Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Environmental Sciences (4)
- Earth Sciences (3)
- Life Sciences (3)
- Agriculture (2)
- Natural Resources Management and Policy (2)
-
- Natural Resources and Conservation (2)
- Oceanography and Atmospheric Sciences and Meteorology (2)
- Other Environmental Sciences (2)
- Soil Science (2)
- Anthropology (1)
- Archaeological Anthropology (1)
- Atmospheric Sciences (1)
- Environmental Monitoring (1)
- Forest Sciences (1)
- Geochemistry (1)
- Meteorology (1)
- Other Earth Sciences (1)
- Plant Sciences (1)
- Social and Behavioral Sciences (1)
- Institution
- Publication
- Publication Type
Articles 1 - 5 of 5
Full-Text Articles in Physical Sciences and Mathematics
Identification Of Ancient Maya Agriculture In The Periphery Of Motul De San José, Alexandra E. Smofsky
Identification Of Ancient Maya Agriculture In The Periphery Of Motul De San José, Alexandra E. Smofsky
Electronic Thesis and Dissertation Repository
Agricultural systems were investigated in the Motul de San José periphery, an ancient Maya polity in Guatemala, using soil geochemical techniques. The δ13C values of soil organic matter delineated areas of ancient maize agriculture at the satellite center of Kante’t’u’ul. A new method to locate areas of former cacao cultivation or processing was developed using HPLC to detect theobromine, an alkaloid of the cacao plant, preserved in soils. Extraction of spiked soils revealed that theobromine adsorption is inversely correlated with organic matter content of soils. Detection of naturally occurring theobromine was successful, demonstrating its utility as a tracer. …
Modeling Gross Primary Production Of Maize And Soybean Croplands Using Light Quality, Temperature, Water Stress, And Phenology, Anthony L. Nguy-Robertson, Andrew E. Suyker, Xiangming Xiao
Modeling Gross Primary Production Of Maize And Soybean Croplands Using Light Quality, Temperature, Water Stress, And Phenology, Anthony L. Nguy-Robertson, Andrew E. Suyker, Xiangming Xiao
School of Natural Resources: Faculty Publications
Vegetation productivity metrics, such as gross primary production (GPP) may be determined from the efficiency with which light is converted into photosynthates, or light use efficiency (ϵ). Therefore, accurate measurements and modeling of ϵ is important for estimating GPP in each ecosystem. Previous studies have quantified the impacts of biophysical parameters on light use efficiency based GPP models. Here we enhance previous models utilizing four scalars for light quality (i.e., cloudiness), temperature, water stress, and phenology for data collected from both maize and soybean crops at three Nebraska AmeriFlux sites between 2001 and 2012 (maize: 26 field-years; soybean: …
Uncertainty In Simulating Gross Primary Production Of Cropland Ecosystem From Satellite-Based Models, Wenping Yuan, Wenwen Cai, Anthony L. Nguy-Robertson, Huajun Fang, Andrew E. Suyker, Yang Chen, Wenjie Dong, Shuguang Liu, Haicheng Zhang
Uncertainty In Simulating Gross Primary Production Of Cropland Ecosystem From Satellite-Based Models, Wenping Yuan, Wenwen Cai, Anthony L. Nguy-Robertson, Huajun Fang, Andrew E. Suyker, Yang Chen, Wenjie Dong, Shuguang Liu, Haicheng Zhang
School of Natural Resources: Faculty Publications
Accurate estimates of gross primary production (GPP) for croplands are needed to assess carbon cycle and crop yield. Satellite-based models have been developed to monitor spatial and temporal GPP patterns. However, there are still large uncertainties in estimating cropland GPP. This study compares three light use efficiency (LUE) models (MODIS-GPP, EC-LUE, and VPM) with eddy-covariance measurements at three adjacent AmeriFlux crop sites located near Mead, Nebraska, USA. These sites have different croprotation systems (continuous maize vs. maize and soybean rotated annually) and water management practices (irrigation vs. rainfed). The results reveal several major uncertainties in estimating GPP which need to …
Understanding Farmers’ Perceptions And The Effects Of Shea Tree Vitellaria Paradoxa Distribution In Agroforestry Parklands Of The Upper West Region, Ghana, Fahimeh Baziari
Dissertations, Master's Theses and Master's Reports - Open
Agroforestry parklands represent a vast majority of the agricultural landscape under subsistent-oriented farming in semi-arid West Africa. Parklands are characterized by the growth of well- maintained trees (e.g., shea) on cultivated fields as a result of both environmental and human influences. Shea (Vitellaria paradoxa) provides a cultural and economic benefit to the local people of Ghana, especially women. Periods between traditional fallow rotation systems have reduced recently due to agricultural development and a demand for higher production. As a result, shea trees, which regenerate during fallow periods, has decreased over the landscape. The aim of this study was …
Response Of Stomatal Density And Bound Gas Exchange In Leaves Of Maize To Soil Water Deficit, Wensai Zhao, Yonglin Sun, Roger Kjelgren, Xiping Liu
Response Of Stomatal Density And Bound Gas Exchange In Leaves Of Maize To Soil Water Deficit, Wensai Zhao, Yonglin Sun, Roger Kjelgren, Xiping Liu
Plants, Soils, and Climate Faculty Publications
Stomatal behavior in response to drought has been the focus of intensive research, but less attention has been paid to stomatal density. In this study, 5-week-old maize seedlings were exposed to different soil water contents. Stomatal density and size as well as leaf gas exchange were investigated after 2-, 4- and 6-weeks of treatment, which corresponded to the jointing, trumpeting, and filling stages of maize development. Results showed that new stomata were generated continually during leaf growth. Reduced soil water content significantly stimulated stomatal generation, resulting in a significant increase in stomatal density but a decrease in stomatal size and …