Peat Vermiculite Research Articles

Thermal protection properties of profiled timber with peat-vermiculite insulation

Today, the use of environmentally friendly materials is becoming increasingly important. The construction of energy-saving buildings with enclosing structures made of insulated profiled timber, is one of the most promising areas in low-rise construction.Materials having minimum negative impact on the environment during their operation, include new construction insulation materials based on peat-vermiculite granules. The paper studies the main physical properties of wooden exterior walls made of profiled timber, in which peat vermiculite is used as insulation, thermal conductivity of which ranges from 0.05 to 0.06 W/(m·K). For this purpose, numerical simulation is performed for the heat-mass transfer in wooden enclosing structures made of insulated timber with three different connector options.The temperature and heat flow distributions are obtained as a result of modeling stationary thermal conductivity processes in timber structures. It is shown that plywood connectors do not affect the thickness temperature distribution in wooden walls with peat-vermiculite insulation. An increase in thermal conductivity of insulation has no significant effect on the temperature difference along the connector axis or outside the region of its temperature influence.It is found that the thickness of the peat-vermiculite insulation layer should be at least 0.176 m to ensure the compliance with the main requirements for thermal protection properties of enclosing structures in the climatic conditions of Tomsk. The greatest heat loss with a minimum insulation thickness is observed for the wall made of profiled insulated timber with T-shaped connectors. A high-strength timber with the additional central lamella has the best thermal protection with the lowest insulation thickness.

Fungal necromass increases soil aggregation and organic matter chemical stability under improved cropland management and natural restoration

The formation and stability of soil organic matter (SOM) is crucial for food security, soil health, and climate change mitigation. Although various SOM stabilization mechanisms have been proposed and investigated, the contribution of plant- and microbial-derived carbon into physical and chemical stabilization processes remain unclear. Therefore, this study investigates lignin phenols, microbial necromass, soil aggregation and SOM chemical composition under three cropland management and two natural restoration strategies: NPK, NPK + manure (NPK + M) and NPK + peat vermiculite (NPK + PV) after 5 years, and natural restoration for 10 and 40 years (NR10 and NR40, respectively). Addition of manure or peat vermiculite and NR40 increased soil organic carbon (SOC) by 86–122 % and 16 %, respectively, compared to the NPK fertilization. Lignin phenols and bacterial necromass-C were the highest under NPK + M, and lignin phenols increased by 0.07 g and microbial necromass-C by 0.44 g with each additional 1 g of SOC. Fungal necromass-C in NPK + PV was 0.14–1.1 times higher than in other treatments. The mean weight diameter of aggregates was the highest, while macroaggregate turnover was the slowest under NPK + PV, indicating increased soil aggregation and physical stability. Natural restoration reduced lignin phenols by 33–40 % and labile O-alkyl C by 4–9 %, but increased resistant alkyl C by 9–15 % compared with other treatments, reflecting the highest chemical stability. High fungal necromass was beneficial to the accumulation of particulate and mineral-associated C and aggregate stability, and decelerated macroaggregate turnover. Aromatic C increased but aliphatic-C/aromatic-C decreased with increasing fungal necromass-C. Consequently, fungal necromass C increases SOM physical stability by slowing aggregate turnover and enhances the chemical stability through the accumulation of recalcitrant C under improved cropland management and natural restoration.

Physical and mechanical properties of lightweight concrete based on gypsum binders and peat vermiculite granules

Introduction. An analysis of the literature and experimental data on the resource provision of the construction market has shown that the development of new and effective materials with improved quality parameters is an urgent task, and in the long term will serve as an impetus for the development of the building materials market. Currently, the peat industry in Russia is experiencing a serious decline in the extraction of peat raw materials, the reserves of which are practically inexhaustible. One of the possible ways to develop this industry in the Tomsk region can be the organisation of the production of competitive structural, heat-insulating and heat-insulating materials using local raw materials, namely lowland peat and vermiculite, which will improve the economic prestige of the region, create new enterprises and jobs.Materials and methods. The studies using the methods and tests set out in national standards were carried out. The measurement of the obtained material density was carried out in accordance with GOST 17177-94. The determination of the samples strength in compression and in bending was carried out in accordance with GOST 23789-2018. The determination of the moisture content percentage of the samples was carried out in accordance with GOST 23789-2018.Results. The results of the research made it possible to determine the basic requirements for the designed composition of lightweight concrete based on gypsum binders and peat vermiculite granules. The relationship between the strength characteristics and density of lightweight concrete has been studied, it has been established that at average density values in the range of 530-850 kg/m3, the resulting material meets the basic technical requirements of heat-insulating lightweight concrete (GOST 25820-2014).Discussion and conclusions. In the work, experimental studies determined the rational ratio of the components of lightweight concrete based on gypsum binder and peat vermiculite granules, at which the maximum value of their strength is achieved at a minimum average density. Based on the data obtained, it was found that in order to achieve the necessary physical and mechanical properties of lightweight concretes based on gypsum binders, the optimal size of peat-vermiculite granules should be no more than 5 mm.

Experimental evaluation of the rainfall retention and inorganic pollutant mitigation effect by dual-layer and polyacrylamide-modified green roofs.

Research on substrate layer modification and filler configuration is an important direction for improving the retention and interception efficiency of green roofs. In this study, four green roof modules were established using peat soil, vermiculite, and zeolite as the main substrate layer. In addition, a polyacrylamide (PAM) modifier was added and mixed with these substrates. By simulating seven rainfall events, this study calculated and analyzed the outflow of each green roof as well as the average event mean concentration (EMC) and cumulative outflow quantity (COQ) of turbidity, ammonia nitrogen ([Formula: see text]), nitrate nitrogen ([Formula: see text]), total nitrogen (TN), and total phosphorus (TP). At the same time, the nitrogen mass balance of each green roof was analyzed. The experimental results showed that the interception capacity of the LP module was higher than the unmodified green roofs under heavy rain conditions. The modules also showed an improved capacity to inhibit the leaching of [Formula: see text]; therefore, TN was effectively suppressed. However, suppression of [Formula: see text] did not significantly improve. The outflow turbidity from the MP and LP modules was low and stable, and the TP concentration showed no apparent change. After the simulated rainfall experiment with the rainfall of 426.3 mm, the proportion of TN leaching out of the LP module was at its lowest (0.85%), and the residual proportion of TN reached 80.7%. Overall, the addition of PAM to the dual-substrate layer can better form the soil aggregate structure, to improve the retention and purification effect of the extensive green roofs.

Biofertilizing Effect of Chlorella sorokiniana Suspensions on Wheat Growth

The potential of microalgae as a biofertilizer in agriculture is increasingly recognized. We studied the effect of applications of Chlorella on growth of wheat in terms of its phytostimulating capacity and its potential for substituting chemical fertilizers. Four biofertilizer treatments were used in this experiment: (i) Biomass of Chlorella sorokiniana harvested by centrifugation from cultures in the exponential growth phase and re-suspended in spent growth medium (Solution 1); (ii) filtered BG11 medium used for algae culture after the algae biomass was harvested (Solution 2); (iii) harvested algae that were re-suspended in fresh BG11 medium (Solution 3); and (iv) fresh BG11 medium (Control). Seeds of Triticum aestivum were germinated in pots containing a growing substrate (peat vermiculite 1:1 (v/v) mixture) and grown for 15 days with applications of the four treatments solutions. In general, plant length was increased by 30% with Solution 2; total dry biomass of aboveground and belowground parts were improved by 22% and 51%, respectively, in treatments with filtrate of Chlorella sorokiniana (Solution 2), as compared to the control, indicating that nutrients and extracellular substances excreted by algae in the filtrate were pertinent to the beneficial effects on plant growth.

Biochar effects on the seedling quality of Quercus serrata and Prunus sargentii in a containerized production system

Biochars are used to improve soil quality and crop productivity as well as to increase carbon sequestration in soil. However, it is important to identify the characteristics of biochar prior to its application because of the positive and negative effects on soil and crop productivity. The purpose of this study was to investigate the effects of charcoals on the growth and seedling quality of Quercus serrata and Prunus sargentii in a containerized seedling production system. Two of the charcoals used in our research were from oak tree; one produced at 1200 °C and the other at 700 ∼ 800 °C, and a bamboo charcoal produced at about 800 °C. Three charcoals were mixed with artificial soil (peat moss, perlite, and vermiculite with a ratio of 1:1:1 (v/v/v)), and applied commercial fertilizer at two concentrations; 0.5 and 1.0 g L−1. Growth parameters, such as height, root collar diameter, and dry weight, were decreased in charcoal treatments compared to control. However, charcoal treatments significantly increased the quality index of seedlings by 8.3% in Q. serrata and by 19.9% in P. sargentii. Our results suggested that charcoal can be applied to improve seedling quality in the containerized Q. serrata and P. sargentii seedling production system.

Comparison of Coconut Coir, Rockwool, and Peat Cultivations for Tomato Production: Nutrient Balance, Plant Growth and Fruit Quality.

Rockwool (RC) and peat are two common substrates used worldwide in horticultural crop production. In recent years environmental and ecological concerns raised the demand for reducing the use of RC and peat. Although coconut coir (CC) has been increasingly used as an alternative to RC and peat, it is still needed to comprehensively evaluate the feasibility of CC before widely used. To meet this need, CC, RC, and peat-vermiculite (PVC) cultivations were used as tomato cultivation substrates to evaluate their effects on EC, pH and mineral ions in root-zone solution and drainage, nutrient uptake by crops, nutrient balance of cultivation system, plant growth and fruit quality. In general, CC significantly increased K and S uptake by crops, photosynthesis, individual fruit weight and total fruit yield compared to RC, and increased P and K uptake by crops and total fruit yield compared to PVC. Moreover, CC significantly increased organic acid of fruit in first truss compared to both RC and PVC. The uncredited nutrient was overally lower under CC than under RC and PVC (the lower, the better). For all substrates, the blossom-end rot (BER) of fruit increased gradually from 3rd to 13th trusses. The BER of fruit was not significantly influenced by CC compared to RC or PVC, but was sginificantly decreased by PVC compared to RC. Our results infer that CC was a potential substrate that could be widely used in tomato production. However, the inhibition of BER was still a challenge when CC was used as cultivation substrate for tomato.

Norway spruce emblings as cutting donors for tree breeding and production

ABSTRACTIn the Nordic countries, Norway spruce (Picea abies) is a major species in tree breeding. In order to facilitate breeding work and availability of highly bred forest regeneration material, the time required for breeding and implementation of results should be shortened. This could be done by accelerating production of clonal material for field testing, and possibly for planting stock, by combining production of rooted cuttings with somatic embryogenesis (SE). This would allow efficient production of numerous plants of the same genotype, with equal age and propagation history between genotypes. In the present work, we studied the rooting potential of cuttings from Norway spruce emblings. Altogether 36 clones from 12 families representing elite breeding materials and ornamental forms were examined under different rooting conditions (container type and rooting media) in 2015 and 2016. Our results show that Norway spruce emblings are good donors for cuttings. Best combination (peat–vermiculite mixture and Plantek 81f containers) resulted in 91% rooting, variation among the tested clones of elite breeding materials being 55–100% per treatment. The rooting variation between families is acceptable for breeding purposes. High rooting (87–96%) of ornamental forms indicates propagation potential with the combination of SE and rooted cuttings.

Effect of humic acid as an additive to growing media to enhance the production of eggplant and tomato transplants

SummaryIn two experiments, conducted in 2011 and in 2012, 14 different growing media were prepared from peat moss, vermiculite, and/or perlite with or without 0.5 g l–1 humic acid (HA) to determine the optimum growing medium for eggplant (Solanum melongena L.) and tomato (Lycopersicum esculentum Mill.) transplants. None of the media tested affected the percentages of seedling emergence or survival in either crop, although the rates of emergence were affected. Higher dry weights, relative water contents, membrane stability indices, and N, P, and K uptake values were recorded for eggplant and tomato transplants in all HA-supplemented media than in the corresponding HA-free media. In terms of efficacy, the best medium among all 14 tested was 0.5 g l–1 HA + 50% (v/v) vermiculite + 50% (v/v) perlite, followed by 0.5 g HA + 65% (v/v) vermiculite + 35% (v/v) perlite, then 50% (v/v) vermiculite + 50% (v/v) perlite without HA. The first medium was significantly better for all traits measured than the standard medium currently used for tomato and eggplant transplant production in Middle Eastern countries.

Changes in the physical properties of two Acacia compost-based growing media and their effects on carob (Ceratonia siliqua L.) seedling development

In arid zones, the use of compost for plant production in forest nurseries is hindered by a lack of water. The main objectives of this study were (1) to evaluate the physical stability of composts produced from shredded branches of Acacia cyanophylla and A. cyclops subjected to a repeated drying and wetting cycles, similar to those used at the operational scale in nurseries in arid regions and to compare these composts with a standard peat-vermiculite (PV) substrate; (2) to identify the relevant substrate physical variables that correlate with seedling growth. Carob (Ceratonia siliqua L.) was cultivated during a production cycle of 27 weeks in a completely randomized block experiment. Substrate physical variables were measured at the beginning, middle and end of the experiment. Seedling growth variables were evaluated over the course of the production cycle, while gas exchange and water-relation variables were measured during a wetting and drying cycle at the end of the experiment. All three substrates produced vigorous seedlings with well-developed root systems that colonized the entire root plug. The growth of seedlings produced in the PV substrate was better than those grown in the compost-based substrates. No significant differences in gas exchange capacities and water relation variables were observed among the three substrates at the end of experiment with the exception of net photosynthesis, which was higher for the PV substrate at high substrate matric potential. Excessive drainage was negatively correlated with growth variables while water availability in the early growth phase and air porosity towards the end of experiment were positively correlated. Performance of the two composts could be increased by improving their initial structure and stability and by adjusting the irrigation regime.

The effects of soil sterilization, mycorrhizal inoculation, and rates of phosphorus on growth and survival of Kalopanax septemlobus microplants during the acclimatization period

In order to establish some cultural practices that can improve growth and survival of somatic embryo (SE)-derived microplants during the acclimatization period, Kalopanax septemlobus was uninoculated or inoculated with mycorrhizal fungi coded as AMM6 (a mixture of unidentified species of Glomus and Acaulospora collected in a closed mine tailing site in Bonghwa, Korea) during ex vitro and grown in oven-sterilized peat vermiculite medium. After 2 months, treated microplants were transferred into pots filled with the same medium amended with phosphorus fertilizer {0, 2, 4, 8, 16 and 32 mg P [as Ca(H2PO4)2·H2O] kg medium−1 coded as P0, P2, P4, P8, P16 and P32, respectively}. At this stage, inoculated plants were greener, with broader leaves and well-developed root systems and had higher survival than the uninoculated ones. After 6 months, inoculated plants were 54 % heavier than the uninoculated counterpart. In sterile medium, total dry weight of uninoculated plants was promoted at P8 and highest at P16. Total dry weight at P16 by uninoculated plants was attained at P4 by the mycorrhiza-inoculated counterpart. In non-sterile medium, total dry weight of inoculated plants was increased at P8. By contrast, uninoculated plants did not respond to the applied P rates. In conclusion, more SE-derived microplants survived and grew better in sterile medium. Maximum benefits from AMM6 was attained with applied 4 and 8 mg P kg medium−1 (P4–P8) in sterile and non-sterile medium, respectively.

Allometry, nitrogen status, and carbon stable isotope composition ofPinus ponderosaseedlings in two growing media with contrasting nursery irrigation regimes

Nursery irrigation regimes that recharged container capacity when target volumetric water content reached 72%, 58%, and 44% (by volume) influenced Pinus ponderosa Douglas ex Lawson & C. Lawson growth more than either a 1:1 (by volume) Sphagnum peat – vermiculite (PV) or a 7:3 (by volume) Sphagnum peat – sawdust (PS) medium. Exponential fertilization avoided confounding irrigation and fertilization. Temporary nitrogen (N) immobilization in PS caused transient allometric differences prior to hardening. Subsequent release of immobilized N during the onset of hardening, when daily N flux decreased from 4.2% to 1.6%, allowed PS seedlings to avoid foliar N dilution experienced by PV seedlings. Media yielded seedlings with similar final morphological characteristics, although PS seedlings had improved N status. At onset, particle density and volumetric water content were similar for both media, but PS held about 10% more water than PV at all water potentials at experiment conclusion. Exposure to the driest water content (44%) decreased seedling growth and root N status compared with cohorts that were provided ample moisture (72%). Despite maximum tissue heterogeneity within samples and regardless of irrigation regime, seedlings became 1.3‰ more depleted of13C as the growing season progressed. Refinement of sampling procedures, with focus on ontogenetics, may improve subsequent use of stable carbon isotopes in nursery research.

Evaluation of New Container Media for Aglaonema Production

Mandated processing of waste by‐products in the United States has inspired national interest in addressing the effectiveness of using composted biosolids and yard trimmings to grow containerized plants. Diamond bay Chinese evergreen (Aglaonema ‘Diamond Bay’) was transplanted in containers filled with one of eight formulated media (components added by volume). Medium 1 was a standard mix commonly used in Aglaonema production (5:2:3 peat–vermiculite–perlite); medium 2 was formulated on site to contain peat–bark–stalite–rice hulls–coir (2:2:3:1:2); media 3 and 4 contained 40% biosolid–yard waste compost instead of peat and with or without 20% stalite, respectively; and media 5, 6, 7, and 8 were commercially formulated to contain peat–bark–perlite–rice hulls–coir (4:1.5:2.5:1:1, 4:1.5:2.5:1:1, 4:2:2:1:1, and 3.0:2.5:2:1:1.5, respectively). Physical and chemical properties of the eight media were in ranges 50–65% container water‐holding capacity, 2.9–7.8% air‐filled porosity, 55–80% moisture (w/w), 0.11–0.37 g·cm3 bulk density, 0.34–0.96 g·cm3 particle density, 4.2–7.2 pH, 0.12–4.4 dS·m−1 electrical conductivity (EC), 27.3–54.5 meg/100 g cation exchange capacity (CEC), 17.9–39.0% carbon (C), and 0.22–1.7% nitrogen (N). Medium 4 (40% compost) had 5.5 times more ammoniacal N (NH4‐N) and 1.7 times more nitrate N (NO3‐N) than that of the standard commercial mix. At week 8, plants grown in media 2 and 5 were 8.9% to 9.5% taller than plants grown in medium 1 (commercial standard). At week 16, there were no significant differences in plant heights or growth indices among media. At week 24, there were no significant differences in plant height, growth index, visual quality, shoot dry weight, and root dry weight among media. However, cumulative phosphorus (P) leaching from media 1, 4, and 5 was significantly more than leaching from media 2 and 8. This study suggests that compost may serve as a horticulturally suitable and cost‐effective alternative to peat‐based media for Aglaonema production.

Reducing airborne ectomycorrhizal fungi and growing non-mycorrhizal loblolly pine (Pinus taeda L.) seedlings in a greenhouse

Atmospheric spores of ectomycorrhizal (ECM) fungi are a potential source of contamination when mycorrhizal studies are performed in the greenhouse, and techniques for minimizing such contamination have rarely been tested. We grew loblolly pine (Pinus taeda L.) from seed in a greenhouse and inside a high-efficiency particulate air-filtered chamber (HFC) constructed within the same greenhouse. Seedlings were germinated in seven different sand- or soil-based and artificially based growth media. Seedlings grown in the HFC had fewer mycorrhizal short roots than those grown in the open greenhouse atmosphere. Furthermore, the proportion of seedlings from the HFC that were completely non-mycorrhizal was higher than that of seedlings from the greenhouse atmosphere. Seedlings grown in sterilized, artificially based growth media (>50% peat moss, vermiculite, and/or perlite by volume) had fewer mycorrhizal short roots than those grown in sand- or soil-based media. The HFC described here can minimize undesirable ECM colonization of host seedlings in greenhouse bioassays. In addition, the number of non-mycorrhizal seedlings can be maximized when the HFC is used in combination with artificially based growth media.

Production, Survival, and Evaluation of Solid-Substrate Inocula of Penicillium oxalicum, a Biocontrol Agent Against Fusarium Wilt of Tomato

ABSTRACT Production of conidia of Penicillium oxalicum (ATCC number pending), a biocontrol agent of Fusarium oxysporum f. sp. lycopersici, was tested in liquid and solid fermentation. P. oxalicum produced 250-fold more conidia in solid than in liquid fermentation at 30 days after inoculation of substrate. Solid fermentation was carried out in plastic bags (600 cm(3)) especially designed for solid fermentation (VALMIC) containing 50 g of peat/vermiculite (PV) (1:1, wt/wt) with 40% moisture, sealed, sterilized, and then inoculated with 1 ml of a conidial suspension of P. oxalicum (10(5) conidia g(-1) dry substrate), sealed again, and incubated in darkness at 20 to 25 degrees C for 30 days. Addition of amendments to PV in a proportion of 0.5 (wt/wt) significantly increased conidial production of P. oxalicum. The best production was obtained on PV plus meal of cereal grains (barley) or leguminous seeds (lentil) (100-fold higher). Conidial production obtained after 5 days of inoculation was similar to that obtained at 30 days. However, viability of conidia produced in PV plus lentil meal was 35% higher than that of conidia produced in PV plus barley meal. Changes in proportions (1:1:0.5, wt/wt/wt; 1:1:1, wt/wt/wt; 1:0.5:0.5, wt/wt/wt; 1:1:0.5, vol/vol/vol) of components of the substrate (peat/vermiculite/lentil meal) did not enhance production or viability of conidia. Optimal initial moisture in the substrate was 30 to 40%. At lower moistures, significant reductions of production of conidia were observed, particularly at 10%. There was a general decline in the number of conidia in bags with time of storage at -80, -20, 4, and 25 degrees C, or at room temperature (range from 30 to 15 degrees C), with the highest decline occurring from 60 to 180 days. Conidial viability also was reduced with time, except for conidia stored at -20 degrees C. Fresh conidia produced in solid fermentation system or those conidia stored at -20 degrees C for 180 days reduced Fusarium wilt of tomato by 49 and 61%, respectively.

445 Solid Matrices for Supporting Plant Growth in Space

In preparation for a spaceflight experiment to measure photosynthesis of wheat (PESTO), four solid media were evaluated for use in the rooting modules of the Biomass Production System (BPS), a new plant growth unit for microgravity. The media were commercial peat-vermiculite (PV) mixture, zeolite developed at Johnson Space (Z/JSC), commercial zeolite developed by Boulder Innovative Technologies (Z/BIT), and arcillite (AR) with slow-release fertilizer. Wheat (cv. USU Super Dwarf) was grown in the media at 1500 μmol/mol CO2, 350 μmol·m-2·s-1 PAR, 23 °C, and 75% relative humidity for 18 to 21 days. Water was delivered to the media through porous tubes imbedded in the media, and NDS pressures of -0.1 to -0.5 kPa were maintained with either a static or recirculating standpipe. Plant height, leaf area, and fresh mass were determined for each experiment. Results indicated that the AR and Z/BIT media resulted in larger and more uniform plants than Z/JSC or PV at the same NDS pressure. Additional experiments were conducted with AR to evaluate interactions between particle size and NDS pressure. At ≈14 days after planting, there was a loss of NDS prime in AR >2.0 mm when the NDS pressure was less than -0.3kPa. This resulted in drying of the media and poor plant growth. There was excess water in the media, which resulted in reduced plant size, in AR <1.0 mm at NDS pressures more than -0.3 kPa.

Monitoring Chemical Properties of Growing Media with Small Soil Solution Samplers

Hydrophilic polymer tubes (2.5 mm OD, 1.4 mm ID, 10-cm length, 0.1-mm pore diameter) attached to PVC hose were used to extract solution from soilless media at container capacity and analyzed for pH, EC, NO3-N and NH4-N. Media chemical properties were also analyzed by the Saturated Media Extract (SME) and Pour-Through (PT) methods. Extraction and analyses were conducted in peat: vermiculite (PV) and peat: perlite (PP) media irrigated for 1 week with Hoagland solution at 0.25, 0.5, 1, 2 and 4x. A 10-mL syringe was used as the vacuum source (48.1 ± 0.5 kPa) for the solution samplers (SS), yielding ≈2–5 mL of solution over a 3-min period. Simple correlation coefficients for EC, NO3-N and NH4-N between SS and SME and PT were high (>0.99). When measured by PT, these chemical properties were similar to SS (within 1% to 6%), whereas SME values were much lower than SS (12% to 15% and 35% to 38% in PV and PP media, respectively). Correlation coefficients for pH were lower than in other chemical properties, particularly in the PV medium. With an estimated life of ≈6 months in soil, SS are excellent monitoring tools for mineral nutrition research and horticultural crop production.

CHEMICAL AND PHYSICAL PROPERTIES OF COAL BOTTOM ASH–BASED ROOT MEDIA AND THEIR EFFECT ON POINSETTIA NUTRITIVE STATUS, GROWTH, AND FLOWERING

Rooted cuttings of `Supjibi' poinsettia were potted in peat vermiculite, mixed with coal bottom ash at 0%, 25%, 50%, 75%, or 100% by volume. Values of pH were higher in media containing coal bottom ash. In general, pH increased for the first 4 weeks, during which time 50–100 ppm (N) fertilizer was being applied, decreased temporarily when 200 ppm fertilizer began, and then increased and stabilized for the last 5 weeks. At first, pH tended to be higher with increase in ash, but when 200 ppm fertilizer was begun, pH became the same in all coal ash levels. Once fertilization was stopped, pH tended again to be higher in ash media. Levels of EC remained low in all media when 50–100 ppm of fertilizer was applied, but increased after 200 ppm fertilizer was begun, increasing to excessive levels 2 weeks later. With more watering, EC declined in the 0% ash, but remained high in 50% to 100% ash media. Leaf Ca content increased with increase in media ash but was below the normal range in all plants. With increase in media ash, water capacity decreased, but bulk density increased. Bract color development in plants in ash media appeared delayed.

Effect of simulated acid rain on mycorrhizae of Aleppo pine (Pinus halepensis Miller) in calcareous soil

particular root development, of Pinus halepensis were studied in relation to the influence of pH from simulated rain in pot cultures. Four treatments of water (7.5, 6.0, 4.5 and 3.0) were established by adding a mixture of sulphuric and nitric acids (2:1, v/v) or 10% NaOH to distilled water. Three experiments were carried out: i) seedlings growing in calcareous forest soil; ii) 2-year-old naturally mycorrhizal seedlings, transplanted into vermiculite in order to differentiate old and new-formed roots; and iii) seedlings growing in peat vermiculite, inoculated with mycelial inoculum of Suillus collinitus. Although no visible effects on the aerial part were observed, a reduction of root length in the most acidic treatment was noted. Enhancement of ectomycorrhizae formation was also recorded in this treatment in the three experiments. In substrata of neutro-basic pH, short-term exposures to acid rain positively affected ectomycorrhizal fungi, in particular, Suillus species.

157 SUITABILITY OF A SHREDDED NEWSPAPER, KITCHEN WASTE COMPOST AS A ROOT SUBSTRATE FOR TOMATO SEEDLINGS

A small, continuous flow compost reactor was employed to produce a compost from a shredded newspaper/kitchen waste mixture. Transit time through the reactor was 4 weeks and the compost was then stockpiled for 5, 7, 8 or 9 weeks prior to evaluation. Cress seed germination was not reduced in graded aqueous compost extracts, however, seedling radicle length was significantly reduced in the nondiluted extract.. Elemental analysis of the compost showed PO4 ond K to be about 20 and 2 times recommended levels and No 5 times the maximum level at 577 mg. liter-1. Electrical conductivity of the compost was 5 dS.m-1 and pH range was 6.2-7.3. Composts were leached with water to E.C.'s of 1-1.5 dS.m-1 before planting tomato seedlings. Dry weights of tomato seedlings grown 5 weeks in the composts were equal to those in a peat vermiculite control, except that dry weights of seedlings in the compost stockpiled for 5 weeks were less than those of control plants. Some residual inhibition of growth may hove remained in the compost for at least 5 weeks after the production dote but by the 7th week, no growth inhibition was apparent.