Production Period Research Articles

Examining the source and composition of organic matter through saturated hydrocarbons, δ13C, and δ15N in a subtropical water reservoir

The sources of organic matter in the sediments of the Passaúna reservoir, an important water supply for the local population, were thoroughly investigated. The objective was to identify the origins of organic matter through the analysis of saturated hydrocarbons, elemental composition (total organic carbon and total nitrogen), and the content of δ13C and δ15N isotopes. This comprehensive approach allowed us to trace the sources of organic matter and discerns indicating heightened primary productivity within the reservoir. To achieve this, two sediment cores spanning a 140-year interval (1880–2020) were retrieved from the reservoir. Core 2 accumulates the majority of sediments, particularly near the dam area. In these parts, sediment deposits can reach up to 1 m above the pre-impoundment soil. Sediments near the area where core 1 was collected contain more sand, resulting in lower thickness compared to core 2. Sediment core 1 primarily reflects terrestrial sources of organic matter, as supported by stable isotope values of δ13C and δ15N. The δ13C values ranged from −23.0 ‰ to −25.7 ‰ in core 1 and from −28.4 ‰ to −29.2 ‰ in core 2. Meanwhile, the δ15N values ranged from 6.6 ‰ to 10.8 ‰ in core 1 and from 3.8 ‰ to 7.6 ‰ in core 2. The distribution of saturated hydrocarbons revealed that organic matter originates from both allochthonous and autochthonous sources. Periods of intense primary productivity were indicated by the presence of n-C16, n-C17, n-C18, and n-C19 alkanes. Additionally, we observed periods characterized by high primary productivity, indicative of elevated nutrient input likely resulting from increased urbanization and industrial activity in the area.

Changing rates of escarpment retreat linked to environmental change in a sedimentary tableland, Stołowe Mountains, SW Poland

Long-term rates of escarpment retreat in sedimentary tablelands have been rarely determined and their possible variability in relation to major environmental changes has often been speculative, especially in older contributions. Moreover, rates reported so far were almost exclusively from arid regions. In this paper we present a dataset of 20 cosmogenic exposure ages, obtained for cliffs and boulders produced by rock-slope disintegration, left in front of a retreating 150-m-high escarpment of a sandstone mesa in SW Poland. The most distant boulders are >400 m away from the cliffs. Following previous research in the region, boulders are mainly products of in situ disintegration and hence, their present-day position on the slope approximates the past position of the cliffs, allowing for the calculations of cliff retreat. Exposure ages systematically increase with the distance from the present-day cliff line and cover the last 100 kyr, implying an average retreat rate of 4.18 mm/yr. However, the dataset splits into several sub-populations, each with its own trend, meaning that the rates of retreat varied with time. A maximum was reached during the Late Pleistocene and transition to the Holocene, when the rates exceeded 10 mm/yr and may have reached 100 mm/yr. The rates seemed distinctly lower between MIS5 and LGM and during the Holocene. We propose that the transition towards a warmer climate at the Pleistocene/Holocene boundary, with an increased frequency of freezing-thawing cycles, the degradation of permafrost and unblocking of groundwater drainage enhanced caprock disintegration and accelerated the break-off rates of caprock. During periods of most efficient cliff disintegration and boulder production the rates of escarpment retreat at the field site could have been two orders of magnitude higher than in the hyperarid areas. However, despite changing rates of retreat major processes involved in escarpment evolution seem to have remained the same.

Analysis of Changes in In-Store and Online Shopping Frequencies Due to the COVID-19 Pandemic: A Case Study from Bahrain

Online shopping (e-shopping) has been growing steadily in recent years; however, the COVID-19 pandemic resulted in a sudden increase in this growth. This study compares the in-store shopping and e-shopping frequencies within three distinct periods, i.e., before, during, and after the COVID-19 pandemic. It further investigates the frequencies and determinants of e-shopping across the three periods. The data on the in-store shopping and e-shopping frequencies for four different product categories, i.e., grocery, household essentials, electronics, and clothes, were collected through an online questionnaire in Bahrain, resulting in a total of 401 valid responses. Wilcoxon signed-rank tests were conducted to compare the frequencies of in-store shopping and e-shopping within the three periods as well as the frequencies of e-shopping across the three periods. The effects of the determinants of e-shopping were evaluated using chi-square tests. The results revealed that e-shopping experienced a temporary surge during the COVID-19 pandemic, returning to pre-pandemic levels afterward. The frequency of e-shopping varied across product categories and periods, and e-shopping during the pandemic was higher than before. However, no significant difference was found between the periods during and after the pandemic. This study provides insights for urban and transport planners regarding the frequencies and determinants of e-shopping behavior in the context of pandemics.

Origin and significance of macroscopic organic aggregates from the lacustrine Aptian Crato Konservat-Lagerstätte

The Crato Konservat-Lagerstätte is one of the main Mesozoic fossil sites from Gondwana, recording a wide diversity of terrestrial and non-marine aquatic fossils of great paleobiological and evolutionary significance. This conservation deposit is recorded in a 9 m-thick interval of laminite, microbialite, and grainstone deposited in a lake system with variable water level, alternating moments of hypersaline and freshwater conditions. Despite numerous studies describing new species of plants, arthropods, fish, pterosaurs, birds, and many others, there remains a significant gap in our understanding of the most common and archetypal fossils, which are the rod-shaped macrofossils found on bedding surfaces in distinct stratigraphic intervals of the Crato Konservat-Lagerstätte. The rod-shaped macrofossils are up to 1.6 cm-long and 0.1 cm-wide, straight to curved compressions that preserve pyritized microfossils. Here we interpret the rod-shaped macrofossils as macroscopic organic aggregates that sank into the lakebed in a process called lake snow. During high organic productivity periods in the epilimnion, planktonic organisms thrived and produced exopolymers responsible for aggregation. Their concentrations in the limestone bedding planes reflect intensity of lake snow and environmental seasonality. Aggregates are prolate particles that are commonly oriented, suggesting their transport as bedload for short distances, which was facilitated by biostabilization by microbes and their exopolymers. Finally, pyritization was mediated by microbial communities living in the lakebed.

Thermal, Electrical, and Economic Performance of a Hybrid Solar-Wind-Geothermal System: Case Study of a Detached House in Hamburg and Sylt, Germany

Germany is undergoing an energy transition. By 2045, fossil fuels will be gradually replaced by clean energy. An alternative option is to use geothermal, solar and wind energy to generate heat or electricity. Currently, an economic model that considers these three energy sources and incorporates the design and installation of the energy system as well as operational costing focusing on the local market is lacking. In this study, we present a concept for a hybrid energy system combining solar, wind and geothermal energy for small, detached houses. We also develop a simplified economic model for the German market and local energy subsidy policies. The model was applied to two different cities in northern Germany, calculating the installation and long-term operating costs of different energy systems and combinations over a period of 100 years, including the consideration of the lifespan of variable equipment. The calculations show that for this small hybrid energy system the initial installation costs can vary from EUR 20,344 to EUR 70,186 depending on different portfolios. Long-term operating costs come mainly from electricity purchased from the grid to compensate for periods of low solar or wind production. In addition, the study included a calculation of the payback period for retrofitting a natural gas heating system. Results show that combining a photovoltaic system with a ground source heat pump, especially in the form of a near-surface heat exchanger, yields a shorter payback period (5 to 10 years). However, the incorporation of on-roof wind turbines into the hybrid energy system may significantly prolong the payback period and is therefore not recommended for use in low wind speed areas.

Research on the Current Status of Light Supplementation Technology for Dragon Fruit

Dragon fruit has a good market prospect for its good taste and high nutritional value. At the same time, since its planting conditions are easy to meet, dragon fruit is widely planted in many regions of China. However, the problem of insufficient sunlight in spring and winter still leads to an insufficient supply of dragon fruit production. To improve the quality as well as the annual supply cycle of dragon fruit fresh fruit, and improve the economic benefits of dragon fruit cultivation, fruit growers generally use artificial light supplementation technology to regulate the flowering cycle of dragon fruit to prolong the production period. This paper reviews the impact of different light qualities, light intensities, and photoperiod on the production and quality of dragon fruit, and summarizes the shortcomings of the existing supplementation technology. The feasibility of the combination of photovoltaic, energy storage, and dragon fruit light supplementation technology is also comprehensively analyzed, and the outlook is put forward, aiming to provide a direction for the further development of dragon fruit light supplementation technology.

Development and evaluation of three sorghum varieties under different fermentation period for silage production

Development and evaluation of three sorghum varieties under different fermentation period for silage production

Viability of Cull Bee Brood (<i>Apis mellifera</i>) as an Additive in Chicken Feed for Enhanced Food Security

There is insufficient knowledge by African beekeepers on how to utilize and integrate culled bee brood into their chicken feed or food systems instead of dumping broods as wastes. Culling out access bee brood combs, diseased, old combs with brood remains will reduce over reproduction of bee brood in the bee colony and hence improving hygiene in bee hive colony which will increase its fitness. African bee keepers regularly practice bee brood culling of unwanted, damaged, diseased and excessive combs with brood during production and harvesting periods and throw away culled bee brood Africa beekeepers. Therefore, this study came up with new ways on how to collect, process, utilize and integrate culled bee brood into chicken feeds as additives instead of throwing them away as wastes. This would create new production opportunity among bee keeper now and in the future as culled bee brood to be an alternative source of protein in chicken feeds systems leading to improved food security. The study was conducted in three districts of southwestern Uganda (Kiruhura, Mbarara, Rwampara). Current Nutritional composition and hygiene practice were analyzed after sampling practices and collection. Analyzed 966 culled bee brood combs from 46 beekeeper’s colony. Data was analyzed using r-statistical program. All assumptions for statistical tests were met. A total of seven (7) apiaries participated in cull brood removal sample from 46 bee hives from each district that was sampled making a total of 966 colonies. a repeated measures ANOVA both at beginning of the season and the end of the season was used to analyze the beekeepers’ data from different apiary yard in western Uganda and five (5) colonies (bee hive) from an on-farm trial experiment at Mbarara, Kiruhura, Rwampara western Uganda, three (3) treatment and two control were utilized. Repeated measures ANOVA was used to analyze this data. Using computer aided software of R-statistical package for analysis. Results were presented in table form from different seasons from laboratory analysis. The study also adds to existing literature where some insects are used industrially for selling as seen with the Nsenene (grass hoppers) in Uganda and crickets and black soldier’s flies in western Kenya at Jaramongi Odinga Oginga University of Science and Technology. MP2 has the highest metabolizable energy with slightly less microbes, and average moisture content. This makes it a good choice of feeds with bee brood additives for the chicken.

Ectodermal origin and tissue dedifferentiation in the podocyst production by the polyps of the Asian moon jelly (Aurelia coerulea).

The histological origin of podocysts in scyphozoans has long been undetermined, with uncertainty whether they arise from mesenchymal amoebocytes or stalk and pedal disc ectoderm in polyps. Histological investigation on the pedal disc was difficult due to the settlement of polyps on hard substrates. In this study, we investigated the histological characteristics of polyps during podocyst production in Asian moon jelly (Aurelia coerulea) with utilizing those attached on thin polystyrene substrates. Fine histological features of the pedal disc became possible after the substrates were decomposed during histological processing. Our findings unequivocally demonstrate that the cell mass of podocysts originates from the ectoderm of the pedal disc and the stalk without the involvement of amoebocytes in the mesoglea. Preceding the podocyst formation, the pedal disc undergoes enlargement facilitated by the elongated stalk ectodermal cells, which attach to a substrate. Subsequently, the pedal disc ectoderm give rise to the primary podocyst cells with accumulating nutrient granules in the cytoplasm and forming the cyst capsule cooperatively with the invaginated pedal disc ectoderm. Direct transformation from the ectodermal cells to podocyst cells suggests that podocyst formation involves tissue dedifferentiation. Throughout the period of podocyst production, the gastrodermis of polyps is physically separated from the ectoderm by the mesoglea and shows no histological changes, and no amoebocytes appear in the mesoglea. These histological properties are totally different from those in other modes of asexual reproduction, which incorporate the endoderm of polyps, suggesting the developmental and evolutionary differences between these asexual reproductions and podocyst production in Scyphozoa.

Enhanced Day-Ahead Electricity Price Forecasting Using a Convolutional Neural Network–Long Short-Term Memory Ensemble Learning Approach with Multimodal Data Integration

Day-ahead electricity price forecasting (DAEPF) holds critical significance for stakeholders in energy markets, particularly in areas with large amounts of renewable energy sources (RES) integration. In Japan, the proliferation of RES has led to instances wherein day-ahead electricity prices drop to nearly zero JPY/kWh during peak RES production periods, substantially affecting transactions between electricity retailers and consumers. This paper introduces an innovative DAEPF framework employing a Convolutional Neural Network–Long Short-Term Memory (CNN–LSTM) model designed to predict day-ahead electricity prices in the Kyushu area of Japan. To mitigate the inherent uncertainties associated with neural networks, a novel ensemble learning approach is implemented to bolster the DAEPF model’s robustness and prediction accuracy. The CNN–LSTM model is verified to outperform a standalone LSTM model in both prediction accuracy and computation time. Additionally, applying a natural logarithm transformation to the target day-ahead electricity price as a pre-processing technique has proven necessary for higher prediction accuracy. A novel “policy-versus-policy” strategy is proposed to address the prediction problem of the zero prices, halving the computation time of the traditional two-stage method. The efficacy of incorporating a suite of multimodal features: areal day-ahead electricity price, day-ahead system electricity price, areal actual power generation, areal meteorological forecasts, calendar forecasts, alongside the rolling features of areal day-ahead electricity price, as explanatory variables to significantly enhance DAEPF accuracy has been validated. With the full integration of the proposed features, the CNN–LSTM ensemble model achieves its highest accuracy, reaching performance metrics of R2, MAE, and RMSE of 0.787, 1.936 JPY/kWh, and 2.630 JPY/kWh, respectively, during the test range from 1 March 2023 to 31 March 2023, underscoring the advantages of a comprehensive, multi-dimensional approach to DAEPF.

Following the Rain: Climates of Opinion

This article foregrounds La Niña’s role in establishing climate optimism in the southeastern states of Australia in the 1860s and 1870s. It examines the perceptions of climate as influenced by the cycles of the El Niño Southern Oscillation (ENSO), underscored by the decadal cycles of the Interdecadal Pacific Oscillation (IPO) and the influence in some areas of the intensity of the subtropical ridge. It finds an abundance of very wet La Niña years coincided with a key period of Australian immigration and the expansion of pastoralism and agriculture. The article concludes that this period of productivity and expansion substantially contributed to a false sense of optimism. It suggests nineteenth-century ideas about climate can illuminate contemporary cultural understandings.

The Selection of Optimal Gas Production Rate using Dynamic Reservoir Simulation in Field X

Indonesian government has targeted a gas production rate of 12 BSCFD by 2030 to balance the energy demands and the carbon emission reduction. To achieve this goal, a comprehensive evaluation of a gas field will be carried out regarding Recovery Factor, Stable Production Period (Plateau Time), Total Production Period, and Profits using simulation programme. Dynamic Reservoir Simulation is an integrated field development simulation that combines physics, mathematics, reservoir engineering, and computer programming to analyze and predict the wells performance or how fluid flows through reservoir rocks to the surface over time under various operating conditions. There are stages in the simulation include Reservoir Model Creation, Initialization, History Matching, and Production Performance Forecasting. This research is a continuation of static reservoir modeling research done by LEMIGAS, which started by reinitializing the model and ended by forecasting the production performance of field X using several gas production flowrate scenarios to find out the optimal gas production flowrate for Field X in ten years period. The simulation result showed that the best gas production flowrate for a ten-year period is 3 mmscfd. It gives 78,505% recovery factors, with cumulative profit of $40,915,872 USD over a plateau period of 6.6 years.

Maintenance of steady-state mRNA levels by a microRNA-based feed forward loop in the presence of stochastic gene expression noise

Abstract All vital functions of living cells rely on the production of various functional molecules through gene expression. The production periods are burst-like and stochastic due to the discrete nature of biochemical reactions. In certain contexts, the concentrations of RNA or protein require regulation to maintain a fine internal balance within the cell. Here we consider a motif of two types of RNA molecules – mRNA and an antagonistic microRNA – which are encoded by a shared coding sequence and form a feed forward loop (FFL). This control mechanism is shown to be perfectly adapting in the deterministic context. We demonstrate that the adaptation (of the mean value) becomes imperfect if production occurs in random bursts. The FFL nevertheless outperforms the benchmark feedback loop in terms of counterbalancing variations in the signal. Methodologically, we adapt a hybrid stochastic model, which has widely been used to model a single regulatory molecule, to the current case of a motif involving two species; the use of the Laplace transform thereby circumvents the problem of moment closure that arises owing to the mRNA–microRNA interaction. We expect that the approach can be applicable to other systems with nonlinear kinetics.

Scalable-produced micro-elastic triboelectric sensing ground for all-weather large-scale applications

Large-scale smart floor will be one potential form for a human–machine interface, but is also facing many difficulties and challenges in the materials science and information engineering. Here, we present a straightforward method for fabricating large-scale micro-elastic triboelectric nanogenerator (ME-TENG) arrays, which can be assembled as triboelectric sensing ground for real-time interface interaction and all-weather monitoring. ME-TENG unit of 6 by 6 arrays offers a maximum power density of 5.84 mW·m−2 under a load resistance of 70 MΩ. It displays a sensitivity of 132.48 mV/kPa in the pressure range of 0 to 180 kPa. The electrical output signals have remained stable in the durability tests over 10 days with various weather conditions. Furthermore, successfully demonstrated a regional comprehensive security monitoring (RCSM) system for enabling all-weather monitoring of the features, position, and movement trajectories of an object. Even more gratifying is that the ME-TENG unit of 30 cm by 30 cm prepared by a simple and fast “all-in-one” method, takes costs of 14.84 dollars/m2 and the production period of 2 h, compared with the most cost-effective piezoelectric sensors, the cost and duration were reduced by 98.67 % and 42.86 %, respectively. This work will greatly contribute to the development and implementation of large-scale sensing and the multidimensional security system.

Greenhouse gas emissions and their driving factors among different flowering Chinese cabbage (Brassica campestris L.) varieties.

Crop cultivars have an influence on greenhouse gas (GHG) emissions, and there is variation between varieties. However, there are few reports available on the differences in GHG emissions and their driving factors among vegetable varieties. In this study, we conducted a field experiment to examine the variances in GHG emissions and their contributing factors among eight flowering Chinese cabbage varieties (considering growth period, leaf shape, and colour). The results showed significant differences in GHG emissions within varieties; early-maturing varieties exhibited GHG by 25.6% and 15.3%, respectively, when compared to mid- and late-maturing varieties. Among the different leaf types and color classifications, light-colored and sharp-leafed varieties had the lower global warming potential (GWP) overall. Cumulative CO2 emissions were influenced by leaf SPAD values and biomass, while cumulative N2O emissions were driven mainly by stem thickness, carbon accumulation, leaf SPAD values, and biomass. In summary, the selection of light-colored varieties with pointed leaves and shorter growth periods in actual production contributed positively to the reduction of carbon emissions from flowering Chinese cabbage production. Through efficient variety screening, this study provides a win-win strategy for achieving efficient vegetable production while also addressing the global climate challenge.

Forecasting Palm Oil Production Using Long Short-Term Memory (LSTM) With Time Series Cross Validation (TSCV)

Oil palm plant (Elaeis guineensis Jacq.) is a plantation crop that has a high economic value for Indonesia, because the results of oil palm plantations can increase the country's foreign exchange. Oil palm plantations can create jobs for the people of Indonesia, thus reducing unemployment in Indonesia. Oil palm plantations in Indonesia have spread to various regions, besides being found on the islands of Sumatra and Kalimantan, now oil palm plantations are almost found in various regions in Indonesia both small-scale plantations and large-scale plantations. This research uses historical data in the form of monthly palm oil production to predict the price of strategic food commodities. The period of palm oil production used is from January 1997 to December 2023 obtained from the website of PT. X or documentation data at PT. X. In this study the data was divided into 4 data scenarios using the Time Series Cross Validation (TSCV) method. The results of palm oil production modeling with LSTM that have been carried out show that palm oil production data shows differences in forecasting values and accuracy in the number of neurons and epochs used. The conclusion of this study is that from data processing and analysis in the previous chapter, it can be concluded that forecasting the amount of palm oil production in PT X can be modeled with LTSM and SARIMA method using Time Series Cross Validation (TSCV) data.

Longevity of dairy cows depending on the age of first calving

Research to study the traits of duration of use and cows productive longevity of Ukrainian Black-andWhite dairy (UBWD) and Holstein breeds, depending on the age of frst calving, was carried out in the herd of PE "Burynske" Pidlisniv branch of Sumy district. The division of animals into gradations, depending on the age of frst calving, established that higher indicators of the duration and efciency of lifelong use were observed in animals of both breeds that frst calved at the age of 25.1-26 months. Early, before 24, and late, over 26 months, frst calving shortened lifetime, productive period, number of calvings, and reduced lifelong milk yield and milk fat. With an increase in the age of frst calving in UBWD and Holstein cows, a gradual reduction in lifetime and productive use reached a difference in these indicators between the best (25.1-26 months) and the frst calving group of more than 30 months, respectively 332 and 491 and 523 and 628 days (P<0.001). The influence of the age of frst calving on the lifetime productivity of cows of the UBWD breed was evidenced by a signifcant difference in favor of animals with the frst calving at 25.1-26 months, compared to the group of frst calving before 24 months, which was 3432 and 127 kg, respectively, in terms of lifetime milk yield and milk fat (P<0.001). The difference when comparing the groups of the frst calving older than 26.1 months by lifetime milk yield and milk fat was, respectively, 2082-12896 and 70-486 kg (P<0.001). The highest indicators of traits characterizing the longevity of Holstein cows, lifetime and productive use, were also obtained from the group of animals of the frst calving at the age of 25.1-26 months. According to these traits, there was a signifcant difference in their favor compared to the group of frst calving up to 24 months (282 and 173 days; P <0.05) and groups older than 26.1 months. (247-523 days; P<0.05-0.001 and 337-628 days; P<0.01-0.001). Animals of the frst calving at the age of 25.1-26 months, with a milk yield during life of 29337 kg, exceeded in this trait cows that frst calved earlier 24 months of age, with a difference in 3679 kg of milk (P <0.001) and animals with an age of frst calving older 26.1 months with a difference of 1790-12990 kg (P<0.05-0.001). By lifetime milk fat yield, the difference between these comparisons was 135 kg (P<0.001) and 56-486 kg (P<0.05-0.001), respectively. Key words: Ukrainian Black-and-White dairy, Holstein, lifespan, productive use, frst calving, lifetime productivity.

Real-world waste dispersion modelling for benthic integrated multi-trophic aquaculture.

In real-world situations, marine fish farms accommodate multiple fish species and cohorts within the farm, leading to diverse farm layouts influenced by cage dimensions, configurations, and intricate arrangements. These cage management practices are essential to meet production demands, however, farm-level complexities can impact model predictions of waste deposition and benthic impact near fish cages. This is of particular importance when the cages are used for integrated multi-trophic aquaculture (IMTA) with benthic feeders, where this waste not only affects environmental conditions but also provides a potential food source. The Cage Aquaculture Particulate Output and Transport (CAPOT) model incorporated multiple species, cohorts, and cage arrangements to estimate waste distribution from a commercial fish farm in the Mediterranean between October 2018 and July 2019. This spreadsheet model estimated dispersion for individual fish cages using a grid resolution of 5 m x 5 m. The study categorized discrete production periods for each fish cage every month, aligning with intermittent changes in biomass and food inputs due to different cage management practices throughout production. This approach facilitated the use of detailed input data and enhanced model representativeness by considering variations in cage biomass, food types, settling velocities, and configurations. Model outputs, represented in contour plots, indicated higher deposition directly below fish cages that varied monthly throughout fish production cycles. Deposition footprints reflected changes in cage biomass, food inputs, and farm-level practices reflecting this real-world scenario where aquaculture does not follow a production continuum. Moreover, cohort dynamics and cage movements associated with the cage management practices of the fish farm influenced the quantity and fate of wastes distributed around fish cages, revealing variability in deposition footprints. Clearly, these findings have important implications for the design of benthic IMTA systems, with species such as sea cucumber and polychaetes. Variability in waste deposition creates challenges in identifying where the benthic organisms should be placed to allow optimal uptake of waste to meet their food requirements and increase survivability. Evidently, models have an important role to play and this study emphasizes the need for representative input data to describe actual food inputs, cage biomass changes, and management practices for more representative farm-scale modelling and essentially to improve particulate waste management. To effectively mitigate benthic impacts through IMTA, models must quantify and resolve particulate waste distribution and impact around fish farms to maintain a balanced system with net removal of wastes. Resolving farm-level complexities provides vital information about the variability of food availability and quality for extractive organisms that helps improve recycling of organic wastes in integrated systems, demanding a more representative modelling approach.

Comparison of the economic performance of organic and conventional corn–soybean–winter wheat rotations in southwestern Ontario, Canada

The economic viability of using summer-seeded legume cover crops (crimson clover, red clover, and hairy vetch) as a primary nitrogen (N) source for an organic corn ( Zea mays L.)–soybean ( Glycine max (L.) Merr.)–winter wheat ( Triticum aestivum L.) rotation was determined on a sandy loam soil in southwestern Ontario, Canada, by comparing gross profit for organic production (organic sources of N and phosphorus, no herbicides) to conventional production (no cover crops, synthetic fertilizers and herbicides added). Profits were determined for the initial 3-year transition period from conventional to organic production (2015–2017), and for 5 years of certified organic production (2018–2022). During the transition period when conventional crop prices applied to both production systems, organic production profits (CAD $1148–$1869 ha−1 per rotation) were lower than conventional profits (CAD $2126 ha−1 per rotation). During the certified organic period when price premiums were applied, organic soybean and corn profits (CAD $1995–$2274 ha−1 and $2819–$3195 ha−1 per year, respectively) were significantly greater than conventional soybean and corn profits (CAD $536 ha−1 and $1926 per ha−1, respectively). Winter wheat profits were slightly higher for organic production (CAD $426–$825 ha−1 per year) than for conventional production (CAD $371 ha−1 per year). During the certified organic production period, profits from the 3-year rotations were CAD $5533–$6153 ha−1 for organic production, and CAD $2860 ha−1 for conventional production. It was concluded that an organic rotation of corn–soybean–winter wheat/legume cover crop can be economically viable and more profitable than conventional production on sandy loam soil in southwestern Ontario.

A fully coupled compositional wellbore/reservoir model for predicting liquid loading in vertical and inclined gas wells

Liquid loading presents a formidable challenge for mature gas wells, often resulting in substantial economic losses. Traditional research has predominantly centered on the analysis of gas-liquid two-phase flow within the wellbore to predict critical gas velocity or rate, aiding in identifying the onset of liquid loading. This study introduces a fully coupled compositional wellbore-reservoir simulator designed to detect liquid loading in both vertical and inclined gas wells. Leveraging the drift-flux model to evaluate flow pattern transitions, this simulator employs pressure or rate constraints at the wellhead as boundary conditions. It comprehensively captures the flow dynamics in both the wellbore and reservoir, unveiling significant changes in gas production rate, water production rate, gas velocity, flow regime, and the reserved position of the liquid film under liquid-loaded conditions. Moreover, the accumulation of liquid at the bottom hole leads to increased reservoir pressure and gas saturation near the wellbore. The simulator predicts a typical unstable production period, emphasizing its crucial role in implementing effective strategies to mitigate liquid loading. This paper investigates the capability of the coupled wellbore-reservoir model to characterize transient liquid loading phenomena from a systematic perspective. The proposed model can function as a real-time tool for predicting the status of liquid loading in gas wells.