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Effect of Anhydrous Ammonia and Organic Matter on Components of Nitrogen Fixation and Yield of Soybeans 1
Author(s) -
Criswell J. G.,
Hume D. J.,
Tanner J. W.
Publication year - 1976
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1976.0011183x001600030021x
Subject(s) - nitrogen fixation , anhydrous , dry matter , nitrogen , nodule (geology) , organic matter , ammonia , nitrogenase , zoology , biology , isotopes of nitrogen , agronomy , chemistry , biochemistry , ecology , paleontology , organic chemistry
Experiments were conducted in 1972 on ‘Vansoy’ soybeans [ Glyclne max (L.) Merr.] to investigate the effects of deep‐placed nitrogen fertilizer and organic matter additions on seed yields, nodule dry weights, and seasonal amounts of nitrogen fixed/ha. Treatments included applying 112 kg NH 3 ‐N/ha, (N); passing the anhydrous applicator tines through the soil without added N, (T); applying 4.5 metric tons/ha of shredded corn cobs as an organic matter source (OM); N+OM; T+OM; and control, (C). Seed yields were not affected by treatments, but seasonal amounts of N 2 fixed, estimated by an acetylene reduction assay, were stimulated by OM, T, and T+OM and decreased by applied N. Regression analyses were used to separate N 2 fixation responses into effects on nodule mass/plant and fixation/unit of nodule mass. Increased fixation following OM and T+OM treatments could be fully accounted for by larger amounts of nodule mass/plant, which fixed less N 2 /unit of nodule mass than control plants. NH 3 ‐N reduced N 2 fixed/ha by 39 to 48% below control plots, by reducing both nodule mass and nodule efficiency. Application of N+OM increased nodule mass slightly but reduced nodule efficiency and seasonal N 2 fixation. The attempt to maintain nodule mass in the presence of deep‐placed NH 3 ‐N through the addition of organic matter was successful but a seed yield response was not obtained.