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Interpretive Summaries:
2002 - Evaluation of Site-Specific Precision Farming Systems for Soybeans
2001 - Evaluation of site-specific precision farming systems for soybeans
2000 - Evaluation of site-specific precision farming systems for soybeans
1999 - Evaluation of site-specific precision farming systems for soybeans
1998 - Evaluation of site-specific precision farming systems for soybeans
1997 - Evaluation of site-specific precision farming systems for soybeans
Evaluation of Site-Specific Precision Farming Systems for Soybeans, 2002
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This project is a continuation of a project started in the Midwest in 1995-1996 to evaluate the agronomic, economic, and environmental implications of implementing site-specific precision farming technology in soybean management systems.
One component of this study investigated the possibility of using isotopic carbon (13C) discrimination in plant tissue as an index of water stress in soybeans. Studies were conducted in five eastern South Dakota fields. Measurements included crop reflectance, gravimetric soil water content, yield, and total above-ground plant nitrogen (N) concentration. In four fields, yields were between 20 and 50% less in summit/shoulder areas than footslope areas. Based on soil water and 13C discrimination measurements, reduced yields in summit and shoulder areas were attributed to water stress. Results from this experiment suggest that remote sensing combined with 13C discrimination can be used to assess the impact of water stress in corn and soybean fields.
Another component of this study was to determine the influence of landscape position on weed seed germination. Landscape position and the associated soil properties at different landscape positions influenced weed seed germination and plant establishment in 2002. In cold (46ºF) backslope areas, no weeds were present on April 16 compared with 17 and 15 weeds/ft2 (primarily common lambsquarters and green foxtail) in warm (54°F) summit and toeslope positions, respectively. Weed numbers in the cold toeslope, summit, and warm toeslope positions were about 17, 50, and 103 plants/ft2, respectively, on May 1. In a second study, green foxtail emerged earlier and at higher densities in the summit than the toeslope position. Landscape position and soil temperature (most likely a function of soil water content) did influence weed distribution very early in the season. Findings from this study suggest that the efficiency of pre-emergence or early post-emergence herbicides can be improved by considering the effect of landscape position on germination. SD-08F |
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