Substrate Amendment Research Articles

Response of Methanogens in Arctic Sediments to Temperature and Methanogenic Substrate Availability.

Although cold environments are major contributors to global biogeochemical cycles, comparatively little is known about their microbial community function, structure, and limits of activity. In this study a microcosm based approach was used to investigate the effects of temperature, and methanogenic substrate amendment, (acetate, methanol and H2/CO2) on methanogen activity and methanogen community structure in high Arctic wetlands (Solvatnet and Stuphallet, Svalbard). Methane production was not detected in Stuphallet sediment microcosms (over a 150 day period) and occurred within Solvatnet sediments microcosms (within 24 hours) at temperatures from 5 to 40°C, the maximum temperature being at far higher than in situ maximum temperatures (which range from air temperatures of -1.4 to 14.1°C during summer months). Distinct responses were observed in the Solvatnet methanogen community under different short term incubation conditions. Specifically, different communities were selected at higher and lower temperatures. At lower temperatures (5°C) addition of exogenous substrates (acetate, methanol or H2/CO2) had no stimulatory effect on the rate of methanogenesis or on methanogen community structure. The community in these incubations was dominated by members of the Methanoregulaceae/WCHA2-08 family-level group, which were most similar to the psychrotolerant hydrogenotrophic methanogen Methanosphaerula palustris strain E1-9c. In contrast, at higher temperatures, substrate amendment enhanced methane production in H2/CO2 amended microcosms, and played a clear role in structuring methanogen communities. Specifically, at 30°C members of the Methanoregulaceae/WCHA2-08 predominated following incubation with H2/CO2, and Methanosarcinaceaeand Methanosaetaceae were enriched in response to acetate addition. These results may indicate that in transiently cold environments, methanogen communities can rapidly respond to moderate short term increases in temperature, but not necessarily to the seasonal release of previously frozen organic carbon from thawing permafrost soils. However, as temperatures increase such inputs of carbon will likely have a greater influence on methane production and methanogen community structure. Understanding the action and limitations of anaerobic microorganisms within cold environments may provide information which can be used in defining region-specific differences in the microbial processes; which ultimately control methane flux to the atmosphere.

A call for applying trophic structure in ecological restoration

Ecological restoration projects have traditionally focused on vegetation as both a means (seeding, planting, and substrate amendments) and ends (success based upon primary productivity and vegetation diversity). This vegetation‐centric approach to ecological restoration stems from an historic emphasis on esthetics and cost but provides a limited measure of total ecosystem functioning and overlooks alternative ways to achieve current and future restoration targets. We advocate a shift to planning beyond the plant community and toward the physical and biological components necessary to initiate autogenic recovery, then guiding this process through the timely introduction of top predators and environmental modifications such as soil amendments and physical structures for animal nesting and refugia.

The Utilize of Vermicomposting Outputs in Substrate Culture for Producing Snap Bean

The need for increasing the agricultural area to secure food production and the sustainability under the climate change impacts and current conditions of Egypt, especially the shortage of available water and soil were the driving forces for developing ecology substrate culture via using vermicomposting outputs. The study was carried out at Central Laboratory for Agricultural Climate (CLAC), Giza, Egypt under unheated double span plastic house during two successive autumn seasons of 2012/2013 and 2013/2014 for investigating the effect of vermicompost as substrate amendment mixed with perlite or sand in different proportions 0, 10, 20 and 30 % of substrate combined with three sources of nutrient solutions (compost tea, vermi-liquid and chemical) on the growth and yield of snap bean cv. Alhamma in split plot design with four replicates. Data revealed that increasing vermicompost rate from 0 to 20 % had positive significant effects on vegetative growth, yield and quality of snap bean pods while increasing the rate up to 30 % had no subsequent effect. Sand + vermicompost (80: 20 v/v) followed by perlite + vermicompost (80: 20 v/v) recorded the highest results of the vegetative growth characteristics during the two successive seasons compared to other treatments. The highest values of early and total yield / m2 were recorded by sand + vermicompost (80: 20 v/v) 1494 and 6947 g / m2 during the first season, respectively. In addition, it recorded the highest early yield on the second season (1552 g / m2). While treatment of sand + vermicompost (70: 30 v/v) recorded the highest total yield (7035 g/ m2). Otherwise, obtained results of the effect of nutrient solution sources indicated that the chemical nutrient solution recorded the highest vegetative growth traits and yield characteristics. Perlite + vermicompost (70: 30 v/v) combined with chemical nutrient solution had the highest results of early (1605) and total yield (7734) (g / m2). The study supports the use of vermicompost as substrate amendment and compost tea and vermi-liquid as a source of nutrient solution in ecology soilless production of snap bean plants. The environmental impacts of vermicomposting could create sustainable source of organic substrate and fertilizer besides mitigating CO2 emission.

Effect of freshwater sapropel on plants in respect to its growth-affecting activity and cultivable microorganism content

A positive effect of organic-rich sediments sapropels on plant growth has been suggested in general, but has not been proven on an experimental basis. The aim of the present investigation was to study biological activity of freshwater sapropel and its product including analyses of plant growth-affecting activity and cultivable microorganisms. Besides mineral nutrients, sapropel contained unspecified substances promoting plant growth in a seedling growth test with beetroot, Swedish turnip, carrot and tomato. Summed plant growth-affecting activity of sapropel and sapropel-containing substrate BioDeposit Agro had a relatively high growth-enhancing component together with an extremely low growth-inhibiting component. Substrate amendment with BioDeposit Agro resulted in a significant increase in dry matter accumulation only in lettuce plants but not in winter rye plants. High level of aerobic heterotrophic bacteria, high level of yeasts and variable level of filamentous fungi with a low diversity were found in all sapropel samples tested. Plant growth-stimulating activity negatively correlated with the number of colony forming units of both yeasts and fungi. There was no correlation between the number of bacteria and plant growth-stimulating activity.

Animal Tissue Compost as a Potential Substrate Amendment for Production of Four Annual Floriculture Crops

The objectives of this study were to determine the effectiveness of using animal tissue compost (ATC) as a substrate amendment for ornamental plant container production. The compost was produced using soiled sawdust bedding mixed with assorted animal tissues and actively composted for at least 6 months and cured for 6 to 10 months. Five substrate treatments that consisted of four different ratios of ATC and Canadian sphagnum peatmoss were formulated, all containing 20% medium grade horticultural perlite. Four species [geranium (Pelargonium ×hortorum ‘Maverick Red’), marigold (Tagetes erecta ‘Inca II Yellow’), pansy (Viola ×wittrockiana ‘Delta Premium Yellow Blotch’), and petunia (Petunia ×hybrida ‘Prostrate Wave Purple Improved’)] were evaluated with weekly plant measurements. Geranium and petunia exhibited 100% survival for all treatments. Marigold and pansy showed 100% survival for the control treatment (0% ATC) and the treatment with the smallest amount of ATC (20% ATC). Treatments for pansy and marigold with more than 40% ATC exhibited 40% to 90% survival. All ATC substrate treatments produced the same number of flowers and buds as the control in geranium, marigold, and petunia, while the treatments containing 20% to 60% of ATC for pansy exhibited more flowers and buds than the control. Measurements of pH and electrical conductivity (EC) varied based on treatment. Based on the species and the ratios of peat, ATC, and perlite tested here, ATC has the potential to be a peat extender in floriculture substrates when used in ratios of 20% or less.

Pyrosequencing reveals the effect of mobilizing agents and lignocellulosic substrate amendment on microbial community composition in a real industrial PAH-polluted soil

Bacterial and fungal biodiversity throughout different biostimulation and bioaugmentation treatments applied to an industrial creosote-polluted soil were analyzed by means of polyphasic approach in order to gain insight into the microbial community structure and dynamics. Pyrosequencing data obtained from initial creosote polluted soil (after a biopiling step) revealed that Alpha and Gammaproteobacteria were the most abundant bacterial groups, whereas Fusarium and Scedosporium were the main fungal genera in the contaminated soil.At the end of 60-days laboratory scale bioremediation assays, pyrosequencing and DGGE data showed that (i) major bacterial community shifts were caused by the type of mobilizing agent added to the soil and, to a lesser extent, by the addition of lignocellulosic substrate; and (ii) the presence of the non-ionic surfactant (Brij 30) hampered the proliferation of Actinobacteria (Mycobacteriaceae) and Bacteroidetes (Chitinophagaceae) and, in the absence of lignocellulosic substrate, also impeded polycyclic aromatic hydrocarbons (PAHs) degradation.The results show the importance of implementing bioremediation experiments combined with microbiome assessment to gain insight on the effect of crucial parameters (e.g. use of additives) over the potential functions of complex microbial communities harbored in polluted soils, essential for bioremediation success.

Composted Cotton Stalks and Cotton Gin Trash Substrate Amendments and Irrigation/Ground Cover Management II. Effect on Growth and Disease Suppression for Azalea and Juniper

‘Sunglow’ azalea and ‘Blue Pacific’ juniper were grown in pine bark (PB) and pine tree (PT) substrates that were amended with cotton stalks composted with a N source (CSN), cotton stalks composted without an N source (CS), and cotton gin trash (CGT) to evaluate the substrate's effect on plant growth and disease suppression. The plants were grown under two different, commonly used, irrigation/ground surface management regimes — overhead, sprinkler irrigation with black geotextile weed fabric covering the ground (OH) or low-volume, spray stake irrigation with gravel covering the ground (LV). In 2010, with OH, all PB-amended substrates produced significantly larger azalea shoots than PT-amended substrates. In 2011, with OH, all azalea shoots were similar in size when grown in all substrates except for PT:CS, where plants were significantly smaller. With LV, in 2010 and 2011, azalea shoot growth was largest when grown in a PB substrate amended with CSN or CGT and lowest in PT:CS. Junipers with OH produced generally larger shoot growth with the PB-based substrates in both 2010 and 2011 compared to the PT-based substrates. With LV, PT:CGT produced the numerically smallest juniper shoot growth for both years. Overall, PT-based substrates appeared to produce greater consistency in growth, because responses were more similar in 2010 and 2011, however irrigation method and management can impact growth regardless of substrate composition. CGT added to PB- or PT-based substrates enhanced Ca and Mg uptake by both species but not P uptake. OH generally kept ground surface and substrate temperatures lower than LV regardless of substrate composition. The substrates tested neither enhanced nor deterred P. cinnamomi infection in azalea or juniper.

Composted Cotton Stalks and Cotton Gin Trash Substrate Amendments and Irrigation/Ground Cover Management I. Effect on Physical and Chemical Properties of Pine Bark and Pine Tree Substrates

This project evaluated two cotton waste products (cotton stalks and cotton gin trash) as amendments to pine bark (PB) and pine tree (PT) substrates for their impact on substrate physical and chemical properties. PB or PT substrates were amended (v/v) with cotton stalks composted with a N source (CSN), cotton stalks composted without an N source (CS), or aged cotton gin trash (CGT) at 4:1 PB:CS (PB:CS), 4:1 PB:CSN (PB:CSN), 9:1 PB:CGT (PB:CGT), 1:1 PT:CS (PT:CS), 1:1 PT:CSN (PT:CSN) and 4:1 PT:CGT (PT:CGT) (by vol). In 2010, PB-amended substrates had larger percentages of coarse (> 2.0 mm) and fine (< 0.5 mm) particles while PT-amended substrates had larger percentages of medium (0.5–2.0 mm) particles. In 2011, PB-amended substrates again had larger percentages of coarse particles, while PT-amended substrates had more medium and fine particles. Generally, most physical properties were within adequate ranges and were better than or comparable to the 100% PB control. Substrate solution pH was generally higher in the PT- than the PB-based substrates. Electrical conductivity (EC) of the substrate solution was also generally higher in the PT-based substrates compared to the PB-based substrates. Inorganic nitrogen (NH4 + NO3 + NO2), urea, P, K, Ca, and Mg concentrations in all substrate solutions, regardless of compost addition, were all below the recommended ranges by the last sample time (October 4, 2011) for the study indicating that nutrients supplied by the composts were depleted or below detection limits. However, CGT increased substrate solution P concentrations in both PB- and PT-based substrates with both overhead, sprinkler irrigation with black geotextile weed fabric covering the ground (OH) and low-volume, spray stake irrigation with gravel covering the ground (LV).

Microbial community responses to organophosphate substrate additions in contaminated subsurface sediments.

BackgroundRadionuclide- and heavy metal-contaminated subsurface sediments remain a legacy of Cold War nuclear weapons research and recent nuclear power plant failures. Within such contaminated sediments, remediation activities are necessary to mitigate groundwater contamination. A promising approach makes use of extant microbial communities capable of hydrolyzing organophosphate substrates to promote mineralization of soluble contaminants within deep subsurface environments.Methodology/Principal FindingsUranium-contaminated sediments from the U.S. Department of Energy Oak Ridge Field Research Center (ORFRC) Area 2 site were used in slurry experiments to identify microbial communities involved in hydrolysis of 10 mM organophosphate amendments [i.e., glycerol-2-phosphate (G2P) or glycerol-3-phosphate (G3P)] in synthetic groundwater at pH 5.5 and pH 6.8. Following 36 day (G2P) and 20 day (G3P) amended treatments, maximum phosphate (PO4 3−) concentrations of 4.8 mM and 8.9 mM were measured, respectively. Use of the PhyloChip 16S rRNA microarray identified 2,120 archaeal and bacterial taxa representing 46 phyla, 66 classes, 110 orders, and 186 families among all treatments. Measures of archaeal and bacterial richness were lowest under G2P (pH 5.5) treatments and greatest with G3P (pH 6.8) treatments. Members of the phyla Crenarchaeota, Euryarchaeota, Bacteroidetes, and Proteobacteria demonstrated the greatest enrichment in response to organophosphate amendments and the OTUs that increased in relative abundance by 2-fold or greater accounted for 9%–50% and 3%–17% of total detected Archaea and Bacteria, respectively.Conclusions/SignificanceThis work provided a characterization of the distinct ORFRC subsurface microbial communities that contributed to increased concentrations of extracellular phosphate via hydrolysis of organophosphate substrate amendments. Within subsurface environments that are not ideal for reductive precipitation of uranium, strategies that harness microbial phosphate metabolism to promote uranium phosphate precipitation could offer an alternative approach for in situ sequestration.

Diverse sulfate-reducing bacteria of the Desulfosarcina/Desulfococcus clade are the key alkane degraders at marine seeps.

Biogeochemical and microbiological data indicate that the anaerobic oxidation of non-methane hydrocarbons by sulfate-reducing bacteria (SRB) has an important role in carbon and sulfur cycling at marine seeps. Yet, little is known about the bacterial hydrocarbon degraders active in situ. Here, we provide the link between previous biogeochemical measurements and the cultivation of degraders by direct identification of SRB responsible for butane and dodecane degradation in complex on-site microbiota. Two contrasting seep sediments from Mediterranean Amon mud volcano and Guaymas Basin (Gulf of California) were incubated with (13)C-labeled butane or dodecane under sulfate-reducing conditions and analyzed via complementary stable isotope probing (SIP) techniques. Using DNA- and rRNA-SIP, we identified four specialized clades of alkane oxidizers within Desulfobacteraceae to be distinctively active in oxidation of short- and long-chain alkanes. All clades belong to the Desulfosarcina/Desulfococcus (DSS) clade, substantiating the crucial role of these bacteria in anaerobic hydrocarbon degradation at marine seeps. The identification of key enzymes of anaerobic alkane degradation, subsequent β-oxidation and the reverse Wood-Ljungdahl pathway for complete substrate oxidation by protein-SIP further corroborated the importance of the DSS clade and indicated that biochemical pathways, analog to those discovered in the laboratory, are of great relevance for natural settings. The high diversity within identified subclades together with their capability to initiate alkane degradation and growth within days to weeks after substrate amendment suggest an overlooked potential of marine benthic microbiota to react to natural changes in seepage, as well as to massive hydrocarbon input, for example, as encountered during anthropogenic oil spills.

Microbial ecology of arsenic‐mobilizing Cambodian sediments: lithological controls uncovered by stable‐isotope probing

Microbially mediated arsenic release from Holocene and Pleistocene Cambodian aquifer sediments was investigated using microcosm experiments and substrate amendments. In the Holocene sediment, the metabolically active bacteria, including arsenate-respiring bacteria, were determined by DNA stable-isotope probing. After incubation with (13) C-acetate and (13) C-lactate, active bacterial community in the Holocene sediment was dominated by different Geobacter spp.-related 16S rRNA sequences. Substrate addition also resulted in the enrichment of sequences related to the arsenate-respiring Sulfurospirillum spp. (13) C-acetate selected for ArrA related to Geobacter spp. whereas (13) C-lactate selected for ArrA which were not closely related to any cultivated organism. Incubation of the Pleistocene sediment with lactate favoured a 16S rRNA-phylotype related to the sulphate-reducing Desulfovibrio oxamicus DSM1925, whereas the ArrA sequences clustered with environmental sequences distinct from those identified in the Holocene sediment. Whereas limited As(III) release was observed in Pleistocene sediment after lactate addition, no arsenic mobilization occurred from Holocene sediments, probably because of the initial reduced state of As, as determined by X-ray Absorption Near Edge Structure. Our findings demonstrate that in the presence of reactive organic carbon, As(III) mobilization can occur in Pleistocene sediments, having implications for future strategies that aim to reduce arsenic contamination in drinking waters by using aquifers containing Pleistocene sediments.

Methanogen community composition and rates of methane consumption in Canadian High Arctic permafrost soils

Increasing permafrost thaw, driven by climate change, has the potential to result in organic carbon stores being mineralized into carbon dioxide (CO2) and methane (CH4) through microbial activity. This study examines the effect of increasing temperature on community structure and metabolic activity of methanogens from the Canadian High Arctic, in an attempt to predict how warming will affect microbially controlled CH4 soil flux. In situ CO2 and CH4 flux, measured in 2010 and 2011 from ice-wedge polygons, indicate that these soil formations are a net source of CO2 emissions, but a CH4 sink. Permafrost and active layer soil samples were collected at the same sites and incubated under anaerobic conditions at warmer temperatures, with and without substrate amendment. Gas flux was measured regularly and indicated an increase in CH4 flux after extended incubation. Pyrosequencing was used to examine the effects of an extended thaw cycle on methanogen diversity and the results indicate that in situ methanogen diversity, based on the relative abundance of the 16S ribosomal ribonucleic acid (rRNA) gene associated with known methanogens, is higher in the permafrost than in the active layer. Methanogen diversity was also shown to increase in both the active layer and permafrost soil after an extended thaw. This study provides evidence that although High Arctic ice-wedge polygons are currently a sink for CH4, higher arctic temperatures and anaerobic conditions, a possible result of climate change, could result in this soil becoming a source for CH4 gas flux.

Reductions of Fe(III) and pentachlorophenol linked with geochemical properties of soils from Pearl River Delta

Soils in the Pearl River Delta (PRD) of South China contain iron with a higher abundance and reactivity formed under a subtropical monsoon climate with a unique biogeochemistry. Iron cycle plays a vital role in transformation of contaminants. However, the linkage between iron cycle and contaminants transformation vs. geochemical properties of soils remains unclear. In this study, a set of experiments for reductions of Fe(III) and pentachlorophenol (PCP) were conducted to fill up the gap between Fe(III) reducibility and PCP transformation on the view of geochemistry. Fourteen soil samples were collected from the A (0 to 20cm) horizon in the PRD and were divided into three groups based on their land use types (LUTs, i.e., vegetable fields, paddy soils and mangroves). The experiments were designed and subsequently conducted at pH 7.0±0.2 (excluding pH interference) in three different conditions (i.e., soil-sterile, soil, and soil+lactate). Kinetic measurements showed that the reduction rates (μmax) of Fe(III) and PCP could be calculated using a logistic model. The stepwise regression analyses showed that oxalate-extractable iron (Feo) was likely one of the most active iron sources for soil Fe(III) reduction. Feo and dithionite-extractable iron (Fed) had close correlations with the rate of PCP reductive transformation. Moreover, parallel correlations exist between μmax-PCP and μmax-Fe(II)sorbed, illustrating the crucial effect of sorbed Fe(II) on PCP reduction in soils. The variance analysis results showed significant differences in the average μmax-PCP and μmax-Fe(II)sorbed value under different LUTs (vegetable field<paddy soil≤mangroves) and soil types (Chinese soil taxonomy (CST), Typic Gleyi-Stagnic Anthrosols<Typic Fe-Leachi-Stagnic Anthrosols≤Sulfic Aqui-Orthic Halosols). Moreover, terminal restriction fragment length polymorphism results showed that the differences in reduction of Fe(III) and PCP should be attributable to microbial communities compositions in different soil type (i.e., LUTs or CST). Substrate amendments would obviously impact the bacterial community structure, which could further affect Fe(III) reducibility and PCP transformation. These findings could improve our general understanding of the vital role of iron redox chemistry in PCP transformation vs. geochemical properties of soils. The results also indicated that the linkage of Fe(III) reducibility and PCP transformation on the view of soil microbiology should be gained attention in future studies.

Evaluating locally available organic substrates for vertical flow passive treatment cells at Cerro Rico de Potosí, Bolivia

Vertical flow cells (VFCs) are key components of passive acid mine drainage (AMD) treatment systems and require organic substrates that create anaerobic conditions and encourage bacterial sulfate reduction. In the high elevation desert of Potosi, Bolivia, the low productivity landscape limits the availability of sustainable and economical organic substrates. Locally available brewery waste, llama manure, and cow manure were evaluated as potential VFC substrates in a preliminary laboratory fed-batch study to assist in passive treatment system design. Two abandoned AMD discharges were collected from Cerro Rico de Potosi. Discharge A had an initial pH of 2.96, specific conductance of 3.31 mS/cm, and acidity of 1,350 mg/L as CaCO3 equivalent. Discharge B had an initial pH of 3.85, specific conductance of 1.87 mS/cm, and acidity of 1,000 mg/L as CaCO3 equivalent. Triplicate fed-batch reactors were set up in 1-L cubitainers with each potential substrate exposed to each AMD, yielding a total of 18 reactors exposed for 9 days and sampled two times for anions and dissolved metals. Cow manure reactors exhibited the greatest pH and alkalinity increases. Cd, Co, Fe, Mn, Ni, Pb, and Zn decreased in all reactors. SO4 concentrations only decreased in brewery waste reactors. However, SO4 reducing bacteria was higher for cow manure reactors. Results suggest that llama and cow manure are the more labile substrates, with llama manure being the most affordable. Brewery waste could be a suitable less-labile long-term substrate amendment. However, longer-term studies are needed to determine the optimum VFC substrate mixture in this unique circumstance.

Substrate amendment mediated enhancement of the valorization potential of microalgal lipids

Abstract Our study focused towards screening the modes of nutrition of Chlorella sorokiniana under standard laboratory conditions and its upscaling in a photobioreactor for enhanced lipid productivity. Time course studies using glucose under mixotrophic and heterotrophic conditions vis a vis autotrophy revealed highest values of growth, lipid productivity (29.33% DCW) and lipid content (755. 00 mg/L) under mixotrophic conditions on the 14th day of growth. Upscaling in a photobioreactor with selected substrates (Glucose and tryptophan), along with sodium thiosulphate as a reducing agent was undertaken. Lipid productivity of 34.16% and 36.49% was recorded after 4th and 8th day, respectively, in both substrates, vis a vis 11% with glucose alone. FAME analyses revealed a 2% enhancement in total saturated fatty acids (SFA) in tryptophan supplemented culture, which also exhibited an almost ideal fatty acid ratio for use as biodiesel (2.6:4:1 of 16:1.18:1 and 14:1). Interestingly, glucose+sodium thiosulphate grown culture exhibited an almost 2 folds enhancement in PUFA content (especially 18:1 and 18:2), illustrating its promise for use as an edible oil blend. Our study revealed the step-wise scale up and promise of substrate amendment and mixotrophy as promising tools for valorization of microalgal lipids.

Use of rice husk to enhance peach tree performance in soils with limiting physical properties

This study evaluated the use of rice husk as an amendment in a soil with limiting physical conditions. The research was conducted in a commercial peach orchard planted in 2011 using a ridge planting system. Six soil and water management treatments were evaluated in 18 experimental units, which were set up in the field using a randomized complete block design. The treatments were compared both in terms of soil physical condition effects and crop response. Localized substrate amendment of the soil significantly increased both saturated hydraulic conductivity and aeration porosity by 90-fold and 76%, respectively, compared with unamended treatments. In the case of growth parameters, amended trees presented the highest overall values without affecting crop water status. In terms of canopy ratio (CR), the amended treatment produced the highest overall value (0.56m2m−3), a 44% increase compared to control treatment. Localized soil amendment with rice husk contributed to both peach tree performance and residue management.

Zoysia matrella cover rate and drought tolerance in adaptive extensive green roof systems

Turfgrass use in adaptive extensive green roof systems could provide a sustainable solution for increasing urban greening in semi-arid regions. The aim of the study was as follows: (i) to investigate the effects of four different substrate formulations from locally available materials (S15:Pum60:P20:Z5, S15:Pum60:C20:Z5, S30:Pum40:P20:Z10, and S30:Pum40:C20:Z10, where S, sandy loam soil; Pum, pumice; P, peat; C, compost; and Z, zeolite in volumetric proportions as indicated by their subscripts), and two substrate depths (7.5cm and 15cm) on the lateral growth of Manilagrass (Zoysia matrella L. [Merr.] ‘Zeon’); (ii) to evaluate the capacity of locally produced compost to be substituted for peat as an organic substrate amendment in an effort to reduce its horticultural use; (iii) to determine the effect of increasing soil participation in substrate formulations on growth and drought resistance of Manilagrass; (iv) to evaluate the effects of the four substrate types and two substrate depths on Manilagrass drought resistance. The measurements included: (a) determination of substrate characteristics, such as particle size distribution, saturated and dry bulk density, total porosity, water potential curves, in situ substrate moisture, pH and electrical conductivity and (b) determination of turfgrass quality and physiological status that included green turf cover (GTC), normalized difference vegetation index (NDVI), and leaf stomatal resistance (LSR). It was found that during establishment, when adequate irrigation of turfgrass was applied, the deeper profiles (15cm) combined with compost-amended substrates (S15:Pum60:C20:Z5 and S30:Pum40:C20:Z10) provided higher GTC values while the shallow profiles (7.5cm) with peat-amended substrates (S15:Pum60:P20:Z5 and S30:Pum40:P20:Z10) provided the lowest GTC. The opposite phenomenon was observed during water-deficit periods, since the peat-amended substrate S15:Pum60:P20:Z5 combined with the deeper profile (15cm) resulted in the least drought stress imposition to Manilagrass while providing the highest GTC and NDVI and the lowest LSR values. By contrast, the compost-amended substrates S15:Pum60:C20:Z5 and S30:Pum40:C20:Z10 increased the drought stress imposition to Manilagrass when combined with shallow profiles (7.5cm). Substrate depth was the most influential factor, since Manilagrass drought stress was alleviated as substrate depth increased from 7.5cm to 15cm.

Increasing Soil Water Retention with Native‐Sourced Mulch Improves Seedling Establishment in Postmine Mediterranean Sandy Soils

AbstractSeasonal drought and heavily impeded soils reduce restoration success in Mediterranean‐type postmine soils, where up to 90% seedling mortality has been observed after 2 years. To alleviate these barriers, amendments were incorporated into the soil profile of a freshly mined sand quarry. Within the quarry, three 223 m2 replicate sites contained two substrate amendments: 12% v/v native‐sourced mulch or gravel incorporated within the top 50 cm of the soil profile. Three remnant sites provided a “natural” reference system. Seeds of two autochthonous trees, Banksia attenuata (R.Br.) and B. menziesii (R.Br.) were sown across all treatments. Soil impedance, moisture, and seedling stomatal conductance were monitored for 2 years, at which point seedlings were excavated, and nutrient concentration, root morphology, and soil chemical properties were measured. Roots in all restoration treatments were restricted to the top 40 cm of the profile due to increases in soil impedance, regardless of amendment, compared to &gt;70 cm in the natural system. Seedling mortality was greatest after the second summer in the control and inorganic amendment treatments, with stomatal conductance indicating severe drought stress. Survival in the organic treatment was 24–42% greater than the control, with higher soil moisture and stomatal conductance rates 2.5 times that of the control. The increased soil water retention by a native‐sourced mulch was shown to improve postmine restoration success for these native trees.

Vermicompost as Substrate Amendment for Tomato Transplant Production

&lt;p&gt;Vermicompost may be a promising substitute for peat especially in transplant production. Vermicomposting is a sustainable solution for management of organic wastes. However, due to variability of organic wastes, vermicomposts might have varying nutrient content levels. The study compared vermicomposts from different sources on growth and nutrition of tomato (&lt;em&gt;Solanum lycopersicum&lt;/em&gt; L.) transplants. Chemical composition of vermicomposts differed. Common characteristics were high pH and very high electrical conductivity. All vermicomposts stimulated growth of tomato transplants, with up to a 2.2-fold increase occurring in shoot biomass. Differences in growth were attributed mainly to differences in nutrient content of the potting mixtures, but some changes in physical and biological properties of the substrate could also be responsible.&lt;/p&gt;

Weed Biodiversity Studies of a Waste Engine Oil-polluted Soil Exposed at Different Intervals of Natural Attenuation and Substrate Amendment

Weed Biodiversity Studies of a Waste Engine Oil-polluted Soil Exposed at Different Intervals of Natural Attenuation and Substrate Amendment