Horticultural Peat Research Articles

Effect of coconut water, darkness and auxins on morphogenesis ofAriocarpus kotschoubeyanus(Cactaceae)

This study describes a method to micropropagate Ariocarpus kotschoubeyanus, using coconut water and darkness conditions. The longitudinal explants from seedlings germinated in vitro were cultivated on Murashige and Skoog medium (MS) with 2 mg/l zeatin. The calli generated were transferred to medium containing 5 ml, 10 ml or 15 ml of coconut water per litre. After 84 days, five green shoots per callus were generated under photoperiod but 14 well defined shoots were produced in darkness. The shoots were cultivated on media with activated charcoal and polyethyleneglycol to reduce callus and hyperhydricity, respectively. To induce rooting the effect of the auxins indolacetic acid and indolbutyric acid (1 mg/l) were tested. The roots type II (20 to 30 mm) and type III ( > 30 mm) were observed after 120 days onto media containing auxins but not in control medium. The regenerated plants were transferred to horticultural earth, peat moss and sand (30:30:40) and the survival of the plants in soil was 80%. The plant adaptation was complete and the first flowering was observed after 1 year in greenhouse conditions. The procedure developed is an alternative to the successful propagation of A. kotschoubeyanus and reduces the risk of extinction of this species.

Spontaneous revegetation of mined peatlands in eastern Canada

Many North American peatlands previously mined for horticultural peat have been abandoned recently, allowing natural recolonization to occur. The two dominant methods for peat extraction, hand block-cutting and vacuum-mining, have created distinctly different abandoned surfaces, leading to different recolonization patterns. Both types of exploitation can be found throughout eastern Canada where we conducted a vast survey of 26 abandoned mined peatlands in the provinces of Québec and New Brunswick. The aim of this study is to describe the revegetation patterns and to assess the impact of local and regional variables as well as the time since abandonment on Sphagnum re-colonization. We inventoried the vegetation structure in all trenches (2571) and baulks (2595) of abandoned block-cut areas as well as in all vacuum fields (395) of the mechanically mined areas. We also conducted detailed species relevés in 242 of these peat fields. In comparison to vacuum-mined peatlands, block-cut peatlands regenerated remarkably well. Approximately 80% of all baulks and trenches in block-cut peatlands had 50% or higher cover of ericaceous shrubs compared with only 16% found on vacuum fields. Herb cover in the three types of abandoned fields was similar to that in natural peatlands. However, Sphagnum percent cover was below 2% in baulks and vacuum fields and was 30% on average in the trenches, which is clearly below cover estimates in natural peatlands. Sphagnum cover and richness were both higher in trenches with thin residual peat deposit, and Sphagnum richness increased with latitude. Our surveys revealed that abandoned mined peatlands have a high diversity of peatland vascular plants species and a low diversity of non-peatland species.Key words: cutover peatlands, regeneration, milled peatlands, block-cut peatlands, vacuum-mined peatlands, colonization patterns.

Threats and protection for peatlands in Eastern Canada

Peatlands (or mires) are acidic freshwater wetlands that cover 4 million km2 (i.e., 3-4 %) of the planet’s surface, according to recent estimates. Although pristine peatlands are becoming rare in many European countries, most of the peatlands in Canada remain untouched. A recent estimate of the total area of peatlands in Canada is approximately 170 million ha. Precise statistics on peatland destruction and disturbance are difficult to obtain for the entire country, due to its large size. Here, we present detailed information on two provinces of eastern Canada : Québec and New-Brunswick. Approximately 120 000 ha of peatland in Québec have been flooded as a result of construction of hydroelectric dams, the main factor for peat-land lost in that province. It represents 1 % of the total peat-land area. For New-Brunswick, peat extraction is the main threat for peat-lands, with 6 800 ha of peat-land mined for horticultural peat which represents 5 % of the total peat-land resources of that province. Nevertheless, peat-lands in certain regions are strongly affected by human activities and conservation actions must be undertaken to assure equal representation of peatlands across the country. Manitoba, Nova Scotia, Prince Edward Island and New-Brunswick are the four provinces that have achieved the highest conservation rates with 25, 15, 12,5 and 11 % of their peatlands under protection, respectively. The situation is different in other provinces such as Québec, where 3,6 % of the total peatland area occurs in protected areas. Provincial legislation and protection plans need to be further developed in the future to attain international standards.

Advanced bioconversion of biowaste for production of a peat substitute and renewable energy

Traditional composting systems for biowaste generally produce low quality composts that may endanger recycling. A pilot-scale bioconversion process yielding quality compost and renewable energy was designed and tested. The process consisted of a set of wet physical separation units, composting and anaerobic digestion. Biowaste was divided in four streams by physical separation: (1) organic fraction >2 mm, (2) inorganic fraction 0.05–2 mm, (3) residual fraction composed of organics 0.05–2 mm and the fraction <0.05 mm and (4) a fraction solubilised in the washing water. The organic fraction >2 mm was composted and the compost, high in organic matter and low in EC and heavy metals, aimed at replacing peat in horticulture. The inorganic fraction 0.05–2 mm was completely made up of sand and can be used as a construction material. Solubilised organic matter in the washing water was converted to CH4 by anaerobic digestion. The residual fraction can be used as landfill cover material.

Detection of glass contamination in horticultural peat with dual-energy X-ray absorptiometry (DXA)

The application of dual-energy X-ray absorptiometry (DXA) to the detection of glass contamination in horticultural peat was studied using contaminated peat specimens, imaged with X-ray energies of 40 and 70 kVp and without any physical disruption of the peat samples. The source was an uncollimated beam from an industrial X-ray non-destructive testing system. X-ray transmission characteristics of peat and glass were determined from chemical composition data using XCOM software. The DXA images were analysed for detectivity figure (DF), signal-to-noise ratio (SNR) and contrast. These quantities were compared with those of the unprocessed 40 kVp images. There was >75% detection of glass presence if thicker than 3 mm, but 100% detection of glass fragments thicker than 1 mm. It was not possible to distinguish between glass and stone. DF values were dependent on peat and glass type, and contrast more than doubled with the DXA-derived images compared with their 40 kVp counterparts. Comparison with reported figures for a luggage inspection system shows that this system performs better than expected for commercial security systems. Better DXA results may be possible using simultaneous energy detection, and such a multi-energy sensing system could allow glass/stone detection as part of peat quality assurance, and the determination of peat chemical composition.

Repeated-load behaviour of geosynthetic-built unbound roads

In a study of the working load behaviour of unbound roads, small-scale models of unbound, geosynthetic-built road sections, constructed on reconstituted, milled horticultural peat subgrades, were tested in plane strain under repeated loads. The results of load tests on the peat subgrades were used to derive an appropriate relation for the coefficient of peat subgrade reaction (or stiffness), which was input to a previously derived three-parameter mechanical analogue for the road sections, in order to predict road section stiffness. The validity of the model was checked by comparing its predictions for surface displacements under loading against those observed in the tests. The predicted displacements being sufficiently accurate, it was concluded that using the simple three-parameter model for unbound geosynthetic-built road section repeated-load behaviour is an appropriate approach for the design of such roads from the stiffness point of view. (A)

Remediation of contaminated land by formation of heavy metal phosphates

Phosphate compounds of Pb and Zn are highly insoluble and their formation in contaminated soils would aid immobilisation of heavy metals. In preliminary experiments to induce heavy metal phosphates in soils, two mine-waste contaminated soils were treated by the addition of soluble inorganic phosphate and the growth of Agrostis capillaris on soil amended with horticultural peat. After incubation for three months, EDX and XRD analysis were performed and the soil grains characterised using an automated SEM/EDX programme. The results showed the presence of Pb and Zn phosphates in the phosphate amended soils and in the rhizosphere of Agrostis. Therefore, both treatments have the potential to induce the formation of heavy metal phosphates. This study describes an additional benefit of vegetative remediation techniques which are more ecologically acceptable than the addition of soluble phosphate compounds.

THE USE OF OVERLAND FLOW WETLAND TREATMENT SYSTEMS1 TO REMOVE NICKEL FROM NEUTRAL MINE DRAINAGE

In 1992, two overland flow wetland treatment systems were built in existing natural wetlands in northeastern Minnesota to remove copper, nickel, cobalt and zinc from neutral mine drainage. Typical input metal concentrations ranged from 2 - 5 mg/L for nickel, to less than 0.1 mg/L for copper, cobalt and zinc. Flow rates were on the order of 75 L/min for both systems. The treatment systems covered 4200 m{sup 2} and 7000 m{sup 2} and m{sup 2} contained a series of soil berms installed across the wetlands and about a 30 cm layer of a mixture of peat and peat screenings (a waste material generated during the processing of horticultural peat). Although these systems have been successful in removing about 70 - 90% of the input metals, output nickel concentrations in one of the wetlands exceeded the discharge standard by as much as a factor of four. Average flow rates were greater than the design value by a factor of two, and the wetland was unable to adequately treat this flow volume. In 1993 and 1994, changes made to reduce the hydraulic gradient and minimize channeling improved performance, but nickel concentrations still exceeded permit requirements during periods of high flow andmore » during the fall as temperature decreased. In 1995, the mining company constructed an additional 10,000 m{sup 2} of wetland to provide additional treatment. After the expansion, the discharge was in compliance with permit requirements, until high flows and decreasing temperatures in the fall caused nickel concentrations to exceed standards.« less

Peat extraction, conservation and the rural economy in Northern Ireland

Northern Ireland has a tradition of peat cutting; 78 per cent by area of remaining lowland bogs and 46 per cent of blanket bogs have been cut in the past. Since the early 1980s, machine peat extraction for fuel and horticulture has increased, against a background of changing economic support for agriculture, high rural unemployment and agricultural underemployment. Cutting fuel peat can reduce household fuel costs and some peat fuel is sold to gain income. Horticultural peat is cut mainly for sale. Expansion of machine extraction, with possible environmental impacts, occurred as interest in peatland conservation increased. Potential conflict arises between local economic needs and conservation. Machine cutting for fuel is widespread, but affects only 2.6 per cent of the blanket peat area; horticultural extraction is more localized and is only one-fifth of the extent of fuel extraction. Altitude, distance from roads, land ownership and rights, turbary, religious affiliation, local economic needs and the role of government departments all contribute to explaining the distribution and extent of extraction.

Recycling of Spent Mushroom Substrates by Aerobic Composting to Produce Novel Horticultural Substrates

The mushroom industry in the United Kingdom, the country's second largest user of horticultural peat, considers it important to examine alternative materials. Reflecting this objective, a series of trial were conducted to examine whether SMS could hygienically and rapidly be recomposted and reused as a peat alternative for mushroom casing. Alternative horticultural uses of recomposted SMS, such as greenhouse crop substrates, also were considered. Analyses were conducted on leaching, physical and chemical factors, mushroom yields, disease generation, and the economics of different approaches.

Removal of chromium from wastewater by peat filters

Abstract The effectiveness of Saskatchewan horticultural peat for removing chromium from the City of Regina wastewater was investigated by using two peat columns each of 100 mm diameter, one column with a 300 mm depth of peat and the second column with a 500 mm depth of peat. Wastewater containing approximately 0.5 mg/L of dissolved chromium was applied to the columns twice daily for a total loading of 1 litre per day. The pH of the wastewater was between 4.0 and 5.0, and the temperature was 23±1°C. The columns were operated for a period of approximately four weeks. The 300 mm and 500 mm columns were found to produce effluents containing a mean dissolved chromium concentration of 0.031 mg/L and 0.018 mg/L respectively with removal efficiencies 94.0% and 96.6% respectively. Fully developed break‐through curves could not be developed for either column within the test period.

Evaluating peat as a growing medium for jack pine seedlings. 1. Conventional quality indices

Jack pine (Pinusbanksiana Lamb.) seedlings were grown in paperpots filled with 26 different horticultural peat moss substrates to evaluate conventional laboratory indices for characterizing container growing media. Seedling growth performance varied on the different substrates; dry weight differed 52% and height at harvest differed 37% between the best and poorest yielding peat. Precultural physical and chemical properties of the growing media varied widely, but correlated weakly with growth and nutrient composition of the seedlings, suggesting that conventional laboratory indices were not sensitive enough to predict peat suitability for jack pine culture. Height growth was significantly related to nutrient composition of the seedlings; however, correlations were low when tested against initial measures of peat nutrient status. Foliar vector diagnoses of both high- and low-yield plants identified N and P as the primary and secondary nutritional constraints upon growth, respectively. Since plants received a common fertilizer regime, seedling development may be more closely associated with specific fertilizer–substrate interactions rather than conventional precultural test measures. Further research is needed to develop quality indices more sensitive to potential nutrient supply and fertilizer reactions in container rooting media.

Treatment of Oily Waters Using Peat

Abstract Peat offers itself as an effective medium in the treatment of oily waters, due to its known capacity to remove oil and its abundant availability in Canada. Horticultural peat produced by the Saskatchewan Minerals was used in this study to assess its potential for the removal of oil from various oil-in-water emulsions. The representative oil-in-water emulsions included the following: (1) Medium viscous (130 cP) standard mineral oil (SMO), (2) low viscous (50 cP) Midale crude oil (MCO), cutting oil (CO) and (4) refinery effluent (RE). Batch kinetic studies were conducted to identify equilibrium time and isotherm patterns. The adsorption of oil by peat was well represented by the BET isotherm compared to the Langmuir and the Freundlich equations. Column studies were conducted using a 100 mm diameter, 600 mm long acrylic pipe with 300 mm depth peat bed. Initially eight-hour tests were run for three different flow rates of 12, 48 and 300 mL/min (2.13, 8.52 and 53.28 m/d). These column studies showed that removal of oil varied between 34 and 99 percent depending upon the influent oil concentration, the type of emulsion, and the flow rate. Breakthrough studies were undertaken for an optimum flow rate of 50 mL/min (8.88 m/d) for SMO and MCO and 25 mL/min (4.44 m/d) for CO and RE to assess the ultimate capacity of peat under dynamic conditions. The data obtained from breakthrough studies were applied to scale-up and kinetic models to estimate the amount of peat required to remove oil from a flow rate of 150 m3/d of oily waters.

Use of peat in the removal of oil from produced waters

Abstract Horticultural peat Was used in this study to assess its potential for the removal of oil from produced waters recovered from the petroleum field operations. Isotherm analyses of the kinetic data showed that generally the adsorption pattern followed the Langmuir and the Freundlich isotherms. Column studies using a 300 mm depth of peat on an 8‐hour run with flow rates of 12 and 48 mL min‐1 (2.13 and 8.52 md‐1) showed an average oil removal of approximately 80%. Scale‐up and kinetic models based on column breakthrough data, were utilized to design a peat adsorption column for treating a flow of 150 m3 d‐1 produced waters.

Batch studies on septic tank effluent treatment using peat

Batch studies were conducted to determine the efficiency of Saskatchewan horticultural peat to remove biochemical oxygen demand (BOD), chemical oxygen demand (COD), phosphorus, nitrogen, and indicator microorganisms from septic tank effluent. Results of the studies showed that peat was effective in adsorbing 35–50% of dissolved BOD, COD, and organic carbon from the septic tank effluent and in removing indicator microorganisms to the extent of 45–70%. The studies showed that peat has the potential to be used as a medium for septic tank effluent treatment in areas with high water table and with bedrock at shallow depths. Because of leaching of pollutants from peat in the 2-h batch studies, it is necessary to conduct long-term column studies to observe the length of time up to which leaching continues and to evaluate the performance of a peat filtration system under dynamic conditions. Key words: batch studies, septic tank effluent, treatment, peat, adsorption isotherms, indicator microorganisms.

Compressibility properties of a horticultural peat: Morin, P Geotech Test JV11, N1, March 1988, P44–48

Compressibility properties of a horticultural peat: Morin, P Geotech Test JV11, N1, March 1988, P44–48

Compressibility Properties of a Horticultural Peat

Abstract The compressibility of a typical horticultural peat has been studied in the laboratory. Compressibility is an important factor in the processing of this material since volume governs the cost of shipping. The final reconstituted volume and the appearance of the peat after shipping must also be taken into account for marketing. Compression tests have been carried out on a horticultural peat from Newfoundland. Simple equations relating initial water content, relative volume change, and vertical applied pressure are proposed. A fluff factor has been defined, and it was found to decrease with the maximum applied pressure. Finally the results obtained in the laboratory are applied to storage and processing examples that are encountered in the horticultural peat industry.

Peat Filtration of food-processing wastewaters

Laboratory column studies were conducted to examine the feasibility of using horticultural peat as a filter medium to treat slaughterhouse and dairy wastewaters. A 100 mm diameter column with 300 mm depth of peat was used for each wastewater application. The slaughterhouse wastewater was fed continuously to the column at a hydraulic loading rate of 3·55 m 3 3 /m 2 per day. The column clogged at the end of five days. In the five day period, the system achieved SS, BOD, COD and P removals of 94, 66, 65 and 87% respectively. In the case of dairy wastewater, the column clogged at the end of 18 hours at an application rate of 3·55 m 3 /m 2 per day. When the hydraulic loading rate was lowered to 2·13 m 3 /m 2 per day, the column operated for 81 hours before clogging. At the end of the lower hydraulic loading rate, the system achieved SS, BOD, COD and P removals of 99, 61, 51 and 48% respectively. Earlier clogging noticed in the case of dairy wastewater was due to the higher levels of SS (2650 mg/litre) in comparison to the SS in slaughter house wastewater (243 mg/litre).

Treatment of oil-in-water emulsions using peat

Besides being plentiful and relatively cheap, peat offers itself as an excellent medium for treating oil-in-water emulsions. Laboratory batch and column studies were conducted to assess the potential of Saskatchewan horticultural peat for treating various oil-in-water emulsions. A series of batch studies were conducted to identify the equilibrium time and the isotherm pattern. Based on the excellent adsorption potential exhibited by peat in the batch studies, preliminary column studies were undertaken to study the performance of peat under dynamic conditions. Percentage removals of oil ranging from 90 to 99 were observed depending upon the type of oil-in-water emulsions.

Lindow Man

The first prehistoric 'bog body' to be found in Britain in recent times has created so much interest that a brief preliminary account is warranted-even though the serious scientific investigation is only just beginning. It was discovered at Lindow Moss (SJ 820805) on the outskirtsof Wilmslow, Cheshire, in the parish of Mobberley. Formerly a very extensive bog covering about 600 hectares, Lindow Moss, has now been reduced to a tenth of that size and some 32 hectares are being excavated commercially for horticultural peat. The operators have divided the site into 'rooms' 6 m wide and up to zoo m long, and peat is excavated in spits about I m deep from alternate rooms by a large Hy-Mac, and stacked alongside to dry for about six months. It is then transported by a narrow gauge railway to the depot where it is milled and dispatched from the site.