Leaf area index (LAI) is an important variable for climate modeling, estimates of primary production, agricultural yield forecasting, and many other diverse studies. Remote sensing provides a considerable potential for estimating LAI at local to regional and global scales. Several spectral vegetation indices have been proposed, but their capacity to estimate LAI is highly reduced… More

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Solar radiation and dew point temperature are important input variables for many crop growth ecological, hydrological, and meteorological models. It is also well known that solar radiation and dew point temperature (and relative humidity) data are not readily available for most locations over the globe. To use the above models, estimation of these input variables… More

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Net ecosystem CO2 exchange (NEE) was measured in maize-based agroecosystems in eastern Nebraska, USA, during the growing season in 2001. The objective of this study was to quantify and contrast NEE in irrigated and rainfed maize (Zea maize L.) fields. Daytime NEE showed a strong dependence on incident light at different stages of crop growth…. More

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A new maize (Zea mays L.) simulation model, Hybrid-Maize, was developed by combining the strengths of two modeling approaches: the growth and development functions in maize-specific models represented by CERES-Maize, and the mechanistic formulation of photosynthesis and respiration in generic crop models such as INTERCOM and WOFOST. It features temperature-driven maize phenological development, vertical canopy… More

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Yield maps reflect systematic and random sources of yield variation as well as numerous errors caused by the harvest and mapping procedures used. A general framework for processing of multi-year yield map data was developed. Steps included (1) raw data screening, (2) standardization, (3) interpolation, (4) classification of multi-year yield maps, (5) post-classification spatial filtering… More

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Monitoring crop phenology is required for understanding intra- and interannual variations of agroecosystems, as well as for improving yield prediction models. The objective of this paper is to remotely evaluate the phenological development of maize (Zea mays L.) in terms of both biomass accumulation and reproductive organ appearance. Maize phenology was monitored by means of… More

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Synoptic monitoring of vegetation dynamics relies on satellite observations of the distinctive spectral contrast between red and near infrared reflectance that photosynthetically active green vegetation exhibits. It has long been recognized that the Normalized Difference Vegetation Index (NDVI) suffers a rapid decrease of sensitivity at moderate-to-high densities of photosynthetic green biomass. This decrease can conceal… More

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Annual yield maps are spatially fragmented because of random variation caused by crop management as well as measurement errors. Two approaches for creating maps of spatially contiguous yield classes were evaluated at two irrigated sites. In the first approach, prior-classification interpolation (PCI), grid size was increased from 4, 8, 16, and 32 to 64 m… More

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