New Zealand Journal of Agricultural Research abstracts
Use of Italian ryegrass on seasonal dairy farms
in northern New Zealand
1. Feed production and persistence
E. R. THOM
Dairying Research Corporation
Private Bag 3123
Hamilton, New Zealand
R. A. PRESTIDGE
AgResearch
Ruakura Agricultural Research Centre
Private Bag 3123
Hamilton, New Zealand
Abstract Four field plot experiments were conducted to
determine the effects different methods of establishment, nitrogen (N)
fertiliser applications, and sowing time, had on the growth of Italian ryegrass
(Lolium multiflorum Lam. cv. Concord), particularly in late winter/early
spring when feed shortages occur on seasonal dairy farms. Data were collected
on the seasonal herbage accumulation and persistence of autumn-sown Concord
ryegrass, and its chemical composition and digestibility. An insecticide
treatment was applied to examine possible damage by insects such as Argentine
stem weevil (Listronotus bonariensis (Kuschel)) at various sowing dates.
These experiments provided background data for a large-scale farmlet trial
measuring milk production responses, following the introduction of Concord
ryegrass. Compared with existing unrenovated pasture (EP), Concord ryegrass
drilled into plots after spraying existing pasture with herbicide (DD),
accumulated, on average over consecutive years, twice as much extra dry matter
(DM) in late winter/early spring (0.8 t DM/ha) as did those that were undersown
(US, 0.4 t DM/ha). Responses to winter-applied N fertiliser were small. Initial
density of Concord ryegrass was nearly twice as high in DD as in US plots (1182
vs 632 plants/m2); 64 and 51% of plants, respectively, were lost
following the first grazing. Regardless of treatment, losses of Concord plants
were high during the first summer and only 2% of the established population (20
plants/m2) remained in the second winter. Drilling in February as
opposed to March produced an extra 1-2.5 t DM/ha, and insecticide treatment
increased herbage accumulation by 30% in the first regrowth period after
drilling, although the risk of damage from Argentine stem weevil appeared to be
low. The chemical composition and digestibility of Concord ryegrass were
generally similar to perennial ryegrass, and adequate for lactating dairy cows.
It was concluded that removal of existing pasture provided the best
winter/spring growth from Concord ryegrass, and the persistence of Concord over
summer was poor.
Keywords Italian ryegrass; Lolium multiflorum Lam.;
seasonal growth; persistence; nitrogen response; drilling time; establishment
method; pasture renovation; chemical composition; digestibility; Argentine stem
weevil; Listronotus bonariensis (Kuschel); dairy pastures
New Zealand Journal of Agricultural Research, 1996, Vol. 39: 223-236
0028-8233/96/3902-0223 $2.50/0 (c) The Royal Society of New Zealand
1996
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