Many farmers are aware of the benefits of white clover grassland. It is very palatable and highly nutritious. The main problem is the difficulty to control clover content in the sward, particularly during the second part of the growing season. Barenbrug co-operates with several institutes to better understand the behaviour of clover and to formulate solutions and instructions for white clover management. Thanks to the Louis Bolk Institute in the Netherlands (organic farming), Animal Science Group Wageningen University in the Netherlands and AgResearch in New Zealand (breeding institute), we can make a number of recommendations for optimum white clover management.
Development of white clover during the season
Clover is a thermophilic plant. Due to this the growth of clover starts 2-3 weeks later than grass. This results is a relatively low clover content in spring whilst in the summer high clover contents can be expected, sometimes over 70%. After mild winters the clover content in the first cut can be rather high. The root system of a white clover plant is only 10-15% as large as that of a grass plant. Due to this, clover cannot
compete with grass for P and K. It therefore is important to have good P and K fertilization levels in the top layer of the soil. Clover will have problems to grow on soils with pH <5.5 and high organic substance content, e.g. peaty soils.
Optimum Clover content for cutting management
The optimum clover content depends on several factors. The more clover in the sward the more nitrogen will be fixated and dry matter production will increase. The optimum white clover content should be between 50-70%. For nitrogen fixation the optimum is 70%, for dry matter yield it is 50%. Higher percentages will give reduced dry matter yields. Too much clover also leads to high protein levels and lower dry matter content in the feed.
Optimum Clover content for grazing management
A high clover content is not wanted in case of grazing or zero-grazing without supplementary feeding. Nitrogen losses are big and there is an increasing risk of bloating. Besides, pastures are more susceptible to poaching. For this reason a clover content of 30-50% is most desirable. A white clover content of 30-50% is difficult to maintain due to seasonal influences. It starts with a low content in spring and ends with a large content in the summer. Also, the clover content fluctuates over the years. The aim is to avoid this yoyo effect. Experiences from several trials and demonstration projects have learned that the imbalance in the white clover content can be avoided by using a good grass-clover mixture and crop management. For the best results the following is advised:
1) Reseeding is preferred in all situations over seeding
2) Sow a grass clover mixture in a poor nitrogen stubble
- best preceding crop is cereal because of soil structure and harvest time
- if the preceding crop is grass or grass-clover, it is recommended to reseed in springtime
3) Select the white clover variety in the mixture on persistency (Alice, Crusader, Barblanca, Barbian)
4) Select the grass on yield potency and sod density
5) Best sowing period will be March/April or August/early September
6) pH of the soil must be at least 5.5 (sand and clay). P and K in the soil must be good
7) In case of poor nitrogen stubble, a light slurry application (10-20 m3 dairy slurry/ha) is recommended
8) Particularly at autumn sowing, the grass-clover needs to be cut short before winter. Sheep grazing is also possible to cut down the grass.
9) Use limited fertilisation in the first year after sowing (max 40-50 m3 slurry per ha)
10) Nitrogen fertilization from slurry; not from artificial fertilizer. Max 150-200 kg N/ha/year
11) Avoid too heavy cuts. This will slow down the regrowth of the grass and will give clover much greater
opportunity to dominate in the sward.