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Journal = Drones
Section = Drones in Agriculture and Forestry

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20 pages, 1346 KiB  
Article
Integrated Smart Farm System Using RNN-Based Supply Scheduling and UAV Path Planning
by Dongwoo You, Yukai Chen and Donkyu Baek
Drones 2025, 9(8), 531; https://doi.org/10.3390/drones9080531 - 28 Jul 2025
Viewed by 222
Abstract
Smart farming has emerged as a promising solution to address challenges such as climate change, population growth, and limited agricultural infrastructure. To enhance the operational efficiency of smart farms, this paper proposes an integrated system that combines Recurrent Neural Networks (RNNs) and Unmanned [...] Read more.
Smart farming has emerged as a promising solution to address challenges such as climate change, population growth, and limited agricultural infrastructure. To enhance the operational efficiency of smart farms, this paper proposes an integrated system that combines Recurrent Neural Networks (RNNs) and Unmanned Aerial Vehicles (UAVs). The proposed framework forecasts future resource shortages using an RNN model and recent environmental data collected from the field. Based on these forecasts, the system schedules a resource supply plan and determines the UAV path by considering both dynamic energy consumption and priority levels, aiming to maximize the efficiency of the resource supply. Experimental results show that the proposed integrated smart farm framework achieves an average reduction of 81.08% in the supply miss rate. This paper demonstrates the potential of an integrated AI- and UAV-based smart farm management system in achieving both environmental responsiveness and operational optimization. Full article
(This article belongs to the Section Drones in Agriculture and Forestry)
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26 pages, 11912 KiB  
Article
Multi-Dimensional Estimation of Leaf Loss Rate from Larch Caterpillar Under Insect Pest Stress Using UAV-Based Multi-Source Remote Sensing
by He-Ya Sa, Xiaojun Huang, Li Ling, Debao Zhou, Junsheng Zhang, Gang Bao, Siqin Tong, Yuhai Bao, Dashzebeg Ganbat, Mungunkhuyag Ariunaa, Dorjsuren Altanchimeg and Davaadorj Enkhnasan
Drones 2025, 9(8), 529; https://doi.org/10.3390/drones9080529 - 28 Jul 2025
Viewed by 249
Abstract
Leaf loss caused by pest infestations poses a serious threat to forest health. The leaf loss rate (LLR) refers to the percentage of the overall tree-crown leaf loss per unit area and is an important indicator for evaluating forest health. Therefore, rapid and [...] Read more.
Leaf loss caused by pest infestations poses a serious threat to forest health. The leaf loss rate (LLR) refers to the percentage of the overall tree-crown leaf loss per unit area and is an important indicator for evaluating forest health. Therefore, rapid and accurate acquisition of the LLR via remote sensing monitoring is crucial. This study is based on drone hyperspectral and LiDAR data as well as ground survey data, calculating hyperspectral indices (HSI), multispectral indices (MSI), and LiDAR indices (LI). It employs Savitzky–Golay (S–G) smoothing with different window sizes (W) and polynomial orders (P) combined with recursive feature elimination (RFE) to select sensitive features. Using Random Forest Regression (RFR) and Convolutional Neural Network Regression (CNNR) to construct a multidimensional (horizontal and vertical) estimation model for LLR, combined with LiDAR point cloud data, achieved a three-dimensional visualization of the leaf loss rate of trees. The results of the study showed: (1) The optimal combination of HSI and MSI was determined to be W11P3, and the LI was W5P2. (2) The optimal combination of the number of sensitive features extracted by the RFE algorithm was 13 HSI, 16 MSI, and hierarchical LI (2 in layer I, 9 in layer II, and 11 in layer III). (3) In terms of the horizontal estimation of the defoliation rate, the model performance index of the CNNRHSI model (MPI = 0.9383) was significantly better than that of RFRMSI (MPI = 0.8817), indicating that the continuous bands of hyperspectral could better monitor the subtle changes of LLR. (4) The I-CNNRHSI+LI, II-CNNRHSI+LI, and III-CNNRHSI+LI vertical estimation models were constructed by combining the CNNRHSI model with the best accuracy and the LI sensitive to different vertical levels, respectively, and their MPIs reached more than 0.8, indicating that the LLR estimation of different vertical levels had high accuracy. According to the model, the pixel-level LLR of the sample tree was estimated, and the three-dimensional display of the LLR for forest trees under the pest stress of larch caterpillars was generated, providing a high-precision research scheme for LLR estimation under pest stress. Full article
(This article belongs to the Section Drones in Agriculture and Forestry)
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20 pages, 2421 KiB  
Article
Mitigation of Water-Deficit Stress in Soybean by Seaweed Extract: The Integrated Approaches of UAV-Based Remote Sensing and a Field Trial
by Md. Raihanul Islam, Hasan Muhammad Abdullah, Md Farhadur Rahman, Mahfuzul Islam, Abdul Kaium Tuhin, Md Ashiquzzaman, Kh Shakibul Islam and Daniel Geisseler
Drones 2025, 9(7), 487; https://doi.org/10.3390/drones9070487 - 10 Jul 2025
Viewed by 392
Abstract
In recent years, global agriculture has encountered several challenges exacerbated by the effects of changes in climate, such as extreme water shortages for irrigation and heat waves. Water-deficit stress adversely affects the morpho-physiology of numerous crops, including soybean (Glycine max L.), which [...] Read more.
In recent years, global agriculture has encountered several challenges exacerbated by the effects of changes in climate, such as extreme water shortages for irrigation and heat waves. Water-deficit stress adversely affects the morpho-physiology of numerous crops, including soybean (Glycine max L.), which is considered as promising crop in Bangladesh. Seaweed extract (SWE) has the potential to improve crop yield and alleviate the adverse effects of water-deficit stress. Remote and proximal sensing are also extensively utilized in estimating morpho-physiological traits owing to their cost-efficiency and non-destructive characteristics. The study was carried out to evaluate soybean morpho-physiological traits under the application of water extracts of Gracilaria tenuistipitata var. liui (red seaweed) with two varying irrigation water conditions (100% of total crop water requirement (TCWR) and 70% of TCWR). Principal component analysis (PCA) revealed that among the four treatments, the 70% irrigation + 5% (v/v) SWE and the 100% irrigation treatments overlapped, indicating that the application of SWE effectively mitigated water-deficit stress in soybeans. This result demonstrates that the foliar application of 5% SWE enabled soybeans to achieve morpho-physiological performance comparable to that of fully irrigated plants while reducing irrigation water use by 30%. Based on Pearson’s correlation matrix, a simple linear regression model was used to ascertain the relationship between unmanned aerial vehicle (UAV)-derived vegetation indices and the field-measured physiological characteristics of soybean. The Normalized Difference Red Edge (NDRE) strongly correlated with stomatal conductance (R2 = 0.76), photosystem II efficiency (R2 = 0.78), maximum fluorescence (R2 = 0.64), and apparent transpiration rate (R2 = 0.69). The Soil Adjusted Vegetation Index (SAVI) had the highest correlation with leaf relative water content (R2 = 0.87), the Blue Normalized Difference Vegetation Index (bNDVI) with steady-state fluorescence (R2 = 0.56) and vapor pressure deficit (R2 = 0.74), and the Green Normalized Difference Vegetation Index (gNDVI) with chlorophyll content (R2 = 0.73). Our results demonstrate how UAV and physiological data can be integrated to improve precision soybean farming and support sustainable soybean production under water-deficit stress. Full article
(This article belongs to the Special Issue Recent Advances in Crop Protection Using UAV and UGV)
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17 pages, 4293 KiB  
Article
Predicting Nitrogen Flavanol Index (NFI) in Mentha arvensis Using UAV Imaging and Machine Learning Techniques for Sustainable Agriculture
by Bhavneet Gulati, Zainab Zubair, Ankita Sinha, Nikita Sinha, Nupoor Prasad and Manoj Semwal
Drones 2025, 9(7), 483; https://doi.org/10.3390/drones9070483 - 9 Jul 2025
Viewed by 1642
Abstract
Crop growth monitoring at various growth stages is essential for optimizing agricultural inputs and enhancing crop yield. Nitrogen plays a critical role in plant development; however, its improper application can reduce productivity and, in the long term, degrade soil health. The aim of [...] Read more.
Crop growth monitoring at various growth stages is essential for optimizing agricultural inputs and enhancing crop yield. Nitrogen plays a critical role in plant development; however, its improper application can reduce productivity and, in the long term, degrade soil health. The aim of this study was to develop a non-invasive approach for nitrogen estimation through proxies (Nitrogen Flavanol Index) in Mentha arvensis using UAV-derived multispectral vegetation indices and machine learning models. Support Vector Regression, Random Forest, and Gradient Boosting were used to predict the Nitrogen Flavanol Index (NFI) across different growth stages. Among the tested models, Random Forest achieved the highest predictive accuracy (R2 = 0.86, RMSE = 0.32) at 75 days after planting (DAP), followed by Gradient Boosting (R2 = 0.75, RMSE = 0.43). Model performance was lowest during early growth stages (15–30 DAP) but improved markedly from mid to late growth stages (45–90 DAP). The findings highlight the significance of UAV-acquired data coupled with machine learning approaches for non-destructive nitrogen flavanol estimation, which can immensely contribute to improving real-time crop growth monitoring. Full article
(This article belongs to the Section Drones in Agriculture and Forestry)
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30 pages, 25636 KiB  
Article
Cluster-Based Flight Path Construction for Drone-Assisted Pear Pollination Using RGB-D Image Processing
by Arata Kuwahara, Tomotaka Kimura, Sota Okubo, Rion Yoshioka, Keita Endo, Hiroyuki Shimizu, Tomohito Shimada, Chisa Suzuki, Yoshihiro Takemura and Takefumi Hiraguri
Drones 2025, 9(7), 475; https://doi.org/10.3390/drones9070475 - 4 Jul 2025
Viewed by 326
Abstract
This paper proposes a cluster-based flight path construction method for automated drone-assisted pear pollination systems in orchard environments. The approach uses RGB-D (Red-Green-Blue-Depth) sensing through an observation drone equipped with RGB and depth cameras to detect blooming pear flowers. Flower detection is performed [...] Read more.
This paper proposes a cluster-based flight path construction method for automated drone-assisted pear pollination systems in orchard environments. The approach uses RGB-D (Red-Green-Blue-Depth) sensing through an observation drone equipped with RGB and depth cameras to detect blooming pear flowers. Flower detection is performed using a YOLO (You Only Look Once)-based object detection algorithm, and three-dimensional flower positions are estimated by integrating depth information with the drone’s positional and orientation data in the east-north-up coordinate system. To enhance pollination efficiency, the method applies the OPTICS (Ordering Points To Identify the Clustering Structure) algorithm to group detected flowers based on spatial proximity that correspond to branch-level distributions. The cluster centroids then construct a collision-free flight path, with offset vectors ensuring safe navigation and appropriate nozzle orientation for effective pollen spraying. Field experiments conducted using RTK-GNSS-based flight control confirmed the accuracy and stability of generated flight trajectories. The drone hovered in front of each flower cluster and performed uniform spraying along the planned path. The method achieved a fruit set rate of 62.1%, exceeding natural pollination at 53.6% and compared to the 61.9% of manual pollination. These results demonstrate the effectiveness and practicability of the method for real-world deployment in pear orchards. Full article
(This article belongs to the Special Issue UAS in Smart Agriculture: 2nd Edition)
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15 pages, 3092 KiB  
Article
Geostatistical Vegetation Filtering for Rapid UAV-RGB Mapping of Sudden Geomorphological Events in the Mediterranean Areas
by María Teresa González-Moreno and Jesús Rodrigo-Comino
Drones 2025, 9(6), 441; https://doi.org/10.3390/drones9060441 - 16 Jun 2025
Viewed by 566
Abstract
The use of UAVs for analyzing soil degradation processes, particularly erosion, has become a crucial tool in environmental monitoring. However, the use of LiDAR (Light Detection and Ranging) or TLS (Terrestrial Lasser Scanner) may not be affordable for many researchers because of the [...] Read more.
The use of UAVs for analyzing soil degradation processes, particularly erosion, has become a crucial tool in environmental monitoring. However, the use of LiDAR (Light Detection and Ranging) or TLS (Terrestrial Lasser Scanner) may not be affordable for many researchers because of the elevated costs and difficulties for cloud processing to present a valuable option for rapid landscape assessment following extreme events like Mediterranean storms. This study focuses on the application of drone-based remote sensing with only an RGB camera in geomorphological mapping. A key objective is the removal of vegetation from imagery to enhance the analysis of erosion and sediment transport dynamics. The research was carried out over a cereal cultivation plot in Málaga Province, an area recently affected by high-intensity rainfalls exceeding 100 mm in a single day in the past year, which triggered significant soil displacement. By processing UAV-derived data, a Digital Elevation Model (DEM) was generated through geostatistical techniques, refining the Digital Surface Model (DSM) to improve topographical change detection. The ability to accurately remove vegetation from aerial imagery allows for a more precise assessment of erosion patterns and sediment redistribution in geomorphological features with rapid spatiotemporal changes. Full article
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19 pages, 4044 KiB  
Article
A Deep Reinforcement Learning-Driven Seagull Optimization Algorithm for Solving Multi-UAV Task Allocation Problem in Plateau Ecological Restoration
by Lijing Qin, Zhao Zhou, Huan Liu, Zhengang Yan and Yongqiang Dai
Drones 2025, 9(6), 436; https://doi.org/10.3390/drones9060436 - 14 Jun 2025
Viewed by 425
Abstract
The rapid advancement of unmanned aerial vehicle (UAV) technology has enabled the coordinated operation of multi-UAV systems, offering significant applications in agriculture, logistics, environmental monitoring, and disaster relief. In agriculture, UAVs are widely utilized for tasks such as ecological restoration, crop monitoring, and [...] Read more.
The rapid advancement of unmanned aerial vehicle (UAV) technology has enabled the coordinated operation of multi-UAV systems, offering significant applications in agriculture, logistics, environmental monitoring, and disaster relief. In agriculture, UAVs are widely utilized for tasks such as ecological restoration, crop monitoring, and fertilization, providing efficient and cost-effective solutions for improved productivity and sustainability. This study addresses the collaborative task allocation problem for multi-UAV systems, using ecological grassland restoration as a case study. A multi-objective, multi-constraint collaborative task allocation problem (MOMCCTAP) model was developed, incorporating constraints such as UAV collaboration, task completion priorities, and maximum range restrictions. The optimization objectives include minimizing the maximum task completion time for any UAV and minimizing the total time for all UAVs. To solve this model, a deep reinforcement learning-based seagull optimization algorithm (DRL-SOA) is proposed, which integrates deep reinforcement learning with the seagull optimization algorithm (SOA) for adaptive optimization. The algorithm improves both global and local search capabilities by optimizing key phases of seagull migration, attack, and post-attack refinement. Evaluation against five advanced swarm intelligence algorithms demonstrates that the DRL-SOA outperforms the alternatives in convergence speed and solution diversity, validating its efficacy for solving the MOMCCTAP. Full article
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14 pages, 7214 KiB  
Article
Agroecological Alternatives for Substitution of Glyphosate in Orange Plantations (Citrus sinensis) Using GIS and UAVs
by María Guadalupe Galindo Mendoza, Abraham Cárdenas Tristán, Pedro Pérez Medina, Rita Schwentesius Rindermann, Tomás Rivas García, Carlos Contreras Servín and Oscar Reyes Cárdenas
Drones 2025, 9(6), 398; https://doi.org/10.3390/drones9060398 - 28 May 2025
Viewed by 1079
Abstract
Field mapping is one of the most important aspects of precision agriculture, and community drones will be able to empower young rural entrepreneurs who will be the generational replacement of a new agrosocial paradigm. This research presents an agroecological participatory innovation methodology that [...] Read more.
Field mapping is one of the most important aspects of precision agriculture, and community drones will be able to empower young rural entrepreneurs who will be the generational replacement of a new agrosocial paradigm. This research presents an agroecological participatory innovation methodology that utilizes precision technology through geographic information systems and unmanned aerial vehicles to evaluate the integrated ecological management of weeds for glyphosate substitution in a transitional area of Citrus sinensis in San Luis Potosí, Mexico. Modeling methods and spatial analyses supported by intelligent georeference protocols were used to determine the number of weeds with tolerance and glyphosate resistance. Four control flights were conducted to monitor seven treatments. Glyphosate-resistant weeds were represented with the highest number of individuals and frequency in all experimental treatments. Although the treatment with maize stubble showed a slightly better result than the use of Mucuna pruriens mulch, which prevents the emergence of glyphosate resistant weeds before emergence, the second treatment is considered better in terms of the cost–benefit ratio, not only because of significantly lower cost but also because of the additional benefits it offers. Geospatial technologies will determine the nature of citrus and fruit tree agroecological treatments and highlight areas of the plot with binomial soil and plant nutrient deficiencies and pest and disease infestations, which will improve the timely application of bio-inputs through the development of accurate maps of agroecological transitions. Full article
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18 pages, 2484 KiB  
Article
Empowering Smallholder Farmers with UAV-Based Early Cotton Disease Detection Using AI
by Halimjon Khujamatov, Shakhnoza Muksimova, Mirjamol Abdullaev, Jinsoo Cho, Cheolwon Lee and Heung-Seok Jeon
Drones 2025, 9(5), 385; https://doi.org/10.3390/drones9050385 - 21 May 2025
Viewed by 829
Abstract
Early detection of cotton diseases is critical for safeguarding crop yield and minimizing agrochemical usage. However, most state-of-the-art systems rely on multispectral or hyperspectral sensors, which are costly and inaccessible to smallholder farmers. This paper introduces CottoNet, a lightweight and efficient deep learning [...] Read more.
Early detection of cotton diseases is critical for safeguarding crop yield and minimizing agrochemical usage. However, most state-of-the-art systems rely on multispectral or hyperspectral sensors, which are costly and inaccessible to smallholder farmers. This paper introduces CottoNet, a lightweight and efficient deep learning framework for detecting early-stage cotton diseases using only RGB images captured by unmanned aerial vehicles (UAVs). The proposed model integrates an EfficientNetV2-S backbone with a Dual-Attention Feature Pyramid Network (DA-FPN) and a novel Early Symptom Emphasis Module (ESEM) to enhance sensitivity to subtle visual cues such as chlorosis, minor lesions, and texture irregularities. A custom-labeled dataset was collected from cotton fields in Uzbekistan to evaluate the model under realistic agricultural conditions. CottoNet achieved a mean average precision (mAP@50) of 89.7%, an F1 score of 88.2%, and an early detection accuracy (EDA) of 91.5%, outperforming existing lightweight models while maintaining real-time inference speed on embedded devices. The results demonstrate that CottoNet offers a scalable, accurate, and field-ready solution for precision agriculture in resource-limited settings. Full article
(This article belongs to the Special Issue Advances of UAV in Precision Agriculture—2nd Edition)
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18 pages, 1579 KiB  
Article
LSTM-H: A Hybrid Deep Learning Model for Accurate Livestock Movement Prediction in UAV-Based Monitoring Systems
by Ayub Bokani, Elaheh Yadegaridehkordi and Salil S. Kanhere
Drones 2025, 9(5), 346; https://doi.org/10.3390/drones9050346 - 3 May 2025
Viewed by 1326
Abstract
Accurately predicting livestock movement is a cornerstone of precision agriculture, enabling smarter resource management, improved animal welfare, and enhanced productivity. However, the unpredictable and dynamic nature of livestock behavior poses significant challenges for traditional mobility prediction models. This study introduces LSTM-H, a hybrid [...] Read more.
Accurately predicting livestock movement is a cornerstone of precision agriculture, enabling smarter resource management, improved animal welfare, and enhanced productivity. However, the unpredictable and dynamic nature of livestock behavior poses significant challenges for traditional mobility prediction models. This study introduces LSTM-H, a hybrid deep learning model that combines the sequential learning power of Long Short-Term Memory (LSTM) networks with the real-time correction capabilities of Kalman Filters (KFs) to enhance livestock movement prediction within UAV-based monitoring frameworks. The results demonstrate that LSTM-H achieves a mean error of just 11.51 m for the first step and 40.68 m over a 30-step prediction horizon, outperforming state-of-the-art models by 4.3–14.8 times. Furthermore, LSTM-H exhibits robustness across noisy and dynamic conditions, with a 90% probability of errors below 13 m, as shown through cumulative error analysis. This enhanced accuracy enables UAVs to optimize flight trajectories, reducing energy consumption and improving monitoring efficiency in real-world agricultural settings. By bridging deep learning and adaptive filtering, LSTM-H not only enhances prediction accuracy but also paves the way for scalable, real-time livestock and UAV monitoring systems with transformative potential for precision agriculture. Full article
(This article belongs to the Special Issue Advances of UAV in Precision Agriculture—2nd Edition)
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17 pages, 1965 KiB  
Article
Dermal Exposure of Operators, Bystanders and Residents Derived from Unmanned Aerial Spraying Systems (UASS) in Vineyard
by Luis Sánchez-Fernández, Francisco Díaz-García, Manuel Pérez-Ruiz, Pilar Sandin-España, Jose Luis Alonso-Prados, Miguelina Mateo-Miranda, Jorge Martínez-Guanter, Esther García-Montero, Maria del Carmen Márquez and Isaac Abril-Muñoz
Drones 2025, 9(5), 345; https://doi.org/10.3390/drones9050345 - 1 May 2025
Viewed by 985
Abstract
The increasing adoption of unmanned aerial spraying services presents a transformative opportunity for precision agriculture, enabling targeted and efficient application of plant protection products. However, ensuring their safe and regulated integration into European farming requires a comprehensive understanding of exposure risks for operators, [...] Read more.
The increasing adoption of unmanned aerial spraying services presents a transformative opportunity for precision agriculture, enabling targeted and efficient application of plant protection products. However, ensuring their safe and regulated integration into European farming requires a comprehensive understanding of exposure risks for operators, bystanders, and residents. Expanding scientific knowledge in this domain is crucial for establishing a dedicated risk assessment framework for unmanned aerial spraying applications. This study evaluates dermal exposure levels among operators, residents, and bystanders, comparing unmanned aerial spraying applications with conventional vehicle-based and manual handheld spraying methods based on existing risk assessment and exposure models. Results suggest that unmanned aerial sprayers reduce dermal exposure for pilots, residents, and bystanders due to their remote operation and reduced drift compared to conventional spraying methods. However, critical exposure points arise during mixing, loading, and auxiliary tasks, where dermal exposure levels exceed model estimates. These elevated exposure levels are attributed to the higher frequency and concentrated handling of plant protection products in unmanned aerial spraying operations compared to traditional spraying methods. These findings highlight the need for targeted risk mitigation strategies to enhance operator safety, such as implementing closed transfer systems, optimized handling protocols, and specialized protective equipment. Full article
(This article belongs to the Section Drones in Agriculture and Forestry)
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13 pages, 2802 KiB  
Article
Experimental Study on UAV-Assisted Pollination in Hybrid Rice
by Le Long, Jinlong Lin, Muhua Liu, Xiongfei Chen, Peng Fang, Liping Xiao, Yihan Zhou and Xiaoya Dong
Drones 2025, 9(5), 327; https://doi.org/10.3390/drones9050327 - 24 Apr 2025
Viewed by 636
Abstract
To address challenges in hybrid rice seed production—specifically labor dependence, low uniformity of pollen distribution, and low operational efficiency—which collectively drive up large-scale production costs, technological innovations are critical. However, despite the demonstrated potential of UAV-assisted pollination, the quantitative relationships between its operational [...] Read more.
To address challenges in hybrid rice seed production—specifically labor dependence, low uniformity of pollen distribution, and low operational efficiency—which collectively drive up large-scale production costs, technological innovations are critical. However, despite the demonstrated potential of UAV-assisted pollination, the quantitative relationships between its operational parameters (altitude, speed, flight patterns) and pollen dispersal dynamics remain poorly understood, impeding standardization efforts. In this study, guided by agronomic pollination requirements, we developed an integrated analytical framework linking “pollen density-yield” dynamics to elucidate the governing mechanisms of flight parameters on pollination quality. A DJI T50 UAV was used to carry out the assisted pollination test on two varieties of hybrid rice, Changtian You 405 and Wanxiang You 377, to explore the effects of different flight speeds, altitudes, and trajectories of the UAV on pollination quality and to evaluate the cost-effectiveness ratio, taking the yield and its composition as the evaluation indexes. The experimental results showed that the UAV flight operation parameters had a significant effect on the pollination quality, and the best pollination quality was obtained when the flight altitude was 4 m and the speed was 3 m/s, achieving yields of 2.64 and 3.15 t/hm2; the average yields of the UAV-assisted pollination were 2.10 and 2.61 t/hm2, and the filled grain percentages were 15.76% and 34.2%, respectively. These increased the yields by 21.4% and 11.06%, respectively, and the filled grain percentages by 8.69% and 3.95%, compared with artificial pollination. The results also showed that the cost-effectiveness ratio of UAV-assisted pollination was 28.11% lower than that of artificial operation. The results indicate that UAVs have great application prospects in hybrid rice pollination. Full article
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17 pages, 2085 KiB  
Article
Agricultural Drone-Based Variable-Rate N Application for Regulating Wheat Protein Content
by Senlin Guan, Yumi Shimazaki, Kimiyasu Takahashi, Hitoshi Kato, Koichiro Fukami and Shuichi Watanabe
Drones 2025, 9(4), 310; https://doi.org/10.3390/drones9040310 - 16 Apr 2025
Viewed by 1319
Abstract
Implementing a variable-rate application (VRA) of fertilization based on real-time crop growth status reduces costs and enhances work efficiency. However, the technical challenges associated with obtaining accurate growth-distribution maps and applying VRA, particularly with agricultural drones, remain underexplored. In this study, we specifically [...] Read more.
Implementing a variable-rate application (VRA) of fertilization based on real-time crop growth status reduces costs and enhances work efficiency. However, the technical challenges associated with obtaining accurate growth-distribution maps and applying VRA, particularly with agricultural drones, remain underexplored. In this study, we specifically focused on agricultural drone-based VRA fertilization for regulating wheat protein content. First, normalized difference vegetation index (NDVI) distribution maps were obtained using multispectral images captured using a small unmanned aerial vehicle. Subsequently, a prescription map based on the NDVI values was generated to facilitate the implementation of VRA for fertilization. Continuous monitoring of changes in related vegetation indices was conducted from post-topdressing to harvest. Experimental results indicated that selecting targeted experimental survey areas based on different growth conditions can result in accurate predictions of the final yield. However, it is sill ineffective for predicting protein content or protein yield. Additionally, VRA fertilization with less fertilizer in high-NDVI areas and more fertilizer in low-NDVI areas showed no significant difference in final protein content or protein yield compared to conventional uniform fertilization. These findings provide reference data for advancing precision agriculture by addressing field-scale variability for high-quality and uniform production while presenting further research challenges. Full article
(This article belongs to the Special Issue Advances of UAV in Precision Agriculture—2nd Edition)
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25 pages, 1980 KiB  
Review
UAV-Based Soil Water Erosion Monitoring: Current Status and Trends
by Beatriz Macêdo Medeiros, Bernardo Cândido, Paul Andres Jimenez Jimenez, Junior Cesar Avanzi and Marx Leandro Naves Silva
Drones 2025, 9(4), 305; https://doi.org/10.3390/drones9040305 - 14 Apr 2025
Viewed by 1904
Abstract
Soil erosion affects land productivity, water quality, and ecosystem resilience. Traditional monitoring methods are often time-consuming, labor-intensive, and resource-demanding, while unmanned aerial vehicles (UAVs) provide high-resolution, near-real-time data, improving accuracy. This study conducts a bibliometric analysis of UAV-based soil erosion research to explore [...] Read more.
Soil erosion affects land productivity, water quality, and ecosystem resilience. Traditional monitoring methods are often time-consuming, labor-intensive, and resource-demanding, while unmanned aerial vehicles (UAVs) provide high-resolution, near-real-time data, improving accuracy. This study conducts a bibliometric analysis of UAV-based soil erosion research to explore trends, technologies, and challenges. A systematic review of Web of Science and Scopus articles identified 473 relevant studies after filtering for terms that refer to types of soil erosion. Analysis using R’s bibliometrix package shows research is concentrated in Asia, Europe, and the Americas, with 304 publications following a surge. Multi-rotor UAVs with RGB sensors are the most common. Gully erosion is the most studied form of the issue, followed by landslides, rills, and interrill and piping erosion. Significant gaps remain in rill and interrill erosion research. The integration of UAVs with satellite data, laser surveys, and soil properties is limited but crucial. While challenges such as data accuracy and integration persist, UAVs offer cost-effective, near-real-time monitoring capabilities, enabling rapid responses to erosion changes. Future work should focus on multi-source data fusion to enhance conservation strategies. Full article
(This article belongs to the Special Issue Advances of UAV in Precision Agriculture—2nd Edition)
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21 pages, 11935 KiB  
Article
Tree Species Classification Using UAV-Based RGB Images and Spectral Information on the Loess Plateau, China
by Zhen Li, Shichuan Yu, Quanping Ye, Mei Zhang, Daihao Yin and Zhong Zhao
Drones 2025, 9(4), 296; https://doi.org/10.3390/drones9040296 - 10 Apr 2025
Cited by 1 | Viewed by 809
Abstract
Accurate and efficient tree species classification and mapping is crucial for forest management and conservation, especially on the Loess Plateau, where forest quality urgently needs improvement. This study selected three research sites—Yongshou (YS), Zhengning (ZN), and Yanchang (YC)—on the Loess Plateau and classified [...] Read more.
Accurate and efficient tree species classification and mapping is crucial for forest management and conservation, especially on the Loess Plateau, where forest quality urgently needs improvement. This study selected three research sites—Yongshou (YS), Zhengning (ZN), and Yanchang (YC)—on the Loess Plateau and classified the main forest tree species using RGB images acquired by an unmanned aerial vehicle (UAV). The RGB images were normalized, and vegetation indices (VIs) were extracted. Feature selection was performed using the Boruta algorithm. Two classifiers, Support Vector Machine (SVM) and Random Forest (RF), were used to evaluate the contribution of different input features to classification and their performance differences across regions. The results showed that YC achieved the best classification performance with an overall accuracy (OA) of over 83% and a Kappa value of at least 0.78. The results showed that YC achieved the best classification performance (OA > 83%, Kappa ≥ 0.78), followed by ZN and YS. The addition of VIs significantly improved classification accuracy, particularly in the YS region with imbalanced sample distribution. The OA increased by more than 13.27%, and the Kappa improved by more than 0.17. Feature selection retained most of the advantages of the complete feature set, achieving slightly lower accuracy. Both RF and SVM are effective for tree species classification based on RGB images, with comparable performance (OA difference ≤ 1.5%, Kappa difference < 0.02). This study demonstrates the feasibility of UAV-based RGB images in tree species classification on the Loess Plateau and the great potential of RGBVIs in tree species classification, especially in areas with imbalanced class distributions. It provides a viable approach and methodology for tree species classification based on RGB images. Full article
(This article belongs to the Section Drones in Agriculture and Forestry)
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