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Yield and Leaf Nitrogen of Nodulating and Nonnodulating Soybeans as Affected by Nitrogen and Molybdenum 1
Author(s) -
Parker M. B.,
Harris H. B.
Publication year - 1977
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1977.00021962006900040007x
Subject(s) - molybdenum , nitrogen , cultivar , yield (engineering) , soil water , agronomy , chemistry , ultisol , horticulture , biology , materials science , inorganic chemistry , ecology , organic chemistry , metallurgy
Investigators have suggested that soybean [ Glycine max (L.) Merr.] response to Mo was essentially a correction of N deficiency, and a series of experiments was conducted on acid soils (pH ranged from 4.5 to 5.6) to evaluate the suggestion. In the first series of experiments, yield response to Mo and N rates was studied for 3 years on soybean cultivars grown on Dyke 1 (Typic Rhodudult) and State 1 (Typic Hapludult) soils. Molybdenum was as effective in increasing yields as 134 kg N/ha in one experiment, 67 kg N/ha in a second experiment, and less effective than 67 kg N/ha in a third experiment. However, the combined effect of Mo plus N was greater in two out of three experiments than each element applied singly. In the second series of experiments, plant response to Mo and N rates was studied for 3 years on nodulating and nonnodulating isolines of soybeans grown on State 1, Etowah sl (Typic Palendult), and Cecil scl (Typic Hapludult) soils. Leaf N of nonnodulating soybeans was increased by N, but Mo was ineffective in all experiments on nonnodulating isolines. Molybdenum without N increased leaf N on nodulating types in all four experiments where leaf N was determined. Nitrogen without Mo increased leaf N of nodulating types in three of four experiments. Yields of nonnodulating isolines were not affected by Mo in any of the experiments, but Mo increased yields on nodulating isolines in four of five experiments. Average yields for five experiments with nodulating types indicated that Mo without N produced yields greater than did 67 kg N/ha but less than was produced by 134 and 201 kg N/ha. Results from four of eight exeriments with nodulating soybeans indicate that N efficiency may be improved by the addition of Mo. Results of these experiments indicate that the primary function of Mo was to correct a N deficiency and that enough soil Mo was available for nitrate reduction but not for symbiosis.