Machine Learning-Based Sugarcane Yield Prediction Using Multispectral Time-Series Imagery

Accurate sugarcane yield prediction is important for the sugar industry in serving the demands for decision-making systems such as harvest timing, product handling, and forward sales. Accurate yield modelling offers sugarcane farmers with a deeper knowledge of spatial and temporal crop variability, enhancing the quality and quantity of sugarcane yields while minimizing production costs and alleviating adverse environmental consequences. High-performance Machine Learning (ML) algorithms were applied to Remote Sensing (RS) images so that the timely acquired data with both spatial and temporal resolutions could be processed efficiently to interpret the complexity and variability of sugarcane yield. In this context, we tested advanced ML algorithms on diverse RS datasets such as Unmanned Aerial Vehicle (UAV), Sentinel-2, and Landsat-8 images, validated the results using ground measurements such as wet and dry biomasses, and crop yields; and developed a model that predicts sugarcane crop yield at the earliest possible growth stage with the least amount of spectral data. To demonstrate the scalability of the proposed yield prediction model, its performance was assessed in two regions: an experimental site in Queensland, Australia, and some sugarcane fields in Khuzestan Province, Iran. The predictive model was expanded using freely accessible Sentinel-2 satellite data so that it could be applied to a variety of sugarcane yield studies in various crop systems. For example, the expanded prediction model is particularly useful if ground data collection is limited, or UAV data is not feasible due to surveying costs. This research is anticipated to benefit agricultural producers and farmers in their decision-making and agricultural operation planning and help establish their management practises for optimal productivity

Intra-field Canopy Nitrogen Retrieval from Unmanned Aerial Vehicle Imagery for Wheat and Corn Crops in Ontario, Canada

The optimization of crop nitrogen fertilization to accurately predict and match the nitrogen (N) supply to the crop N demand is the subject of intense research due to the environmental and economic impact of N fertilization. Excess N could seep into the water supplies around the field and cause unnecessary spending by farmers. Understanding the detailed spatial information about a crop status is known as a farming management technique called precision agriculture, which allows farmers to maximize their yield and profit while reducing the inputs of fertilizers, pesticides, water, and insecticides. The goal of this study is to document and test the applicability and feasibility of using Unmanned Aerial Vehicle (UAV) to predict nitrogen weight of wheat and corn fields in south-west Ontario. This is investigated using various statistical modelling techniques to achieve the best accuracy. Machine learning techniques such as Random Forests and Support Vector Regression are used, which provide more robust models than traditional linear regression models. The results demonstrate that most spectral indices have a non-linear relationship with canopy nitrogen weight and show high degree of multicollinearity among the variables. In this thesis, the final nitrogen prediction maps of wheat and corn fields using UAV images and the derived models are provided

Анализ данных разновременной мультиспектральной аэрофотосъемки для обнаружения границ исторического антропогенного воздействия

The article presents the application of a statistical analysis algorithm for multi-temporal multispectral aerial photography data to identify areas of historical anthropogenic impact on the natural environment. The investigated site is located on the outskirts of the urban-type village of Znamenka (Znamensky District, Tambov Region) in a forest-steppe zone with typical chernozem soils, where arable lands were located in the second half of the 19th - early 20th centuries. Grown vegetation as a result of secondary succession in abandoned areas can be a sign for identifying traces of historical anthropogenic impact. Distinctive signs of such vegetation from the surrounding natural environment are its type, age and growth density. Thus, the problem of detecting the boundaries of anthropogenic impact on multispectral images is reduced to the problem of vegetation classification. The initial data were the results of multi-temporal multispectral imaging in green (Green), red (Red), edge of red (RedEdge) and near-infrared (NIR) spectral ranges. The first stage of the algorithm is the calculation of the Haralick texture features on multispectral images, the second stage – reduction in the number of features by the principal component analysis, the third stage – the segmentation of images based on the obtained features by the k-means method. The effectiveness of the proposed algorithm is shown by comparing the segmentation results with the reference data of historical cartographic materials. The study of multi-temporal multispectral images makes it possible to more fully characterize and take into account the dynamics of phytomass growth in different periods of the growing season. Therefore, the obtained segmentation result reflects not only the configuration of areas of an anthropogenic transformed natural environment, but also the features of overgrowth of abandoned arable land.В работе представлено применение алгоритма статистического анализа данных разновременной мультиспектральной аэрофотосъемки с целью выявления участков исторического антропогенного воздействия на природную среду. Исследуемый участок расположен на окраине поселка городского типа Знаменка (Знаменский район Тамбовской области) в лесостепной зоне с типичными черноземными почвами, где во второй половине XIX – начале XX вв. были расположены пашни. Признаком для выявления следов исторического антропогенного воздействия может быть растительность, возникшая в результате вторичной сукцессии на заброшенных участках. Отличительной особенностью такой растительности от окружающей природной среды является ее тип, возраст и плотность произрастания. Таким образом, задача обнаружения границ антропогенного воздействия по мультиспектральным изображениям сводится к задаче классификации растительности. Исходными данными являлись результаты разновременной мультиспектральной съемки в зеленом (Green), красном (Red), краевом красном (RedEdge) и ближнем инфракрасном (NIR) спектральных диапазонах. На первом этапе алгоритма предполагается вычисление текстурных признаков Харалика по данным мультиспектральной съемки, на втором этапе – уменьшение количества признаков методом главных компонент, на третьем – сегментация изображений на основе полученных признаков методом k-means. Эффективность предложенного алгоритма показана при сопоставлении результатов сегментации с эталонными данными исторических картографических материалов. Полученный результат сегментации отражает не только конфигурацию участков анотропогенно-преобразованной природной среды, но и особенности зарастания заброшенной пашни, поскольку исследование разновременных мультиспектральных снимков позволяет более полно охарактеризовать и учесть динамику наращивания фитомассы в разные периоды вегетации

Анализ данных разновременной мультиспектральной аэрофотосъемки для обнаружения границ исторического антропогенного воздействия

В работе представлено применение алгоритма статистического анализа данных разновременной мультиспектральной аэрофотосъемки с целью выявления участков исторического антропогенного воздействия на природную среду. Исследуемый участок расположен на окраине поселка городского типа Знаменка (Знаменский район Тамбовской области) в лесостепной зоне с типичными черноземными почвами, где во второй половине XIX – начале XX вв. были расположены пашни. Признаком для выявления следов исторического антропогенного воздействия может быть растительность, возникшая в результате вторичной сукцессии на заброшенных участках. Отличительной особенностью такой растительности от окружающей природной среды является ее тип, возраст и плотность произрастания. Таким образом, задача обнаружения границ антропогенного воздействия по мультиспектральным изображениям сводится к задаче классификации растительности. Исходными данными являлись результаты разновременной мультиспектральной съемки в зеленом (Green), красном (Red), краевом красном (RedEdge) и ближнем инфракрасном (NIR) спектральных диапазонах. На первом этапе алгоритма предполагается вычисление текстурных признаков Харалика по данным мультиспектральной съемки, на втором этапе – уменьшение количества признаков методом главных компонент, на третьем – сегментация изображений на основе полученных признаков методом k-means. Эффективность предложенного алгоритма показана при сопоставлении результатов сегментации с эталонными данными исторических картографических материалов. Полученный результат сегментации отражает не только конфигурацию участков анотропогенно-преобразованной природной среды, но и особенности зарастания заброшенной пашни, поскольку исследование разновременных мультиспектральных снимков позволяет более полно охарактеризовать и учесть динамику наращивания фитомассы в разные периоды вегетации

Evaluation of the Influence of Field Conditions on Aerial Multispectral Images and Vegetation Indices

Remote sensing is a method used for monitoring and measuring agricultural crop fields. Unmanned aerial vehicles (UAV) are used to effectively monitor crops via different camera technologies. Even though aerial imaging can be considered a rather straightforward process, more focus should be given to data quality and processing. This research focuses on evaluating the influences of field conditions on raw data quality and commonly used vegetation indices. The aerial images were taken with a custom-built UAV by using a multispectral camera at four different times of the day and during multiple times of the season. Measurements were carried out in the summer seasons of 2019 and 2020. The imaging data were processed with different software to calculate vegetation indices for 10 reference areas inside the fields. The results clearly show that NDVI (normalized difference vegetation index) was the least affected vegetation index by the field conditions. The coefficient of variation (CV) was determined to evaluate the variations in vegetation index values within a day. Vegetation index TVI (transformed vegetation index) and NDVI had coefficient of variation values under 5%, whereas with GNDVI (green normalized difference vegetation index), the value was under 10%. Overall, the vegetation indices that include near-infrared (NIR) bands are less affected by field condition changes

Evaluation of the Influence of Field Conditions on Aerial Multispectral Images and Vegetation Indices

Remote sensing is a method used for monitoring and measuring agricultural crop fields. Unmanned aerial vehicles (UAV) are used to effectively monitor crops via different camera technologies. Even though aerial imaging can be considered a rather straightforward process, more focus should be given to data quality and processing. This research focuses on evaluating the influences of field conditions on raw data quality and commonly used vegetation indices. The aerial images were taken with a custom-built UAV by using a multispectral camera at four different times of the day and during multiple times of the season. Measurements were carried out in the summer seasons of 2019 and 2020. The imaging data were processed with different software to calculate vegetation indices for 10 reference areas inside the fields. The results clearly show that NDVI (normalized difference vegetation index) was the least affected vegetation index by the field conditions. The coefficient of variation (CV) was determined to evaluate the variations in vegetation index values within a day. Vegetation index TVI (transformed vegetation index) and NDVI had coefficient of variation values under 5%, whereas with GNDVI (green normalized difference vegetation index), the value was under 10%. Overall, the vegetation indices that include near-infrared (NIR) bands are less affected by field condition changes

A Review of Vegetation Phenological Metrics Extraction Using Time-Series, Multispectral Satellite Data

Vegetation dynamics and phenology play an important role in inter-annual vegetation changes in terrestrial ecosystems and are key indicators of climate-vegetation interactions, land use/land cover changes, and variation in year-to-year vegetation productivity. Satellite remote sensing data have been widely used for vegetation phenology monitoring over large geographic domains using various types of observations and methods over the past several decades. The goal of this paper is to present a detailed review of existing methods for phenology detection and emerging new techniques based on the analysis of time-series, multispectral remote sensing imagery. This paper summarizes the objective and applications of detecting general vegetation phenology stages (e.g., green onset, time or peak greenness, and growing season length) often termed “land surface phenology,” as well as more advanced methods that estimate species-specific phenological stages (e.g., silking stage of maize). Common data-processing methods, such as data smoothing, applied to prepare the time-series remote sensing observations to be applied to phenological detection methods are presented. Specific land surface phenology detection methods as well as species-specific phenology detection methods based on multispectral satellite data are then discussed. The impact of different error sources in the data on remote-sensing based phenology detection are also discussed in detail, as well as ways to reduce these uncertainties and errors. Joint analysis of multiscale observations ranging from satellite to more recent ground-based sensors is helpful for us to understand satellite-based phenology detection mechanism and extent phenology detection to regional scale in the future. Finally, emerging opportunities to further advance remote sensing of phenology is presented that includes observations from Cubesats, near-surface observations such as PhenoCams, and image data fusion techniques to improve the spatial resolution of time-series image data sets needed for phenological characterization

Artificial Neural Networks in Agriculture

Modern agriculture needs to have high production efficiency combined with a high quality of obtained products. This applies to both crop and livestock production. To meet these requirements, advanced methods of data analysis are more and more frequently used, including those derived from artificial intelligence methods. Artificial neural networks (ANNs) are one of the most popular tools of this kind. They are widely used in solving various classification and prediction tasks, for some time also in the broadly defined field of agriculture. They can form part of precision farming and decision support systems. Artificial neural networks can replace the classical methods of modelling many issues, and are one of the main alternatives to classical mathematical models. The spectrum of applications of artificial neural networks is very wide. For a long time now, researchers from all over the world have been using these tools to support agricultural production, making it more efficient and providing the highest-quality products possible

Remote Sensing in Agriculture: State-of-the-Art

The Special Issue on “Remote Sensing in Agriculture: State-of-the-Art” gives an exhaustive overview of the ongoing remote sensing technology transfer into the agricultural sector. It consists of 10 high-quality papers focusing on a wide range of remote sensing models and techniques to forecast crop production and yield, to map agricultural landscape and to evaluate plant and soil biophysical features. Satellite, RPAS, and SAR data were involved. This preface describes shortly each contribution published in such Special Issue

UAV and field spectrometer based remote sensing for maize phenotyping, varietal discrimination and yield forecasting.

Doctoral Degree. University of KwaZulu-Natal, Pietermaritzburg.Maize is the major staple food crop in the majority of Sub-Saharan African (SSA) countries. However, production statistics (croplands and yields) are rarely measured, and where they are recorded, accuracy is poor because the statistics are updated through the farm survey method, which is error-prone and is time-consuming, and expensive. There is an urgent need to use affordable, accurate, timely, and readily accessible data collection and spatial analysis tools, including robust data extraction and processing techniques for precise yield forecasting for decision support and early warning systems. Meeting Africa’s rising food demand, which is driven by population growth and low productivity requires doubling the current production of major grain crops like maize by 2050. This requires innovative approaches and mechanisms that support accurate yield forecasting for early warning systems coupled with accelerated crop genetic improvement. Recent advances in remote sensing and geographical information system (GIS) have enabled detailed cropland mapping, spatial analysis of land suitability, crop type, and varietal discrimination, and ultimately grain yield forecasting in the developed world. However, although remote sensing and spatial analysis afforded us unprecedented opportunities for detailed data collection, their application in maize in Africa is still limited. In Africa, the challenge of crop yield forecasting using remote sensing is a daunting task because agriculture is highly fragmented, cropland is spatially heterogeneous, and cropping systems are highly diverse and mosaic. The dearth of data on the application of remote sensing and GIS in crop yield forecasting and land suitability analysis is not only worrying but catastrophic to food security monitoring and early warning systems in a continent burdened with chronic food shortages. Furthermore, accelerated crop genetic improvement to increase yield and achieve better adaptation to climate change is an issue of increasing urgency in order to satisfy the ever-increasing food demand. Recently, crop improvement programs are exploring the use of remotely sensed data that can be used cost-effectively for varietal evaluation and analysis in crop phenotyping, which currently remains a major bottleneck in crop genetic improvement. Yet studies on evaluation of maize varietal response to abiotic and biotic stresses found in the target production environments are limited. Therefore, the aim of this study was to model spatial land suitability for maize production using GIS and explore the potential use of field spectrometer and unmanned aerial vehicles (UAV) based remotely sensed data in maize varietal discrimination, high-throughput phenotyping, and yield prediction. Firstly, an overview of major remote-sensing platforms and their applicability to estimating maize grain yield in the African agricultural context, including research challenges was provided. Secondly, maize land suitability analysis using GIS and analytical hierarchical process (AHP) was performed in Zimbabwe. Finally, the utility of proximal and UAV-based remotely sensed data for maize phenotyping, varietal discrimination, and yield forecasting were explored. The results showed that the use of remote sensing data in estimating maize yield in the African agricultural systems is still limited and obtaining accurate and reliable maize yield estimates using remotely sensed data remains a challenge due to the highly fragmented and spatially heterogeneous nature of the cropping systems. Our results underscored the urgent need to use sensors with high spatial, temporal and spectral resolution, coupled with appropriate classification techniques and accurate ground truth data in estimating maize yield and its spatiotemporal dynamics in heterogeneous African agricultural landscapes for designing appropriate food security interventions. In addition, using modern spatial analysis tools is effective in assessing land suitability for targeting location-specific interventions and can serve as a decision support tool for policymakers and land-use planners regarding maize production and varietal placement. Discriminating maize varieties using remotely sensed data is crucial for crop monitoring, high throughput phenotyping, and yield forecasting. Using proximal sensing, our study showed that maize varietal discrimination is possible at certain phenological growth stages at the field level, which is crucial for yield forecasting and varietal phenotyping in crop improvement. In addition, the use of proximal remote sensing data with appropriate pre-processing algorithms such as auto scaling and generalized least squares weighting significantly improved the discrimination ability of partial least square discriminant analysis, and identify optimal spectral bands for maize varietal discrimination. Using proximal sensing was not only able to discriminate maize varieties but also identified the ideal phenological stage for varietal discrimination. Flowering and onset of senescence appeared to be the most ideal stages for accurate varietal discrimination using our data. In this study, we also demonstrated the potential use of UAV-based remotely sensed data in maize varietal phenotyping in crop improvement. Using multi-temporal UAV-derived multispectral data and Random Forest (RF) algorithm, our study identified not only the optimal bands and indices but also the ideal growth stage for accurate varietal phenotyping under maize streak virus (MSV) infection. The RF classifier selected green normalized difference vegetation index (GNDVI), green Chlorophyll Index (CIgreen), Red-edge Chlorophyll Index (CIred-edge), and the Red band as the most important variables for classification. The results demonstrated that spectral bands and vegetation indices measured at the vegetative stage are the most important for the classification of maize varietal response to MSV. Further analysis to predict MSV disease and grain yield using UAV-derived multispectral imaging data using multiple models showed that Red and NIR bands were frequently selected in most of the models that gave the highest prediction precision for grain yield. Combining the NIR band with Red band improved the explanatory power of the prediction models. This was also true with the selected indices. Thus, not all indices or bands measure the same aspect of biophysical parameters or crop productivity, and combining them increased the joint predictive power, consequently increased complementarity. Overall, the study has demonstrated the potential use of spatial analysis tools in land suitability analysis for maize production and the utility of remotely sensed data in maize varietal discrimination, phenotyping, and yield prediction. These results are useful for targeting location-specific interventions for varietal placement and integrating UAV-based high-throughput phenotyping systems in crop genetic improvement to address continental food security, especially as climate change accelerates