Takashi S. T. Tanaka

Aarhus University | AU · Department of Agroecology

The establishment of soybean [Glycine max (L.) Merr.] seedlings are largely affected by environmental conditions, including precipitation and soil properties; these factors often affect yield. Soil clods are the product of soil properties and weather conditions. In this current study, remote sensing imagery was used to assess seedling establishment...

In-season crop growth and yield prediction at high spatial resolution are essential for informing decision-making for precise crop management, logistics and market planning in horticultural crop production. This research aimed to establish a plant-level cabbage yield prediction system by assimilating the leaf area index (LAI) estimated from UAV ima...

Crop growth monitoring is essential for both crop and supply chain management. Conventional manual sampling is not feasible for assessing the spatial variability of crop growth within an entire field or across all fields. Meanwhile, UAV-based remote sensing enables the efficient and nondestructive investigation of crop growth. A variety of crop-spe...

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 invo...

The phenotyping of field crops quantifies a plant's structural and physiological characteristics to facilitate crop breeding. High-throughput unmanned aerial vehicle (UAV)-based remote sensing platforms have been extensively researched as replacements for more laborious and time-consuming manual field phenotyping. This review aims to elucidate the...

Accurate modeling of site-specific crop yield response is key to providing farmers with accurate site-specific economically optimal input rates (EOIRs) recommendations. Many studies have demonstrated that machine learning models can accurately predict yield. These models have also been used to analyze the effect of fertilizer application rates on y...

Crop yield prediction models are critical tools for evaluating growth performance and informing decisions during farm management. Developing yield prediction models that are robust not only in the ranges of the model spatial domain but also in additional locations using a data-driven approach is challenging. The main objective of this study was to...

Chestnut trees are economically significant in Europe and Asia and contribute to the ecosystem and landscape, making it crucial to monitor their on-tree chestnut fruits (burs). Accurate burs counting aids in estimating yield and fruit load, providing informed guidance to growers. Manual burs counting is labor-intensive, lacking efficiency. Machine...

Rice (Oryza sativa L.) is one of the most important cereals, which provides 20% of the world’s food energy. However, its productivity is poorly assessed especially in the global South. Here, we provide a first study to perform a deep-learning-based approach for instantaneously estimating rice yield using red-green-blue images. During ripening stage...

The assimilation of remotely-sensed data into crop simulation models is expected to improve the prediction of the spatial distribution of crop yield. This study aimed to predict plant-level cabbage yield using the assimilation of UAV-derived LAI into a crop simulation model, WOrld FOod STudies (WOFOST). For the data assimilation, the two-dimensiona...

To evaluate robustness and precision in site-specific crop yield response modelling, spatio-temporal effects on crop yield should be considered. This study aimed to generate more realistic and interpretable synthetic data for validating site-specific crop yield response modelling using a crop simulation model, WOFOST (WOrld FOod STudies) and gaussi...

On-farm experimentation (OFE) is increasing worldwide. Appropriate OFE procedures may differ depending on the characteristics and circumstances surrounding farms, such as climate, field conditions, farm size, degree of agricultural digitalization, and a farmer's socioeconomic background. This study aims to guide the future development of OFE in Jap...

Precise yield predictions are useful for implementing precision agriculture technologies and making better decisions in crop management. Convolutional neural networks (CNNs) have recently been used to predict crop yields in unmanned aerial vehicle (UAV)-based remote sensing studies, but weather data have not been considered in modeling. The aim of...

The on‐tree counting of chestnut fruit (bur) is essential for yield estimation and monitoring of fruit load as well as tree health, which is important in determining the management strategy for orchards, markets, and tree health monitoring. However, the practice is still conducted by manual count or farmers’ intuition. Precise and effective countin...

An inexpensive and precise crop yield prediction technology is required for facilitating precision agriculture for Asian countries in which small-scale fields are primarily managed. One of the most popular deep learning methods, convolutional neural networks (CNNs), yield better performances for classification problems than other general machine le...

Soil test is a key step toward providing recommendations for better crop management. Several soil samples have been traditionally assumed to be sufficient for soil tests to represent field-specific values in conventional Japanese small-scale paddy fields. However, rethinking soil sampling design is required, as many small-scale (<0.3 ha) paddy fiel...

Estimating site-specific crop yield response to changes to input (e.g., seed, fertilizer) management is a critical step in making economically optimal site-specific input management recommendations. Past studies have attempted to estimate yield response functions using various Machine Learning (ML) methods, including the Random Forest (RF), Boosted...

Along with land consolidation and the recent increase in the scale of farming in Japan, it is important to assess the relationships between soil properties, topography before land consolidation, and crop characteristics within fields through on-farm research. The objectives of this study were to evaluate the impacts of soil properties and presence/...

Crop productivity is poorly assessed globally. Here, we provide a deep learning-based approach for estimating rice yield using RGB images. During ripening stage and at harvest, over 22,000 digital images were captured vertically downwards over the rice canopy from a distance of 0.8 to 0.9 m, and rice yields were obtained in the corresponding area r...

On-farm experiments can provide farmers with information on more efficient crop management in their own fields. Developments in precision agricultural technologies, such as yield monitoring and variable-rate application technology, allow farmers to implement on-farm experiments. Research frameworks including the experimental design and the statisti...

Considering that studies handling machine learning approaches for data analysis of OFEs are increasing recently, our study may be helpful for enhancing the model inter-pretability of crop yield response to variable rate application of fertilizer and seed. We describe the risk of overfitting and enhanced model explainability by introducing spatial s...

On-farm experiments (OFEs) have been widely implemented by large-scale farmers. The aim of this study was to examine the benefits of an OFEs for intensive farming systems with small- to moderate-scale fields. Thus, three OFEs based on strip trials with different fertiliser application rates were conducted in Japanese rice and wheat fields (six fiel...

The plant density of soybean is a critical factor affecting plant canopy structure and yield. Predicting the spatial variability of plant density would be valuable for improving agronomic practices. The objective of this study was to develop a model for plant density measurement using several data sets with different spatial resolutions, including...

Global warming may increase the occurrence of heat-induced floret sterility (HIFS) in rice. The effects of meteorological factors and plant traits on the occurrence of floret sterility have only been examined independently and under controlled or simplified conditions. The aim of this study was to comprehensively clarify the role and impact of thes...

To reduce human drudgery and the risk of labor shortages in the Asian developing countries, the appropriate introduction of agricultural machinery, especially combine harvesters, is an urgent task. Custom hiring services (CHSs) are expected to contribute to making paddy harvesters prevalent in developing countries; however, the economic performance...

Precise use of fertilizers has been a focal point in world agriculture for years because it increases crop production and reduces the negative impact of over-fertilization. Smart fertilizer management using information/data, sensors, and smart tools allows correct fertilization in precision agriculture, smart agriculture, and integrated nutrient ma...

Prediction of crop yield and quality is an essential component of successful implementation of precision agriculture. Given the recent commercialization of low-cost multispectral cameras mounted on unmanned aerial vehicles and advances in machine learning techniques, prediction systems for crop characteristics can be more precisely developed using...

Mechanized agriculture plays a key role in the overall socio-economic development in terms of food security, value addition, employment, poverty alleviation and export earnings. Due to the migration of agricultural labor in non-farm sectors and increasing climate vulnerability, it is a great challenge to keep pace of food production for the exponen...

On-farm experiments can provide farmers with information on more efficient crop management in their own fields. Developments in precision agricultural technologies, such as yield monitoring and variable-rate application technology, allow farmers to implement on-farm experiments. Research frameworks including the experimental design and the statisti...

We examined the effect of panicle position relative to canopy and of panicle angle on pollination and floret sterility in rice at anthesis in a paddy field. We set panicles of pot-grown rice at the flowering stage either upright (0°) or inclined (30°), either above or at canopy height (Experiment 1) and either beneath or at canopy height (Experimen...

Soil organic matter (SOM) is one of the important parameters in agriculture management, thus estimating its distribution on the land will be essential. Remote sensing can be utilized to map the SOM distribution in the large-scale area. The objective of this research was to determine the estimation of SOM distribution on the paddy field in Sukoharjo...

Rice pollination occurs when pollen grains fall by gravity from the anther onto the stigma and has been thought to be assured under suitable conditions. However, the position of the stigma relative to the anther pores may affect pollination. The inclination of panicle, that is quite usual in agricultural scene, may change the relative position of a...

Wheat is often grown in upland fields converted from paddy fields in Japan. These recently consolidated large-scale paddy fields may show high spatial heterogeneity in soil properties. Thus, the spatial variability in soil properties and their impacts on wheat yield were evaluated using structural equation modelling and semivariogram. The results s...

Brown spot (BS) breakouts the third most common disease of Japanese rice crop. Normalized difference vegetation index (NDVI), which is calculated from spectral reflectance in red and near infrared band, is commonly used in remote sensing which has been put into practical use recently. It was suggested that the estimation of the amount of growth and...

Emergent aquatic macrophytes play an important role in the removal of nutrients in constructed wetlands (CWs). However, plant biomass supplies litter after the onset of senescence. Although litter-derived nitrogen (N) has been considered a nutrient source for the internal loading that may reduce CW performance, little is known about the quantitativ...

The anaerobic digestion of livestock manure is an environmentally compatible technology used for the production of renewable energy. Anaerobically digested residual slurry has been used worldwide as a liquid fertilizer in both upland and paddy fields. However, a controversial question remains as to whether the application of slurry to rice paddy fi...

Increase in production of whole crop rice silage is expected to improve the food self-sufficiency rate in Japan. Introduction of forage rice cultivation under late seeding conditions into the rice-wheat cropping systems is considered a means of cultivation management for high land use efficiency, high productivity, and reduction in cost and labor....

The species/lineage delimitation and possible hybridization/introgression are prerequisites in the management of invasive organism. Phragmites australis invaded diverse habitats and displaced the native lineages in North America as a consequence of the introduction from the Eurasia. Such species threatened the biodiversity safety of the invaded reg...

Phragmites is a cosmopolitan perennial emergent macrophyte that is distributed worldwide. In recent years, Phragmites has attracted attention for its potential use as roughage. Given the increasing demand for feed and the number of constructed wetlands (CWs) vegetated with Phragmites, Phragmites is expected to play an important role in roughage pro...

Large amounts of farmland have been converted from traditional cereal cropping to intensive vegetable cropping in China, creating environmental risks. Previous studies utilized several methods of estimating nitrate accumulation in soil and leaching to groundwater under intensive vegetable cultivation, such as comparing intensive cropping to non-int...

Overuse of chemical fertilizer and/or manure in agriculture is a principal factor in water eutrophication in China. Our previous study indicated that reducing chemical fertilizer input effectively decreased the soil nitrogen, phosphorus, and potassium in an intensive vegetable cropping system in the coastal area of southeast Lake Dianchi, China. Th...

In recent decades, constructed wetlands dominated by common reeds [Phragmites australis (CAV.) Trin. ex Steudel] have been utilized for treating nitrogen-rich wastewaters. Although plant harvest is a vegetation management in constructed wetlands for the purpose of improving nutrient removal, harvested biomass has become a problem in many places. Th...

Recently, constructed wetlands (CWs) dominated by common reed [Phragmites australis (CAV.) Trin. ex Steudel] have increased for treating wastewaters in China. The biomass waste became a serious issue of management of CWs. The purpose of this work was to identify a potential use of common reed as roughage for ruminants in southwest China. Potential...

To ensure higher yields, farmers in China have increased cropping intensity with a large input of chemical fertilizer and livestock manure since 1980s, which has led to unsustainable agricultural productivity and environmental quality. This study aimed to evaluate the effects of intensive cropping on nutrient absorption and biomass production of cr...

Plant harvest is one of the most important management practices in constructed wetlands. In this study, we evaluated the impact of harvesting Phragmites australis (Cav.) Trin. ex Steudel on the activity and community structure of nitrifiers and denitrifiers in a free-water surface constructed wetland. The nitrifiers were targeted using bacterial an...

The surface water samples were collected in river Dahe and its tributaries, which flow into severely eutrophic lake Dianchi, Yunnan Province, China, in order to elucidate factors controlling water quality fluctuations. The temporal and spatial distribution of water quality tendency was observed. The water quality of each river is dependent on the h...