Nitrogen fixation by caucasian clover and white clover in irrigated ryegrass pastures
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Date
2001
Type
Conference Contribution - published
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Abstract
The N₂ fixation ability of caucasian clover was
compared with that of white clover in irrigated
ryegrass pastures over years 2 and 3 of a grazing
experiment, using the ¹⁵N enrichment technique.
‘Endura’ caucasian clover was inoculated with
the specific Rhizobium strain ICC148. The N
concentration in clover herbage and the proportion
of clover N derived from N₂ fixation (PN) were
similar for both clovers at averages of 4.6%N and
50–60% respectively over the 2 years. The amount
of N₂ fixed per hectare was directly related to the
amount of clover dry matter (DM) produced by
the two clover species. Caucasian clover produced
four times the DM yield of white clover in year 2
(5400 cf. 1450 kg DM/ha) and four times the
amount of N₂ fixed in herbage (136 cf. 36 kg N/
ha). In year 3, caucasian clover produced 50%
more clover DM (3450 cf. 2370 kg DM/ha) and
N₂ fixed (98 cf. 66 kg N/ha) than white clover.
The increased N input from caucasian clover
increased grass %N and N uptake from soil in
caucasian clover pastures resulting in higher total
pasture production compared with white clover
pastures (15.7 cf. 14.2 t DM/ha) by year 3. In this
study, caucasian clover demonstrated greater
potential than white clover to meet the N demands
of high-yielding perennial ryegrass in an intensive
pastoral system.
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Copyright © The Authors and New Zealand Grassland Association.