ISSN:
1573-5036
Keywords:
clover
;
direct 15N leaf labelling
;
facilitation
;
grassland
;
15N isotope dilution
;
nitrogen transfer
;
ryegrass
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Nitrogen (N) transfer from one species to another is important for the N cycling in low-input grassland. In the present work, estimates obtained by an indirect 15N dilution technique were compared with estimates obtained by a direct 15N leaf feeding technique over two complete growing seasons in red clover-ryegrass and white clover-ryegrass mixtures under field conditions. The direct technique confirmed that N transfer between clovers and ryegrass is a bi-directional process. The transfer of N from both clovers to ryegrass occurred within 25 days upon the first labelling event. A very high N transfer occurred from white clover to the associated ryegrass, 4.5 and 7.5 g m−2 in the 1st and 2nd production year, respectively. The corresponding values for transfer from red clover to the associated ryegrass were 1.7 and 3.6 g m−2. Quantified relatively to the total above-ground N content of white clover- ryegrass and red clover-ryegrass mixtures, the N transfer exceeded 50% and 10%, respectively, in three out of seven harvests. The N transfer from 15N labelled grass to associated clovers constituted a relatively constant proportion of approx. 8% of the above-ground N content of the mixtures. Estimates based on the soil 15N dilution technique generally underestimated the net N transfer by more than 50% compared to the direct 15N labelling technique. Furthermore, the indirect 15N dilution technique estimated only marginal differences between red and white clover in the quantities of N transferred, whereas the direct 15N labelling technique showed the N transfer from white clover to the associated ryegrass to be significantly higher than that involving red clover. It is concluded that N transfer is a much more dynamic and quantitatively important process in grassland than previously recognised.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1026535401773
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