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Fine-grained management of rice fields can enhance the yield and quality of rice crops. Challenges in achieving fine classification include interference from similar vegetation, the irregularity of natural field shapes, and complex scale variations. This paper introduces Rice Attention Cascade Network (RACNet), for the fine classification of rice fields in high-resolution satellite remote sensing imagery. The network employs the Hybrid Task Cascade network as the base framework and uses spectral and indices mixed multimodal data as input to reinforce the feature differentiation of similar vegetation. Initially, a Channel Attention Deformable-ResNet (CAD-ResNet) was designed to enhance the feature representation of rice on different channels. Deformable convolution improves the ability of CAD-ResNet to capture irregular field shapes. Then, to address the issue of complex scale changes, the multi-scale features extracted by the CAD-ResNet are progressively fused using an Asymptotic Feature Pyramid, reducing the loss of scale information between non-adjacent layers. Experiments on the Meishan rice dataset show that the proposed method is capable of accurate instance segmentation for fragmented or irregularly shaped rice fields. The evaluation metric AP50 of RACNet reaches 50.8%. [ABSTRACT FROM AUTHOR]

Because of the importance of the Central Valley of California, USA, to shorebirds along the Pacific Flyway, conservation investments have been made in the area's agricultural fields and managed wetlands. Increasingly, landowner incentive programs are being used to deliver shorebird habitat, presenting opportunities to answer remaining questions about which implementation strategies and field management practices are most effective at attracting birds. To provide management guidance for these investments, we collected and analyzed 5 years of data (2014–2018) on shorebird abundance in flooded rice fields enrolled in a dynamic habitat incentive program. The program incentivized flooding in fallow and post‐harvest rice fields in seasons when habitat is relatively sparse, specifically the early fall and late spring. Across nearly 9,000 field observations over 5 years, we explored the relationship between abundance and density (birds/ha) of shorebirds and vegetation cover, soil clay, landscape‐level flooding, and local flood timing, duration, and depth. We observed more shorebirds in fields that were approximately 50% flooded, had water depths of 5–10 cm, and had minimal rice straw or stubble cover, with strong or very strong evidence for each of these relationships. We found that the timing of habitat provisioning was important, with moderate evidence that earlier fall flooding and strong evidence that the duration of fall flooding was associated with higher shorebird density. We observed lower shorebird densities in locations with ample flooded rice habitat in surrounding areas, potentially because shorebirds spread out across the landscape. We found very strong evidence that flooding consistency, either at a site that was continually flooded over many months or a site that had been flooded in previous years, was associated with higher shorebird density. Soil clay content was associated with decreased observed shorebird density, potentially through its influence on the ability of shorebirds to forage for invertebrate prey. These results suggest best practices for shorebird habitat creation in agricultural landscapes, providing important information for conservation and population recovery. [ABSTRACT FROM AUTHOR]

• A MAE-IC-ICP-MS method was set up to determine Se species in rice plants. • The accumulated Se by rice plants in Se(VI)-added soil was higher than that in Se(IV)-added soil. • Arsenite and As(V) facilitated the conversion of Se(IV) into Se-Cys and Se-Me. • Arsenite and As(V) had higher antagonism on Se species in Se(VI)-added soil than that in Se(IV)-added soil. • Arsenite had higher inhibiting effect on the Se species than As(V) in Se(VI)-added soil. Selenium (Se) in paddy rice is one of the significant sources of human Se nutrition. However, the effect of arsenic (As) pollution in soil on the translocation of Se species in rice plants is unclear. In this research, a pot experiment was designed to examine the effect of the addition of 50 mg As/kg soil as arsenite or arsenate on the migration of Se species from soil to indica Minghui 63 and Luyoumingzhan. The results showed that the antagonism between inorganic As and Se was closely related to the rice cultivar and Se oxidation state in soil. Relative to the standalone selenate treatment, arsenite significantly (p < 0.05) decreased the accumulation of selenocystine, selenomethionine and selenate in the roots, stems, sheaths, leaves, brans and kernels of both cultivars by 21.4%-100.0%, 40.0%-100.0%, 41.0%-100%, 5.4%-96.3%, 11.3%-100.0% and 26.2%-39.7% respectively, except for selenocystine in the kernels of indica Minghui 63 and selenomethionine in the leaves of indica Minghui 63 and the stems of indica Luyoumingzhan. Arsenate also decreased (p < 0.05) the accumulation of selenocystine, selenomethionine and selenate in the roots, stems, brans and kernels of both cultivars by 34.9%-100.0%, 30.2%-100.0%, 11.3%-100.0% and 5.6%-39.6% respectively, except for selenate in the stems of indica Minghui 63. However, relative to the standalone selenite treatment, arsenite and arsenate decreased (p < 0.05) the accumulation of selenocystine, selenomethionine and selenite only in the roots of indica Minghui 63 by 45.5%-100.0%. Our results suggested that arsenite and arsenate had better antagonism toward Se species in selenate-added soil than that in selenite-added soil; moreover, arsenite had a higher inhibiting effect on the accumulation of Se species than arsenate. [Display omitted] [ABSTRACT FROM AUTHOR]

The current study focused on quantifying hazardous heavy metals (As, Cd, Cr, Pb, Ni, and Zn) in soil-rice systems near the Buriganga River in Bangladesh to assess their impact on human health and the environment. The mean concentrations of As, Cd, Cr, Ni, and Zn in soil exceeded FAO/WHO acceptable limits, and the metal pollution index (MPI) indicated that all soil samples collected from the rice fields were severely polluted (MPI˃30) than water and rice grain samples. According to the sum of pollution index (SPI) by studied metals, rice grains collected from Kamrangirchor (29.36), Dhakauddan (28.75), and Bosila (18.08) were severely polluted. Mean Bio-concentration factors (BCFs) and Transfer factors (TFgrain/soil) in rice grains were in the following order: Cd (6.034) > Zn (1.752) > Pb (0.697) ˃ Ni (0.666) > Cr (0.135) > As (0.037), and Cd (1.150) > Zn (0.421) > Ni (0.112) ˃ Pb (0.072) > Cr (0.015) > As (0.034) respectively indicating higher accumulation of Cd in rice grain than others toxic heavy metal. The potential ecological risk index (RI) showed that except for water in Kamrangirchar and Keraniganj rice fields, all other rice fields soil and water samples did not pose severe ecological pollution (RI˂110) by different toxic heavy metals. Health risk assessment showed that rice grains are unsafe for human consumption as the carcinogenic health risk (CHR˃10-3) and non-carcinogenic health risk (HI ˃1) quotients seem more than the safe level in all samples collected from rice fields surrounding the Buriganga River. Findings show that heavy metal concentrations are high in rice fields near the Buriganga River, endangering the environment and consumer health. [ABSTRACT FROM AUTHOR]

The yellow stem borer (YSB), Scirpophaga incertulas (Walker), is a major insect pest that significantly damages rice crop. This study investigates methods to predict YSB populations in rice fields, aiming to develop an early warning system. Traditionally, rice farmers rely on light traps to monitor YSB presence. However, this study goes beyond this approach by combining light‐trap data with weather information (temperature, humidity, rainfall) and utilizing powerful artificial intelligence (AI) techniques to forecast future YSB populations. Two AI methods, multilayer perceptron (MLP) and long short‐term memory (LSTM), were employed to estimate YSB populations and assess their performance. The results revealed that the LSTM model outperformed the MLP model based on statistical metrics like RMSE, MAE, and R2 values. Utilizing LSTM model with historical data, stakeholders in the Eastern Coastal Plains and Hills agro‐climatic zone of India can gain a significant advantage in predicting YSB populations well in advance. This early warning system can alert stakeholders of potential YSB outbreaks, allowing them to take timely management actions and protect their rice crops from substantial yield losses. [ABSTRACT FROM AUTHOR]

• Spider community composition changed during the rice growing season. • The rice field development generally decreased the number of horizontal web-building spiders and captured detritivorous prey. • Species identity and species traits of spider as well as environmental factors affect prey capture by web-building spiders. Understanding the effects of microhabitat changes on arthropod predator communities and their prey in agroecosystems is essential for field management and biocontrol. Few studies have investigated the trait composition of web-building spider communities in rice ecosystems. Here, we examined how temporal changes during the rice field development affect the abundance and traits of orb-web spiders, and how these effects consequently influence captured prey number and prey composition in irrigated rice ecosystems in southern Thailand. We used structural equation models to evaluate direct and indirect, spider-mediated effects of rice field development on captured prey numbers in each different guild. We found that the number of horizontal web-building spiders decreased during the rice field development, whereas there was no significant change in number of vertical web-building spiders. The number of captured detritivorous insects was positively related to the numbers of horizontal and vertical web-building spiders, while phytophagous insects and others were positively related only to the numbers of vertical web-building spiders. Moreover, the prey number captured by vertical web-building spiders seems to be indirectly increased through the decreasing number of horizontal web-building spiders in the late rice season. A fourth-corner analysis showed that spider species identity, spider traits (web type, web height and web diameter), vegetation height, and water level generally influenced the prey captured by web-building spiders. Horizontal web-building spider species with lower web placement during the flooding phase captured high numbers of detritus-feeding insects, while vertical web-building spider species with higher web placement captured high numbers of rice pests, predators and others. Our results suggest that the field development acted as an environmental factor that determined the species identity and traits of web-building spider communities. The findings of this study can help to predict the ecosystem services provided by the web-building spider community in rice ecosystems. [ABSTRACT FROM AUTHOR]

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Changes in hydrological processes in watersheds are triggered by various factors, including land use land cover changes (LULCC) emerging from human activities. Hence, it is crucial to elucidate the interaction among hydrological processes to improve sustainable water management plans. The current study explored the effects of LULCC on hydrological processes in the Gala Lake catchment over a 30‐year temporal period. In this context, to evaluate LULCC, land cover maps were obtained using the supervised classification method with Landsat images (5 TM, 7 ETM+, 8 OLI) of 1993, 2008, and 2023. Hydrological processes were assessed using the Soil and Water Assessment Tool (SWAT), a commonly applied eco‐hydrological model. The model was utilized to evaluate the potential effect of LULCC on processes like surface runoff, infiltration, evapotranspiration, and erosion. Between 1993 and 2023, significant LULCC have been observed in the study area. There has been a decrease of 4.3%, 1%, 1.6%, and 5.3% in agricultural lands, forested lands, inland marshes, and pasture lands, respectively, while artificial surfaces, rice fields, and water bodies have seen an increase of 7%, 3.4%, and 1.9%, respectively. The potential effects of these changes were observed as a decrease in the runoff, a decrease in permeability, and an increase in processes such as evapotranspiration and erosion throughout the basin and sub‐basin. In general, LULCC significantly affect the hydrological status of the catchment. Therefore, establishing different conservation and utilization strategies that consider land use dynamics to maintain the resilience of ecosystems in the basins is vital in the sustainable management of water resources. [ABSTRACT FROM AUTHOR]

The article examines a legal dispute over plant variety rights in China, focusing on the case of 'Liannuo No. 2' and 'Fengnuo 1246,' which were alleged to be the same variety. Topics include the uniqueness of plant variety names, the requirement for consistent naming throughout the approval process, and the legal implications of discrepancies in naming between variety rights and approval.

The use of some organophosphate insecticides is restricted or even banned in paddy fields due to their high toxicity to aquatic organisms. The aim of this study is to elucidate the main pathways and target organs of organophosphate insecticide toxicity to fish exposed via different routes by integrating histopathological and biochemical techniques. Using malathion as the model drug, when the dosage is 20–60 mg/L, the toxicity of whole body and head immersion drugs to zebrafish is much higher than that of trunk immersion drugs. A dose of 21.06–190.44 mg/kg of malathion feed was fed to adult zebrafish. Although the dosage was already high, no obvious toxicity was observed. Therefore, we believe that the drug mainly enters the fish body through the gills. When exposed to a drug solution of 20 mg/L and 60 mg/L, the fish showed significant neurological behavioral abnormalities, and the pathological damage to key organs and brain tissue was the most severe, showing obvious vacuolization and the highest residual amount (8.72–47.78 mg/L). The activity of acetylcholinesterase was the most inhibited (54.69–74.68%). Therefore, brain tissue is the key toxic target organ of malathion in fish. In addition, we compared the bioaccumulation effects of different water-soluble organophosphorus insecticides in fish and their toxic effects. We found that the higher the water solubility of organophosphorus insecticides, the lower their toxicity to fish. [ABSTRACT FROM AUTHOR]

Brazil, a leading rice producer globally, faces challenges in systematically mapping its diverse rice fields due to varying cropping systems, climates, and planting calendars. Existing rice mapping methods often rely on complex techniques like deep learning or microwave imagery, posing limitations for large-scale mapping. This study proposes a novel approach utilizing Sentinel-2 spectral–temporal metrics (STMs) in conjunction with a random forest classifier for rice paddy mapping. By extracting diverse STMs and training both regional and global classifiers, we validated the method across independent areas. While regional models tended to overestimate rice areas, the global model effectively reduced discrepancies between our data and the reference maps, achieving an overall classifier accuracy exceeding 80%. Despite the need for further refinement to address confusion with other crops, STM exhibits promise for national-scale rice paddy mapping in Brazil. [ABSTRACT FROM AUTHOR]

Changes in the flavor and taste profiles of Paddy Field Carp after deodorization with perilla juice (PJ), cooking wine (CW) and a mixture of the two (PJ-CW) were analyzed using the E-nose, E-tongue, gas chromatography–ion mobility spectrometry (GC-IMS), free amino acid analysis and taste nucleotide analysis. The E-nose and E-tongue revealed that deodorization reduced the content of sulfur-containing compounds, enhanced umami, bitterness, sourness and astringency, and decreased saltiness. PCA and OPLS-DA analysis successfully distinguished between the effects of the treatments. Free amino acids increased from 8777.67 to 11,125.98 mg/100 g and umami amino acids increased from 128.24 to 150.37 mg/100 g after PJ-CW deodorization (p < 0.05). Equivalent umami concentration (EUC) comparisons showed that PJ-CW treatment produced the greatest synergistic umami enhancement (to 3.15 g MSG equiv./100 g). GC-IMS detected 52 aroma compounds; PJ treatment produced the greatest diversity of aldehydes, including heptanal, nonanal, hexanal, 3-methylbutanal, (E)-2-heptenal and (E,E)-2,4-heptadienal. The total content of volatile flavor compounds was the highest after PJ-CW treatment, and the content of many characteristic flavor substances (3-hydroxy-2-butanone, benzaldehyde, 5-methyl-2(3H)-furanone) increased. These findings provided a theoretical basis for the further development of deodorization methods for Paddy Field Carp. [ABSTRACT FROM AUTHOR]

To investigate the dynamics of stomata, transpiration, and photosynthesis under varying light intensities and CO2 conditions during leaf development, the light response and CO2 response of stomatal conductance (gsw), transpiration rate (Tr), and net photosynthetic rate (Pn) were observed for rice leaves at different days after leaf emergence (DAE). The results showed that (1) as photosynthetically active radiation (PAR) increased, leaf gsw, Tr, and Pn initially increased rapidly and linearly, followed by a more gradual rise to maximum values, and then either stabilized or showed a declining trend. The maximum gsw, Tr, and Pn were smaller and occurred earlier for old leaves than for young leaves. The gsw, Tr, and Pn all exhibited a linear decreasing trend with increasing DAE, and the rate of decrease slowed down with the reduction in PAR; (2) as the CO2 concentration (Ca) increased, gsw and Tr decreased gradually to a stable minimum value, while Pn increased linearly and slowly up to the maximum and then kept stable or decreased. The gsw, Tr, and Pn values initially kept high and then decreased with the increase of DAE. These results contribute to understanding the dynamics in gsw, Tr, and Pn during rice leaf growth and their response to varied light and CO2 concentration conditions and provide mechanistic support to estimate dynamic evapotranspiration and net ecosystem productivity at field-scale and a larger scale in paddy field ecosystems through the upscaling of leaf-level stomatal conductance, transpiration, and photosynthesis. [ABSTRACT FROM AUTHOR]

Direct seeding is employed to circumvent the labor-intensive process of rice (Oryza sativa) transplantation, but this approach requires varieties with vigorous low-temperature germination (LTG) when sown in cold climates. To investigate the genetic basis of LTG, we identified the quantitative trait locus (QTL) qLTG11 from rice variety Arroz da Terra, which shows rapid seed germination at lower temperatures, using QTL-seq. We delineated the candidate region to a 52-kb interval containing GENERAL REGULATORY FACTOR14h (GF14h) gene, which is expressed during seed germination. The Arroz da Terra GF14h allele encodes functional GF14h, whereas Japanese rice variety Hitomebore harbors a 4-bp deletion in the coding region. Knocking out functional GF14h in a near-isogenic line (NIL) carrying the Arroz da Terra allele decreased LTG, whereas overexpressing functional GF14h in Hitomebore increased LTG, indicating that GF14h is the causal gene behind qLTG11. Analysis of numerous Japanese rice accessions revealed that the functional GF14h allele was lost from popular varieties during modern breeding. We generated a NIL in the Hitomebore background carrying a 172-kb genomic fragment from Arroz da Terra including GF14h. The NIL showed superior LTG compared to Hitomebore, with otherwise comparable agronomic traits. The functional GF14h allele from Arroz da Terra represents a valuable resource for direct seeding in cold regions. Author summary: Rice serves as a fundamental crop sustaining over half of the global population. With the rapid growth of the world's population, it will become increasingly important to improve rice productivity. On the other hand, the aging of rice farmers in Japan has resulted in a constant labor shortage. To address this, direct seeding, in which seeds are sown directly in rice fields without going through the most labor-intensive part of the rice cultivation process, i.e., seedling production and transplanting, has been recommended. However, prevalent elite rice varieties are known to be unsuitable for direct seeding due to their poor seed germination ability under low-temperature conditions. In this study, we show for the first time that GF14h gene from the Portuguese variety Arroz da Terra improves seed germination at low temperatures (LTG). In addition, a novel cross-bred line was generated by introducing the GF14h-containing genomic segment from Arroz da Terra into Hitomebore, a widely cultivated variety in northern Japan. This line is expected to be used as a pre-breeding material to enhance LTG. This study will provide a genetic basis for LTG and contribute to basic and applied research progress. [ABSTRACT FROM AUTHOR]

As socially engaged art has played a vibrant role in responding to the crisis of the postmodernist art regime, the current post-Occupy condition has manifested itself in artistic interventions in rural China. In contrast to social writing, which encompasses street art, designers going to the countryside, and industrial empowerment to construct "good cultural governance" or "good cultural taste," the term personal writing as used here describes a type of avant-garde intervention that has sparked interest in vernacular communities. It provides a socially minded critique of art production as bifurcated from the remaking of everyday social relations and subjectivities, political and cultural possibilities, and the rural Chinese future. Grounded in a contextual analysis of the social turn in Chinese contemporary art and the lingering "rural problem" under post-socialism, this article takes artist Mao Chenyu's Paddy Film project as an example of personal writing and proposes this artist's activisms at Dongting Lake as a specific intervening field, visual ethnography as a method, paddy rice as a distinctive "thing," and archival practices as a deconstructive pathway that together have promoted the emergence of a resistance narrative in artistic intervention in Chinese rural communities. [ABSTRACT FROM AUTHOR]

Simple Summary: Methanogens are a group of microorganisms with the capability to convert inorganic or organic compounds into methane, impacting the global carbon cycle and greenhouse gas emissions. In anaerobic environments such as wetlands, paddy fields, and reservoirs, methanogens are the primary contributors to methane production. In this study, high-throughput sequencing of the mcrA functional gene was utilized to conduct a comprehensive analysis of the community structure, metabolic pathways, and influencing factors of methanogens in the sediment of 18 reservoirs on the northeastern Qinghai Plateau. The results indicated that the construction of reservoirs has altered the physicochemical properties of river water and sediments, significantly impacting the distribution and succession of methanogenic communities in the sediment. In general, this study can improve our understanding of the biological mechanisms of methane emissions from the reservoirs on the Qinghai Plateau. Reservoirs are a hotspot for methane emissions, a potent greenhouse gas. However, the microbial basis for methane production in the Qinghai Plateau reservoirs remains unclear. To explore the characteristics of methanogenic communities in reservoir sediments on the northeastern Qinghai Plateau, sediment samples were collected from 18 reservoirs in the Yellow River basin during May 2023 (dry season) and August 2023 (wet season). High-throughput sequencing technology was employed to analyze the community composition, diversity, and co-occurrence network of methanogens. Furthermore, FAPROTAX and Mantel analysis were used to assess the metabolic functions of methanogens and their influencing factors. The results showed that (1) the predominant genera of methanogens were Methanobacterium (28.87%) and Methanosarcina (21.67%). Hydrogenotrophic methanogenesis was the main pathway in the sediments. (2) Significant spatiotemporal differences were observed in the diversity of methanogenic communities (p < 0.05). The composition and diversity of these communities were found to be significantly influenced by temperature, pH, altitude, organic carbon, and total nitrogen (p < 0.05). (3) Methanosarcina, Methanobacterium, and Methanospirillum play crucial roles in maintaining the stability of methanogenic community networks. The co-occurrence network nodes are predominantly positively correlated (99.82%). These results provide data for further studies on carbon cycling in the Qinghai Plateau reservoirs. [ABSTRACT FROM AUTHOR]

Ratoon rice (RR) has emerged as an active adaptation to climate uncertainty, stabilizing total paddy rice yield and effectively reducing agriculture-related ecological environmental issues. However, identifying key remote sensing parameters for RR under cloudy and foggy conditions is challenging, and existing RR monitoring methods in these regions face significant uncertainties. Here, given the sensitivity of synthetic aperture radar (SAR) backscattering signals to the crop phenological period, this paper introduces a threshold model utilizing Sentinel-1A SAR data and phenological information for mapping RR. The Yongchuan District of Chongqing, which is often cloudy and foggy, was selected as a specific study region where VH-polarized backscatter coefficients of Sentinel-1 images were obtained at 10 m spatial resolution in 2020. Based on the proposed threshold model, the RR extraction overall accuracy was up to 90.24%, F1 score was 0.92, and Kappa coefficient was 0.80. Further analysis showed that the extracted RR boundaries exhibited high consistency with true Sentinel-2 remote sensing images and the RR extracted area was in good agreement with the actual planted area situation. This threshold model demonstrated good applicability in the studied cloudy and foggy region, and successfully distinguished RR from other paddy rice types. The methodological framework established in this study provides a basis for extensive application in China and other significant RR-producing regions globally. [ABSTRACT FROM AUTHOR]

In Asia, rice is the most consumed grain by humans, serving as a staple food in India. The yield of rice paddies is easily affected by nutrient deficiencies and leaf diseases. To overcome this problem and improve the yield productivity of rice, nutrient deficiency and leaf disease identification are essential. The main nutrient elements in paddies are potassium, phosphorus, and nitrogen (PPN), the deficiency of any of which strongly affects the rice plants. When multiple nutrient elements are deficient, the leaf color of the rice plants is altered. To overcome this problem, optimal nutrient delivery is required. Hence, the present study proposes the use of Fuzzy C Means clustering (FCM) with Improved Tunicate Swarm Optimization (ITSO) to segment the lesions in rice plant leaves and identify the deficient nutrients. The proposed ITSO integrates the Tunicate Swarm Optimization (TSO) and Bacterial Foraging Optimization (BFO) approaches. The Hybrid Convolutional Neural Network (HCNN), a deep learning model, is used with ITSO to classify the rice leaf diseases, as well as nutrient deficiencies in the leaves. Two datasets, namely, a field work dataset and a Kaggle dataset, were used for the present study. The proposed HCNN-ITSO classified Bacterial Leaf Bright (BLB), Narrow Brown Leaf Spot (NBLS), Sheath Rot (SR), Brown Spot (BS), and Leaf Smut (LS) in the field work dataset. Furthermore, the potassium-, phosphorus-, and nitrogen-deficiency-presenting leaves were classified using the proposed HCNN-ITSO in the Kaggle dataset. The MATLAB platform was used for experimental analysis in the field work and Kaggle datasets in terms of various performance measures. When compared to previous methods, the proposed method achieved the best accuracies of 98.8% and 99.01% in the field work and Kaggle datasets, respectively. [ABSTRACT FROM AUTHOR]

With growing concerns about global warming, it is crucial to adopt agronomic practices that enhance rice yields from paddy fields while reducing greenhouse gas (GHG) emissions for sustainable agriculture. An optimal nitrogen (N) fertilization rate and planting density are vital to ensure high rice yields, minimize GHG emissions, and understand emission behavior for better field management. We hypothesized that optimizing N application rates and planting density to improve nitrogen use efficiency (NUE) in rice cultivation would reduce resource losses and GHG emissions. To test this hypothesis, we implemented five treatments with a rice straw return cultural system: two planting densities (16 hills m−2 (traditional density, D1) and 20 hills m−2 (25% higher density, D2)) and three N application rates (no N fertilizer (N0), 180 kg N ha−1 (N1), and 144 kg N ha−1 (N2)). The control treatment (CK) was traditional planting density with no N fertilizer. The four new cropping modes were N1D1, N1D2, N2D1, and N2D2. We investigated the effects of N application rates and planting density on rice grain yield, NUE, and GHG emissions in multiple rice-growing seasons. The N1D2 treatment exhibited the highest grain yield over the three years, with a value of 10,452 kg ha−1, representing an increase of 12.2% compared to CK. Moreover, N uptake in N1D2 was the highest, averaging 39.2% (p < 0.05) higher than CK, and 8.5%, 3.5%, and 2.8% (p < 0.05) higher than N1D1, N2D1 and N2D2, respectively. N2D2 exhibited the highest NUE, with a value of 58.99 kg kg−1, surpassing all other treatments over the three years. GHG emissions, global warming potential (GWP), and greenhouse gas intensity (GHGI) in N2D2 were lower than in N1D1, N1D2, and N2D1. Additionally, reducing N application (comparing N1D1 to N2D1) and increasing plant density (comparing N1D1 to N1D2) improved N agronomic efficiency (NAE) and N partial productivity (PFPN). The negative correlation between the NAE and PFPN with GWP and GHG emissions further supports the potential for optimized N management and denser planting density to reduce environmental impact. These findings have important implications for sustainable rice cultivation practices in Southwest China and similar agroecosystems, emphasizing the need for integrated nutrient management strategies to achieve food security and climate change mitigation goals. [ABSTRACT FROM AUTHOR]

Drying involves the evaporation of moisture, accompanied by simultaneous heat transfer, mass transfer, and momentum transfer. While the diffusion law is considered an applicable model for explaining the drying phenomenon, the actual drying process cannot be accurately predicted using an analytical solution with a constant diffusion coefficient. Energy efficiency in the drying process is low due to an insufficient understanding of the mechanisms governing moisture migration from solids to air. The development of drying theory has stalled due to an unsolvable discrepancy between experimental results and analytical results. This study analyzes the effect of the binding energy of moisture in paddy rice on the diffusion coefficient. The theoretical relationship between water activity and drying rate in paddy rice was investigated, and the drying process was successfully explained by analyzing free energy transfer and transition theory. The mechanism of rice grain drying was described using a new theoretical solution for the drying process. These results provide new insights into the development of a scientific evaluation standard for assessing the efficiency of actual drying processes. [ABSTRACT FROM AUTHOR]

A precision agriculture approach that uses drones for crop protection and variable rate application has become the main method of rice weed control, but it suffers from excessive spraying issues, which can pollute soil and water environments and harm ecosystems. This study proposes a method to generate variable spray prescription maps based on the actual distribution of weeds in rice fields and utilize DJI plant protection UAVs to perform automatic variable spraying operations according to the prescription maps, achieving precise pesticide application. We first construct the YOLOv8n DT model by transferring the "knowledge features" learned by the larger YOLOv8l model with strong feature extraction capabilities to the smaller YOLOv8n model through knowledge distillation. We use this model to identify weeds in the field and generate an actual distribution map of rice field weeds based on the recognition results. The number of weeds in each experimental plot is counted, and the specific amount of pesticide for each plot is determined based on the amount of weeds and the spraying strategy proposed in this study. Variable spray prescription maps are then generated accordingly. DJI plant protection UAVs are used to perform automatic variable spraying operations based on prescription maps. Water-sensitive papers are used to collect droplets during the automatic variable operation process of UAVs, and the variable spraying effect is evaluated through droplet analysis. YOLOv8n-DT improved the accuracy of the model by 3.1% while keeping the model parameters constant, and the accuracy of identifying weeds in rice fields reached 0.82, which is close to the accuracy of the teacher network. Compared to the traditional extensive spraying method, the approach in this study saves approximately 15.28% of herbicides. This study demonstrates a complete workflow from UAV image acquisition to the evaluation of the variable spraying effect of plant protection UAVs. The method proposed in this research may provide an effective solution to balance the use of chemical herbicides and protect ecological safety. [ABSTRACT FROM AUTHOR]

Crop straw returning to the field is an effective practice for straw utilization to improve soil fertility and sustain crop productivity. However, little information is available about the long-term effects of paddy straw return on soil properties and rice yield under a double-rice system. The objectives of this study were to test the hypothesis of the effects of different amounts of paddy straw returned to the field on soil physicochemical properties and rice yield, and to clarify the correlation between crop yield and soil physicochemical properties as well as quick-acting nutrients under different straw-returning modes. The experiment, initiated in the 2005 rice season, utilized "Xiang 45" and "Xiang 13" long-grained rice cultivars within a double-season rice cropping system. Three straw-returning treatments were implemented: rotary tillage with full rice straw incorporation (RTS), incorporation of one-third of the rice straw (1/3RTS), and incorporation of two-thirds of the rice straw (2/3RTS). This study found that among the three straw return rates, 2/3RTS had the most significant impact on soil physicochemical properties. Soil nitrogen content was identified as a crucial factor influencing soil organic carbon (SOC) accumulation, while pH levels significantly affected rice yield. Straw incorporation effectively increased the content and stocks of SOC. [ABSTRACT FROM AUTHOR]

Based on the actual distribution data of Guizhou kam sweet rice in field records and literature, the Maximum Entropy Model (MaxEnt) optimised by the Kuenm packet was used to study the suitable regions of Guizhou kam sweet rice and the dominant climatic factors affecting the distribution of kam sweet rice under the historical and future climate scenarios, which provides a reference basis for rational planning of distribution of kam sweet rice production in the context of climate change. The results showed that: (1) during the historical period of 1970-2000, the potential suitable region of kam sweet rice were mainly concentrated in the southeastern part of Qiandongnan prefecture, Guizhou province, and the highly suitable regions were distributed in Congjiang, Rongjiang, and Liping counties. (2) Compared with the historical period, the highly suitable region of kam sweet rice under the SSP126 climate scenario increases in region and moves to higher altitude in 2041-2060, and decreases in region and moves to higher latitude in 2081-2100, and increases in region and moves to higher latitude in 2041-2060, and decreases in region and moves to higher latitude in 2081-2100 under the SSP245 climate scenario. In the SSP585 climate scenario, the highly suitable region of kam sweet rice increases in region and moves to higher altitudes in 2081-2100. (3) Among the 19 climate impact factors, the min. temperature of the coldest month and the mean diurnal range difference are the main climate factors affecting the distribution of kam sweet rice, with contribution rates of 34.8% and 13.8%, respectively. Generally speaking, climate change will lead to the expansion of the highly suitable region of kam sweet rice in 2041-2060 and the reduction of the region in 2081-2100, so it is necessary to pay attention to the climate change, and rationally plan the production layout of kam sweet rice to ensure the food security. [ABSTRACT FROM AUTHOR]

In floodplains, which are highly modified and less inundated, trees are expanding, thus raising concerns regarding their impact on freshwater organisms. We analyzed the relationship between forest expansion and the change in Odonata (dragonflies and damselflies) assemblage over an extended period of time in the floodplain with ponds of the Kiso River, central Japan. In the 1970s, the ponds were mainly surrounded by grasslands, and approximately 80% of Odonata species were non-forest species. However, the number of forest species increased and that of non-forest species largely decreased with the forest expansion over the past five decades, resulting in almost a similar number of forest and non-forest species in 2021. Whereas the abundance of the non-forest species had been greater than that of the forest species until the 2000s, the difference has been much smaller in the 2010s, and the non-forest species occupied approximately only 30% of the number of individuals in 2021. The forest expansion may have reduced the open-lentic habitats for the non-forest species, which require riparian grasslands for resting, foraging, and reproduction, and may disturb the immigration of non-forest species from the adjacent rice paddy fields and rivers. The development of canopy cover over the waterbodies may have decreased the light and temperature above and within the ponds, which might have caused a decline in species that prefer warm and open-water environments. Maintaining shifting-mosaic patterns of vegetation around the floodplain waterbodies through active management may be effective in conserving floodplain Odonata communities, including both forest and non-forest species. [ABSTRACT FROM AUTHOR]

Taking fresh soil samples from a rice–wheat rotation field (RW), a permanently flooded rice field (PF), and a double-rice cropping field (DR: DRE for the early rice; DRL for the late rice), we measured the CH4 production potential (MPP), the relative contribution of acetate-dependent methanogenesis (ƒac), soil properties, and methanogenic archaeal communities mainly in order to reveal the temporal variation and corresponding influencing factors of methanogenic pathways in paddy soils. Consistent with the change in dissolved organic C (DOC) content, the MPP generally decreased with rice growth in RW and DRL while increasing in PF and DRE. Based on the measurements of stable carbon isotopes, the estimated ƒac-value in PF dropped sharply from 54%-61% at the tillering stage to 30%-35% at the booting stage and rose again at the ripening stage. This variation pattern was positively correlated with that of acetate content, perhaps resulting from the activation of acetoclastic Methanosarcina. In contrast, the ƒac-value in RW and DR rose from 20%-44% at the tillering stage to 49%-59% at the ripening stage, possibly owing to the increase in the relative abundance of acetoclastic Methanothrix. The relative abundance of Methanosarcina in PF was 3%-4% higher than those in RW and DR, whereas that of Methanothrix was 3%-7% lower (P < 0.05). Soil acetate, DOC, and moisture contents significantly affected the methanogenic community composition. Our results demonstrate that the temporal variation of methanogenic pathways was influenced by the relative abundance of acetoclastic methanogens depending on the acetate level. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) residues (root and straw) are unique substrates for microbes in paddy soils. Microbial respiration (RH) of paddy soils is likely to be affected by substrate quality. However, no relevant study on the effects of changed rice residue chemistry by climate change on the temperature sensitivity (Q10) of the RH of soils amended with the residues is available. To fill this knowledge gap, we conducted an incubation experiment (at 15, 25, and 35 °C) with rice residues of which lignin, nonstructural carbohydrate (NSC), and carbon-to-nitrogen ratio (C/N) were modified by growing the rice plants under different CO2 and air temperature (Tair). Co-elevated CO2 and Tair decreased lignin and C/N but increased the NSC contents of the residues, leading to the greater RH in the soils amended with rice residues produced under co-elevated CO2 and Tair compared to other CO2 or Tair treatments. However, the Q10 values of the RH of soils amended with rice residues produced under different CO2 and Tair were marginally changed, probably due to other confounding factors such as soil enzyme activity and nutrient availability. Despite that, there was a negative relationship between NSC and Q10 for soils amended with straw of which C/N is lower than root, agreeing with the kinetic theory on "substrate quality–Q10 relationship". Our result suggests that residue chemistry may not affect the Q10 of soils with root residue, but for straw-amended soils, less-recalcitrant NSC rather than more-recalcitrant lignin of straw may be critical in determining the Q10 of the soils. [ABSTRACT FROM AUTHOR]

Irrigated and rain-fed rice fields are unique agroecosystems and anthropogenic wetlands whose main feature is seasonal flooding. Flooded soils are characterized by spatiotemporal shifts and oscillation of the oxygen status and redox potential, sustaining varieties of microbial metabolisms, where bacteria and methanogenic archaea play principal roles and thus have been the major research targets. In this review, we focus on the diversity and ecology of protists—often overlooked biological entities—in wetland rice field soils. Protists with different ecological functions, i.e., phagotrophs, phototrophs, saprotrophs, and parasites, inhabit a rice field soil with a community- and individual-level adaptation to the wide range of oxygen tensions and redox potential. Other agricultural managements like fertilization and char application also influence the protist community. They link to the material cycling in rice soil and affect the activities and community composition of the microorganisms involved in the biogeochemical cycles. Rice roots are the hot spot for protists, which control the rhizospheric bacterial community and could increase the plant productivity through enhancing nutrient release and altering bacterial activities. This review highlights the essential roles of protists in a wetland rice field soil and needs for further research to fill the gaps in knowledge regarding the diversity and functions of the protists in this unique agroecosystem. [ABSTRACT FROM AUTHOR]

AbstractThis study aimed to assess the efficacy of commonly used post-emergence herbicides under flooded rice fields, for Conyza spp. control. The greenhouse experiment employed a factorial setup with factor A denoting the presence or absence of a water layer post-application, and factor B representing different herbicides, to C. sumatrensis. In field trials, were applied when the rice plantation was on V3 stage. Evaluations were control (%), roots and shoot dry weight of Conyza spp., as well as injury (%), number of grains per panicle, and grain yield (ha−1) of rice. The applications of imazapyr + imazapic, florpyrauxifen-benzyl, imazethapyr, penoxsulam, quinclorac, bentazon, triclopyr-butyl, saflufenacil and ethoxysulfuron followed by water layer entry led to Conyza spp. control surpassing 80% at 28 DAA. The herbicides florpyrauxifen-benzyl, quinclorac, triclopyr-butyl, and saflufenacil, without flooding after application, demonstrated Sumatran fleabane control equal to or greater than 80% at 28 DAA. Effective water layer management is crucial for Conyza spp. control in zero-grade rice cultivation areas. [ABSTRACT FROM AUTHOR]

Peruvian watergrass (Luziola peruviana J.F. Gmel.) is a perennial weed often found in paddy fields in the southern region of Brazil. Its chemical control is performed mainly by herbicides such as glyphosate in burndown, whose efficacy depends on soil moisture. Under excess‐water soil conditions, glyphosate efficacy is reduced, probably due to reduced translocation and the involvement of photoassimilates partition. Furthermore, little is known about the stress tolerance of these plants subjected to water deficit. Based on that, we performed experiments to verify the effect of soil moisture on the biochemical parameters of Peruvian watergrass and glyphosate translocation to the stolon and roots. Total soluble sugars, sucrose, starch, and glyphosate concentrations in leaves, culms, roots, and glyphosate partitioning were quantified. The malondialdehyde content and the lipid peroxidation increased with the drainage. Under drainage conditions, superoxide production was higher in roots than leaves, while peroxide production was lower in roots than leaves. The electrolyte leakage increased with the drainage and glyphosate application. The total soluble sugar content varied in each organ with a significant increase in the culm 14 days after application in the draining treatment. Sucrose varied considerably and reached its maximum concentration at 21 days after herbicide application. The starch accumulation in the culm was 7 days after applying the highest glyphosate dose. The presence of glyphosate in the roots subjected to soil drainage indicates the movement of this herbicide. In conclusion, soil drainage profoundly impacts Peruvian watergrass physiology, increasing the photoassimilates and glyphosate translocation to the stolon and root. This explains why glyphosate efficacy is higher under drainage conditions. [ABSTRACT FROM AUTHOR]

Dry direct-seeding can get rid of the constraints of high-water demand, and is the simplest and most laborsaving mode in rice (Oryza sativa L.) cultivation. However, weeds are more prone to occur in dry direct-seeding rice fields, coupled with increased herbicide resistance, leading to confusion among growers regarding herbicide selection. In this study, our investigation results revealed total grass quantity reached 458.82 plants m-2. Two round of field experiments were conducted to determine suitable post-emergence herbicides for dry directseeding indica rice. The results showed that among the herbicides safe to indica rice, the efficacy of the combination of pyraquinate (a new 4-hydroxyphenylpyruvate dioxygenase inhibitor, 150.0 g ai ha-1) + florpyrauxifen-benzyl (13.5 g ai ha-1) on Leptochloa chinensis (L.) Nees, Eclipta prostrata (L.) L., Cyperus iria L., Fimbristylis miliacea auct., and total grasses were 89.1%, 97.8%, 97.2%, 90.1%, and 92.8%, respectively; the efficacy of metamifop (120.0 g ai ha-1) + florpyrauxifen-benzyl (18.0 g ai ha-1) and 22.0% cyhalofop-butyl + pyrazosulfuron-ethyl + bispyribac-sodium OD (148.5 g ai ha-1) on main weeds also exceeds 85.0%, except for cyhalofop-butyl-resistant L. chinensis. The combination of metamifop + florpyrauxifen-benzyl and 22.0% cyhalofop-butyl + pyrazosulfuron-ethyl + bispyribac-sodium OD can be selected for fields where L. chinensis is not resistant to acetyl-CoA carboxylase (ACCase) inhibitors. The combination of pyraquinate + florpyrauxifenbenzyl is the most promising combination to control multiple weeds, even ACCase inhibitors-resistant weeds. This study could also provide references for herbicides selection and management of ACCase inhibitors-resistant L. chinensis in dry direct-seeding indica rice field worldwide. [ABSTRACT FROM AUTHOR]

The identification and classification of pests in rice field are the prerequisites of early warning systems for pest dis-asters. Among these pests, the rice planthoppers cause the most serious damage. However, the existing deep learning models for rice planthopper recognition are characterized by large size and numerous parameters, which makes them unsuitable for the deployment on embedded devices with limited computational resources. To address this issue, a lightweight rice planthopper recognition model based on YOLOv5 is proposed in this paper. In the model, a lightweight convolutional network named GhostNet is employed as the backbone to reduce the operational parameters. Additionally, a convolutional attention module (CBAM) is integrated into the backbone network to effectively enhance the transmission of deep information, so as to improve the model's ability of recognizing rice planthopper images. The original CIoU loss function is replaced by the SIoU loss function to expedite model convergence. Experimental results demonstrate that the modified model achieves the mAP@0.5 as 82.8%, with the parameter count of 3.12x106 and the model size of 7.2MB. Compared to the original model, it is a reduction of 46.7% in size and 43.3% in parameters, with a minor accuracy loss of 0.1%. Clearly, the improved model can achieve lightweight characteristics and robust performance, and thus it provides a theoretical and practical foundation for early warning systems against rice planthopper infestations in rice fields. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Agro-Environment Science is the property of Journal of Agro-Environment Science Editorial Board and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Methanotrophs of the genus Methylocystis are frequently found in rice paddies. Although more than ten facultative methanotrophs have been reported since 2005, none of these strains was isolated from paddy soil. Here, a facultative methane-oxidizing bacterium, Methylocystis iwaonis SD4, was isolated and characterized from rhizosphere samples of rice plants in Nanjing, China. This strain grew well on methane or methanol but was able to grow slowly using acetate or ethanol. Moreover, strain SD4 showed sustained growth at low concentrations of methane (100 and 500 ppmv). M. iwaonis SD4 could utilize diverse nitrogen sources, including nitrate, urea, ammonium as well as dinitrogen. Strain SD4 possessed genes encoding both the particulate methane monooxygenase and the soluble methane monooxygenase. Simple and rapid genetic manipulation methods were established for this strain, enabling vector transformation and unmarked genetic manipulation. Fast growth rate and efficient genetic tools make M. iwaonis SD4 an ideal model to study facultative methanotrophs, and the ability to grow on low concentration of methane implies its potential in methane removal. [ABSTRACT FROM AUTHOR]

BACKGROUND: Barnyardgrass (Weed Science Society of America recommended) or Barnyard grass (Britannica recommended) (Echinochloa crus‐galli (L.) P. Beauv.) is one of the most problematic and dominant weeds in world agricultural systems, especially in paddy fields, where tillering and grain yield can be reduced by 50–70% because of its competitive pressure. The frequent use of chemical herbicides to control E. crus‐galli has led to the evolution of herbicide resistance. Developing bioherbicides using pathogenic fungi to control E. crus‐galli could be an alternative option. RESULTS: In a previous study we showed that a strain of Bipolaris yamadae (HXDC‐1‐2) was promising in controlling gramineous weeds. Here we present a study that evaluated this fungus as a mycoherbicide against E. crus‐galli in greenhouse and paddy fields, characterized mycelium growth and conidial production, and examined the infection development. The median effective dose (ED50) and 90% effective dose (ED90) values of microcapsulated B. yamadae strain HXDC‐1‐2 on E. crus‐galli in the greenhouse were 7.17 × 102 and 9.35 × 103 conidia mL−1, respectively. Conidial germination, mycelial growth, and attachment formation occurred on E. crus‐galli leaves within 1 to 6 h. The hyphae directly invaded cells and stomata, primarily from the appressorium on the epidermis, and necrotic lesions were observed on the leaf surface within 20 to 24 h. Applied to E. crus‐galli plants at 1 × 105 conidia mL−1, the fungus reduced the weed's fresh weight of 75%. CONCLUSION: B. yamadae strain HXDC‐1‐2 has the potential to be developed as a bioherbicide against E. crus‐galli plants, especially in rice fields. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Global population continuous growth and increasing consumers' demands for protein-rich diets have posed sustainability challenges for traditional livestock feed sources. Consequently, exploring alternative and sustainable protein sources has become imperative to address the environmental burden and resource limitations associated with conventional ingredients. With respect to food security assurance, insects have emerged as a promising solution due to their exceptional nutritional profile, rapid reproduction rates, and low environmental impact. In the present pilot study, 10% of a soybean meal-based diet was replaced by adult mosquitoes harvested from rice fields. The objective was to assess the effect of this partial substitution on meat quality aspects and consumer acceptance. A total of 40 Cobb hybrid broiler chickens were randomly placed in a control and a mosquito-fed group. The study was conducted for 42 days and carcass physicochemical, nutritional, and microbiological characteristics, as well as sensory attributes were evaluated. Overall, results regarding quality attributes were comparable between the control and the treatment group. The organoleptic evaluation showed that the thighs from the mosquito-fed group had the highest overall consumer acceptance. These outcomes indicate that mosquitoes could be successfully used as a protein source for broiler feed without compromising the quality and acceptability of the meat. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: Nitrogen (N) fertilizer is a critical factor in achieving high rice yields, but it can also contribute to increased CH4 emissions from rice paddies. Determining how to utilize N fertilizer to effectively balance the contradiction between methane (CH4) emissions and rice yield remains an urgent need in the face of unstoppable climate change. Materials and methods: In this study, the response of CH4 fluxes in rice paddies to elevated carbon dioxide (CO2) concentration (e[CO2]) and reduced N application were investigated. The rice biomass and yield, CH4 fluxes, soil properties, and methanogenic characteristics were observed in control (CK) (ambient CO2 concentration + application of 250 kg N ha−1 urea), C+ (e[CO2] by 200 ppm + 250 kg N ha−1 urea), N− (ambient CO2 concentration + 150 kg N ha−1 urea), and C+N− (e[CO2] by 200 ppm + 150 kg N ha−1 urea) treatments. Results and discussion: The results revealed that the C+ and C+N− treatments significantly increased the CH4 emissions/yield by 20.0% and 18.8%, respectively, while the N− treatment significantly suppressed the CH4 emissions/yield by 13.3% compared to CK. The N− treatment weakened the promotion effect of C+ on the rice total biomass, the soil dissolved organic carbon (DOC) concentration and invertase activity, and the CH4 emissions/yield. Moreover, the C+N− treatment significantly reduced the soil DOC concentration and the abundance of the mcrA gene in the grain-filling stage compared to C+. Conclusions: Overall, under climate change conditions, N reduction can mitigate CH4 fluxes from rice paddies by affecting rice growth, soil methanogenic characteristics, and the C substrate. [ABSTRACT FROM AUTHOR]

Manure application is a recommended method to improve soil quality and mitigate global warming via soil carbon (C) sequestration. However, such application can significantly increase ammonia (NH3) volatilization loss and cause secondary environmental problems, such as acidification, eutrophication, and particulate matter formation. To investigate the potential of reducing NH3 emissions in flooded rice paddies, three types of stabilized swine manure amendments (fresh, composted, and biochar) were applied at a rate of 12 Mg ha-1 (dry weight) under standard fertilization (N-P2O5-K2O = 90-45-57 kg ha-1), and NH3 emission was characterized using the static chamber method. Regardless of manure management practices, NH3 fluxes increased significantly immediately after application of an inorganic nitrogen (N) fertilizer (urea). The manure was applied completely as the basal fertilizer before rice transplanting, but the NH3 emission rates increased more dramatically following urea application in the manure treatments. Fresh and composted manure applications significantly increased seasonal NH3 volatilization losses compared to the control but the biochar did not. Compost manure significantly increased rice grain productivity owing to the higher N content, while fresh and biochar manures did not increase rice productivity because of fewer panicles per hill and fewer grains per panicle. Consequently, biochar application resulted in lower NH3 flux intensity and seasonal NH3 flux per grain yield, whereas fresh and compost manures substantially increased this intensity. Therefore, biochar manure may be a more reasonable organic amendment than fresh and composted manures for reducing NH3 emission impacts on rice paddies. [ABSTRACT FROM AUTHOR]

Data on the soil nutrient content are required to calculate fertilizer rate recommendations. The soil laboratory determines these soil properties, yet the measurement is time-consuming and costly. Meanwhile, portable devices to assess the soil nutrient content in real-time are limited. However, a proprietary and low-cost NPK sensor is available and commonly used in IoT for agriculture. This study aimed to assemble and test a portable, NPK sensor-based device in irrigated and rainfed paddy soils from Java, Indonesia. The device development followed a prototyping approach. The device building included market surveys and opted for an inexpensive, light, and compact soil sensor, power storage, monitor, and wire connectors. Arduino programming language was used to write scripts for data display and sub-device communication. The result is a real-time, portable soil nutrient detector that measures the soil temperature, moisture, pH, electrical conductivity, and N, P, and K contents. Field tests show that the device is sensitive to soil properties and location. The portable soil nutrient detector may be an alternative tool for the real-time measurement of soil nutrients in paddy fields in Indonesia. [ABSTRACT FROM AUTHOR]

Plants acquire potassium (K) not only from exchangeable K fractions but also from non-exchangeable K fractions. However, factors affecting the amount of K supplied from the non-exchangeable K fraction have not been well understood. In this study, the effects of soils and exchangeable K on the amount of K supplied to rice from the non-exchangeable K fraction were investigated for six Japanese paddy soils diluted with different rates of quartz sand. The amounts of K supplied from the non-exchangeable K fractions (recharged K) ranged from 14.4 to 137 mg K2O kg−1, equivalent to 10 to 61% of the total K acquired by rice. The amounts of recharged K were affected by the exchangeable K levels in three out of six soils. Although the cultivation experiments were conducted under various K conditions including severe K deficiency, exchangeable K was detected after cultivation in all soils, and the contents of exchangeable K were almost identical for each soil regardless of the dilution ratio of soil with quartz sand. Accordingly, there would be at least three types of non-exchangeable K fractions which dissolve into soil solution to attain a specific level of exchangeable K: (i) a non-exchangeable K fraction that releases K regardless of the exchangeable K level; (ii) a non-exchangeable K fraction that easily releases K with the decrease in exchangeable K under sufficient K conditions without inducing K-deficient symptoms in rice; and (iii) a non-exchangeable K fraction that releases K with the decrease in exchangeable K only under severe K-deficient conditions with accompanying deficient symptoms in rice. The application of K fertilizer would reduce the amount of recharged K acquired by rice from fractions (ii) and (iii), whereas fraction (i) would remain unaffected by the fertilized K until the level of exchangeable K reaches a specific level for each soil. The release of K from a fraction (iii) only occurred under conditions of severe K deficiency; hence, farmers should not rely on this fraction for K supply. [ABSTRACT FROM AUTHOR]

Wheat and barley yields in Japan are considerably lower than those in the UK, even where similar Climate Zones (CZs) of relatively cold and humid nature are shared. In order to understand this difference, it is first necessary to find out if any common climate–yield relationship exists between the two countries. The Climate Zonation Scheme (CZS) developed in the Global Yield Gap Atlas (GYGA) was used to analyse actual yield (Ya) with three climatic factors of the GYGA-CZS, i.e., growing degree days (GDD), aridity index (AI) and temperature seasonality (TS). A significant relationship was found between AI scores and Ya values across the two countries. Ya values decreased with an increase in AI scores; in other words, lower yields are associated with higher AI scores. In addition, the degree of yield reduction with the rise in AI scores was greater in Japan than in the UK. The present study also proposed a novel method to link CZs of the GYGA-CZS to regional classification units, especially for countries where statistical crop yield data are available only at a coarse scale. [ABSTRACT FROM AUTHOR]

Paddy field leveling is an essential step before rice transplanting. During the operation of a paddy field grader, a common issue is the wrapping of rice straw around the blades, resulting in a low rice straw burial rate. This study focused on analyzing the operating parameters of a disc spring–tooth-combined paddy field grader. A soil–straw mechanism simulation model was created using EDEM 2021 software to simulate the field operation status. Firstly, the single-factor test was carried out, with the working speed, the working depth of the disc cutter roller, and the rotation speed of the cutter roller as the factors and the straw-buried rate (SBR) and the machine forward resistance (MFR) as the test indexes, and the parameter range was optimized. The parameters were optimized by the response surface method (RSM) and machine learning algorithms. The results indicated that the genetic algorithm–back propagation (GA-BP) neural network outperformed other optimization models in terms of prediction accuracy and stability. By utilizing the GA-BP regression model and RSM model for regression fitting, two sets of optimal parameter combinations were obtained. Verification experiments were carried out using two sets of parameter combinations. Taking the average of the experimental results, the simulation results showed that the straw burial rate was 93.47% and the forward resistance was 6487 N for the parameter combinations of RSM, and the straw burial rate was 94.86% and the forward resistance was 6352 N for the parameter combinations of GA-BP; the field experiments showed that the straw burial rate was 92.86% and the forward resistance was 6518 N for the parameter combinations of RSM, and the straw burial rate was 95.17% and the forward resistance was 6249 N for the parameter combinations of GA-BP. The results demonstrated that the GA-BP prediction model exhibited better predictive capabilities compared to the traditional RSM, providing more accurate predictions of the paddy field grader's field operation performance. [ABSTRACT FROM AUTHOR]

The surge in global agricultural input prices, particularly for nitrogen (N) fertilizers, has presented challenges for farmers facing stagnant crop prices and rising production costs. This study explored a system designed to sustain or enhance farmers' income while reducing production costs, with a specific focus on implementing practices that involve cultivating crops with lower rates of fertilizer than conventional rates, particularly in smaller land settings, through on-farm experimentation (OFE). OFE was conducted over three years across 11 fields in Gifu, Japan, utilizing a strip trial design to investigate the effect of fertilizer input rates on rice yield. To collect yield data, unmanned aerial vehicle (UAV)-mounted multispectral cameras were deployed. A Gaussian process model was used to address the impact of fertilizer input rates on yield while accounting for spatial yield variation. The study further assessed the number of field trials achieving positive profits at certain probability levels by integrating outcomes from multiple OFEs. The results highlighted little rice yield response to fertilizer input in most of the fields, while several fields showed significant positive yield responses. Notably, the use of lower fertilizer input rates in certain fields proved to be more profitable whereas higher fertilizer input rates were less profitable in most fields. The results further emphasized the economic viability of lower rates, especially when fertilizer prices are high, thus contributing valuable insights for sustainable and profitable rice production in Japanese cultivation. [ABSTRACT FROM AUTHOR]

The positioning of paddy field weeding wheels is of great significance for compensating the operation deviation between the weeding wheel and the seedling row in paddy field mechanical weeding. In this paper, a visual positioning method for determining the three-dimensional coordinates of weeding wheels in the camera coordinate system is proposed. By fixing the laser rangefinder with the weeding wheel, the proposed method converts the positioning of weeding wheels into solving the relative pose relationship between the laser rangefinder and the camera. Then, based on the constraints of the laser spots on the AprilTag calibration plane, a nonlinear optimization model is established to obtain the relative pose parameters. In the experiment, two evaluation indicators were proposed to evaluate the calibration accuracy. The experimental results showed that the proposed visual positioning method of the weeding wheel can reach a mean positioning error of 2.766 mm and a mean pixel error of 7.161 pixels. [ABSTRACT FROM AUTHOR]

Purpose: The study's objective is to assess the environmental performance of rice production in Northern Italy, in particular in Piedmont, the first Italian and European district for the rice-growing area, and thus identify the most critical hotspots and agricultural processes. In particular, as a case study, a farm located in Vercelli (VC) has been chosen. Subsequently, the study results were compared with other different cultivation practices to evaluate the most sustainable choice. Methods: The application of the LCA has been performed, highlighting the phases of rice production that have the most significant impact. Then, uncertainty and sensitivity analyses have been made to estimate the robustness of the results and assess the influence of changing some input variables on emission reduction. Finally, multivariate statistical, specifically a principal component analysis (PCA), was conducted to aid the interpretation of the output dataset of this case study. LCA, uncertainty analysis, and sensitivity analysis were performed with SimaPro 9.2.0, using ReCiPe 2016 Midpoint (H) methodology, and PCA with R software. Results and discussions: The hotspot with the highest environmental load is irrigation, which compared to the other phases impacts more in 15 out of 18 categories, including 12 with impacts greater than + 75%. This is because irrigation causes direct impacts, related to the methanogenesis in rice fields, but also indirect impacts related mainly to the production of the energy mix required to move the large masses of irrigation water. Therefore, different water management systems were compared and results show that the irrigation systems based on intermittent paddy submergence (DSI) could result in − 40% lower impacts, resulting to be the preferable technique over the other irrigation systems analyzed, including the traditional one used in this study. Conclusions: In order to reduce the environmental impacts related to the irrigation process, a water management system characterized by intermittent flooding of the paddy field (DSI) could be used as it reduces the environmental impacts the most (− 40%), while the least suitable system is one characterized by continuous flooding without drought periods, as it causes the highest impacts. [ABSTRACT FROM AUTHOR]

To investigate difference in the quality of the different parts (back, tail muscles, and fish skin) of Opsariichthys bidens from pond and rice field cultures, a comparative study was conducted in terms of nutritional composition, volatile flavor profiles and gut microbiota. In detail, the texture, free amino acids, fatty acids were further assessed. The results suggested that the moisture content, crude protein and crude fat content in the skin of O. bidens are higher than those in the back and tail muscles, regardless of breeding modes. The fish cultured in the rice field had a higher protein content than those from the pond culture, while the fat content of the rice field-cultured fish was significantly low compared to the fish from the pond culture, especially in the back and tail parts. A total of 43 volatile components were detected by Gas Chromatography–Mass Spectrometry (GC-MS), with a maximum of 18 types of aldehydes and the highest concentration being nonanal. Compared to pond cultures, the fish from the rice field cultures showed more abundant flavor composition and odor-active compounds. The total content of DHA (Docosahexaenoic Acid) and EPA (Eicosapentaenoic Acid) in the rice field-cultured fish was higher than that of the pond group, while no significant disparity in amino acid composition was observed (p > 0.05). Comparative and clustering analyses of gut microbiota revealed notable discrepancies in the gut microbiota of O. bidens from two aquaculture systems. However, an inherent correlation between the gut microbiome and meat quality would be further emphasized in further studies. This study can offer a theoretical reference for the development of high-quality aquatic products by selecting the appropriate aquaculture models. [ABSTRACT FROM AUTHOR]

Background: Crop diversification is considered as an imperative approach for synchronizing the plant nutrient demands and soil nutrient availability. Taking two or more crops from the same field in one year is considered as multiple cropping. It improves the diversity and abundance of soil microbes, thereby improving the growth and yield of crops. Therefore, the present study was conducted to explore the effects of different multiple winter cropping on soil microbial communities in paddy fields. In this study, eight rice cropping patterns from two multiple cropping systems with three different winter crops, including Chinese milk vetch (CMV), rape, and wheat were selected. The effects of different multiple winter cropping on soil microbial abundance, community structure, and diversity in paddy fields were studied by 16 S rRNA high-throughput sequencing and real-time fluorescence quantitative polymerase chain reaction (PCR). Results: The results showed that different multiple winter cropping increased the operational taxonomic units (OTUs), species richness, and community richness index of the bacterial community in 0 ~ 20 cm soil layer. Moreover, soil physical and chemical properties of different multiple cropping patterns also affected the diversity and abundance of microbial bacterial communities. The multiple cropping increased soil potassium and nitrogen content, which significantly affected the diversity and abundance of bacterial communities, and it also increased the overall paddy yield. Moreover, different winter cropping changed the population distribution of microorganisms, and Proteobacteria, Acidobacteria, Nitrospira, and Chloroflexi were identified as the most dominant groups. Multiple winter cropping, especially rape-early rice-late rice (TR) andChinese milk vetch- early rice-late rice (TC) enhanced the abundance of Proteobacteria, Acidobacteria, and Actinobacteria and decreased the relative abundance of Verrucomicrobia and Euryarchaeota. Conclusion: In conclusion, winter cropping of Chinese milk vetch and rape were beneficial to improve the soil fertility, bacteria diversity, abundance and rice yield. [ABSTRACT FROM AUTHOR]