White clover is a second-half player

July 1st is the half time whistle in the grazing calendar. The Grass10 blueprint to grow 14t DM/ha and achieve 10 grazings per paddock is now at the half way mark, John Douglas, Grass10 Advisor, tells us more.

Farmers who use this model to grow lots of high quality grass should have five rotations completed, although the soil moisture deficits during late May and June will have delayed meeting this target for many farms. Farmers can check there grazing progress by loading their annual tonnage report on PastureBase.

Another player who is well warmed up with above average soil temperatures is the white clover plant. It really is a second-half player and is now starting to come into its peak. Grass-white clover swards make a great team. The white clover plant will experience a lot of stolon development over the next 8-10 weeks. As the stolon grows, it sends roots into the soil which form nodules and in a collaborative effort with rhizobium bacteria it fixes nitrogen. This nitrogen then becomes available for the grass plant to use as the nodules decay and release it.

White clover, where the average sward content on a dry matter basis is 20%+, has the capacity to fix between 100-200kg N/ha across the year. Most of this fixation will be done over the next few months, so it is time to pass the ball and let it do the work.

To maintain pasture production on your farm whilst reducing chemical fertiliser requires trust. You need to be able to trust that when you reduce chemical nitrogen the white clover will be there to fill the gap.

To do this, Teagasc has developed a simple way of measuring white clover’s ability to fix enough nitrogen. It is called clover scoring. Clover scoring is simply quantifying the amount of clover in each paddock relative to a scoring card which was developed by Teagasc and is available for you to download here.

Paddocks are scored based on the clover content of the sward. This is done on a dry matter basis, not on a visual basis. However to convert the visual assessment to dry matter, a quick rule of thumb is that the dry matter is about half of the visual assessment. For example, if it looks like there is 50% clover in the sward, then this is closer to 25% on a dry matter basis.

Clover scores

Score 1 is anything less than 10%. There is not enough clover to reduce nitrogen, these paddocks can be targeted for oversowing next year to boost clover content.

Score 2 is anything between 10-20% and these paddocks are nearly ready to reduce; those closer to the 20% could receive a lower amount. Grazing these paddocks at a lighter pre-grazing yield and a tight residual can help let more light down to encourage stolon development and boost the clover content of the sward.

Any paddocks at a score 3 or above are ready to reduce chemical nitrogen. Each rotation, it is advised that 7-10u N/ac be applied (this is about half the normal rate). This can be applied through parlour washings or very watery slurry at a rate of 1,500-2,000 gallons/ac through LESS, or 0.5 bag per acre of 18-6-12+S if there is an allowance for P. Other compounds without P are also available.

If clover content is gone too strong and taking over the grass, let this paddock carry a high cover over the winter to reduce light to the base, and lower the clover content for next year.

If clover content is high or conditions aren’t right, bloat becomes a bigger risk. It is important to have all necessary precautions in place to avoid it. Graze high clover paddocks in drier weather. The higher dry matter reduces the bloat risk. Put up a 3-hour break with a strip wire and let all animals into paddock at the same time. This forces them to graze grass and clover together, thus increasing fibre intake. You can also add fibre (straw, hay, silage) to diet before entering the paddock, and add bloat oil to the water two days before entering the high clover paddock.

Now is the time to get out and assess clover content in your paddocks. You can allocate a clover content to your paddocks on PastureBase. Recording this makes it easier to remember which paddocks have what, so you can adjust your fertiliser applications in line with this.

Make sure you download the clover scoring card and bring it with you on your next farm walk. Don’t get hung up on being right the first time, just be consistent and practice it every few months to train your eye in to measure clover content on your paddocks. This will pay big time when you count up all the savings made on chemical nitrogen.

Also read: Silage out as growth recovers on Teagasc/Tirlán Future Farms

Also read: Ballyhaise's road to clover incorporation