Peat Replacement Research Articles

Development of an alternative artificial soil for earthworm toxicity testing in tropical countries

The standard soil invertebrate toxicity tests developed by OECD and ISO use an artificial soil as the test substrate, which contains sphagnum peat as a component. This type of peat is not widely available. Investigation of possible alternative substrates using locally available materials therefore is vital for performing such ecotoxicity tests, particularly in the tropics. We studied the suitability of paddy husk (PH), saw-dust (SD), non-composted (NCCP) and composted coco peat (CCP) as a replacement for sphagnum peat. Artificial soil (AS) was prepared by mixing 70% sand and 20% kaolin clay with 10% PH, SD, NCCP or CCP. First, the reproduction potential of the earthworm Eisenia andrei was investigated in modified artificial soil (MAS) using the original OECD AS as the control. The number of juveniles produced in OECD AS, MAS PH and MAS CCP was not significantly different but it was significantly reduced ( p < 0.05) in MAS SD and MAS NCCP. The toxicity of chlorpyrifos, carbendazim and carbofuran for E. andrei was determined to validate the substrates. The 28-day LC 50s for the three pesticides in original AS, MAS CCP and MAS PH were not significantly different, but the EC 50 for effects on reproduction in the MAS PH was significantly lower ( p < 0.05) compared to OECD AS and MAS CCP. We conclude that composted coco peat might be a suitable replacement for sphagnum peat in AS for soil ecotoxicity studies.

The effect of rockwool on physical properties of growing substrates for perennials 38

The possibility of peat replacement with crushed water absorbent rockwool in growing substrates in the amount of 35% vol. was verified in the experiment with perennials in containers. Three types of substrates, i.e. peat, and two mixtures of peat with alternative components &amp;ndash; green waste compost (25% vol.) or composted spruce bark (40% vol.) were compared. A sand box in the range of &amp;ndash;0.5 to &amp;ndash;10 kPa was used to determine retention curves and other physical properties of the components and substrates. The addition of rockwool to the peat substrate increased content of air and easy available water, the plant growth was not affected. Plants grown in substrates with alternative organic components were smaller in comparison to peat substrate. The growth of perennials significantly decreased, mainly in substrates with bark, but the plants had good market value. The addition of rockwool to these substrates had no significant effect on the growth. Crushed rockwool in the amount of 35% vol. can replace peat in peat substrates and in mixtures with alternative components.

Using compost of grape manufacture and farm wastes as growing media in vegetable ad ornamental nurseries

This work was conducted at private nursery in Kafr El-Sheikh governorate during 2006 and 2007 seasons to investigate the possibility of using grape manufacture waste compost (GMWC) and farm wastes compost (FWC) in ornamental and vegetable nurseries as partially or totally replacement of coconut peat (CP) and vermiculite (V) in the growing medium and also to find out the optimum media of tomato (Lycopersicon esculentum, cv. Castle Rock) and Cockscomb (Celosia plumosa) as comparing to a mixture of CP and V (1:1 v/v). The authors used a ten mixtures as followed: 1- Control (CP+V at 1:1 v/v), 2-GMWC (100 %), 3- GMWC +CP (1:1 v/v), 4- GMWC + V(1:1 v/v),5- GMWC +CP + V (1:1:1 v/v/v), 6- FWC (100 %),7- FWC+ CP (1:1 v/v), 8- FWC+ V (1:1 v/v), 9- FWC+ CP+ V (1:1:1 v/v/v), 10- GMWC+FWC+CP+V (1:1:1:1 v/v/v/v). Data recorded as seedling height, No. of leaves, total pigments, shoot fresh and dry weights, root length and root fresh and dry weights in order to assess the quality of both transplants of tomato and cockscomb. Both seedlings grown in medium contain a mixture of GMWC+CP+V displayed quality traits similar or better as to those of recorded from the control treatment.

The potential role of compost in reducing greenhouse gases

The contribution of the agricultural sector to emissions of climate change gases is becoming better understood. At the same time, the potential role of the sector as a means through which to tackle climate change, widely neglected in the past, is becoming more widely acknowledged. The absorption potential of agricultural soils could contribute significantly to constraining growth in greenhouse gas emissions, while also contributing to improvements in soil quality in some areas. In addition to the measures listed above, other benefits of compost application may have some relevance. Some of these measures include replacement of chemical fertilizers (implying avoidance of greenhouse gases related to their production) reduced use of pesticides (avoiding emissions associated with their production), improved tilth and workability (less consumption of fuels). Typically, life-cycle analyses (LCAs) exhibit limitations related to assessing the effects of 'time-limited' carbon sequestration in soils. This has tended to obscure the potentially important effect of composting, in which biogenic carbon is held in soils for a period of time before the carbon is released. The paper seeks to understand these effects and offers comments on the contribution of biological treatments to tackling climate change issues. Key issues include the replacement of fertilizers, reduction of N2O emissions, and peat replacement.

CRUSHED ROCKWOOL AS A COMPONENT OF GROWING SUBSTRATES

CRUSHED ROCKWOOL AS A COMPONENT OF GROWING SUBSTRATES

Coloration, Anthocyanin Concentration, and Growth of Croton (Codiaeum variegatum L.) as Affected by Cotton Gin Trash Compost Use in the Potting Medium

Compost from cotton gin trash was evaluated as a peat substitute in Codiaeum variegatum L. production. Rooted cuttings were grown for 8 months in media containing cotton gin trash compost, sphagnum peatmoss, and perlite in 1:3:4, 1:1:2, and 3:1:4 ratios respectively, and their growth was compared with a control medium of 1 peat : 1 perlite (by volume). Even when 75% of peat in the control medium was replaced by cotton gin trash compost, plant height, leaf number, and leaf size were unaffected, whereas root dry weight was increased in the medium with 25% peat replacement. Although replacement of peat by cotton gin trash compost did not affect quantitative characteristics of croton foliage growth, it affected the foliage color, as plants in media with cotton gin trash compost had more areas colored red in their leaves. The increase of red coloration was proportional to the increase of cotton gin trash compost in the medium. The phenomenon was more intense in the lower leaves than the apical ones. Anthocyanin concentration measurements showed that the gradual increase of cotton gin trash compost level in the growth medium caused a gradual increase of the anthocyanin concentration in the leaves. This effect is discussed in relation to chemical properties of the media, as electrical conductivity, pH, and nutrient concentrations. The gradual increase of cotton gin trash compost level caused an analogous increase of N, P, and K concentrations in the medium. Also, media with cotton gin trash compost had high electrical conductivity at the beginning of the culture period, related to the cotton gin trash compost level, which was reduced to values similar to that in the control medium after 50 days of culture. Na concentration in the media ranged similarly to electrical conductivity. The pH was positively related to cotton gin trash compost level, and media with a high cotton gin trash compost level had increased pH during the culture period compared with the control.

Growth of Geranium Plants in Soilless Media Containing Sphagnum Peat and Anaerobic Digestion-Derived Biosolids

Anaerobic digestion-derived biosolids (ADB) has the potential to become a complete or partial substitute for sphagnum peat in the greenhouse and nursery industry. Bedding plant production being one of the largest segments of the floriculture industry may possess the greatest application for this new organic addendum to soilless media. An experiment was conducted in which geraniums (Pelargonium ×hortorum `Red Elite') were grown in potting mixes formulated with vermiculite and perlite plus various concentrations and combination of anaerobic digestion-derived biosolids (ADB) and sphagnum peat to determine if ADB could be used as a partial or complete replacement for sphagnum peat in soilless horticultural growing media. Plants were grown during June and July 2003–05 in the greenhouse at 75 ± 5 °F and normal light and photoperiod. Plant growth was assessed by measuring the dry weight of stem tissue. Plants were harvested when at least 50% of the total number of plants produced at least one inflorescence. Floriferousness was measured by counting the number of visible inflorescences per plant. Dry weight of plants grown in media containing ADB was greater than those grown in media containing sphagnum peat as the sole organic addendum. Plants grown in media containing ADB were also more floriferous. This study demonstrates that ADB has great potential for use as an organic addendum to horticultural growing media as a partial or complete replacement for sphagnum peat. Use of anaerobic digester-derived biosolids in horticultural growing media is a protected intellectual property and available for license through the WiSys Technology Foundation.

(299) The Use of Worm Castings As an Alternative to Sphagnum Peat Moss in Tomato (Lycopersicon esculentum Mill.) Transplant Production in Chile

Intensive peat mining in Chile and worldwide produces a significant increase in production costs and less market availability. Alternative systems to promote peat mining sustainability are an immediate necessity. A viable alternative for replacing peat in tomato transplant production is to use worm castings or vermicompost. Vermicomposting is a biological process that relies on the action of earthworms (Eisenia sp.) to stabilize waste organic materials. The objective of this study was to evaluate the use of Ecobol-S® worm castings as a replacement for peat in tomato transplant production. Three experiments were designed using a randomized complete-block design containing two factors (planting date and worm casting rate). Tomatoes were seeded in a growth chamber using five growth media made up of the different ratios of worm castings, peat, and rice hulls [0:70:30 (control) 18:52:30; 35:35:30; 52:18:30; and 70:0:30], respectively. It was determined that Ecobol-S® worm castings have an adequate C:N and particle size for tomato transplant production. However, limitations were observed due to its high EC and low C content. During early fall, with high temperature in the growth chamber, it is not recommended to use worm castings in transplant production due to nutrient leaching caused by frequent irrigation. In mid-fall, it is recommended to use a rate of 35% worm castings, while in early winter it is recommended to use a rate of 52% to obtain strong and healthy transplants. Therefore, worm castings can be used as a viable alternative in the tomato transplant industry in Chile and possibly worldwide.

POTENTIAL OF ADAPTED MUSHROOM COMPOST AS A GROWING MEDIUM IN HORTICULTURE

POTENTIAL OF ADAPTED MUSHROOM COMPOST AS A GROWING MEDIUM IN HORTICULTURE

Olive-mill Waste Compost as a Growth Medium Component for Foliage Potted Plants

Research was carried out to evaluate composted olive-mill waste as a peat substitute in foliage potted plant production. Rooted cuttings of Codiaeum variegatum (L.) A. Juss and Syngonium podophyllum Schott were grown for 5 months and Ficus benjamina L. for 10 months in media containing olive-mill waste compost (OWC), sphagnum peat and perlite in 1:3:4, 1:1:2, and 3:1:4 ratio (by volume), respectively, and their foliage and root growth was determined and compared to a control medium of 1 peat: 1 perlite (by volume). When up to 75% of peat in the control medium was replaced by OWC, C. variegatum foliage and root growth were similar compared with the control, while a 50% peat replacement gave the best growth. Syngonium podophyllum was more sensitive to peat replacement compared to C. variegatum, as only 25% of peat could be replaced by OWC without any reduction in foliage growth. The dry weight of the roots was not affected in all media tested. In F. benjamina, peat could be replaced up to 75% without effects on plant height and lateral shoot number, while the length of the laterals was progressively reduced with increasing OWC level. However, only at the highest OWC level (75% peat replacement) the laterals were shorter compared with the control. There was also a progressive reduction of main stem diameter, foliage fresh weight, and root dry weight with increasing OWC level in the medium. Even the lowest OWC level (25% peat replacement) caused a decrease of foliage and root weight compared with the control, with no effect though on plant visual quality. Even a 25% peat replacement by OWC caused an increase in bulk density. A considerable decrease of total porosity and readily available water were measured in media where 50% or 75% of peat was replaced by OWC. The pH of the medium with the highest OWC level was high during the first 4 months of culture compared to the other media. The electrical conductivity initially related to OWC level, but it decreased to values similar to that in the control medium during the first month of culture.

Changes in the chemical and physicochemical properties of the solid fraction of cattle slurry during composting using different aeration strategies

Replacement of peat as a growing medium by a renewable material, such as an organic waste, is an issue of concern since harvesting of peat has a considerable environmental impact and, actually, it is a non-renewable resource. Cattle manure is a readily available organic waste, which means that once it goes through the composting process, it can be used as an alternative to peat, specifically, the solid fraction obtained from mechanical liquid–solid separation of cattle slurry (SF). Studies have shown it to be suitable for such uses. The purpose of this study was to detect possible changes in the physicochemical and chemical properties of SF when it is composted using different aeration strategies, with an emphasis on the changes that would make it feasible for use as a substrate. With this aim in mind, an experiment was designed with three aeration strategies that would be used during composting. The first consisted of applying air through a static method (forced ventilation). The second involved improving aeration by adding a bulking agent and a dynamic turning method. In the third strategy, aeration was carried out by turning (control). The results show that the different aeration strategies had a clear effect on the evolution of pH, electrical conductivity (EC), nitrate-N, ammonia-N and bicarbonate content. Nitrification was favored under good aeration conditions using the static composting method, probably due to the greater availability of ammonia-N that was transformed into nitrate-N. In general, the low buffering capacity allowed for a reduction of the pH during the curing stage of composting (in conjunction with low temperatures during this period), a characteristic that favors the use of this compost as a growing medium. We also conclude that measuring bicarbonate levels during composting could be used as an indicator of the possible acidification of the material and as a way of evaluating the level of material aeration.

Improving quality of composted biowaste to enhance disease suppressiveness of compost-amended, peat-based potting mixes

Biowaste can be converted into compost by composting or by a combination of anaerobic digestion and composting. Currently, waste management systems are primarily focused on the increase of the turnover rate of waste streams whereas optimisation of product quality receives less attention. This results in low quality composts that can only be sold on bulk markets at low prices. A new market for quality compost could be potting mixes for horticultural container-grown crops to partially replace non-renewable peat and increase the disease suppressiveness of potting mixes. We report here on the effect of wetsieving biowaste prior to composting on compost quality and on disease suppressiveness against the plant pathogen Pythium ultimum of peat mixes amended with this compost. The increased organic matter and decreased salt content of the compost allow for significantly higher substitution rates of peat by compost. In this study up to 60% v/v compost peat replacement did not affect cucumber growth. However, disease suppressiveness of the potting mixes strongly increased from 31 to 94% when the compost amendment rate was increased from 20 to 60%. It was shown that general disease suppression for P. ultimum can only be effective when the basal respiration rate is sufficiently high to support microbial activity. In addition, organic matter of the compost should reach a sufficient stability level to turn from disease conducive to disease suppressive. Increasing the compost addition from 20 to 60% did not significantly affect plant yield, yield variation were due to differences in nutrient levels. It can be concluded that compost from wetsieved biowaste has high potential to replace peat in growing media for the professional market.

Effects of Compost Amended Container Media on Ornamental Plant Growth

Compost has great potential for use in horticulture; however, the relationship between compost feedstock materials and resultant compost characteristics must be well understood. Research examining plant growth response from the addition of compost to container growing media is limited. This research had two parts: the first part examined the relationship between compost feedstock materials and resultant mature compost characteristics. The second part investigated plant growth responses when compost replaced the peat component of container growing media. Two feedstock treatments were aerobically composted in turned windrows. Compost characteristics examined include pH, EC, C:N Ratio, Solvita Maturity, and several biological characteristics (total and active bacteria, total and active fungi, protozoa, spore forming bacteria, E. coli O157:H7, and total coliformic bacteria). To examine plant growth response, compost was substituted for peat (from 0%-40% by total volume) in container growing media. Crops tested were Antirrhinum majus `Rocket White', Viola × wittrockiana `Crown Azure', Oriental Hybrid Lilium `Siberia', and Chrysanthemum × grandiflorum `Yellow Kodiak'. Quantitative plant growth response measurements (shoot fresh and dry weight, percent root necrosis, flower number, and flower size) were recorded and compared by treatment. Despite initial feedstock differences between the two compost treatments, both resulted in similar compost biology and species richness. Coliformic bacteria and E. coli O157:H7 levels were below detection limits in final compost. Choice of compost feedstock materials had a significant effect on the chemical characteristics of the finished product. Compost replacement for peat resulted in plant growth greater than or equal to those of the control treatment.

Olive-mill wastes compost as growing medium component for the production of poinsettia

The research work was conducted in order to investigate the possibility of using olive-mill wastes compost (OWC) in the production of ornamentals replacing part of the peat in the growing medium. Rooted cuttings of Euphorbia pulcherrima cv. Peterstar white were grown in media containing OWC, peat and perlite in various ratios, and their vegetative growth, root growth and flowering was determined. A medium of 1 peat:1 perlite (by volume) was used as control. Increasing replacement of the peat in the medium by OWC, up to 75%, caused analogous increase of the electrical conductance that was however rapidly reduced during the culture period. A total of 50 and 75% replacement of peat caused decrease of the total porosity and the easily available water. Increasing replacement of peat by OWC induced a gradual decrease of the plant height, bract number and node number where the first bract was initiated. All the above parameters of growth were significantly reduced even when 25% of peat was replaced, except the bract number that was significantly reduced only in case of 50% or more peat replacement. Root dry weight was reduced only when 75% of the peat was replaced. The restriction of vegetative growth occurred only during the first month of culture in media with 25 and 50% peat replacement, while in 75% replacement there was growth restriction all over the culture period. Media with 50 and 75% peat replacement caused delayed pigmentation of the bracts and flowering, while plants in the medium with 25% peat replacement showed colour and flowered simultaneously with the control.

Compost and Rubber Tire Chips as Peat Substitutes in Nursery Container Media: Growth Effects

Abstract This research investigated the feasibility of using composted yard wastes, composted municipal solid waste and shredded rubber tire chips in nursery container media. Containerized Physocarpus opulifolius ‘Dart's Gold’, Forsythia × ‘Meadowlark’, Spiraea × billiardii, Juniperus chinensis ‘Seagreen’, J. sabina ‘Mini Arcade’, J. horizontalis ‘Hughes’, and Lamiastrum galeobdolon were grown in media amended with five recycled waste materials used as peat substitutes in a standard container medium of composted woodchips, peat, and sand (3:2:1 by vol). Waste materials used included three yard waste composts, one municipal solid waste compost and shredded rubber tire chips. Fifty or 100% of the peat in the standard growing medium was replaced with each amendment. Ten treatments (five amendments, each at 50% and 100% peat replacement) and a control (standard medium) were used for all seven plant species. Visual ratings, height and width measurements (crown volume), number of growing points and plant dry weights indicated that media in which 50% of the peat was replaced by an amendment produced larger plants of superior quality compared to the control. Rubber tire chips were acceptable as a 50% peat substitute for plants that prefer well-drained conditions, while 100% peat substitution with tire chips was detrimental to plant growth and performance. Use of immature compost in container media negatively influenced plant growth.

Compost and Rubber Tire Chips as Peat Substitutes in Nursery Container Media: Effects on Chemical and Physical Media Properties

Abstract Physocarpus opulifolius ‘Dart's Gold’, Forsythia x ‘Meadowlark’, Spiraea x billiardii, Juniperus chinensis ‘Seagreen’, J. sabina ‘Mini Arcade’, J. horizontalis ‘Hughes’, and Lamiastrum galeobdolon were grown in container media amended with three yard waste (YW) composts, one municipal solid waste (MSW) compost and shredded rubber tire chips. Each of the five amendments was used to replace 50% or 100% of the sphagnum peat in a standard container medium resulting in eleven media treatments. Effects of peat replacement with compost or tire chips were compared relative to chemical and physical media characteristics. Amendments evaluated had limited long term nutritional value. Initial pH was increased when peat was replaced with compost or rubber tire chips; the increase in pH was proportional to the amount of peat replaced (50 or 100%). Over time, pH of all media equilibrated with irrigation water pH. Soluble salts were reduced for media amended with rubber tire chips while peat replacement with compost had variable effects on soluble salt levels based on compost source. Media amended with compost exhibited increased bulk density and decreased porosity, water infiltration capacity and water holding capacity compared to the standard, peat-based control medium. Peat replacement with rubber tire chips increased bulk density and porosity and decreased water holding capacity compared to the standard control medium. Water infiltration capacity was greatly increased and water holding capacity decreased when peat was replaced 100% with rubber tire chips.

Properties of coir dust, and its use in the formulation of soilless potting media

Abstract Data from two experiments have shown that for adequate growth of Petunia ’Celebrity Salmon’ in soilless potting media based on or containing coir dust it was necessary to amend the media with Ca, S, Cu and Fe. When coir dust is used as a direct replacement for natural peat, about 10 mg/L medium extra N per week must be provided. The high K content of coir dust means that fertilizers need not contain as much K as is normally used for plants in media based on other products. The high Cl content of some coir products requires that they be leached if they are to make up a high proportion of a medium. The low CEC of the coir products (21–30 m.m (+)/L, compared with 78 m.m (+)/L for a peat), indicates a low ability to retain cations and to buffer against pH change. Two coir products had lower air‐filled porosities than did the peat tested and they retained more water at 10 kPa suction.

The history of Erica erigena R. Ross, an Irish plant with a disjunct European distribution

AbstractScanning electron microscopy combined with pollen, spore, rhizopod and fungal analyses of two peat profiles at Claggan Mountain, Co. Mayo, sheds new light on the Holocene history of Erica erigena in western Ireland. This heather is referred to the Mediterranean‐Atlantic group in the Irish flora, and is remarkable for its disjunct distribution in Europe, where it occurs in Ireland, Bordeaux in France, and in Spain and Portugal.Scanning electron microscopy has proved a powerful tool, allowing the unambiguous identification of ericoid pollens to species level and it is used to identify the first occurrence of Erica erigena pollen in the peat profiles. Radiocarbon dating of the profiles shows that Erica erigena is a relatively recent arrival at Claggan Mountain, appearing for the first time in the historic period at 1431 AD. The details of vegetational changes associated with the expansion of E. erigena have been explored by conventional pollen, spore, rhizopod and fungal analyses. Drying of the peat surface and replacement of bog vegetation by ericaceous heathland during a period of marked agricultural activity in the region was associated with its spread.The relatively recent arrival of E. erigena at Claggan Mountain, suggests that introduction might explain its presence here, and its disjunct distribution in Europe. Documented trade and pilgrimage routes between Ireland and those areas in Europe where the heather occurs may have allowed its recent introduction into Ireland. Further pollen analysis work, using SEM techniques, will be required if an earlier occurrence for the heather in Ireland is to be proved. The combination of techniques described here may prove useful in the study of the history of other plants with pollen that is difficult to identify using conventional light microscopy.

Some skeletal measurements in patients with primary anorexia nervosa

This study assesses the potential for composted bamboo residues to serve as a renewable replacement for peat in horticultural growing media. Bamboo residues and wheat bran compost (ratio 90:10) were prepared in two batches, with (B1) and without (B2) effective microorganisms, and mixed with peat at 25%, 50%, 75%, and 100% by volume. Both batches were then used in greenhouse tests with two horticultural plants, Osmanthus fragrans (Thunb.) Lour. and Hydrangea macrophylla (Thunb.) Ser., using pure peat as a control. Batch B1 showed higher peak temperature and longer thermophilic phase than B2 during composting, and had higher N but lower total C and C/N ratio than B2. The addition of either batch to the growth media increased bulk density, particle density, and air space compared with pure peat, but decreased total pore space and total water-holding capacity. At lower compost content, the physical and chemical properties of the test batches were very similar to those of an ideal substrate, especially those mixed with B1. Plants grown in media mixed with B1 (25% or 50%) or B2 (25%) showed no significant differences in growth rates for height and ground diameter compared to those of the pure peat control. The results suggest that using effective microorganisms can increase mineralization during composting of bamboo residues, and that composted bamboo residues should be considered as a component of horticultural growth media in partial substitution for costly and less sustainable peat.