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Seasonal Dry Matter, Nitrogen, and Dinitrogen Fixation Patterns of Crimson and Subterranean Clovers
Author(s) -
Brink G. E.
Publication year - 1990
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/cropsci1990.0011183x003000050031x
Subject(s) - trifolium subterraneum , biology , lolium multiflorum , dry matter , nitrogen fixation , agronomy , forage , pasture , genetics , bacteria
Annual legumes are potential N sources in forage‐livestock systems, but information on the quantity and distribution of N 2 fixed is lacking. Field experiments were conducted to determine the quantity and seasonal distribution of N 2 fixed by two annual clovers, ‘Tibbee’ crimson clover ( Trifolium incarnatum L.) and ‘Mt. Barker’ subterranean clover ( T. subterraneum L.), having diverse annual dry matter (DM) production patterns. Plots were established on a Catalpa silty clay soil (fine, montmorillonitic, thermic Fluvaquentic Hapludoll) in each of 2 yr. Dinitrogen fixation was estimated by the I5 N isotope dilution method with ‘Marshall’ annual ryegrass [ Lolium multiflorum (L.) Lam.] as the non‐N 2 ‐fixing control. A mean of 77% of the annual herbage yield provided by crimson clover was obtained by early April compared to 39% for subterranean clover. Subterranean clover produced greater annual herbage yield than crimson clover the first year (7.6 vs. 6.4 Mg DM ha −1 ), while yields under drought conditions were similar the second year (mean of 4.8 Mg DM ha −1 ). The clovers fixed an average of 196 and 114 kg N ha −1 in the first and second years, respectively. Depending on the harvest date, fixed N 2 comprised 32 to 91% of total N in crimson clover and 75 to 91% of total N in subterranean clover. The average seasonal proportion of N derived from symbiosis by both clovers was equivalent in the first and second year (mean of 81 and 75%, respectively). Seasonal need for herbage production, rather than N 2 fixation capability, may govern the value of crimson vs. subterranean clover in forage‐livestock systems.