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Peat is an unrenewable resource. Compost can partially replace peat in the growing seedling substrates due to its high electrical conductivity (EC), bulk density (BD), and pH. This study aimed to assess the potential of substituting peat for seedling substrate with compost made from a mixture of agricultural and agro-industrial wastes. Four compost piles (C1–C4) were constructed as follows: C1: a 1:1:1.5 weight ratio mixture of filter mud, mushroom waste, and date-palm fronds, while C2–C4: a 0.5:1 weight ratio mixture of either bagasse, cutting grassland, or date-palm fronds and cattle dung. After four months of decomposition, the compost's physical, chemical, and biological properties were estimated in comparison to commercial compost (CC), peatmoss (PM), and their ideal ranges (IR) for seed germination and seedling growth. Composts differed significantly in their physical and chemical properties. Some composts revealed property values within the IR. In comparison to PM, Composts have a lower C/N ratio and organic matter, along with higher BD, EC, and pH. Cattle manure enhanced organic matter and carbon, total nitrogen and potassium, and ammonium levels, and reduced ash levels in C2–C4 compared to filter mud in C1. In winter 2018 and 2019, C1–C4 substrates were compared with CC and PM substrates to determine their suitability for producing crisp lettuce 'Big Bell' seedlings under plastic-house conditions. Substrates had significant effects on lettuce seedling traits. Shoots of C2–C4 substrate seedlings grew more rapidly than those of other substrate seedlings due to the increased length and diameter of their stem and leaf area. [ABSTRACT FROM AUTHOR]

The rapid growth of the horticultural industry has increased demand for soilless cultivation substrates. Peat, valued for its physical and chemical properties, is widely used in soilless cultivation. However, peat is non-renewable, and over-extraction poses serious ecological risks. Therefore, sustainable alternatives are urgently needed. Ammonium incubation, a novel method to reduce phytotoxicity, offers the potential for green waste, a significant organic solid waste resource, to substitute peat. This study optimized the ammonium incubation process to reduce green waste phytotoxicity. It systematically examined different nitrogen salts (type and amount) and environmental conditions (temperature, aeration, duration) affecting detoxification efficiency. Results show a significant reduction in phytotoxicity with ammonium bicarbonate, carbonate, and sulfate, especially carbonate, at 1.5%. Optimal conditions were 30 °C for 5 days with regular aeration. Under these conditions, ammonium salt-treated green waste significantly reduced total phenolic content and stabilized germination index (GI) at a non-phytotoxic level (127%). Using treated green waste as a partial peat substitute in lettuce cultivation showed promising results. This low-cost, low-energy method effectively converts green waste into sustainable peat alternatives, promoting eco-friendly horticulture and environmental conservation. [ABSTRACT FROM AUTHOR]

The purpose of this work was to explore the feasibility of replacing all or part of peat with composted green waste (CGW) for vinca (Catharanthus roseus (L.) G. Don) and zinnia (Zinnia elegans Jacq.) cultivation. Seven different growing media were prepared as follows (volume/volume): T1, 100% CGW; T2, 80% CGW + 20% peat; T3, 60% CGW + 40% peat; T4, 50% CGW + 50% peat; T5, 40% CGW + 60% peat; T6, 20% CGW + 80% peat; and T7, 100% peat. In the course of the experiment, the physicochemical properties of the seven media were analyzed, and the growth of vinca and zinnia was determined. Studies showed that replacing peat completely or partially with CGW could significantly enhance the nutrient content, bulk density, water-holding capacity, total porosity, aeration porosity, water-holding porosity, organic matter, pH, and electrical conductivity of growing media. In comparison with what observed with T7 (control), shoot fresh weight (SFW), shoot dry weight (SDW), root fresh weight (RFW), root dry weight (RDW), plant height (HP), root length (RL), flower number (FN), total chlorophyll, and the content of chlorophyll a, chlorophyll b, and carotenoids in the leaves of vinca cultivated under T5 conditions increased by 36%, 34%, 84%, 27%, 34%, 25%, 157%, 62%, 60%, and 33%, respectively; SFW, SDW, RFW, RDW, HP, RL, FN, total chlorophylls, and the content of chlorophyll a, chlorophyll b, and carotenoids in the leaves of zinnia increased by 341%, 296%, 365%, 302%, 206%, 93%, 180%, 56%, 49%, 67%, 110%, respectively. [ABSTRACT FROM AUTHOR]

The rapid growth of the horticultural industry has increased demand for soilless cultivation substrates. Peat, valued for its physical and chemical properties, is widely used in soilless cultivation. However, peat is non-renewable, and over-extraction poses serious ecological risks. Therefore, sustainable alternatives are urgently needed. Ammonium incubation, a novel method to reduce phytotoxicity, offers the potential for green waste, a significant organic solid waste resource, to substitute peat. This study optimized the ammonium incubation process to reduce green waste phytotoxicity. It systematically examined different nitrogen salts (type and amount) and environmental conditions (temperature, aeration, duration) affecting detoxification efficiency. Results show a significant reduction in phytotoxicity with ammonium bicarbonate, carbonate, and sulfate, especially carbonate, at 1.5%. Optimal conditions were 30 °C for 5 days with regular aeration. Under these conditions, ammonium salt-treated green waste significantly reduced total phenolic content and stabilized germination index (GI) at a non-phytotoxic level (127%). Using treated green waste as a partial peat substitute in lettuce cultivation showed promising results. This low-cost, low-energy method effectively converts green waste into sustainable peat alternatives, promoting eco-friendly horticulture and environmental conservation.

Peat is the major constituent of horticultural growing media. Due to its high climate footprint, its extraction and use are controversial and the need to limit its use is widely recognised. The Peat Use Reduction Strategy of the German government aims to phase out its use and replace it with renewable materials. Despite large potential, stakeholders consider the availability of peat substitutes in sufficient quantity and quality as a critical issue. The goal of this research is to systematically investigate the challenges and opportunities for substituting peat in the resource base of the growing media industry. Based on deep-dive interviews with German growing media producers, the factors determining the supply and use of the main growing media constituents—peat, green compost, wood fibres, composted bark and coir products—were analysed. The results show the critical role of the processing infrastructure on transportation distances and the quality and quantity of the market supply. Additionally, competition with other sectors affects the availability of materials for the growing media industry. Moreover, peat is still economically advantageous compared with its substitutes. Even if this advantage declines due to consumer awareness and the end of domestic extraction, the end of peat use would probably imply new policy measures. [ABSTRACT FROM AUTHOR]

Using rabbit manure to prepare growing media is an effective method to solve environmental pollution and realize resource utilization. The solution to rabbit manure management is the composting process which could produce compost suitable for seedling nursery blocks, which could improve transplanting efficiency and seedlings' survival rate. Seedling nursery blocks were obtained by mixing rabbit manure compost, vermiculite, rice straw, and peat. The effect of cold pressing parameters, including moisture content (25–45%), binder content (1–5%), molding compression ratio (2.5–4.5:1), and strain maintenance time (0–120 s), were investigated on blocks quality (i.e., ventilatory porosity, relaxation density, compressive resistance, and specific energy consumption) through a general rotation combined experiment. These results showed there were significant interaction effects between molding compression ratio and moisture content, moisture and binder content, binder content and strain maintenance time, and molding compression ratio and binder content on block quality. The optimal parameters for manufacturing blocks were that the molding compression ratio, moisture content, binder content, and strain maintenance time were 4:1, 33.5%, 3.1%, and 60 s, and the relaxation density, ventilation porosity, and specific energy consumption were 363.31 kg/m3, 18.72%, and 0.44 J/g, which could achieve emergence performance. [ABSTRACT FROM AUTHOR]

The provision of raw material is an important ecosystem service provided by peatlands. Using materials produced on re-established peatland sites can help to increase the interest of stakeholders in expediting further restoration measures. Promising possibilities include paludiculture and Sphagnum farming, which offer new perspectives for exploring renewable alternatives to peat as constituents of growing media. Therefore, gaining knowledge about processing and physical properties of the material becomes increasingly necessary. The hydro-physical properties of harvested and processed Sphagnum palustre L. biomass can compete with those of peat and coir, which are materials traditionally used in the horticultural industry. Even a partial substitution of peat with Sphagnum biomass increased maximum water-holding capacities and plant available water contents of mixtures while increasing wettability and hydration efficiency.

Peat is the major constituent of horticultural growing media. Due to its high climate footprint, its extraction and use are controversial and the need to limit its use is widely recognised. The Peat Use Reduction Strategy of the German government aims to phase out its use and replace it with renewable materials. Despite large potential, stakeholders consider the availability of peat substitutes in sufficient quantity and quality as a critical issue. The goal of this research is to systematically investigate the challenges and opportunities for substituting peat in the resource base of the growing media industry. Based on deep-dive interviews with German growing media producers, the factors determining the supply and use of the main growing media constituents—peat, green compost, wood fibres, composted bark and coir products—were analysed. The results show the critical role of the processing infrastructure on transportation distances and the quality and quantity of the market supply. Additionally, competition with other sectors affects the availability of materials for the growing media industry. Moreover, peat is still economically advantageous compared with its substitutes. Even if this advantage declines due to consumer awareness and the end of domestic extraction, the end of peat use would probably imply new policy measures.

The addition of Sphagnum to peat-based growing media (‘Sphagnum replacement’) influences plant performance. The primary physical effect of Sphagnum addition appears to be enhanced water retention. Good performance of plants cultivated in Sphagnum seems partly explainable in terms of its water retention properties. The large body of nutrient solution retained in Sphagnum can delay disadvantageous changes in its concentration during cultivation. The physical quantity of Sphagnum per unit volume, i.e. its bulk density, governs the volume of retained water and thus determines the strength of effects contributing to plant performance. When subjected to severe drought, plants cultivated in Sphagnum did not show clear signs of water deficit up to at least 1,572 hPa of matric suction, which is the estimated wilting point for plants grown in light peat. Using Sphagnum to replace peat in the growing medium appears advantageous to plants not only during drought but also during ordinary greenhouse cultivation.

Using rabbit manure to prepare growing media is an effective method to solve environmental pollution and realize resource utilization. The solution to rabbit manure management is the composting process which could produce compost suitable for seedling nursery blocks, which could improve transplanting efficiency and seedlings’ survival rate. Seedling nursery blocks were obtained by mixing rabbit manure compost, vermiculite, rice straw, and peat. The effect of cold pressing parameters, including moisture content (25–45%), binder content (1–5%), molding compression ratio (2.5–4.5:1), and strain maintenance time (0–120 s), were investigated on blocks quality (i.e., ventilatory porosity, relaxation density, compressive resistance, and specific energy consumption) through a general rotation combined experiment. These results showed there were significant interaction effects between molding compression ratio and moisture content, moisture and binder content, binder content and strain maintenance time, and molding compression ratio and binder content on block quality. The optimal parameters for manufacturing blocks were that the molding compression ratio, moisture content, binder content, and strain maintenance time were 4:1, 33.5%, 3.1%, and 60 s, and the relaxation density, ventilation porosity, and specific energy consumption were 363.31 kg/m3, 18.72%, and 0.44 J/g, which could achieve emergence performance.

Due to the major environmental impact of peat-based growing media production and the need of lowering greenhouse gas emissions in all sectors, a wider application of peat substitutes in growing media is requested. All peat substitutes under use have constraints associated with their properties. Therefore, a preliminary test procedure for identifying new raw materials as peat substitutes in growing media was developed and validated. By applying the preliminary test procedure, the potential limitations of cultivation of potential peat substitutes are indicated, and measures for cultivation regulation are recommended. For the development of the new preliminary test procedure, four raw materials were investigated: composted heather, alder, cattail, and reed. The preliminary test procedure comprises several material and technological criteria as well as aspects of plant cultivation, enabling the evaluation of the raw materials and the processed components for growing media. Results derived from the preliminary test procedure were checked and confirmed by experiments with horticultural crops in different sections of commercial horticulture. Within two years, the identification of new peat substitutes was possible by the application of the preliminary test procedure and its test criteria, which provide a structure for the systematic investigation of potential new peat substitutes starting with the raw material. [ABSTRACT FROM AUTHOR]

The surface biomass of moss dominated by Sphagnum fuscum (Schimp.) Klinggr. (Rusty Bog-moss) was harvested from a sparsely drained raised bog. Physical properties of the Sphagnum moss were determined and compared with those of weakly and moderately decomposed peats. Water retention curves (WRC) and saturated hydraulic conductivities (Ks) are reported for samples of Sphagnum moss with natural structure, as well as for samples that were cut to selected fibre lengths or compacted to different bulk densities. The gravimetric water retention results indicate that, on a dry mass basis, Sphagnum moss can hold more water than both types of peat under equal matric potentials. On a volumetric basis, the water retention of Sphagnum moss can be linearly increased by compacting at a gravimetric water content of 2 (g water / g dry mass). The bimodal water retention curve of Sphagnum moss appears to be a consequence of the natural double porosity of the moss matrix. The 6-parameter form of the double-porosity van Genuchten equation is used to describe the volumetric water retention of the moss as its bulk density increases. Our results provide considerable insight into the physical growing media properties of Sphagnum moss biomass.

The provision of raw material is an important ecosystem service provided by peatlands. Using materials produced on re-established peatland sites can help to increase the interest of stakeholders in expediting further restoration measures. Promising possibilities include paludiculture and Sphagnum farming, which offer new perspectives for exploring renewable alternatives to peat as constituents of growing media. Therefore, gaining knowledge about processing and physical properties of the material becomes increasingly necessary. The hydro-physical properties of harvested and processed Sphagnum palustre L. biomass can compete with those of peat and coir, which are materials traditionally used in the horticultural industry. Even a partial substitution of peat with Sphagnum biomass increased maximum water-holding capacities and plant available water contents of mixtures while increasing wettability and hydration efficiency. [ABSTRACT FROM AUTHOR]

Highlights • Co-composting reduces the germination and growth inhibiting effects of hydrochars. • High amount of composted hydrochar improves vegetative and generative plant growth. • Ratio of hydrochar to compost is more important than the type of hydrochar. • Plant growth on co-composted hydrochar substrates (1:1) is equal to gardening soil. • Salinity, pH value and density of substrates strongly influence plant growth. Abstract Hydrothermal carbonization (HTC) is a thermo-chemical process, which converts biomass into a coal-like product, referred to as hydrochar. Hydrochars have low pH and salinity, a high water holding capacity and cation exchange capacity, and thus are correlated to the requirements of horticultural substrates. However, germination- and growth-inhibiting effects were frequently observed in experiments using untreated fresh hydrochars. In this study we investigated the suitability of biological pretreated co-composted hydrochar substrates as growing media for horticultural crops. Hydrochars made from residue feedstocks, such as beer draff and green cuttings, were used to perform seed germination experiments with Chinese cabbage (Brassica rapa ssp. Pekinensis) on fresh, untreated and pretreated hydrochar-compost substrates and ii) pretreated hydrochar-compost substrates in a) different mixing ratios (10, 30 and 50% hydrochar), and b) using different hydrochars in a fixed mixing ratio of 50:50. Moreover, growth experiments with French marigold (Tagetes patula) for a growing season on the co-composted hydrochar substrates were performed. As reference substrates, a peat-based gardening substrate and a compost were used. Germination rate and plant growth were higher for co-composted substrates than on untreated freshly mixed substrates. Growth of French marigold increased with the amount of hydrochar in the mixtures up to equal growth quality compared to a peat-based gardening substrate. Substrate properties including salinity, density and pH value influenced the plant growth as well. The type of hydrochar had only a slight influence. [ABSTRACT FROM AUTHOR]

Due to the major environmental impact of peat-based growing media production and the need of lowering greenhouse gas emissions in all sectors, a wider application of peat substitutes in growing media is requested. All peat substitutes under use have constraints associated with their properties. Therefore, a preliminary test procedure for identifying new raw materials as peat substitutes in growing media was developed and validated. By applying the preliminary test procedure, the potential limitations of cultivation of potential peat substitutes are indicated, and measures for cultivation regulation are recommended. For the development of the new preliminary test procedure, four raw materials were investigated: composted heather, alder, cattail, and reed. The preliminary test procedure comprises several material and technological criteria as well as aspects of plant cultivation, enabling the evaluation of the raw materials and the processed components for growing media. Results derived from the preliminary test procedure were checked and confirmed by experiments with horticultural crops in different sections of commercial horticulture. Within two years, the identification of new peat substitutes was possible by the application of the preliminary test procedure and its test criteria, which provide a structure for the systematic investigation of potential new peat substitutes starting with the raw material.

This research evaluated green waste compost (GWC) and green waste vermicompost (GWV) as peat substitutes in growing media used for the production of geranium ( Pelargonium zonale L.) and calendula ( Calendula officinalis L.). Five growing media were prepared: 100% Peat (P), 50% Peat + 50% GWC (PC), 100% GWC (C), 50% Peat + 50% GWV (PV), and 100% GWV (V). Geranium and calendula seedlings were transplanted into each medium and were grown under commercial nursery conditions for 6 months, i.e., until they attained commercial size. The higher percentage of GWC and GWV in the growing medium could increase bulk density and air space; decrease total pore space and water-filled porosity; and increase pH, electrical conductivity, and macro- and microelement contents. The heavy metal contents of all growing media were within safe ranges. Particle-size distribution and fertility were superior in the vermicompost-based media than in the compost-based media. Geranium growth was reduced in media containing GWC (C and PC). Calendula growth in compost-based growing media was similar to or greater than growth in pure peat. Geranium and calendula growth and flowering were superior in all vermicompost-based media (PV and V) than in the control medium (P). These results indicate that GWV is better than GVC as a partial substitute for peat in the cultivation of geranium and calendula. [ABSTRACT FROM AUTHOR]

In the present work, a new simple and quick eco-friendly method is discussed to handle effectively the green wastes and produce a sustainable peat substitute of high quality on the large scale. Principal physicochemical parameters, i.e., temperature, moisture, specific weight, pH, electrical conductivity and, also, microorganisms, organic matter, humic substances, total Kjeldahl nitrogen and total organic carbon, C/N ratio, ash, metal content and phytotoxicity, were monitored systematically. Humic substances content values were interrelated to both C/N ratio and pH values and, similarly, bulk density, TOC, TKN, C/N, GI, ash and organic matter were found interconnected to each other. A novel biocatalyst, extremely rich in soil microorganisms, prepared from compost extracts and peaty lignite, accelerated the biotransformation. Zeolite was also employed. The compost does not demonstrate any phytotoxicity throughout the entire biotransformation process and has increased humic substances content. Both humic substances content and germination index can be employed as maturation indices of the compost. Addition of compost, processed for 60 days only, in cultivations of grass plants led to a significant increase in the stem mass and root size, annotating the significant contribution of the compost to both growth and germination. The product obtained is comparable to peat humus, useful as peat substitute and can be classified as a first class soil conditioner suitable for organic farming. [ABSTRACT FROM AUTHOR]

The economic importance of the bamboo cultivation in Asia is well known, but the recent rise of interest in Europe required more deep studies on growing techniques. Among the bamboo species, the Phyllostachys pubescens (Carrière) J. Houz. is appreciated for its multiple uses: landscaping, timber and shoots production. In order to identify the best and sustainable combination of substrates and fertilization regimes, a nursery experimental trial was performed in 2016. Eight treatments (four substrates and two fertilization regimes) with 256 young plantlets divided into four randomized blocks were evaluated. The substrates used were: 40% peat, 40% coconut fibers, 20% pumice (standard substrate, S1); 30% peat, 40% coconut fibers, 10% rice husk, 20% pumice (S2); 30% peat, 40% coconut fibers, 20% rice husk, 10% pumice (S3); 30% peat, 40% coconut fibers, 20% wood fibers, 10% pumice (S4). The two fertilization regimes were: 1.6 g l-1 (A) and 0.8 g l-1 (B) NPK (16-11-10) Osmocote Exact®. All substrates were supplemented with a fungal inoculum (2.5 g l-1) and corrected with 2.5 × 10-3 g l-1 of CaCO3. The number of culms and leaves and the SPAD values of six plants of each blocks were monthly measured. Fresh and dry weights, before and after cultivation was recorded. Data were statistically analyzed. Results showed that rice husk should be used only in low percentage, but wood fiber can be more suitable for bamboo cultivation. The combination of alternative materials and low fertilization regimes (S1_B and S4_B) should be the key for a more sustainable cultivation for potted Phyllostachys pubescens in Europe. [ABSTRACT FROM AUTHOR]

Seven media amended with 30% to 75% (by volume) of spent mushroom compost (SMC) were trialed on two oak tree species to evaluate the possibility of using SMC for oak tree container seedling production by comparing the physical and chemical properties of media and assessing the plant growth of oak seedlings. The high electrical conductivity and pH of media amended with SMC decreased quickly by leaching. Seedling quality index of Quercus aliena decreased as the proportion of SMC increased in the media. Only the media with 50% or less SMC yielded seedlings similar to or better than the control. However, for Q. virginiana, all media except that without perlite gave similar or better quality seedlings than the control. Nitrogen, phosphorus and potassium contents of shoot were significantly increased in both species grown on SMC amended media, except the nitrogen of Q. virginiana. No visual symptoms of nutrient deficiency or toxicity were observed. In conclusion, in container seedling production, SMC can be used with perlite as a peat substitute up to 75% for the salt tolerant Q. virginiana, and 50% for Q. aliena. [ABSTRACT FROM AUTHOR]

A spent coffee ground compost (SCGC) was evaluated as an alternative component of growing media to partially replace commercial peat (CP) and fertilizers in the production of potted plants. Seven mixtures (CP 100% + solid mineral fertilizers, CP 100% + liquid mineral fertilizers, CP 90% + SCGC 10%, CP 80% + SCGC 20%, CP 70% + SCGC 30%, CP 60% + SCGC 40%, and CP 100% without fertilizers) were compared for the production of basil and tomato potted plants. SCGC used in a proportion up to 40% enhanced the general plant stand by affecting the dry weight and the measured foliar parameters. Tomato and basil recorded good growth rates on SCGC-amended media, showing quality indices similar to those obtained under fertilization, evidencing compost plant nutrition provision. SCGC appears to be suitable for application as a partial peat substitute in the production of potted plants. [ABSTRACT FROM AUTHOR]

Highlights: [•] The physicochemical parameters and GI ratios of GPC, GPV and SLC are determined. [•] Rosemary, lettuce and onion are plants sensitive to high compost dosages. [•] Leyland cypress and ornamental plants show good growth rates with 65% and 50% respectively of GPC dosage on substrates. [•] Leyland cypress growth is increased when 10% of slumgum compost is included as compared to the peat substrate. [•] 25% GPV mixed with peat could be used as a growth medium for rosemary, Leyland cypress, lettuce, onion, petunia and pansy. [Copyright &y& Elsevier]

A comparative study on the suitability of one compost and two vermicomposts, obtained from the same batch of tomato-crop waste, as growth media for ornamental plant production was carried out. Each material was mixed with Sphagnum peat at 100 : 0, 75 : 25, 50 : 50, 25 : 75, and 0 : 100 (peat control) proportions by volume. Two ornamentals ( Calendula officinalis, Viola cornuta) were sown and grown in the 13 substrates. Substrates were characterized physically and chemically. Seed germination, total leaf chlorophyll (SPAD units), plant growth, and plant nutrient concentrations were determined. The compost and the vermicomposts were markedly different from peat. Compost and the vermicomposts had greater bulk density and lower total porosity than peat. Compost had larger aeration and lower water-holding capacity than vermicomposts and peat. Compost and vermicomposts were alkaline (pH = 8.8 on average) whilst peat was acidic (pH = 5.9). Electrical conductivity was low in peat (0.23 dS m-1) and vermicomposts (0.65 dS m-1), and high in compost (2.85 dS m-1) due to the high concentrations of K+ and SO $ _4^{2-} $. Mixing compost and vermicomposts with peat produced substrates with intermediate characteristics. Physical properties were within adequate range for all mixes except for the compost ones. pH was within adequate range only in pure peat, and salinity was extremely high in the compost mixes. Compost was phytotoxic, as shown by the strong reduction of seed germination, chlorophyll content, and plant growth of both ornamentals. Vermicomposts did not affect seed germination but reduced plant growth, though much less than compost. Mixing these materials with peat improved germination and growth. The diluted materials (compost at the 25 : 75 and vermicomposts at the 50 : 50 and 25 : 75 proportions) produced good-quality plants. [ABSTRACT FROM AUTHOR]

As nursery and greenhouse growers adopt more sustainable production practices, interest has grown in local, recycled organic materials (ROM) as partial or complete substitutes for peat in container substrates. Chrysanthemum xmorifolium Ramat. 'Shasta' was grown in substrates formulated from ROM: 1) 100% Groco, an anaerobically digested biosolids composted with sawdust; 2) 100% Tagro, a thermophilically digested class A biosolid mixed with sawdust and sand; 3) 100% dairy compost, the solids screened from dairy manure slurry and then composted; 4) 100% dairy fiber, the solids fraction from an anaerobic dairy manure digester; 5) 50% Groco: 50% douglas-fir bark (mixed by volume); 6) 50% Tagro: 50% bark; 7) 50% dairy compost: 50% bark; 8) 50% dairy fiber: 50% bark; and 9) the control, a commercial peat-perlite mixture. Soluble fertilizer [200 mg⋅L-1 nitrogen (N)] was applied every second day (high N) or every fourth day (low N). Water was applied through capillary mat subirrigation or overhead sprinkler surface irrigation. Surface irrigation and high N produced shoot dry weight, shoot growth index (SGI), quality, and flower bud counts similar to controls in all ROMs but Groco. Groco SGI was similar to the control but the other parameters were lower. Surface-irrigated, low N shoot dry weight, SGI, and flower buds in all ROM equaled or exceeded the control and quality was similar to or better than controls in all but dairy compost:bark. Subirrigated and high N substrate comparisons indicated that growth, quality, and flower bud measurements were similar to the control except for Groco in which performance was reduced. Low N rate subirrigation produced dry weight, SGI, quality, and flower buds similar to or better than the control in all bur the Groco and dairy compost:bark substrates. The generally inferior performance in Groco is likely the result of its low water-holding capacity. In substrates with higher available N (Groco, Tagro, Tagro:bark, and dairy fiber), plant growth parameters generally did not respond to doubling the applied N; in the other substrates, including the control, growth generally increased in response to additional N. Measured differences in leaf color across treatments were not large. Root growth of plants in the experimental substrates was similar to the control in both irrigation systems. Substrate effects on leachate nitrate-N were small and inconsistent. When properly constituted, biosolids and dairy manure can be used as substrates under reduced fertilization with both surface and subirrigation systems. [ABSTRACT FROM AUTHOR]

Abstract: This study aimed to assess the colonization of thermally treated (i.e. torrefied) grass fibers (TGFs), a new prospective ingredient of potting soil. Eleven bacterial strains and one fungus, Coniochaeta ligniaria F/TGF15, all isolated from TGF or its extract after inoculation with a soil microbial community, were tested for their ability to colonize TGF. Surprisingly, none of these bacteria were able to directly colonize TGF either as single inoculants or as a consortium. Furthermore, bacterial persistence or growth in TGF was not improved by the addition of nutrients or a surfactant. Only extensive washing of the substrate, presumably removing bacteriostatic or bactericidal compounds, allowed bacterial growth on the fibers. Strikingly, the fungal strain consistently colonized TGF up to high densities (up to 1010 CFU per g dry TGF). Given the unique capacity of this fungus to degrade toxic compounds including phenols, TGF was colonized with it for different periods of time, after which a consortium of seven selected bacterial isolates was added. Co-presence of the fungus, or 3 and 24h pre-colonization with it, was insufficient to create a habitable environment for the bacterial consortium. However, fungal pre-colonization of minimally 3 days allowed the bacterial consortium to colonize the TGF at numbers up to 109 to 1010 CFU per g dry substrate. The resultant bacterial community consisted of at least four strains, i.e. Pseudomonas putida 15/TGE5, Serratia plymuthica 23/TGE5, Pseudomonas corrugata 31/TGE5, and Methylobacterium radiotolerans 56/TGF10, as shown by PCR of colonies on plates and PCR–DGGE profiling. Two persisters, S. plymuthica 23/TGE5 and P. corrugata 31/TGE5, were highly antagonistic towards several phytopathogenic fungi. Thus, a microbial community with plant-beneficial potential was established on TGF, provided that the fungus C. ligniaria F/TGF15 first creates habitable space in the matrix. [Copyright &y& Elsevier]

'Prestige' poinsettias (Euphorbia pulcherrima Willd. Ex Klotzsch) were grown at different fertilizer rates in three pine tree substrates (PTS) made from loblolly pine trees (Pinus taeda L.) and a peat-based control. Pine tree substrates were produced from pine trees that were chipped and hammer-milled to a desired particle size. Substrates used in this study included peat-lite (PL), PTS produced with a 2.38-mm screen (PTS1), PTS produced with a 4.76-mm screen (PTS2), and PTS produced with a 4.76-mm screen and amended with 25% peatmoss (v/v) (PTS3). Initial and final substrate physical properties and substrate shrinkage were determined to evaluate changes over the production period. Poinsettias were grown in 1.7-L containers in the fall of 2007 and fertilized at each irrigation with 100, 200, 300, or 400 mg·L -1 nitrogen (N). Shoot dry weight and growth index were higher in PL at 100 mg·L-1 N but similar for all substrates at 300 mg·L-1 N. Bract length was generally the same or longer in all PTS-grown plants compared with plants grown in PL at each fertilizer rate. Postproduction time to wilting was the same for poinsettias grown in PL, PTS1, and PTS3. Initial and final air space was higher in all PTSs compared with PL and container capacity (CC) of PTS1 was equal to PL initially and at the end of the experiment. The initial and final CC of PTS2 was lower than PL. The incorporation of 25% peat (PTS3) increased shoot dry weight and bract length at lower fertilizer rates compared with 4.76 mm PTS alone (PTS2). Substrate shrinkage was not different between PL and PTS1 but greater than shrinkage with the coarser PTS2. This study demonstrates that poinsettia can be successfully grown in a PTS with small particles (2.38-mm screen) or a PTS with large particles (4.76-mm screen) when amended with 25% peatmoss, which results in physical properties (CC and air space) similar to those of PL. [ABSTRACT FROM AUTHOR]

Abstract: Selected chemical and physical properties of 12 different pruning waste compost (PWC) samples were evaluated to assess their suitability as substrates for ornamental plants. Samples were taken periodically from the same composting facility over 18months in order to determine if there was any seasonal variability. In addition to the PWC samples, a Canadian Sphagnum peat and a commercial growing medium (CGM) were used as standard materials. With respect to PWC properties, pH values were above 8, significantly higher than the pH of peat and the commercial substrate. All samples showed adequate levels of organic matter and correspondingly high cation-exchange capacity (CEC) values. The C/N ratio varied between 22 and 48, significantly higher than the optimal values of 15–20. Although composts were sampled from piles established in different seasons, no significant differences were found in their chemical properties. However, water retention characteristics were affected by seasonal changes in components entering the facility. Comparing the properties of PWC to those of peat and commercial growing medium, this material appears to be an acceptable component of a substrate for container-grown ornamental plants. [Copyright &y& Elsevier]

The objective of this work was to study the use of pruning wastes compost (PWC) as a growing media component for ornamental plants. The main physical, chemical and biological characteristics of PWC were analysed in order to evaluate its suitability for use in soil-less cultivation. Six growth substrates were prepared by mixing PWC with peat (P), ground leaves (GL), sand (S) and spent mushroom compost (SMC) in different proportions. Two different pot experiments were carried out to test its characteristics of production using perennial ryegrass (Lolium perenne L.) and cypress (Cupressus sempervirens L.) as indicators and the different media as treatments.The growth experiments showed that PWC required mixing with a nutrient-richer material to produce higher results. Therefore, substrates containing SMC (PWC+P+SMC and PWC+SMC) seems to be the most adequate growing media. After the statistical analysis, we concluded that the PWC could be used as a growing media component. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

Using black soldier fly (Hermetia illucens [L.], Diptera: Stratiomyidae) larvae (BSFL) to upcycle urban solid waste into a growing medium for vegetable cultivation is a potential solution to ease cities' over-reliance on food imports and excessive waste generation. However, rapid composting by BSFL may be insufficient to remove phytotoxins from the waste and further composting may be necessary. Through a growth experiment on pak choi (Brassica rapa), this study evaluated the optimum performance of BSFL frass at three composting stages (freshly produced, composted with forced aeration and naturally composted in larval rearing chambers) in biochar-based substrate cultivation. Plants cultivated in the composted BSFL frass treatments grew larger than those in fresh frass, with 10% naturally composted BSFL frass (v/v) producing the most biomass among all treatments. A seed germination test suggested the presence of phytotoxins in the fresh frass and frass Fourier-transform infrared spectroscopy (FTIR) analysis showed that the fresh frass potentially had the highest phenol concentration. In terms of greenhouse gas emission, a life cycle analysis showed that all three types of frass had a lower global warming potential compared to incineration, with the fresh frass having the lowest emission, the frass composted using forced aeration having the second lowest and the naturally composted frass, the highest emission. Therefore, further composting of BSFL frass with forced aeration would be the most feasible method considering both its compost quality and environmental impact. Image 1 • Black soldier fly larvae (BSFL) frass tested as a sustainable compost. • Rapid composting by BSFL resulted in immature compost. • Further composting increased available nutrients and reduced phytotoxin content. • Pak choi grown in 10–30% BSFL frass (v/v) achieved the highest yields. • Compared to incineration, composted BSFL frass had a lower GWP. [ABSTRACT FROM AUTHOR]