A COMBINATION of cold and wet weather conditions throughout the grazing season in 2012 made management of grass clover swards very difficult.
To help farmers cope with the variable growth and clover contents of their swards AFBI and CAFRE published results from monitor plots fortnightly in the CloverCheck bulletin along with forecasts of growth and clover content, as outputs from the CloverCheck model.
In 2012 the CloverCheck Bulletins also features 12 farmers involved in CAFRE Grass/Clover monitor farm programme. Each fortnight a different farmer was featured and gave practical advice as to how they were managing grass/clover swards under difficult grazing conditions.
Sward growth rates and white clover contents were monitored on plots at five beef/sheep farms in the east and north of the Province cut every four weeks. Results for this year are presented in Fig. 1 and are compared to performance of plots over the previous four years. The data shows a number of interesting points. Firstly, growth rate of grass/clover in spring was particularly slow, with peak growth reached in the second week in June rather than the usual third or fourth week in May. Secondly, although clover content at the beginning of the season was similar to the average for the previous four years, its seasonal increase was much slower and reached a much lower maximum than in the average year.
The growing season got off to a good start with above average air temperatures in February and March (Fig. 2). This promising introduction to spring was short-lived as the warm March was followed by a particularly cold April, with mean air temperatures at AFBI-Crossnacreevy almost 1.5 oC colder than March. Consequently, grass/clover swards throughout April and May performed particularly poorly.
Higher than usual rainfall in April and a particularly wet June compounded the poor growing conditions (Fig. 3). By July-August, average clover content was two thirds that of the average for the previous four years.
As CloverCheck plots are laid down on existing swards on the farms it would be expected that they would have similar clover content to the field as a whole. However, clover content in plots is generally always higher than in the remainder of the field. This year was no exception. Annual clover content in plots ranged from 3 to 32% between sites, while annual content in fields varied between 3 to 13%.
The results from this year demonstrate the need for white clover to be well developed by early summer to ensure a good clover contribution for the remainder of the year. The wide difference between average clover content in plots and in the remainder of the field, especially in this year with above average rainfall, confirms the vulnerability of white clover in wet soils to damage, especially to treading damage and poaching and the need for appropriate management to ensure white clover does not suffer long term damage.
Grass/white clover swards still have the potential to improve animal performance and reduce production costs on beef and sheep farm. For this to be achieved swards must be well managed. In preparation for a good start to white clover early next season, swards should be well grazed down with sheep whenever conditions allow. Care should be taken to avoid poaching. Potassium deficiency can be a limitation to white clover growth so if deficiency is suspected a soil sample should be taken and if needed apply a fertiliser such as muriate of potash next spring. Account should be taken of the adverse effect that potassium can have on magnesium uptake and so excess application should be avoided. The clover content of swards should also be assessed early next spring. If the clover content is low consider options for stitching new clover seed into existing swards.
Results presented in the CloverCheck Bulletins in 2012 have shown that weather can have a big impact on the clover content and performance from grass/clover swards. To minimise this impact it is important that swards are well managed and that poaching damage is minimised.
For further advice on the establishment and management of grass/clover swards, contact your local CAFRE beef and sheep development adviser at the following telephone number 0300 200 7843.