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Kanwar, RS

Alternative cropping systems can improve resource use efficiency, increase corn grain yield, and help in reducing negative impacts on the environment. A 6-yr (1993 to 1998) field study was conducted at the Iowa State University's Northeastern Research Center near Nashua, Iowa, to evaluate the effects of non-traditional cropping systems [strip inter cropping (STR)-corn (Zea mays L.)/soybean (Glycine max L.)/oats (Avena sativa L.)]; alfalfa rotation (ROT)-3-yr (1993 to 1995) alfalfa (Medicago sativa L.) followed by corn in 1996, soybean in 1997, and oats in 1998), and traditional cropping system (corn after soybean (CS) and soybean after corn (SC) on the flow weighted average nitrate-nitrogen (NO3-N) concentrations...
A GLEAMS (ver. 2.10) model was calibrated and validated using three years (1990–1992) of field–measured data to simulate tillage effects on nitrate–nitrogen (NO3–N) and herbicide losses with subsurface drain “tile” water beneath a continuous corn production system. The model was calibrated for chisel plow systems using 1991 field data and was validated against field data of two years (1990 and 1992) for chisel plow and three years (1990–1992) for moldboard plow (MB), ridge till (RT), and no–till (NT) systems. The model simulations were made with a single run using data on measured tile flows; nitrate–nitrogen (NO3–N), atrazine, and alachlor losses with tile flows; N–uptake; and other biomass parameters for the period...
Adoption of precision agriculture requires delineation of the stable management zones so that site-specific management practices can be applied to improve crop productivity and environmental quality. A quantitative approach was developed to delineate the zones by using the map overlay capability of Geographic Information System (GIS) for the soil type, topography and crop yield data layers based on field data from 1996 through 1999. The study was conducted on a 22-ha tile drained corn (Zea mays L.)-soybean (Glycine max L.) rotation field, located near Story City, Iowa. The integration of data layers showed that low yield zones were consistent from year to year and were affected by the interaction of soil type and...
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