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 Title: The role of crop residue and nitrogen in the corn-soybean rotation effect Author(s): Galerani, Paulo Roberto Doctoral Committee Chair(s): Nafziger, Emerson D. Department / Program: Agronomy Discipline: Agronomy Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Agriculture, Agronomy Biology, Plant Physiology Abstract: The objective of this study was to overcome the lack of "rotation effect" in crops by manipulating N rate, N form and crop residue. The hypothesis was that part of this rotation effect may be due to N availability as influenced by its proximity to crop residue (and root growth pattern) in the soil.Dry weight of corn plants, total (N), (NO$\sb{3\sp-}$), and grain yields were all lower in corn grown in the presence of corn residue than without residue or in soybean residue, while harvest index was increased by corn residue. The beneficial rotation effect when corn follows soybean was eliminated by the addition of corn residue, and was not dependent on the presence of soybean residue. Recovery of N fertilizer was greatly influenced by residue and N rate, indicating that plants were more efficient in taking up N when grown in soybean and corn residue.Soybean residue decreased yield of soybean following soybean; addition of corn residue to plots with soybean residue did not alleviate this inhibitory effect. Relative ureides, used as an indicator of dependence on biological fixation as an N source, tended to be higher in plants grown in presence of corn residue than without residue or with soybean residue alone. Leaf nitrate reductase activity (NRA) was inversely correlated with relative ureides.Corn residue and form of fertilizer N did not affect yield, dry weight and total (N) when soybean followed corn. Relative ureides were not influenced in soybean grown with or without corn residue. Form of fertilizer N did not influence NRA, and was again inversely correlated with the relative ureides.While we showed that crop residue and N rate and form had some effect on yield and other parameters associated with N uptake and utilization, we found no consistent interaction between crop residue and N form that would help to manage continuous corn and soybean to overcome the lack of rotation effect. (Abstract shortened by UMI.) Issue Date: 1991 Type: Text Language: English URI: http://hdl.handle.net/2142/23043 Rights Information: Copyright 1991 Galerani, Paulo Roberto Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9210807 OCLC Identifier: (UMI)AAI9210807
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