White clover as a sustainable alternative to nitrogen

Perennial ryegrass (PRG) grass-based systems are both efficient and low cost, however they are dependent on high levels of expensive nitrogen (N) fertiliser. In light of the rising costs associated with N fertiliser, there has been a growing interest in the inclusion of white clover in PRG-based production systems. This would cut costs for farmers as well as reduce the impacts of artificial N on the environment.

A valuable natural resource, white clover can be included in PRG-based systems to increase grass and animal production. It has a lot of agronomic advantages such as possessing the ability to convert atmospheric N into a form that can be used by plants, such as a nitrate. This facilitates accelerated PRG growth and production. Nutritionally, it is also superior feed to PRG alone, as it has lower neutral detergent fibre levels, which promotes higher dry matter intake. This results in a higher milk production per cow.

It is recommended that white clover be established in the sward at a minimum rate of 20% to avail of these benefits. In addition to an increase in milk production as a result of the inclusion of white clover in the sward, there has also been a substantial increase in milk solids. According to research by Teagasc, cows grazing PRG white clover swards had a 6% higher daily milk solids yield, which resulted in a 29kg difference in cumulative lactation milk solids yield. A substantial increase in milk solids was observed at a lower N input level.

Land availability and environmental constraints are two of the biggest limiting factors affecting increasing production on farms, and it is important to note that the inclusion of white clover in PRG swards is a key grassland strategy that can help farmers overcome this.