Andy Nelson

• PhD in Geography
• Professor (Full) at University of Twente

Many modern rice varieties (MVs) have been released but only a few have been widely adopted by farmers. To understand farmers' preferences, we characterized MVs released in the Philippines from 1966 to 2013 and identified important characteristics of the varieties that were widely adopted in Central Luzon using farm surveys conducted in 1966–2012....

70% of the world’s freshwater is used for irrigated agriculture and demand is expected to increase to meet future food security requirements. In Asia, rice accounts for the largest proportion of irrigated water use and reducing or conserving water in rice systems has been a long standing goal in agricultural research. The Alternate Wetting and Dryi...

Good access to resources and opportunities is essential for sustainable development. Improving access, especially in rural areas, requires useful measures of current access to the locations where these resources and opportunities are found. Recent work has developed a global map of travel times to cities with more than 50,000 people in the year 201...

Significance Physical access to services and employment opportunities shapes the lives of people everywhere. For 3.4 billion people living in rural locations, the size of nearby urban centers and the associated travel time affect the breadth of services and opportunities available and their accessibility. We identify catchment areas of urban center...

This study aims to help bring the domestic food transport network into focus for The State of Food and Agriculture 2021 – Making agrifood systems more resilient to shocks and stresses. Transport infrastructure and logistics, not least domestic food transport networks, are an integral part of agrifood systems, and play a fundamental role in ensuring...

The Budyko framework estimates macroscale evapotranspiration (ET) through hydrological partitioning, which determines what proportion of precipitation becomes ET or passes overland as runoff. This method has been widely used for modelling catchment ET and calibrating satellite-based ET algorithms at multi-annual timesteps, as it effectively account...

Accurately mapping crop types in smallholder farming regions is crucial for monitoring crop dynamics and estimating production but remains challenging, especially over large extents. Remote sensing based crop mapping studies in smallholder farming regions often focus on major crops and the challenge of mapping small fields. However, minor but possi...

Fall Armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), poses a significant risk to global food and income security by attacking various crops, particularly maize. Early detection and management of FAW infestation are crucial for mitigating its impact on crop yields. This study investigated the effect of FAW infestation on...

The Global Plant Health Assessment (GPHA) is a collective, volunteer-based effort to assemble expert opinions on plant health and disease impacts on ecosystem services based on published scientific evidence. The GPHA considers a range of forest, agricultural, and urban systems worldwide. These are referred to as (Ecoregion × Plant System), i.e., se...

The increasing frequency and intensity of extreme heat events necessitate reliable global estimates of crop productivity under heat stress. Light use efficiency (LUE) models are commonly used for macroscale crop productivity estimation but exhibit uncertainties under high-temperature extremes related to the representation of model components and th...

Humans shape landscapes to optimize food, fibre, and fuel production. These modifications often fragment ecosystems and degrade ecological functions over time, particularly regulating and cultural ecosystem services (ES). Understanding how ecosystem fragmentation influences the temporal dynamics of ES is critical for biodiversity conservation and s...

Small reservoirs are increasingly common across Africa. They provide decentralised access to water and support farmer-led irrigation, in addition to contributing towards mitigating the impacts of climate change. Water quality monitoring is essential to ensure the safe use of water and to understand the impact of the environment and landuse on water...

Ratooning, the cropping practice of harvesting a second crop from the stubbles of the primary harvest, is gaining renewed popularity as a resource-efficient alternative to increase rice production. Although current remote sensing-based rice monitoring systems have considered rice ratooning systems, nothing is known about the temporal backscatter re...

The water–energy–food (WEF) nexus is an integrated conceptual tool for achieving sustainable development especially for countries facing limitations in one or more of its three pillars. The approach relies on bringing different stakeholders from the water, food and energy sectors together to collaboratively plan and adopt a holistic approach to res...

Soybean is an important crop for food and animal feed. Production and area both continue to increase and expand into new areas and countries. Spatially explicit information on soybean cultivation is essential to crop monitoring, production estimation, and national accounting systems. However, its cultivation in diverse climate conditions, landscape...

Cropping patterns, including intercropping, are recognized as sustainable agricultural practices in many parts of Africa. However, there is a lack of data and information regarding their extent and specific locations. This study aims to understand the dynamics of these cropping patterns using hyperspectral satellite data. We examined the spectral r...

To design more efficient and equitable agricultural technologies and policies, we need to understand why individuals do not act in line with the expectations of researchers and policy makers, and we need to understand how and why interventions exacerbate existing inequalities. Both can be understood by exploring how aspirations influence households...

Urban centers are pivotal in shaping societies, yet a systematic global analysis of how countries are organized around multiple urban centers is lacking. We enhance understanding by delineating city–regions worldwide, classifying over 30,000 urban centers into four tiers—town, small, intermediate and large city—based on population size and mapping...

Crop growth simulation models are often used to estimate crop yield. For most models, this requires crop, water, and soil management information, though this information is often lacking in many regions of the world. Assimilation of Earth observation (EO) data in crop growth models can generate field-level yield estimates over large areas. The use...

Stress caused by high temperatures is a critical limiting factor of crop growth and development. Although remote sensing has been used to investigate the impacts of high temperatures on crops, its ability to detect heat stress independently of other stressors and assess its effects on gross primary production (GPP) estimation is unclear. This study...

Human activities have rapidly altered natural ecosystems worldwide, resulting in fragmented ecosystems that are either culturally or formally protected. These ecosystem patches can be critical for ecosystem services (ES) that support human well-being. In the Ethiopian highlands, the remaining church forests and wetlands have a unique conservation s...

Cereals are an important source of energy, carbohydrates, proteins, fiber, and a myriad variety of micronutrients and make up a substantial part of the diet in both developed and developing nations. Specifically, as wheat contributes 5% of the daily calories and protein, it plays a significant part in ensuring the food security of the global popula...

Intercropping-the planting of more than one crop in the same plot of land-is a prevalent agricultural management practice which can be used for risk reduction. Despite its widespread use, intercropping is not commonly reported in agricultural statistics, resulting to very limited spatially disaggregated information about its prevalence. Remote sens...

Many wetlands in East Africa are farmed and wetland reservoirs are used for irrigation, livestock, and fishing. Water quality and agriculture have a mutual influence on each other. Turbidity is a principal indicator of water quality and can be used for otherwise unmonitored water sources. Low-cost turbidity sensors improve in-situ coverage and enab...

Physical and economic access to food vary spatially. Methods to map that variability at high levels of spatial detail over large areas are scarce, even though suitable datasets and methods exist. Using open-access data for Ethiopia, we developed a method to map the disparities in physical and economic food access at 1-km resolution. We selected 25...

This is an OpenAccess publication. Available online: https://doi.org/10.1016/j.ecoser.2023.101565 Large-scale ecological restorations are recognized worldwide as an effective strategy to combat environmental degradation and promote sustainability. Remote sensing (RS) imagery, such as obtained from Landsat and Sentinel-2 satellites, can provide spa...

Genetic engineers are attempting to meet increased global food demand by rewiring the pathway crops take to convert sunlight and carbon dioxide (CO 2 ) into yield. Most crops use the C 3 pathway. C 4 photosynthesis uses a biological pump that concentrates CO 2 , which makes it less resource demanding than C 3 photosynthesis. C 4 photosynthesis howe...

Evapotranspiration (ET) calculated as the residual of catchment water balance (ETWB) has often been used as a benchmark to evaluate satellite-based ET retrievals that use the energy-balance approach (ETEB). However, errors from water balance components will accrue in ETWB, leading to considerable disparities with ETEB. In this study, we set out to...

Mapping arable field areas is crucial for assessing agricultural productivity but poses challenges in sub-Saharan agroecosystems because of diverse crop calendars, small and irregularly shaped fields, persistent cloud cover, and lack of high-quality model training data. This study proposes several methodological improvements to overcome these chall...

To avoid wetland degradation and promote sustainable wetlands use, decision-makers and managing institutions need quantified and spatially explicit information on wetland ecosystem condition for policy development and wetland management. Remote sensing holds a significant potential for wetland mapping, inventorying, and monitoring. The Wetland Use...

Agricultural field polygons within smallholder farming systems are essential to facilitate the collection of geo-spatial data useful for farmers, managers, and policymakers. However, the limited availability of training labels poses a challenge in developing supervised methods to accurately delineate field boundaries using Earth Observation (EO) da...

Crop yield estimates are an important data output of agricultural monitoring systems. In sub-Saharan Africa, large input requirements of crop growth models, fragmented agricultural systems and small field sizes are substantial challenges to accurately estimate crop yield. Multi-sensor data fusion can be a valuable source of high spatial and tempora...

To effectively address food security, we need tools that assess governance measures (for example, strategic storage reserves, cash transfers or trade regulations) ex ante. Simulation models can estimate the impact of such measures via scenarios with differently governed food systems. On the basis of a systematic review of 110 simulation studies pub...

Extreme events, such as those caused by climate change, economic or geopolitical shocks, and pest or disease epidemics, threaten global food security. The complexity of causation, as well as the myriad ways that an event, or a sequence of events, creates cascading and systemic impacts, poses significant challenges to food systems research and polic...

Cropping patterns are defined as the sequence and spatial arrangement of annual crops on a piece of land. Knowledge of cropping patterns is crucial for crop production and land-use intensity. While cropping patterns are related to crop production and land use intensity, they are rarely reported in agricultural statistics, especially those relating...

Satellite image data deliver consistent and frequent information for crop yield estimation over large areas. Hyperspectral narrowbands are more sensitive spectrally to changes in crop growth than multispectral broadbands but few studies quantified the gains in the former over the later. The PRecursore IperSpettrale della Missione Applicativa (PRISM...

Remnant natural forests act as a source of wild pollinators that are potentially relevant for crop pollination for sustaining the food production system of smallholder farms. In the Ethiopian highlands, sacred forests scattered within agricultural landscapes harbour wild pollinators. The contribution of wild pollinators to crop pollination services...

Earth observation image data are regularly used to capture surface conditions over large areas, but there is a trade-off between high (or low) spatial and low (or high) temporal resolution. The Enhanced Spatial and Temporal Adaptive Reflectance Fusion Model (ESTARFM) overcomes this trade-off by fusing high spatial and temporal resolution multisourc...

In this research, the performance of satellite rainfall estimates (SREs) for crop growth simulation was investigated. Rainfall products selected were CHIRPS 2.0, CMORPH 1.0, MSWEP 2.2, and RFE 2.0. In-situ rainfall from 20 stations within the Lake Victoria basin in Kenya served as reference. Rainfall products were evaluated for onset days, rainfall...

Wetlands are abundant across the African continent and provide a range of ecosystem services on different scales but are threatened by overuse and degradation. It is essential that national governments enable and ensure the sustainable use of wetland resources to maintain these services in the long run. As informed management decisions require reli...

Emphasising connectedness among the many elements of plant‐based systems which are collectively addressed in One Health is a logical outcome of debates generated by the International Year of Plant Health. The notion of One‐Health was implemented through the joint use of the concepts of production situation (PS) ‐‐ the "rice way of life" ‐‐ and inju...

Information on when and where rice is planted and harvested is important for crop management under a changing climate and for monitoring crop production for early warning and market information systems. The diversity of plant genetic, crop management, and environmental conditions leads to a wide variation in the number of rice crops per year and th...

Evapotranspiration (ET) accounts for water movements from land to air and plays a vital role in the terrestrial water, energy, and carbon cycles. Reliable estimates of ET for agricultural landscapes can facilitate water resources management and food security analysis. The widely used Priestley-Taylor Jet Propulsion Laboratory (PT-JPL) model has the...

Reversing ecological degradation through restoration activities is a key societal challenge of the upcoming decade. However, lack of evidence on the effectiveness of restoration interventions leads to inconsistent, delayed, or poorly informed statements of success, hindering the wise allocation of resources, representing a missed opportunity to lea...

Crop lodging reduces yield quantity and grain quality of cereal crops. Understanding seasonal variation in crop lodging susceptibility enables lodging risk assessments and predictions of associated crop yield losses. We demonstrate a novel remote sensing-based approach, using sparse field observations and widely available synthetic aperture radar (...

Resilience thinking is increasingly promoted to address some of the grand challenges of the 21st century: providing water, energy, and food to all, while staying within the limits of the Earth system that is undergoing (climate) change. Concurrently, a partially overlapping body of literature on the water–energy–food (WEF) nexus has emerged through...

This study examines the relationship between yields of modern rice varieties and warming temperatures. Data from a long‐running farm‐level survey in the Philippines, with rich information on planted rice varieties, allow us to estimate fixed effect econometric models of rice yields. We find that increases in temperature, especially minimum temperat...

In this manuscript, we present a remote sensing-based method to evaluate the impact of ecological restoration interventions on the supply of ecosystem services covering a period of over 30 year at a spatial resolution of 30 x 30 m. We integrated the Before-After-Control-Impact (BACI) design with Landsat images, and applied this to an arid rural lan...

Access to healthcare is a requirement for human well-being that is constrained, in part, by the allocation of healthcare resources relative to the geographically dispersed human population1–3. Quantifying access to care globally is challenging due to the absence of a comprehensive database of healthcare facilities. We harness major data collection...

Crop lodging – the bending of crop stems from the vertical – is a major yield-reducing factor in cereal crops and causes deterioration in grain quality. Accurate assessment of crop lodging is important for improving estimates of crop yield losses, informing insurance loss adjusters and influencing management decisions for subsequent seasons. The ro...

Crop lodging assessment is essential for evaluating yield damage and informing crop management decisions for sustainable agricultural production. While a few studies have demonstrated the potential of optical and SAR data for crop lodging assessment, large-scale crop lodging assessment has been hampered by the unavailability of dense satellite time...

Crop lodging - the bending of crop stems from their upright position or the failure of root-soil anchorage systems - is a major yield-reducing factor in wheat and causes deterioration of grain quality. The severity of lodging can be measured by a lodging score (LS)- an index calculated from the crop angle of inclination (CAI) and crop lodged area (...

Planting a cover crop between the main cropping seasons is an agricultural management measure with multiple potential benefits for sustainable food production. In the maize production system of the Netherlands, an effective establishment of a winter cover crop is important for reducing nitrogen leaching to groundwater. Cover crop establishment afte...

Landscape processes fluctuate over time, influencing the intra-annual dynamics of ecosystem services. However, current ecosystem service assessments generally do not account for such changes. This study argues that information on the dynamics of ecosystem services is essential for understanding and monitoring the impact of land management. We studi...

OPEN ACCESS PUBLICATION. USE LINK ABOVE. Considerable efforts and resources are being invested in integrated conservation and restoration interventions in rural arid areas. Empirical research for quantifying ecosystem services – nature’s benefits to people – is essential for evaluating the range of benefits of ecological restoration and to support...

Remote sensing data are used to map the extent of croplands. They are especially useful in sub-Saharan Africa (SSA) where landscapes are complex and farms are small, i.e. less than two ha. In this study, a hierarchical remote sensing approach was developed to estimate field fractions at 30 m spatial resolution in a highly fragmented agricultural re...

Crop lodging Crop angle of inclination SAR Sentinel-1 RADARSAT-2 Support vector regression A B S T R A C T Lodging-the bending of crop stems-reduces the quantity and quality of cereal crop yields. Early quantification of crop lodging is important to prevent further losses and to facilitate harvesting operations. Crop angle of inclination (CAI) is a...

Mapping the extent and location of field boundaries is critical to food security analysis but remains problematic in the Global South where such information is needed the most. The difficulty is due primarily to fragmentation in the landscape, small farm sizes, and irregular farm boundaries. Very high-resolution satellite imagery affords an opportu...

To satisfy a growing demand for food, global agricultural production must increase by 70% by 2050. However, pests and crop diseases put global food supplies at risk. Worldwide, yield losses caused by pests and diseases are estimated to average 21.5% in wheat, 30.0% in rice, 22.6% in maize, 17.2% in potato, and 21.4% in soybean (1); these crops acco...

The objective of this study is to provide complete information on the dynamic relationship between X-band (3.11 cm) backscattering intensity (σ°) and rice crop’s leaf area index (LAI) at all growth phases. Though the relationship between X-band σ° and LAI has been previously explored, details on the relationship at the reproductive phase remain uns...

Lodging is one of the yield-reducing factors in wheat, causing losses of up to 80%. Lodging also has several knock-on effects such as deterioration in grain quality, slower harvest and increased drying costs. The severe effects of lodging can be minimised by detecting its incidence in time so that decisions related to expected crop yield, crop pric...

Lodging is a major yield-reducing factors in wheat, causing reductions up to 80%. Timely detection of lodging can reduce its impacts and support proper decisions regarding expected yield, crop price or its insurance. Since the incidence of lodging is heterogeneous within a field, very high-resolution remote sensing data can be viable for accurate a...

Sub-Saharan African (SSA) wetlands are increasingly brought into focus as a possibility to increase food security. Accordingly, agricultural development in Rwanda’s extensive wetland landscapes is strongly promoted. However, agricultural use is a major reason for wetland degradation and often in conflict with conservation efforts. Detailed and up-t...

Rapid and quantitative assessment of crop lodging is important for understanding the causes of the phenomena, improving crop management, making better production and supporting loss estimates in general. Accurate information on the location and timing of crop lodging is valuable for farmers, agronomists, insurance loss adjusters, and policymakers....

Crop pathogens and pests reduce the yield and quality of agricultural production. They cause substantial economic losses and reduce food security at household, national and global levels. Quantitative, standardized information on crop losses is difficult to compile and compare across crops, agroecosystems and regions. Here, we report on an expert-b...

Improved rice crop and water management practices that make the sustainable use of resources more efficient are important interventions towards a more food secure future. A remote sensing-based detection of different rice crop management practices, such as crop establishment method (transplanting or direct seeding), can provide timely and cost-effe...

Global food security is negatively affected by drought. Climate projections show that drought frequency and intensity may increase in different parts of the globe. Early season forecasts on drought occurrence and severity could help to better mitigate the negative consequences of drought. The objective of this study was to assess if interannual var...

Rice is a staple food crop of India and is grown on 44 Mha (2011–12), 58.6% of which are irrigated. An inevitable phenomenon which looms over all aspects of human life and affects rice production in India is drought. Assessing drought damage using geospatial datasets available in the public domain, such as the Normalized Difference Vegetation Index...

Global food security is negatively affected by drought. Climate projections show that drought frequency and intensity may increase in different parts of the globe. These increases are particularly hazardous for developing countries. Early season forecasts on drought occurrence and severity could help to better mitigate the negative consequences of...

Soil salinity is one of the abiotic stresses that constrains rice crop growth in the extensive coastal regions of India. Monitoring soil condition on such a large scale is time-consuming and expensive and alternative approaches have been proposed. Crop condition can be used as a reference to detect salinity-affected soils in rice crops instead of d...

This article addresses the modelling of crop health and its impact on crop losses, with a special emphasis on plant diseases. Plant disease epidemiological models have many different shapes. We propose a summary of modelling structures for plant disease epidemics, which stem from the concepts of infection rate, of site, of basic infection rate corr...