Nitrogen Transfer from White Clover, Red Clover, and Birdsfoot Trefoil to Associated Grass

Abstract

Information on N transfer from field‐grown forage legumes to associated grass would contribute to elucidation of N budgets and improved N management of pasture mixtures. This research evaluated N transfer by white clover (Trifolium repens L.) (WC), red clover (Trifolium prutense L.) (RC) or birdsfoot trefoil (Lotus corniculatus L.) (BT), grown with tall fescue (Festuca arundinacea Schreb.) (TF) at various legume proportions. Two identical experiments were established on a Typic Argiudoll soil in Uruguay, one in 1983 (Exp. 1) and one in 1984 (Exp. 2), and each was evaluated for approximately 2 yr. The soil of the area was a fine, montmorillonitic, mesic, Typic Argiudoll. Transfer of N to TF was estimated by 15N isotope dilution, using TF grown alone as the reference crop. Mean values for the proportion of grass N derived from legumes (%NT) were 20% for the 60% harvest after seeding, and later increased up to 60%. The increase on %NT over time was greater for WC‐TF and RC‐TF in Exp. 1 and for WC‐TF in Exp. 2. The annual uptake of transferred N (TNY) averaged 18 and 34 kg ha−1 in 1st and 2nd yr, respectively. The WC‐TF mixture usually showed greater annual TNY than RC‐TF on BT‐TF. Transfer by WC in summer often was greater than for RC or BT. Increasing legume proportion generally resulted in linear increases of %NT for the three mixtures, but TNY either did not change or decreased. We conclude that these legumes transferred small amounts of N shortly after seeding, but transfer increased to significant values with time. The concentration of legume‐derived N in TF herbage increased when legume proportion increased, but the amount transferred was not affected or reduced.

Effect of water stress on competition betweenMedicago truncatulaand wheat in15N labeled soil

“…In the second and third experiments, however, N transfer was detected at all water treatments and was higher than that obtained in the first experiment (Table 5). This supports the view that the release of N from breakdown and decomposition of dead legume tissues is the main process involved in nitrogen transfer from legume to associated grass (Henzell & Vallis, 1977;Goodman, 1988;Mallarino et al, 1990).…”

Measurement of biological dinitrogen fixation in grassland: Comparison of the enriched 15N dilution and the natural 15N abundance methods at different nitrogen application rates and defoliation frequencies

“…The transfer of atmospheric derived nitrogen appears to increase with time (Table 3; Heichel and Henjum, 1991;Ledgard et al, 1985b;Mallarino et al, 1990;McNeill and Wood, 1990;Merckx et al, 1985). In a young clover-grass system only small amounts of atmospheric derived nitrogen is expected to be transferred from clover to grass, since the transfer presumably takes place via the microbial biomass.…”

Does the Number of Species in the Seed Mix Affect the Establishment of Four Tallgrass Prairie Species? A Seven-Year Study in Kansas

“…A primary concept emerging from competition theory is that neighboring individuals occupying the same or similar niches should compete more intensely for resources than should neighboring individuals of species occupying dissimilar, complementary niches (Freeman andEmlen 1995, Tilman 1997). Beneficial effects of neighbors include the transfer of nitrogen from legumes to grasses, structural support for vines, enhancement of mycorrhizal associations, shading, and protection from phytophagous insects (Mallarino et al 1990, Piper 1996, Reifner et al 1998, Van der Heijden et al 1998, Severino • 119…”