Variety trials are sown annually at the AFBI Plant Testing Station,
Crossnacreevy in mid-summer, and evaluated over three growing seasons.
- Perennial
ryegrass and Timothy trials are grazed with cattle in the first year and measurements taken during
the second and third years to assess long-term potential. Varieties are assessed under both a simulated
rotational grazing management with 320 kg/ha nitrogen applied per annum and under a 3-cut silage management
with backend simulated grazing, with 350 kg/ha nitrogen applied per annum.
- Hybrid
ryegrass: being best suited to medium-term use, is assessed over three harvest years under a 3-cut
silage management with Spring and backend simulated grazing, at 425 kg/ha nitrogen applied per annum.
- Italian
ryegrass: being best suited to short-term conservation use, is assessed in both first and second
harvest years under a silage management with Spring plus backend simulated grazing, at 425 kg/ha nitrogen
applied per annum.
- White Clover: sown with Fennema perennial
ryegrass, is assessed in the second and third harvest years. Reaction to rotational cattle grazing is
assessed using either 50 kg/ha nitrogen applied in Spring (Low N) or 200 kg/ha nitrogen applied throughout
the season (High N). Yield potential is measured separately in a simulated rotational grazing trial
at ‘High N’.
Key to performance tables.
The
recommended varieties are grouped into tables according to species and maturity and are listed within
each category in order of heading date or leaf size. Therefore, the variety at the top of a list is
not necessarily the best. The parameters recorded in the tables are as follows:
- Heading
date: Indicates the relative maturity of varieties, recorded when half of a set of individual
indicator plants of each variety produce seed heads in an average season at AFBI Crossnacreevy. Dates
are about 4- 6 days earlier than ear emergence in swards and are not the date of the first silage cut.
- Leaf
size: Indicates the relative leaf size of clover varieties as a percentage of Grasslands Huia.
- Total
yield: Total annual dry matter yields (t/ha DM) as a percentage of the bold type diploid varieties
in each table. The tetraploid perennials are expressed as a percentage of the diploid perennial controls
and for Italian and hybrid ryegrasses, all yields are given as a percentage of the first year control
yield.
- Early spring growth: The yield in t/ha DM available
by the end of March at Crossnacreevy.
- Spring growth: The
yield in t/ha DM available by the end of April at Crossnacreevy.
- 2-cut
silage yield: The combined yield from the first two silage cuts as a percentage of the mean of
the bold type diploid varieties.
- 2 cut D-yield: The total
yield of digestible material produced in the first two silage cuts.
- Grazing
grass quality: The D-value of leafy grazing swards in August (differences of less than 2% should
be treated as not significant).
- Sward density: Assessed
at the end of a harvest year on a 0-9 scale of increasing density. Ratings above 6.0 for diploid and
5.0 for tetraploid ryegrasses indicate a high level of persistence.
- Grazing
density: Indicates the relative tolerance of white clover to grazing on a 0-9 scale. High values
represent good persistence and a potential to proliferate under a suitable management.
The
data in the tables are an accumulation from a large over-years data matrix from different trials at
AFBI Crossnacreevy. The number of years of data representing each variety depends on its stage in the
testing programme.
