Make an early-season gain with subterranean clover

• Published date: 13 October 2021
• Publication title: Central Rural Life

As it thrives on drier sites (sunny hill faces, stony soils), with the correct management, subterranean clover can be a valuable component of dryland sheep systems.

Why is subterranean clover useful on dryland farms?

It grows more in spring. As an annual legume, sub clover produces more dry matter (DM) in early spring than perennial legumes such as white clover. This is because annuals germinate and grow at a lower optimum air temperature (10-15degC) than perennial legumes (20-25degC).

Sub clover starts rapid growth at least a month earlier than lucerne, white and Caucasian clovers.

Well-managed dryland pastures can get 50% clover on offer in September and October.

Higher feed value than grasses. Grazing animals, when given the choice, prefer a diet that is 70% clover and 30% grass. Providing quality herbage from August to November helps lactating ewes milk well, ensuring rapid lamb growth rates. This allows lambs to be finished earlier, before summer dry conditions limit pasture production.

Increases grass palatability. Grasses in the sward become more palatable through nitrogen fixation by legumes. Legumes fix about 30kg nitrogen (N) per tonne of DM grown. For example, 4t DM of sub clover grown over a year would fix at least 120kg N/ha. This extra nitrogen is taken up by grasses. Grasses with more crude protein (about 4% N) are much more attractive than N-deficient leaves (less than 2.5% N). The amount of nitrogen present in the leaf is used to estimate the amount of protein in the grass.

Survives on drier sites. On drier sites (sunny hill faces, stony soils) most perennial legumes (with the exception of lucerne) may not survive summer drought (such as white clover). Annual clovers can survive from year to year as they set large amounts of seed in early summer before dying. This provides a seedbank and rapid regeneration of seedlings in autumn.

Subterranean clover production

Pure swards of sub clover can produce 4t to more than 10t DM/ha/year depending on rainfall. This is similar to mixed grass/clover pastures at the same site. However, clover content is likely to be only 20% of the total production in mixed pastures. Given that clover herbage has a higher feeding value than grass, a strong case can be made for using legumes to maximise lamb growth rates during spring ewe lactation, and to get more liveweight gain from the same amount of feed grown.

Lincoln University’s ‘‘Max Clover grazing experiment’’ at dryland sites showed that superior clover...