost tea with 1% molasses, and from 1 at time 0 to over 350,000 CFU ml?1 in chicken manure compost tea by 72 h. E. coli populations increased from 1 at time 0 to approximately 1000 CFU ml?1 in both types of tea by 72 h. Pathogen regrowth did not occur when molasses was eliminated or kept to 0.2%.  相似文献   

12.
Four studies explored the feasibility of year-round composting of lamb and mature sheep mortalities within the arid climate of the Canadian prairies. In all studies, a ratio of 2:1:1 (manure : mortalities : chopped straw) was maintained, although depth of the mortality layer within the bin, number of layers of mortalities per bin, age of animal (lamb or mature sheep) and time of year (summer or winter) were varied. Composting neonatal lambs in the spring/summer was successful whether a single layer (n=15 lambs, weight 99.7 kg) or two, separated layers of mortalities (n=41 lambs, weight 198 kg) were added to a 2.4 m3 open bin. Residual bone, wool and soft tissues were negligible after the lamb compost had completed one heating cycle. In contrast, composting mature sheep in the fall/winter was more difficult due to: (1) over wet manure (31% dry matter) resulting in continuous anaerobic decomposition of carcasses; (2) fat/grease accumulation when composting a layer of carcasses 71 cm in depth (weight of sheep 1020 kg). For mature sheep mortalities, 2 heating cycles were required to eliminate soft tissues and wool. As compost in all studies heated in excess of 60°C in the primary and/or secondary bin, bacterial isolates taken after the compost completed the secondary heating cycle were all innocuous species. Provided that compost is protected from excessive moisture and compost is aerated by turning into a secondary bin, a 2:1:1 (manure:mortalities:straw) ratio allowed for year-round composting of lamb and mature sheep mortalities.  相似文献   

13.
The risk of enteropathogens to food and water is highly dependent on their survival in soil environments. Here, the effects of soil type, particle size, the presence of natural organic matter (NOM) or Fe/Al (hydro)oxides on pathogenic Escherichia coli O157:H7 survival in sterilized soil particles were assessed through survival, attachment, metabolic activity, and qRT-PCR analyses. The abundance of inoculated E. coli O157:H7 in Brown soil (Alfisol) particles increased 0.6–1.4 log10 CFU/g within 3 days (except for NOM-stripped clay), while that in Red soil (Ultisol) particles decreased rapidly in 8 days post-inoculation. Additionally, survival of bacteria was significantly enhanced when Fe/Al (hydro)oxides had been removed from Red soil particles. For the two soils, E. coli O157:H7 survived the longest in NOM-present clays and the bacterial adenosine 5′-triphosphate (ATP) levels were 0.7–2.0 times greater in clays than in sands and silts on day 8. Moreover, clays were more effective than silts and sands in binding cells and changing the expressions of acetate pathway-associated genes (pta and ackA). For silts and sands, E. coli O157:H7 decayed more rapidly in the presence of NOM and similar trends of bacterial ATP levels were observed between NOM-stripped and NOM-present soil particles, indicating that the primary role of NOM was not as a nutrient supply. These findings indicate that soil particles function mainly through attachment to change the metabolic pathway of E. coli O157:H7 and ultimately impact the survival of bacterial pathogens in soils.  相似文献   

14.
After imposition of fees for disposal of cattle carcasses by the rendering industry, on-farm methods of mortality disposal are being investigated. Three open-air mortality compost windrows were constructed in January (JAN) and February (FEB) of 2004 in the cold, semiarid climate of southern Alberta, Canada. Windrow A included a base of barley straw a minimum of 46 cm thick, a layer of cattle mortalities (n=12) and a layer of stockpiled manure (minimum of 46 cm) covering the mortalities. Windrows B and C also had a bottom layer of barley straw, with windrow B containing 9 mortalities in 2 layers and windrow C containing 12 mortalities in 3 layers. Due to ambient temperatures > 0°C, carcasses (range 236 to 673 kg) were frozen at the time of windrow construction. Type ‘T’ thermocouples were embedded at the base of B and C windrows and temperatures within 120 cm of the surface were measured using a stainless steel dial probe. Windrows were turned 3 times at 3 mo intervals. Samples were collected from initial compost amendments and prior to each turning for determination of dry matter (DM), organic matter (OM), N, C and coliform bacteria. Ambient temperature was 13°C higher (P < 0.05) for the initial heating of FEB as compared to JAN compost, although the rate of compost temperature decline did not differ between replicates in this period. Days at maximum temperature did not differ between replicates and maximum temperatures in all windrows exceeded 55°C. After 3 heating periods and 9 mo, flesh was not evident and only fragments of bones (max wt. 740 g) were found. Results of this study demonstrate that ambient temperatures < 0°C and frozen mortalities provide no barrier to the use of open-air windrows for disposal of cattle mortalities. As well, stacking up to 3 layers of full-sized cattle mortalities in a windrow did not affect temperature profiles, residual flesh or bone, or analyses of the finished compost. Under the climatic conditions of southern Alberta, layering mortalities would reduce space requirements for large-animal mortality composting in a feedlot setting.  相似文献   

15.
《Applied soil ecology》2011,47(3):398-404
The inactivation of Escherichia coli O157:H7 (CCUG 44857) and Salmonella enterica serovar Typhimurium was investigated in two agricultural soils (sandy loam and silty clay) amended with poultry manure, cattle manure slurry or human urine. The study was performed in soil lysimeters placed outdoors, and was repeated over two consecutive years. The amendments, inoculated with E. coli O157:H7 and Salmonella Typhimurium, were mixed with soil on the top of the lysimeters. Samples were collected from the top 5-cm layer of each lysimeter at regular intervals, and the inactivation was monitored over 6 months, by the plate spread method and by enrichment. The inactivation was modelled by fitting a non-linear model to the data, and pathogen reduction times were calculated (90 and 99% reduction). The results showed that the inactivation of E. coli O157:H7 and Salmonella Typhimurium varied depending on the manure type used and its carbon content. The longest inactivation time occurred in samples amended with poultry manure, in which both E. coli O157:H7 and Salmonella Typhimurium were detected up to day 90 with the spread plate method. The most rapid inactivation for both pathogens occurred in soil amended with urine. However, low amounts of culturable E. coli O157:H7 and Salmonella Typhimurium were detected by enrichment throughout the study period (180 days), regardless of manure type.  相似文献   

16.
Abstract

Contamination of agricultural soil by fecal pathogenic bacteria poses a potential risk of infection to humans. For the biosafety control of field soil, soil solarization in an upland field was examined to determine the efficiency of solarization on the inactivation of Escherichia coli inoculated into soil as a model microorganism for human pathogenic bacteria. Soil solarization, carried out by sprinkling water and covering the soil surface with thin plastic sheets, greatly increased the soil temperature. The daily average temperature of the solarized soil was 4–10°C higher than that of the non-solarized soil and fluctuated between 31 and 38°C. The daily highest temperature reached more than 40°C for 8 days in total in the solarized soil during the second and third weeks of the experiment. Escherichia coli in the solarized soil became undetectable (< 0.08 c.f.u. g?1 dry soil) within 4 weeks as a result, whereas E. coli survived for more than 6 weeks in the non-solarized soil. Soil solarization, however, had little influence on the total direct count and total viable count of bacteria in the soil. These results indicate that soil solarization would be useful for the biosafety control of soil contaminated by human pathogens via immature compost or animal feces.  相似文献   

17.
水分含量对水葫芦渣堆肥进程及温室气体排放的影响   总被引：2，自引：0，他引：2  
水葫芦经挤压处理后,容积减小、干物质含量提高,利于堆肥生产,但目前缺乏相关堆肥条件的研究。本文通过水稻秸秆与水葫芦渣以不同比例混合来调节堆体水分,探讨在65%、70%、75%、80%水分条件下堆肥效果及环境影响,以获得堆肥的最优水分条件。本试验为静态堆肥,动态监测堆体温度、pH值、碳氮养分和温室气体。结果表明,水分对堆体pH、胡敏酸(堆肥7 d)、富里酸无显著影响,对温度、水溶性碳、胡敏酸(堆肥50 d)、凯氏氮、硝态氮、铵态氮影响显著。其中75%水分处理升温能力最佳,堆肥6 d即达最高堆温(53.4℃);50 d时其凯氏氮、硝态氮、铵态氮显著高于65%和70%的水分处理(P<0.05);75%水分处理堆肥50 d与7 d相比,凯氏氮降低最多(21.1%),硝态氮增加最多(434%),铵态氮降低幅度最小(14.1%)。水分对CH4的产生无显著影响;但高水分促进CO2和N2O排放,75%水分处理的CO2排放能量最高,是其他处理的1.9~2.5倍,80%水分处理的N2O排放通量最高,是其他处理的3.9~23.1倍。综合考虑,水稻秸秆与水葫芦渣混合堆肥,堆体水分为75%较为适宜,能兼顾堆肥效率、品质和环境效益。  相似文献   

18.
Composting broiler litter (a mixture of manure, bedding material, and wasted feed) with commonly available high-C substrates may be a viable alternative to reduce current land disposal practices for litter. Broiler litter with wood shavings as a bedding material and broiler litter with peanut hulls as a bedding material were composted with wheat straw, peanut hulls, pine bark and paper mill sludge in 0.33 m3 batch reactors. Litters and C substrates were mixed to achieve C:N ratios of approximately 30:1. Dry weight, total N, total C, temperature, electrical conductivity and pH were determined at regular intervals. Maximum temperatures peaked near 70°C within 2.25 d after mixing peanut hulls with litter and within 2.58 d for pine bark and litter. Composts made from paper mill sludge approached 50°C within 3.71 d. Wheat straw composts never exceeded 40°C which could present potential health problems associated with pathogenic microorganisms. Mass loss and C:N ratio gradually declined and stabilized approximately 84 d after mixing. Mass loss averaged 73 percent for wheat straw compost, 33 percent for peanut hull composts, and 16 percent for the other mixes. Wheat straw compost C:N ratios stabilized near 14:1 and other mixes remained above 20:1, indicating N limited conditions for complete composting. Compost pH was 5.8 after 84 d from pine bark composted with wood shaving litter and was significantly lower than pH from paper mill sludge compost with an average pH of 6.9 but similar to all other compost mixes (pH 6.7). Electrical conductivity ranged from 0.35 S m?1 for paper mill sludge composted with wood shaving litter to 0.91 S m?1 from wheat straw composted with peanut hull litter. Composting temperature varied considerably among C sources and all required at least 72 d of curing to stabilize the C:N ratio. Composts made from wheat straw were most effective for waste reduction but temperatures were below the 50°C level generally considered necessary to kill pathogens.  相似文献   

19.
ABSTRACT

To ensure the safety of compost products, the Canadian Council of Ministers of the Environment's compost guidelines specify upper limits for certain pathogenic and indicator microbes, which are presumably achieved by exposing every particle of compost to temperatures ≥55°C for at least three consecutive days. A rugged temperature probe that behaves like a random compost particle was used to investigate whether every compost particle meets the time temperature criterion and to measure sanitation efficacy. An inoculum consisting of Salmonella enterica var. Meleagridis, Escherichia coli K12, and phi-S1 bacteriophage (all at levels of ～1 × 106 CFU/PFU mL?1) was added into 17 probes. The probes were randomly introduced into a covered, aerated static pile along with 17 probes that only monitored the temperature. After 56 days of composting, with one pile turn the probes were recovered. Organism levels were determined via culture-based methods. Before turning, 80% of the randomly introduced probes satisfied the time-temperature criterion. After turning, this number increased to 87%, demonstrating that turning is somewhat useful for sanitation. The cool zones largely remained mesophilic with the pile turning having minimal impact, which could potentially be an indication that the pile was not turned thoroughly. One of the 17 probes with cryovials reached only 40.2°C, and survival of S. meleagridis (2.5 × 106 CFU ml?1) was observed. The remaining probes with cryovials exceeded 55°C and were pathogen free. It appears that the specified time-temperature conditions are likely adequate. However, more observations are needed before a firm conclusion can be made.  相似文献   

20.
Pulp and paper mill sludges (PMS) are a significant byproduct of the paper making industry world-wide, and composting with mineral nutrients in Tasmania is viewed as the most environmentally suitable method to convert this material into a horticultural product, thus eliminating the need for landfilling. The major control variables for composting PMS with a high C:N ratio are nutrient and temperature management. Addition of the nutrient requirement prior to composting can result in significant nutrient loss by leaching and may lead to ground water pollution. Alternatively, the nutrient requirement may be added incrementally during composting, thereby decreasing the risk of nutrient loss. Control of temperature is also important as this affects the metabolic activity of microorganisms and may determine the rate at which a cured compost can be produced. This study therefore examined the relationship between the method of nutrient addition and temperature on composting of PMS, using small-scale reactors designed to simulate conditions in a large-scale mechanically turned windrow. The rate of PMS decomposition as determined by the rate of CO2 production and O2, consumption was higher at 55°C than at 35°C. The time to produce a cured compost could be shortened by 30-50 days if composting was undertaken at the higher temperature. The method of nutrient addition had no effect on the respiratory activities of compost microbiota or rates of decomposition, but had a major influence on pH which determined the intensity and period of ammonia volatilization. If pH was controlled, then incremental nutrient addition could be advantageous from the perspective of nutrient conservation.  相似文献   

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