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Selection of the most appropriate reference crop for the assessment of nitrogen fixation by soya bean in Anambra state, Nigeria
Author(s) -
Okereke G U,
Dauda D,
Ayama D
Publication year - 1991
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740570112
Subject(s) - cultivar , nitrogen fixation , crop , soya bean , sowing , agronomy , legume , nitrogen , mathematics , biology , chemistry , food science , organic chemistry
Abstract Nitrogen fixation by various soya bean cultivars was estimated using upland rice, maize and sesame as reference non‐legume crops to enable the selection of the most appropriate reference crop for Nigerian soil. The per cent 15 N atom excess of rice was consistently higher than that of the three soya bean cultivars at all sampling dates, indicating that the soya bean cultivars fixed N whereas rice did not. By contrast, the per cent 15 N atom excesses of sesame and maize were smaller than those of the soya bean cultivars at certain days after planting, giving a false impression of nitrogen fixation by sesame and maize. Using rice to calculate the per cent nitrogen derived from the atmosphere (NDFA) gave larger and consistently positive values. The use of maize and sesame as reference crops gave inconsistent negative and positive values for the NDFA. Thus, upland rice was a better reference crop for the calculation of NDFA under the prevailing conditions of the experimental site.