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Nitrogen Fixation and Translocation in Field‐Grown Fababean 1
Author(s) -
Zapata F.,
Danso F.,
Hardarson G.,
Fried M.
Publication year - 1987
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/agronj1987.00021962007900030020x
Subject(s) - nitrogen fixation , sowing , agronomy , fertilizer , biology , fixation (population genetics) , zoology , legume , nitrogen , vicia faba , chemistry , biochemistry , organic chemistry , gene
Fababean ( Vicia faba L. var. minor ) has high N requirements for optimum yields. There are some indications that this legume can satisfy a greater part of this requirement largely through biological N 2 fixation. To confirm these observations, more quantitative estimates of N 2 fixed in fababean on different soils and over different seasons are necessary. Also, detailed N nutrition and translocation studies could serve as the basis for any required improvement in N 2 fixation. This study assessed the contribution of soil, fertilizer, and fixed N 2 to the nutrition and growth of fababean at seven growth stages. The soil used is classified as a Typic Eutrocrept. The A‐value approach, involving the application of 20 and 100 kg N/ha of l5 N‐labeled ammonium sulphate to fababean and spring wheat ( Triticum vulgare ) as a reference crop, respectively, was used to assess the relative contributions of N from fixation, soil, and fertilizer to plant growth. At physiological maturity harvest (126 days after planting), fababean had accumulated 209 kg N/ha, 79% of which was derived from fixation, with about 20% coming from soil and 1% from the labeled fertilizer. These results confirm that fababean has the ability for high N 2 fixation. Growth and N 2 fixation were, however, low during early growth (0–59 days after planting), but increased rapidly after this period. The maximum N 2 fixation rate was achieved between the early and mid‐pod‐filling stages, an interval during which N 2 fixation accounted for more than 4 kg N/ha/day. The N 2 fixation activity dropped to almost zero after the mid‐podfilling stage. After the mid‐pod‐filling stage, the N demand of the developing seeds and pods was higher than could be satisfied through the negligible soil uptake of N and N 2 fixation. Thus, N translocated from the shoot was virtually the only source for pod and seed development at these final stages. With such a high level of N 2 fixation in fababean, it was estimated that after grain removal, fababean growth led to a net positive residual N level in soil.