White clover provides the dual benefit of free nitrogen and improved animal performance so achieving a healthy population is key to any productive grass sward. It is a perennial plant that has a stoloniferous growth habit with stems attached to the soil, which grow and form new roots and plants. This is its main mechanism for survival, and it does not need to set seed.
White clover should be sown between April and August or when soil temperatures are at least 6℃ to allow the clover to germinate. It is best sown in the Spring which will allow stolon production and give adequate time to build up reserves. Before establishment a target pH of above 6 should be achieved and any phosphate and potash deficiencies should be alleviated. Soil nutrients should be maintained throughout the life of the sward to allow the clover to compete with the grass. The clover should be established into a fine, firm seedbed with care taken to not sow any deeper than 10mm. The field should then be rolled to give good seed to soil contact.
A successful clover establishment is dependent on a good initial sowing rate of 0.75-1.5kg/ac of clover with 13 to 14kg/ac of grass. With care taken to select varieties with a more upright growth habit such as tetraploid ryegrasses which will allow adequate space for the clover to develop.
Sympathetic management of the sward moving forward to encourage clover growth is pivotal. It should be grazed in the autumn or winter to remove proud grass. Close grazing in the Spring will minimise grass competition and the extra light should stimulate the formation of new stolon branches. Avoid large applications of synthetic nitrogen which will discourage the clover from fixing its own nitrogen and cause too much competition from the grasses. A target of 30% white clover in the sward should be the aim with the potential of that fixing 100kg N/ha.
When considering a grass reseed, it is important that you consider the possibility of controlling weeds and how likely it is that a spray may be needed to help eradicate the weeds. This will help determine if the grass mixture you choose, should include white clover, as most weed sprays will harm or kill the white clover.
Establishing white clover into an existing sward When a field has been sprayed for weeds or an older pasture is being let down by a lack of clover, it can often be easily improved by overseeding white clover.
Timing is pivotal with care taken to avoid times of the year where grass growth is strong and making sure there is adequate soil temperature and critically moisture. The field should be tightly grazed or can be sown directly after silage. It should be shallow sown with a grass seed drill or broadcast onto the surface with a roll afterwards. Stock can be returned to the field for a 5 to 7 days post sowing to keep down the existing sward and help trample in the new seeds. They should then be removed before the clover germinates and allow the field to rest for at least a month until the new clover plants are strong enough to be grazed.
White clover plays an important part in livestock performance, with it been very palatable and having a D Value (Digestibility value) when under grazing of 75-83, comparable with perennial ryegrass with a D Value of 73-78. White clover helps raise the protein levels in forage and is also a richer source of minerals than grasses alone. Minerals such as calcium, magnesium, cobalt and selenium. This proves that having a successful clover content in your sward is very important for animal liveweight gain, animal health and milk production.
As well as white clover benefitting nitrogen fixation and livestock health and performance, clover also helps improve the soil health and soil biology underground. With its deep and vigorous tap roots, this helps break up soil compaction, which creates gaps for movement of key nutrients and water infiltration.
