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Full-Text Articles in Life Sciences
Evapotranspiration Information Reporting: I. Factors Governing Measurement Accuracy, Richard G. Allen, Luis S. Pereira, Terry A. Howell, Marvin E. Jensen
Evapotranspiration Information Reporting: I. Factors Governing Measurement Accuracy, Richard G. Allen, Luis S. Pereira, Terry A. Howell, Marvin E. Jensen
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
More and more evapotranspiration models, evapotranspiration crop coefficients and associated measurements of evapotranspiration (ET) are being reported in the literature and used to develop, calibrate and test important ET process models. ET data are derived from a range of measurement systems including lysimeters, eddy covariance, Bowen ratio, water balance (gravimetric, neutron meter, other soil water sensing), sap flow, scintillometry and even satellite-based remote sensing and direct modeling. All of these measurement techniques require substantial experimental care and are prone to substantial biases in reported results. Reporting of data containing measurement biases causes substantial confusion and impedance to the advancement of …
Improving In-Season Nitrogen Recommendations For Maize Using An Active Sensor, J. Schmidt, D. Beegle, Q. Q. Zhu, R. Sripada
Improving In-Season Nitrogen Recommendations For Maize Using An Active Sensor, J. Schmidt, D. Beegle, Q. Q. Zhu, R. Sripada
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
An active crop canopy reflectance sensor could be used to increase N-use efficiency in maize (Zea mays L.), if temporal and spatial variability in soil N availability and plant demand are adequately accounted for with an in-season N application. Our objective was to evaluate the success of using an active canopy sensor for developing maize N recommendations. This study was conducted in 21 farmers’ fields from 2007 to 2009, representing the maize production regions of east central and southeastern Pennsylvania, USA. Four blocks at each site included seven sidedress N rates (0–280 kgNha−1) and one at-planting N …
Geologic Constraints On Rain-Fed Qocha Reservoir Agricultural Infrastructure,Northern Lake Titicaca Basin, Peru, Nathan Craig, Mark Aldenderfer, Catherine Rigsby, Paul Baker, Luis A. Flores
Geologic Constraints On Rain-Fed Qocha Reservoir Agricultural Infrastructure,Northern Lake Titicaca Basin, Peru, Nathan Craig, Mark Aldenderfer, Catherine Rigsby, Paul Baker, Luis A. Flores
Luis FLORES
This paper reports new data on qocha ponds from the Rio PucaraeAzángaro interfluvial zone, northern Lake Titicaca Basin, Peru. Qocha are a little known form of Andean agriculture that developed around 800e500 B.C. and remain in use today. Prior estimates suggested that in the study area, there were more than 25,000 qocha. While most Andean sunken beds are excavated to reach groundwater, qocha are rainfed ponds. How these rain-fed ponds functioned has been an open question, but one that is answered in part by research presented in this paper. We suggest that a thick impermeable stratum of clay that was …