A grassroots approach to white clover

There are many benefits to incorporating clover into a grazing system but it requires careful management, writes

THE benefit of white clover in grassland in terms of savings in fertilizer and increased animal performance has previously been shown at a number of experiments undertaken at Teagasc Moorepark and Teagasc Clonakilty.

Currently there is increased interest in white clover as the cost of nitrogen fertiliser continues to increase, and application rates are limited under the Nitrates Directive.

Clover fixes atmospheric nitrogen and makes it available for grass growth.

Previous research has shown that clover can contribute up to 100kg N/ha/yr through nitrogen fixation, resulting in significant savings for farmers.

White clover, however, can also increase both animal and herbage production when compared to grass only swards. Recent research at Teagasc has shown increases in animal performance; milk solids production increased by between 40kg to 65kg milk solids/ cow/yr, which can result in additional milk revenue of up to €180/cow/year.

The 15pc increase in animal performance is particularly in the second half of the lactation when sward clover content is at its greatest.

Clover growth is very seasonal, and therefore its contribution to sward herbage mass varies across the year.

It is lowest in spring, peaking in late summer and declining during autumn.

When included in grass swards it has been shown to increase overall herbage production by between 900kg to 1500kg DM/ha.

As a result of the increase in farm performance there has been an increased interest in incorporating clover into the grazing system.

However, the question arises, how do you get clover into your swards?

Direct reseeding is very successful method; however, this will take a number of years to establish clover over the entire grazing area.

A simple and low cost method of introducing white clover onto your farm is to over-sow the seed into existing grass swards.

Soil Fertility

Clover will establish and persist only on high fertility soils. Rhizobia bacteria that fix nitrogen in association with clover are more productive in soils with a pH of greater than 6.3.

The phosphorus (P) content of the soil is also important when establishing a clover sward.

White clover seeds are very small and clover seedlings tend to be relatively fragile.

Seedling vigour is favoured by having plenty of P in the vicinity of the establishing seedling.

It is usually recommended that clover seed is broadcast with a fertilizer that contains P fertiliser as this will favour establishment; generally 0-730 or 0-10-20 is recommended.

Michael Egan works in the Teagasc, Animal and Grassland Research and Innovation Centre, Moorepark, Fermoy, Co Cork