Substrate Amendment Research Articles

Reducing Phosphorus Loss in Short-Cycle Horticultural Production Using Activated Aluminum-Amended Substrates and Modified Fertigation Practices.

To support growth, short-cycle horticultural crops require readily available nutrients. However, this often leads to nutrient leaching. Implementing best management practices in production decisions like incorporating fertilizer retaining amendments to substrates or modifying fertilization programs can mitigate nutrient losses to the environment and associated costs. This study examined using an activated aluminum (AA) material as a substrate amendment to retain phosphorus (P) within containers while also assessing methods to reduce P fertilization in Tagetes production over a six-week production cycle. A commercial peat moss substrate (PL) pre-loaded with nutrients was amended with AA, enabling comparisons between substrates with and without AA. Enhanced fertilizer practices involved supplementing the initial nutrients by applying a weekly fertigation solution including nitrogen and potassium over the six weeks, but P for either 0, 2, 4, or 6 weeks. The incorporation of AA significantly reduced P leaching losses by 89.5-97.7%, compared to the PL substrates receiving P the entire six weeks. Regardless of substrate or fertilizer management, all Tagetes had equivalent sizes (growth index) and aboveground biomass. The results indicate that amending substrates with AA and/or reducing additional P inputs are effective strategies to minimize P leaching without compromising Tagetes quality.

Suitability of coconut bran and biochar as a composite substrate for lettuce cultivation in aquaponic systems

Growth substrates are essential for aquaponic systems and play an important role in vegetable growth and water quality. In this study, we explored an innovative combination of coconut bran and coconut shell biochar (CSB) as a composite growth substrate for lettuce cultivation in aquaponic systems. The study included the control (100 % coconut bran as the growth substrate) and treatment groups (T1–T5; containing 10 %, 20 %, 30 %, 40 %, and 50 % CSB as the growth substrate, respectively). The substrate properties; lettuce growth performance; and soil enzyme activity, nitrogen content, and abundance of microbial communities in the substrate were analyzed to determine the optimal substrate. Our findings indicated that CSB incorporation significantly altered the properties of the substrate, resulting in increased dry and bulk densities, pH, and water-holding capacity, and decreased electrical conductivity, water-absorption capacity, and porosity. Furthermore, the fresh weight of lettuce was notably increased in the treatment groups. The activities of fluorescein diacetate hydrolase, urease, nitrate reductase, and hydroxylamine reductase initially increased and further decreased, reaching the maximum in the T3 group. Conversely, the activity of nitrite reductase and contents of available nitrogen, nitrate-nitrogen, and ammonium-nitrogen in the substrates initially decreased and further increased, with the minimum values observed in the T3 group. The microbial sequencing results indicated that CSB incorporation significantly increased the microbial diversity and relative abundance of microorganisms associated with nitrogen transformation. Moreover, 30 % CSB incorporation exhibited the greatest effect on lettuce growth, with a 34.5 % and 31.6 % increase in fresh weight compared to the control during the growth and harvest periods, respectively. This study indicated the enormous potential of biochar in the research and development of green technologies for substrate amendment in aquaponic systems.

Accelerated manganese(II) removal by in situ mine drainage treatment system without organic substrate amendment: Metagenomic insights into chemolithoautotrophic manganese oxidation via extracellular electron transfer

Mine drainage waters often contain elevated concentrations of toxic metals and can be a source of environmental pollution. Manganese (Mn)-oxidizing bacteria (MnOB), which can oxidize soluble Mn(II) to insoluble Mn(III, IV) under neutral pH conditions, are expected to be a promising biological agent in passive mine drainage remediation. However, the diversity, functionality and applicability of MnOB for mine drainage treatment remain mostly unknown. Given that many mine environments are poor in organic substances, it is necessary to elucidate the functions of MnOB communities that contribute to metal removal without supplementation with extra organic matter. Here, we constructed in situ continuous-flow bioreactors for treating mine drainage containing approximately 20 mg L−1 Mn(II) and 6 mg L−1 zinc (Zn) (II) and operated these bioreactors without amended organic matter. The removal of Mn(II) and Zn(II) ions reached more than 98 % at a hydraulic retention time of 0.5 days. The X-ray diffraction pattern of Mn oxides deposited on the surface of limestone carriers indicated woodruffite-like mineral accumulation in the reactors. Several heterotrophic MnOB were isolated from the bioreactor, and metagenomic analysis revealed a predominance of diverse lineages of heterotrophs, including Elusimicrobiota, which harbored MoxA-like multicopper oxidase genes. Furthermore, the metagenomic analysis also suggested the involvement of gammaproteobacterial species that possessed putative genes for extracellular electron uptake and CO2 fixation. Our findings offer the first insights into the potential for chemolithoautotrophic Mn(II) oxidation processes via electron transfer from Mn(II/III) and application of chemolithoautotrophic and heterotrophic MnOB in mine drainage remediation without supplying organic materials.

Effects of Organic Substrate Amendments on Selected Organic Fractions and Biochemical Parameters under Different Soils.

The application of organic substrates can affect soil respiration, dehydrogenase (DH-ase) activity, dissolved organic carbon (DOC), and humic acid (HA) fractions. This study aimed to evaluate the effects of five organic substrates in the organic fractions of degraded alluvial soil, acid sulfate soil, and sandy soils and the physicochemical properties of the soil. Soil samples were amended at a rate of 5 tons ha-1 with (1) water hyacinth compost, (2) sugarcane filter cake compost, (3) biogas sludge-rice straw compost, (4) vermicompost, and (5) sludge. The results showed that soil respiration and DH-ase activity increased rapidly within the first 5 days of incubation, while the concentrations of DOC and HA decreased throughout the incubation period. The highest respiration and DH-ase activity occurred after the application of vermicompost. DOC was found to be the highest in soils amended with sugarcane. The highest concentration of HA was observed with the application of sugarcane residues, regardless of the type of soil. The application of water hyacinth and biogas sludge stimulated cumulative HA only in the acid sulfate soil, while vermicompost improved HA only in the degraded soil. The largest stimulation in respiration and DH-ase activity was observed in degraded and sandy soils, regardless of the type of amendment. In the acid sulfate soil (3.7 mg·C·g-1), larger amounts of DOC and HA were observed than in both degraded (1.7 mg·C·g-1) and sandy soils (1 mg·C·g-1). However, DH-ase activity was the lowest in acid sulfate soil.

Industrial Cannabis sativa-Hemp: Biochar applications and disadvantages

This review paper highlights Industrial Cannabis sativa-Hemp uses and disadvantages particularly in the form of biochar. Biochar is defined as the burning of the organic material at high temperature under limited oxygen supply to produce carbon rich material is known as biochar. Biochar is a carbon-rich product that is formed under pyrolysis of different organic materials. Biochars were generally characterized by having a porous nature and large surface area. Biochar can provide nutrients to the soil directly because it contains nitrogen, phosphorous, potassium, magnesium, and calcium. Progressive mineralization of biochar in soil releases inherent nutrients into the soil. Hemp biochar carbonized at 800–1000°C displayed interesting electrical conductivity, opening opportunities for its use in electrical purposes. Biochar is an important material for environmental management to mitigate greenhouse gas emissions, such as sequestration of CO2 and CH4, and ozone-depleting N2O emissions. Biochar can be utilised as a soil conditioner and a container substrate amendment in agriculture and horticulture. Biochar also has the potential to improve a variety of soil and substrate physical, chemical, and biological qualities. However, there are some disadvantages of biochar, is that the addition of biochar resulted in such a high pH that the plant growth was severely reduced, which might have obscured any potentially beneficial effect of using biochar. This however highlighted the challenge in using biochar in organic growing media due to the difficulty in maintaining the pH at an adequate level for plant growth.

Sugarcane Bagasse Is an Effective Soilless Substrate Amendment in Quick-turn Osteospermum Production

Many greenhouse growers rely on peat-based soilless substrates to produce salable crops in a relatively short period of time. Peat-based substrate suppliers often incorporate additional organic materials such as wood fiber to extend peat supplies. Given the relative success of wood-based substrates, growing interest in other fiber materials such as sugarcane bagasse may provide similar benefits for substrate processers. The objective of this research was to evaluate substrate properties and the productivity of a short-term floriculture crop, Osteospermum ‘Bright Lights Purple’, in a commercially available peat-based substrate (PL) that has been amended with either commercially available wood fiber [Hydrafiber (HF)] or an aged sugarcane bagasse fiber (SCB). Thus, substrates consisting of PL amended with 15% or 30% HF or SCB were developed. Plants were fertigated weekly at rates of 100, 200, or 300 ppm N, respectively. Crop growth and fertility dynamics were assessed. Substrate shrinkage was greatest in the 30% bagasse blend but had minimal impact given the 2-month crop cycle. The incorporation of 15% and 30% SCB and HF produced slight changes in pH over a 9-week growth period, with HF generally raising pH and SCB generally lowering pH compared with the 100% PL, showing promise for bagasse in managing substrate pH where irrigation water has high pH and/or alkalinity. Substrate EC was initially reduced by blending SCB and, to a lesser extent, HF, but differences ceased to exist by the end of the experiment. Chlorophyll and blooms were abundant in all substrates and fertigation rates. Regardless of fertigation rate, 30% HF had the lowest growth index and shoot dry mass, and 30% SCB had the lowest root dry mass, although differences were not visually apparent. Foliar N concentrations were greatest in plants grown in the PL and SCB substrates and lowest in HF blends. Overall, growth and dry mass differences were minimal across substrate treatment and fertigation rate, and all plants were marketable with statistically similar shelf life. In conclusion, this research indicates the potential of using SCB as a substrate amendment for short-term crop systems in a similar manner as wood fiber.

Comparison of Peat–Perlite-based and Peat–Biochar-based Substrates with Varying Rates of Calcium Silicate on Growth and Cannabinoid Production of Cannabis sativa ‘BaOx’

Growers have been searching for alternative horticultural growing media components because of their desire to use sustainable resources. Biochar is a carbon-based material that has been evaluated for use as an alternative aggregate in peat-based soilless substrates. Additionally, silicon (Si) has been examined as a beneficial element to promote plant growth and plant quality in a variety of crops. However, there has been limited research regarding the interaction of biochar as an aggregate and Si in soilless substrates. This study aimed to determine the impact of Si and biochar on plant growth and nutrient uptake for greenhouse-cultivated hemp (Cannabis sativa L.). Hemp plants were grown in one of 12 different substrate blends: with two rates of calcium silicate (CaSiO3), two aggregate types of biochar (medium or coarse) or perlite, and aggregate percentages of 85% peat + 15% aggregate and 70% peat + 30% aggregate. The cannabinoid concentration, plant height, diameter, or total plant biomass were similar across all substrate blends after 12 weeks of growth. Additionally, the use of CaSiO3 as a Si substrate amendment increased Si foliar concentrations, and the addition of biochar to peat-based mixes did not limit the Si availability for plant uptake. However, Si substrate amendments did not impact plant height, diameter, or total plant biomass. This suggests that the biochar tested during this study is suitable in peat-based substrates for C. sativa ‘BaOx’ production at rates up to 30% (by volume) in peat-based substrates with CaSiO3 amendments.

Common Ivy (Hedera helix L.) Derived Biochar’s Potential as a Substrate Amendment: Effects of Leached Nutrients on Arabidopsis thaliana Plant Development

Common Ivy (Hedera helix L.) Derived Biochar’s Potential as a Substrate Amendment: Effects of Leached Nutrients on Arabidopsis thaliana Plant Development

Aroma Composition of Wines Produced from Grapes Treated with Organic Amendments

The application to agriculture of wheat-straw spent mushroom substrate amendments (compost/vermicompost) used to grow Pleurotus ostreatus has been analyzed. The study was conducted in a vineyard where the effect on (1) the physicochemical properties of the soil and the leaf and (2) the analytical characteristics and the aromatic composition of the wine were analyzed. The application of the amendments resulted in an increase in organic matter and macronutrients (NO3−, P2O5 and K2O) in the soil. With regard to the leaves, the NO3− and K2O contents of those vines fertilized with vermicompost were higher, and the metallic content was the same regardless of the treatment applied. The analysis of the colorimetric parameters showed that there was a higher content of compounds with red and violet colorations in the case of wine obtained after treatment with vermicompost. In addition, for this type of wine, a higher concentration of volatile compounds was obtained. Thus, after grouping the aroma compounds into aroma series, the greatest differences among vermicompost wines and the rest were obtained in the fruit, floral, herbaceous, and green fruit series. The principal component analysis showed that the vermicompost treatment clearly differentiated the wine from the rest of the wines, in addition to its effects on the aromatic series, the values in the total polyphenol index, and the compounds responsible for brown tones.

The Use of Silicon Substrate Amendments to Decrease Micronutrient Concentrations at Varying Micronutrient Fertility Rates with Cannabis sativa ‘Auto CBG’

Many abiotic factors impact the yield and growth of Cannabis sativa (cannabis). Cannabis has been reported to be a bio-accumulator of heavy metals. For growers who are targeting floral production and other byproducts for human consumption, this is a concern. Silicon (Si) has been examined as a beneficial plant element to limit the uptake of heavy metals in a variety of crops. The objective of this study was to determine the impact of Si on heavy metal micronutrient uptake and plant growth for greenhouse-cultivated cannabis at varying Si substrate amendments. ‘Auto CBG’ plants were grown in a 70:30 peat:perlite substrate with one of three varying calcium silicate (CaSiO3) (Si) substrate amendment rates, Si0X, Si0.5X, or Si1X (of 0.0, 1.04, and 2.07 kg⋅m−3 CaSiO3), and one of three micronutrient fertility treatments, M1X [0.49 boron (B), 0.19 copper (Cu), 4.02 iron (Fe), 0.99 manganese (Mn), 0.01 molybdenum (Mo), and 0.20 zinc (Zn) mg⋅L−1], M2X, or M4X, using a modified Hoagland’s solution, creating a 3 × 3 factorial. Plants grown with a Si1X substrate amendment exhibited a significantly lower iron concentration in the foliage and root tissue when compared with those grown in a substrate without Si. After 6 weeks of growth, Si0X plants that received a M4X fertility rate exhibited greater foliar micronutrient concentrations of B, Mn, Zn, Fe, and Cu than plants that received a Si substrate amendment when provided a M4X fertility rate. Additionally, lower micronutrient concentrations in floral tissue were observed in plants that received a Si substrate amendment for M2X and M4X when compared with plants that did not. Silicon substrate amendments had no impact on the cannabinoid concentration or plant growth metrics after 12 weeks of growth. This research suggests that using a Si substrate amendment in a greenhouse production system can limit excessive uptake and accumulation of micronutrients in the foliage, roots, and floral material of cannabis without negative impacts on plant growth or cannabinoid concentrations.

Biodegradation of trace sulfonamide antibiotics accelerated by substrates across oxic to anoxic conditions during column infiltration experiments

Frequent occurrence of trace organic contaminants in aquatic environments, such as sulfonamide antibiotics in rivers receiving reclaimed water, is concerning. Natural attenuation by soil and sediment is increasingly relied upon. In the case of riverbank filtration for water purification, the reliability of antibiotic attenuation has been called into question due to incomplete understanding of their degradation processes. This study investigated influence of substrates and redox evolution along infiltration path on biotransformation of sulfonamides. Eight sand columns (length: 28 cm) with a riverbed sediment layer at 3–8 cm were fed by groundwater-sourced tap water spiked with 1 μg/L of sulfadiazine (SDZ), sulfamethazine (SMZ), and sulfamethoxazole (SMX) each, with or without amendments of dissolved organic carbon (5 mg-C/L of 1:1 yeast and humics) or ammonium (5 mg-N/L). Two flow rates were tested over 120 days (0.5 mL/min and 0.1 mL/min). Iron-reducing conditions persisted in all columns for 27 days during the initial high flow period due to respiration of sediment organics, evolving to less reducing conditions until the subsequent low flow period to resume more reducing conditions. With surplus substrates, the spatial and temporal patterns of redox conditions differentiated among columns. The removal of SDZ and SMZ in effluents was usually low (15 ± 11%) even with carbon addition (14 ± 9%), increasing to 33 ± 23% with ammonium addition. By contrast, SMX removal was higher and more consistent among columns (46 ± 21%), with the maximum of 64 ± 9% under iron-reducing conditions. When sulfonamide removal was compared between columns for the same redox zones during infiltration, their enhancements were always associated with the availability of dissolved or particulate substrates, suggesting co-metabolism. Manipulation of the exposure time to optimal redox conditions with substrate amendments, rather than to simply prolong the overall residence time, is recommended for nature-based solutions to tackle target antibiotics.

An Experimentally Validated Selection Protocol for Biochar as a Sustainable Component in Green Roofs

Green roofs contribute to more sustainable cities, but current commercial substrates suffer from important limitations. If carefully selected, biochar could serve as a viable option for a more sustainable green roof substrate. We propose a protocol to select an optimal biochar for green roof substrate amendment. Coffee husks, medium-density fiberboard, palm date fronds, and a mixture of waste wood, tree bark, and olive stone kernels are selected as residues for biochar production to develop a selection protocol. The residues are pyrolyzed at 350, 450, 500, and 550 °C in a lab-scale reactor. A pyrolysis temperature of 450 °C is selected for upscaling and is based on biochar yield, pH, salinity, and elemental composition. From evaluating the biochar characteristics after upscaling, it can be concluded that the biochar’s carbonization degree is mainly controlled by pyrolysis temperature, while yield, pH, and salinity are more dependent on the biomass properties. Ultimately, our procedure evaluates the presence of important contaminants, the biochar’s water holding capacity, salinity, pH, and carbonization degree. To validate the developed protocol, plant coverage experiments on green roofs are performed, which are quantified using a novel digital image processing method, demonstrating its efficient use to facilitate future biochar selection in substrates.

Multiyear Study on Phosphorus Discharge from Extensive Sedum Green Roofs with Substrate Amendments

Multiyear Study on Phosphorus Discharge from Extensive Sedum Green Roofs with Substrate Amendments

Substrate modified with biochar improves the hydrothermal properties of green roofs

Green roof, as an important measure of sponge city construction, is considered as a win-win alternative for alleviating rainwater runoff and urban heat island. The ecological benefits of green roofs are highly dependent on the quality of substrates. Biochar (BC) prepared from agricultural waste biomass has the potential to be used as a substrate amendment for green roofs. However, the influences of BC properties on hydrothermal properties of green roofs remain unclear. We evaluated the effects of natural soils incorporated with two kinds of BCs (particle size and dosage) on runoff retention capacity and roof thermal performance. Results indicated that the runoff reduction benefit of green roofs declines with the increase of rainfall. When the rainfall is less than 10 mm, the green roofs with different substrates hardly generate runoff, otherwise runoff reduction rates of all green roofs reduce below 75%. BC particles have abundant micro-pores and higher specific surface area, significantly improving the water holding-capacity of roof substrate and playing a critical role in the runoff regulation and cooling effect of green roofs. Application of 20% finer BC particles is the optimal for stormwater retention in all BC addition substrates. Moreover, it could reduce the roof upper surface temperature by 3–5 °C and reduced the daily heat gain of the green roof by at least 0.06 MJ/m2 compared with BC-free ones. Overall, adding BC into the substrates of green roofs can achieve better hydrothermal properties, which is beneficial to the design optimization of green roofs.

Enzymatic Activities of Bok Choy (Brassica rapa subsp. Chinensis) Grown Soil with the Amendment of Sandwich Compost

Soil enzymes ensure our food security, yet they are vulnerable to abiotic stresses. Solving the global issues of food waste by amending the Sandwich compost can be a great solution to ensure food security. Food waste Sandwich compost substrate (as soil amendment) and leachate (as seed priming solution and liquid fertilizer) were used to grow Bok Choy for 4 growing cycles, where soil pH, cation exchangeable capacity, moisture content, aggregate stability, and enzyme activity were determined. The Sandwich compost substrate amendment increased soil pH close to neutral and CEC up to 1.5-fold. Anaerobic Sandwich compost substrate-amended soil reduced soil catalase activity. Still, it steadily increased during the growing cycle. The Sandwich compost substrate amendment soil sustained the aggregate stability for 4 growing cycles. On the flip side, aggregate stability without the Sandwich compost substrate amended soil declined from the growing cycle to the next growing cycle. All variables were positively correlated except catalase activity. Henceforward, Sandwich compost substrate is recommended to improve soil quality in the aspects of pH, CEC urease activity, and dehydrogenase activity.

Metabolic responses of thermophilic endospores to sudden heat-induced perturbation in marine sediment samples.

Microbially mediated processes in a given habitat tend to be catalyzed by abundant populations that are ecologically adapted to exploit specific environmental characteristics. Typically, metabolic activities of rare populations are limited but may be stimulated in response to acute environmental stressors. Community responses to sudden changes in temperature and pressure can include suppression and activation of different populations, but these dynamics remain poorly understood. The permanently cold ocean floor hosts countless low-abundance microbes including endospores of thermophilic bacteria. Incubating sediments at high temperature resuscitates viable spores, causing the proliferation of bacterial populations. This presents a tractable system for investigating changes in a microbiome's community structure in response to dramatic environmental perturbations. Incubating permanently cold Arctic fjord sediments at 50°C for 216 h with and without volatile fatty acid amendment provoked major changes in community structure. Germination of thermophilic spores from the sediment rare biosphere was tracked using mass spectrometry-based metabolomics, radiotracer-based sulfate reduction rate measurements, and high-throughput 16S rRNA gene sequencing. Comparing community similarity at different intervals of the incubations showed distinct temporal shifts in microbial populations, depending on organic substrate amendment. Metabolite patterns indicated that amino acids and other sediment-derived organics were decomposed by fermentative Clostridia within the first 12–48 h. This fueled early and late phases of exponential increases in sulfate reduction, highlighting the cross-feeding of volatile fatty acids as electron donors for different sulfate-reducing Desulfotomaculia populations. The succession of germinated endospores triggered by sudden exposure to high temperature and controlled by nutrient availability offers a model for understanding the ecological response of dormant microbial communities following major environmental perturbations.

Assessment and prediction of coastal saline soil improvement effects combining substrate amendments and salt barrier materials in typical region of the Yangtze River Delta

Coastal saline regions are characterized by high salinity, low permeability, organic matter deficiency, shallow groundwater depth, which limit leaching and lead to salt return. However, there remains a lack of targeted research on long-term coastal saline soil improvement by combining permeation promotion and salt return suppression. Based on a case study of the coastal saline area of Jiangsu Province, China, we used dynamic monitoring of soil water and salt transport, along with laboratory and field scale experiments to analyze the effect of combining substrate amendments and salt barrier materials on salt leaching and return. And numerical simulations were used to predicted the effects of the optimized combination improvement schemes under different climatic conditions in the future. The 2–4% (w/w) straw amended soil had a greater increase (＞90%) in desalinization ratio and a higher reduction (more than half) in desalination time due to changes in soil physical properties. The geocomposite isolated salt effectively due to the formation of capillary barrier compared with traditional straw burial. The results of field scale experiments and numerical simulations showed that geocomposite salt barrier material combined with straw substrate amendment scheme provides a cost-effective solution of soil salinization in coastal areas.

Metagenomes and Metagenome-Assembled Genomes from Substrate-Amended Hot Spring Sediment Incubations from Yellowstone National Park.

ABSTRACTHere, we report on eight sediment metagenomes obtained from an alkaline hot spring, with their corresponding metagenome-assembled genomes. Samples had been incubated for 48 h with various substrate amendments in conjunction with the amino acid analog l-homopropargylglycine in a study targeted at identifying anabolicly active uncultured thermophilic archaea and bacteria.

Impact of biochar, calcium magnesium phosphate fertilizer and spent mushroom substrate on humification and heavy metal passivation during composting

The effects of exogenous additives (biochar, calcium magnesium phosphate fertilizer, and spent mushroom substrate) on humification process and heavy metal passivation during pig manure composting were investigated. The aerobic composting trial were carried out in 60 L reactors for 49 d. The calcium magnesium phosphate fertilizer, biochar, and spent mushroom substrate amendment treatments all accelerated the organic matter degradation and increased the temperature, decreased the volatile fatty acid content by 45%–49.0% and promoted humification of the compost (increasing the humic acid content and humus index). The biochar passivated Cu best, calcium magnesium phosphate fertilizer passivated Zn best (passivation rate 13.85%), and spent mushroom substrate passivated Cd, Cr, and Pb best (passivation rates 25.47%–47.91%). The additives amendment improved Cu, Zn, Cd, Cr, and Pb passivation performance by promoting composting humification process.

Changes in soil microbial community activity and composition following substrate amendment within the MicroResp™ system

Changes in soil microbial community activity and composition following substrate amendment within the MicroResp™ system