Search Results (17)

Rock dust (RD) is a by-product of the precious metal mining industry. Some mining operations produce close to 2,000,000 Mg of RD/year, posing disposal issues. This study evaluated the physicochemical and microbial properties of RD from gold mining and its potential use in RD-based growing media. Ten media formulations were tested: Promix (Control), 100% (RD), 100% topsoil (TS), 50% RD + 50% topsoil (RDT), 25% RD + 75% topsoil (RT), 50% RD + 50% Promix (RP), 50% RD + 25% biochar + 25% Promix (RBP), 50% RD + 25% compost + 25% Promix (RCP), 50% RD + 50% biochar (RB), and Huplaso (negative control). RD particle size ranged from 0.1 to 2 mm with a bulk density of 1.5 g cm⁻³, while RD-based media ranged from 0.8 to 1.1 g cm⁻³ showing increased porosity. Nutrient content was analyzed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), and the active microbial community assessed using PLFA biomarkers via GC-MS/FID, n = 4 and p = 0.05. Microbial analysis identified five classes (protozoa, eukaryotes, Gram-positive (G+), Gram-negative (G−), and fungi (F)), with a significant increase in G−, G+, and F in RD-based amendment RBP (28%) compared to control P (9%). G+, G−, and F showed a strong negative correlation (r = −0.98) with pH, while calcium correlated positively (r = 0.85) with eukaryotes and a strong positive correlation (r = 0.95) of cation exchange capacity with G+. This study suggests blending RD with organic amendments improves physicochemical quality and microbial activity, supporting its use in crop production over disposal. Full article

Crop nitrogen (N) management in agricultural fields is crucial in preventing various environmental and socio-economic issues arising from excess N use. However, precise crop N management (PNM) is hindered by its intensive data requirements, high cost, and time requirements. Digital image processing (DIP) offers a promising approach to overcoming these challenges, and numerous studies have explored its application in N management. This review aims to analyze research trends in applying DIP for N management over the past 5 years, summarize the most recent studies, and identify challenges and opportunities. Web of Science, Scopus, IEEE Xplore, and Engineering Village were referred to for literature searches. A total of 95 articles remained after the screening and selection process. Interest in integrating machine learning and deep learning algorithms with DIP has increased, with the frequently used algorithms—Random Forest, Support Vector Machine, Extreme Gradient Boost, and Convolutional Neural Networks—achieving higher prediction accuracy levels. In addition, image data using more variables as model inputs, including agriculture sensors and meteorological data, have increased prediction accuracy. Nonetheless, several challenges associated with DIP, including obtaining high-quality datasets, complex image processing steps, costly infrastructure, and a user-unfriendly technical environment, still need to be addressed. Full article

Understanding trace element (TE) composition and behavior in soil solution is extremely important for assessing ecological and human health impacts. Using lysimeters to collect soil solution with minimum alteration to the in situ phase distribution and concentration of TEs will facilitate a more accurate assessment. However, different lysimeter materials and sampling conditions may lead to vastly different results, demonstrating the need for the optimal choice of lysimeter depending upon environmental conditions. There is no general agreement or overview discussing the best lysimeter type and sampling system to use under various conditions. This review provides a critical summary of various lysimeters that can be used to collect soil solutions for the analysis of TEs and thereby provides key guidance for developing the best lysimeter sampling system for conditions and research questions of interest. This includes a range of aspects related to lysimeters, such as different types and materials, the basic principles of design and operation, advantages and disadvantages, challenges and limitations, techniques for cleaning and pretreatment, correct installation procedures, the influence of soil physical and chemical properties on sampling, and existing research gaps within this field. Full article

Information on the spatiotemporal variability of soil properties and states within the agricultural landscape is vital to identify management zones supporting precision agriculture (PA). Ground-penetrating radar (GPR) and electromagnetic induction (EMI) techniques have been applied to assess soil properties, states, processes, and their spatiotemporal variability. This paper reviews the fundamental operating principles of GPR and EMI, their applications in soil studies, advantages and disadvantages, and knowledge gaps leading to the identification of the difficulties in integrating these two techniques to complement each other in soil data studies. Compared to the traditional methods, GPR and EMI have advantages, such as the ability to take non-destructive repeated measurements, high resolution, being labor-saving, and having more extensive spatial coverage with geo-referenced data within agricultural landscapes. GPR has been widely used to estimate soil water content (SWC) and water dynamics, while EMI has broader applications such as estimating SWC, soil salinity, bulk density, etc. Additionally, GPR can map soil horizons, the groundwater table, and other anomalies. The prospects of GPR and EMI applications in soil studies need to focus on the potential integration of GPR and EMI to overcome the intrinsic limitations of each technique and enhance their applications to support PA. Future advancements in PA can be strengthened by estimating many soil properties, states, and hydrological processes simultaneously to delineate management zones and calculate optimal inputs in the agricultural landscape. Full article

Anaerobic liquid dairy digestate is a by-product of dairy waste anaerobic digestion from dairy operations and is associated with environmental risks if not handled properly, particularly nutrient leaching losses, water contaminations, and greenhouse gas emissions. We tested the applications of anerobic digestate (AD) as a biofertilizer and water source in greenhouse vegetable production to integrate food production and industry waste management for sustainable environments. We used a deep water culture system to assess the effects of AD effluent alone, inorganic nutrient solution (NS), and a combination of AD and NS on the growth, yield, and phytonutrient profile and heavy metal contamination assessment of hydroponically produced lettuce. Lettuce produced in AD had a lower leaf area, total chlorophyll content, and fresh biomass; however, it displayed significantly higher chicoric acid (200%), chlorogenic acid (67%), luteolin (800%), quercetin-3-O-β-d-glucuronide (378%), quercetin-3-glucoside (200%), quercetin-3-O-(6″-O-malonyl)-β-D-glucoside (1077%), folate (248%), pantothenic acid (200%), total phenolics (111%), total antioxidants (44%), and soluble sugars (253%) compared to control (inorganic feed). The AD-produced lettuce also showed significantly lower heavy metal bioaccumulation risks associated with the human consumption. Based on various results, we may conclude that AD utilization in hydroponics can offer a sustainable solution to harvest a better lettuce yield, higher phytonutrients, and environmental benefits. Full article

Chilling stress is one of the major abiotic stresses which hinder seedling emergence and growth. Herein, we investigated the effects of chilling/low temperature stress on the morphological, physiological, and biochemical attributes of two silage corn genotypes during the seedling establishment phase. The experiment was conducted in a growth chamber, and silage corn seedlings of Yukon-R and A4177G-RIB were grown at optimum temperature up to V3 stage and then subjected to five temperature regimes (25 °C as control, 20 °C, 15 °C, 10 °C, and 5 °C) for 5 days. After the temperature treatment, the morphological, physiological, and biochemical parameters were recorded. Results indicated that temperatures of 15 °C and lower significantly affected seedling growth, photosynthesis system, reactive oxygen species (ROS) accumulation, and antioxidant enzyme activities. Changes in seedlings’ growth parameters were in the order of 25 °C > 20 °C > 15 °C > 10 °C > 5 °C, irrespective of genotypes. The chlorophyll content, photosynthetic rate, and maximal photochemical efficiency of PS-II (F_v/F_m) were drastically decreased under chilling conditions. Moreover, chilling stress induced accumulation of hydrogen peroxide (H₂O₂)and malonaldehyde (MDA) contents. Increased proline content and enzymatic antioxidants, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxide (APX), were found to alleviate oxidative damage under chilling stress. However, the genotype of Yukon-R exhibited better adaption to chilling stress than A4177G3-RIB. Yukon-R showed significantly higher proline content and enzymatic antioxidant activities than A4177G3-RIB under severe chilling conditions (temperature ≤ 10 °C). Similarly, Yukon-R expressed low temperature-induced ROS accumulation. Furthermore, the interaction effects were found between temperature treatment and genotype on the ROS accumulation, proline content and antioxidant enzyme activities. In summary, the present study indicated that Yukon-R has shown better adaptation and resilience against chilling temperature stress, and therefore could be considered a potential candidate genotype to be grown in the boreal climate. Full article

Intercropping systems could be a potential source of nutrient-rich forage production in cool climates on podzolic soils common in boreal ecosystems. In this study, we evaluated the effects of corn–soybean intercropping (IC) on the nutritional quality of forage. Two silage corn varieties were cultivated as monocropping (MC) or were intercropped with three forage soybean varieties using a randomized complete block design. IC significantly increased the crude protein (22%) and decreased the acid detergent (14%) and neutral detergent (6%) fibers. Forage net energy, total digestible nutrients, ash, dry matter intake, digestible dry matter and relative feed value were also significantly increased (p ≤ 0.05) in the IC treatments compared to corn MC. The macro and micro nutrients were higher in IC than corn MC. Intercropping increased the omega 3 fatty acid (FA) contents (67%) compared to corn MC. IC also increased the active microbial community in the plant root zone, which may contribute to the improvement in forage nutritional quality because the active soil microbial community composition showed significant correlations with soluble sugars, soluble proteins and potassium contents of the forage. These results demonstrate that corn–soybean IC could be a suitable cropping system to increase the nutritional quality of forage cultivated on podzols in boreal climates. The resultant forage has the potential to be a source of high-value animal feed for livestock production in cool climate regions of the world. Full article

Research into biochar, as an amendment to soil, has increased over the last decade. However, there is still much to understand regarding the effects of biochar type and rates on the physicochemical properties of different soil types. This study aimed to investigate the effects of biochar application on the physicochemical properties of podzolic soils. Soil samples were collected from the research site in Pasadena, Newfoundland, Canada. Experimental treatments consisted of three types of soils (topsoil, E-horizon soil and mixed soil (topsoil 2: E-horizon soil 1)), two biochar types (granular and powder) and four biochar application rates (0%, 0.5%, 1% and 2% on a weight basis). Ten physicochemical parameters (bulk density (BD), porosity, field capacity (FC), plant available water (PAW), water repellency (WR), electrical conductivity (EC), pH, cation exchange capacity (CEC), total carbon (TC), and nitrogen (N)) were investigated through a total of 72 experimental units. Biochar morphological structure and pore size distribution were examined using a scanning electron microscope, whereas specific surface area was assessed by the Brunauer−Emmett−Teller method. The result indicated that the E-horizon soil was highly acidic compared to control (topsoil) and mixed soils. A significant difference was observed between the control and 2% biochar amendment in all three soil mixtures tested in this experiment. Biochar amendments significantly reduced the soil BD (E-horizon: 1.40–1.25 > mixed soil: 1.34–1.21 > topsoil: 1.31–1.18 g cm⁻³), increased the CEC (mixed soil: 2.83–3.61 > topsoil: 2.61–2.70 > E-horizon: 1.40–1.25 cmol kg⁻¹) and total C (topsoil: 2.40–2.41 > mixed soil: 1.74–1.75 > E-horizon: 0.43–0.44%). Water drop penetration tests showed increased WR with increasing biochar doses from 0 to 2% (topsoil: 2.33–4.00 > mixed soil: 2.33–3.33 > E-horizon: 4.00–4.67 s), and all the biochar–soil combinations were classified as slightly-repellent. We found significant effects of biochar application on soil water retention. Porosity increased by 2.8%, FC by 10%, and PAW by 12.9% when the soil was treated with powdered biochar. Additionally, we examined the temporal effect of biochar (0 to 2% doses) on pH and EC and observed an increase in pH (4.3–5.5) and EC (0.0–0.20 dS/m) every day from day 1–day 7. Collectively the study findings suggest 2% powder biochar application rate is the best combination to improve the physicochemical properties of the tested mixed podzolic soil. Granular and powdered biochar was found to be hydrophobic and hydrophilic, respectively. These findings could be helpful to better understand the use of biochar for improving the physicochemical properties of podzolic soils when used for agricultural practices in boreal ecosystems. Full article

Application of the nanopriming technique to alleviate seed dormancy has shown promising results in various agricultural crop species. However, there is a dearth of knowledge regarding its potential use in native peatland boreal forest species to alleviate seed dormancy and improve their propagation or vigor for forest reclamation activities. Herein, we demonstrate the use of nanopriming with carbon nanotubes (CNT) to alleviate seed dormancy, improved seed germination, and seedling vigor in two boreal peatland species. Bog birch (Betula pumila L.) and Labrador tea (Rhododendron groenlandicum L.) seeds with embryo or seed coat dormancy were nanoprimed with either 20 or 40 µg/mL CNT, cold stratified at 2–4 °C for 15 days, and allowed to germinate at room temperature. The emerged seedlings’ lipidome was assessed to decipher the role of lipid metabolism in alleviating seed dormancy. We observed significant (p < 0.05) improvement in seedling germination and seedling vigor in seeds primed with multiwalled carbon nanotubes functionalized with carboxylic acids. Phosphatidylcholine (PC 18:1/18:3), phosphatidylglycerol (PG 16:1/18:3), and lysophosphatidylcholine (LPC 18:3) molecular species (C18:3 enriched) were observed to be highly correlated with the increased seed germination percentages and the enhanced seedling vigor. Mechanistically, it appears that carbon nanoprimed seeds following stratification are effective in mediating seed dormancy by remodeling the seed membrane lipids (C18:3 enriched PC, PG, and LPC) in both peatland boreal forest species. The study results demonstrate that nanopriming may provide a solution to resolve seed dormancy issues by enhancing seed germination, propagation, and seedling vigor in non-resource boreal forest species ideally suited for forest reclamation following anthropogenic disturbances. Full article

Relative permittivity and soil moisture are highly correlated; therefore, the top boundary of saturated soil gives strong reflections in ground-penetrating radar (GPR) profiles. Conventionally in shallow groundwater systems, the first dominant reflection comes from the capillary fringe, followed by the actual water table. The objective of this study was to calibrate and validate a site-specific relationship between GPR-estimated depth to the capillary fringe (D_CF) and measured water table depth (WTD_m). Common midpoint (CMP) GPR surveys were carried out in order to estimate the average radar velocity, and common offset (CO) surveys were carried out to map the water table variability in the 2017 and 2018 growing seasons. Also, GPR sampling volume geometry with radar velocities in different soil layers was considered to support the CMP estimations. The regression model (R² = 0.9778) between D_CF and WTD_m, developed for the site in 2017, was validated using data from 2018. A regression analysis between D_CF and WTD_m for the two growing seasons suggested an average capillary height of 0.741 m (R² = 0.911, n = 16), which is compatible with the existing literature under similar soil conditions. The described method should be further developed over several growing seasons to encompass wider water table variability. Full article

Electromagnetic induction (EMI) technique is an established method to measure the apparent electrical conductivity (EC_a) of soil as a proxy for its physicochemical properties. Multi-frequency (MF) and multi-coil (MC) are the two types of commercially available EMI sensors. Although the working principles are similar, their theoretical and effective depth of investigation and their resolution capacity can vary. Given the recent emphasis on non-invasive mapping of soil properties, the selection of the most appropriate instrument is critical to support robust relationships between EC_a and the targeted properties. In this study, we compared the performance of MC and MF sensors by their ability to define relationships between EC_a (i.e., MF–EC_a and MC–EC_a) and shallow soil properties. Field experiments were conducted under wet and dry conditions on a silage-corn field in western Newfoundland, Canada. Relationships between temporally stable properties, such as texture and bulk density, and temporally variable properties, such as soil water content (SWC), cation exchange capacity (CEC) and pore water electrical conductivity (EC_w) were investigated. Results revealed significant (p < 0.05) positive correlations of EC_a to silt content, SWC and CEC for both sensors under dry conditions, higher correlated for MC–EC_a. Under wet conditions, correlation of MF–EC_a to temporally variable properties decreased, particularly to SWC, while the correlations to sand and silt increased. We concluded that the MF sensor is more sensitive to changes in SWC which influenced its ability to map temporally variable properties. The performance of the MC sensor was less affected by variable weather conditions, providing overall stronger correlations to both, temporally stable or variable soil properties for the tested Podzol and hence the more suitable sensor toward various precision agricultural practices. Full article

Nanopriming has been shown to significantly improve seed germination and seedling vigor in several agricultural crops. However, this approach has not been applied to native upland boreal forest species with complex seed dormancy to improve propagation. Herein, we demonstrate the effectiveness of carbon nanoparticles functionalized with carboxylic acids in resolving seed dormancy and improved the propagation of two native upland boreal forest species. Seed priming with carbon nanoparticles functionalized with carboxylic acids followed by stratification were observed to be the most effective in improving germination to 90% in green alder (Alnus viridis L.) compared to 60% in the control. Conversely, a combination of carbon nanoparticles (CNPs), especially multiwall carbon nanoparticles functionalized with carboxylic acid (MWCNT–COOH), cold stratification, mechanical scarification and hormonal priming (gibberellic acid) was effective for buffaloberry seeds (Shepherdia canadensis L.). Both concentrations (20 µg and 40 µg) of MWCNT–COOH had a higher percent germination (90%) compared to all other treatments. Furthermore, we observed the improvement in germination, seedling vigor and resolution of both embryo and seed coat dormancy in upland boreal forest species appears to be associated with the remodeling of C18:3 enriched fatty acids in the following seed membrane lipid molecular species: PC18:1/18:3, PG16:1/18:3, PE18:3/18:2, and digalactosyldiacylglycerol (DGDG18:3/18:3). These findings suggest that nanopriming may be a useful approach to resolve seed dormancy issues and improve the seed germination in non-resource upland boreal forest species ideally suited for forest reclamation following resource mining. Full article

A field experiment was conducted to evaluate the effects of biochar and dairy manure (DM) on physicochemical properties of podzolic soils, as well as to establish the relationships between selected physicochemical properties and soil electrical conductivity (EC) in a silage-corn production system. Nutrient requirements of the crop were met through different nutrient sources considering soil nutrient status, nutrient availability from DM (DM, DM + biochar) and regional crop nutrient recommendations. Experimental treatments included control, inorganic nitrogen (IN), IN + biochar, IN + DM, and IN + DM + biochar. DM was applied at 30,000 L ha⁻¹, whereas biochar was applied at 20 Mg ha⁻¹ and mixed within the top 20 cm of the soil. Disturbed soil samples as well as time domain reflectometry (TDR) measurements were collected from treatment plots on four field days. Results showed no significant (p > 0.05) treatment effects on soil pH and cation exchange capacity (CEC) within each field day. However, significant temporal effects were recorded for pH, EC, apparent electrical conductivity (EC_a) and electrical conductivity of the soil solution (EC_w). Soil depth (0–10 cm and 10–20 cm) had no significant effect on treatments. Significant positive correlations were recorded for EC with soil organic carbon and CEC (EC_a, EC_w 0–10 cm, & 10–20 cm, p = 0.000). Correlation results show that EC_a measurements as a proxy to investigate the variability of key soil properties over large areas, but further investigation between EC_a data and soil properties should be carried out to address uncertainties associated in predicting these properties. Full article

Boreal agriculture struggles with soils of lower agronomic value, most of which are sandy with a low water holding capacity (WHC) and prone to nutrient leaching. Biochar amendments are associated with positive effects on soil hydraulic properties and enhanced nutrient retention. However, these effects are strongly related to feedstock type and pyrolysis parameters and depend on biochar application rates and soil types. While biochar could increase the productivity of boreal agriculture by improving water and nutrient use efficiency, little is known about its effects on hydraulic processes in podzol. In this study, we investigated the effects of biochar rates (10, 20, 40, 80 Mg carbon ha⁻¹) and maturity on soil hydrology for an agriculturally used Podzol in Labrador, Canada. The in-situ soil water content (SWC) and weather data over an entire growing season were analysed. Hydrus 1D simulations were used to estimate changes in water fluxes. SWC showed clear differentiation among storage parameters (i.e., initial, peak and final SWC) and kinetic parameters (i.e., rate of SWC change). Storage parameters and soil wetting and drying rates were significantly affected by biochar rates and its maturity. The magnitude of the changes in SWC after either wetting or drying events was statistically not affected by the biochar rate. This confirms that biochar mostly affected the WHC. Nevertheless, reductions in cumulative lower boundary fluxes were directly related to biochar incorporation rates. Overall, biochar had positive effects on hydrological properties. The biochar rate of 40 Mg C ha⁻¹ was the most beneficial to agriculturally relevant hydraulic conditions for the tested Podzol. Full article

Considering the increased interests in biochar (BC) as a soil amendment and a growing media substrate in agriculture, we evaluated the effect of BC incorporation on TDR (time-domain reflectometer)-based volumetric soil moisture content (VSMC) estimations in a loamy sand podzolic soil. Two commercial BC types (powdered—BC_P, and granular—BC_G) were mixed in different rates (w/w) with a podzolic soil. The dielectric constants measured using a TDR cable tester (MOHR CT 100) were converted to VSMC. Three commonly used models: (i) Topp’s equation, M-1; (ii) mixing model, M-2; and (iii) the forest soil model, M-3, were used. The accuracy of the estimated VSMC using these three models was statistically compared with measured VSMC. BC_P at lower rates produced very similar results to the actual VSMC with M-1 and M-2 but deviated with increasing rates. The M-3 showed a non-linear relationship with measured VSMC. In BC_G treatments, all models overestimated the VSMC. BC_G rates higher than 15% (w/w) resulted in highly attenuated TDR waveforms and the signal was completely dissipated when rates higher than 50% (w/w) were used (typical application for field soils is less than 5% w/w). These results showed that predictions of the soil moisture content based on the soil dielectric constant might not be feasible for tested podzolic soils amended at high BC rates. Full article