Clover has the potential to add valuable Nitrogen to grazing swards, according to Teagasc’s James Humphreys.

“The key benefit of clover is that it can fix Nitrogen (N) through the bacteria in its roots. These bacteria take N from the air and convert it to a form which is available to grass.

“The higher the clover content, the greater the amount of N fixation,” Humphreys said.

Speaking at a recent organic farm walk in Co. Tipperary, the Teagasc Principal Research Officer said that management is key to keeping clover present in swards.

Managing white clover swards

“Grass will grow when the soil temperature is 5-6 degrees Celcius,  but temperatures have to be 10 degrees Celcius for white clover to grow,” he said.

As a result, the white clover content of grazing swards tends to be quite low early in the year, but it really comes into its own in April and May, he said.

Due to the seasonal growth habit of white clover, grazing management is important to keep it growing in grazing swards, especially when it is grown with perennial ryegrass, he said.

“If you want to maintain a good content of white clover in your swards you have to graze them tight in the late autumn or early spring.

When you cannot get out and graze the sward tight, it will have a negative impact on the clover content of the sward in the subsequent year.

He also said that reseeding is necessary to ensure that white clover remains in the sward for a long period of time, as it tends to die out due to grazing and poaching.

“White clover generally won’t stay in the sward as long as perennial ryegrass. Typically white clover dies out after about five years,” he said.

To maintain the levels of white clover in the sward, he recommended reseeding 20% of the farm each year or over-sowing white clover seed into paddocks that have been mowed or grazed tight.

Red Clover

Also speaking at the farm walk, Teagasc Grass and Clover Breeder, Patrick Conaghan said that red clover can play a huge role in Irish farming systems.

But, like white clover, there is a huge degree of management required to keep it growing on farm.

Good management is key to longevity of the red clover plant, as it is very sensitive to damage from poaching by stock and machinery.

The Teagasc expert said that red clover has the potential to produce high yields of quality forage, as it is capable of growing 12-14t DM/ha annually.

It is also suited for three-to-four cuts of silage each year, he said, but the crop should be cut to a height of 8cm to protect the growing point.

He also said that wilting is necessary to get red clover silage to preserve, which makes management difficult during wet weather.

“Red clover silage be dried to a dry matter content of 25-30%, which will take 24-36 hours.”

However, he said that the crop is also prone to leaf shatter when it is turned too much, which has a negative impact on the silage quality.

Conaghan also said that when red clover is grazed, it should be grazed to a post-grazing height of 4-6cm.

But, care must be taken when grazing red clover swards, he said as more animals suffer from bloat when grazing red clover swards compared to white clover.