Perennial Ryegrass (PRG) dominates any seed mixture of
intensive British agricultural grasslands. This species of grass produces an excellent
yield and has a high sugar content. It responds well to large applications of nitrogen
fertiliser, producing a good yield of grass which may be cut and/or grazed many times
during the growing season. Other species include Italian Ryegrass (IRG). This grass is
high yielding, especially early in the season. Hybrid ryegrasses are also used which have the yields of IRG but with durability and long life
more usually associated with Perennial Ryegrass.
There is more to grass production than the sheer volume of
the crop. The grass also has to be palatable to livestock as well as readily digestible.
It also has to withstand constant cutting and grazing for a number of years. Careful and
ongoing selection through numerous trials and plant breeding programmes has ensured that
PRG meets the criteria of yield, digestibility, palatability and robustness better than
any other grass.
The seed mixture which is sown by the farmer may include
other grasses as well as species such as clover. Clover is protein rich and palatable. It
can also capture nitrogen from the atmosphere through a symbiotic partnership with soil
bacteria. The nitrogen is fixed in nodules in the roots of clover
and this ultimately enhances soil nitrogen levels. In the past high
levels of nitrogen fertiliser fertiliser deterred White Clover. The newer varieties of
White Clover are more tolerant of high levels of nitrogen fertiliser, providing not too
much is applied in the spring. White Clover is also suitable for grasslands which are both
grazed and used for silage making.