The recent ZeroNSile webinar, hosted by AgriSearch, provided an overview of how best to establish productive red clover swards.
But, why should farmers opt to grow red clover swards in the first place? This was the first question addressed Dr. David Patterson, courtesy of his presentation.
Patterson is a grassland agronomist at with the Agri-Food and Biosciences’ Institute (AFBI). He is based at the organisation’s research centre, near Hillsborough in Co. Down.
Red clover
Patterson explained: “Red clover can fix up to 200kg of nitrogen (N)/ha from the air on an annual basis. Crops have the potential to produce up to 15t of dry matter (DM)/ha.
“High animal intakes and comparable levels of animal performance can be achieved with the growth profile of this clover.
“This level of clover output is achieved on the back of up to four silage cuts in the same season.
“The downsides associated with red clover include its lack of persistency. It can be difficult to ensile – crops are problematic from a grazing perspective, and a four-year break is needed between crops of red clover that are established in the same field.
“Four years is the optimal period over which a red clover sward will deliver productive yields. After that, it is a case of moving on to new ground,” he explained.
The agronomist explained that crops of the legume can also be predisposed to clover rot and stem eel worm.
This is the reason why a four-year break is required when it comes to establishing red clover in the same location.
Preparation
According to Patterson, all previous vegetation in a field must be killed-off with a herbicide prior to the establishment of a new red clover sward.
“After that, any tradition cultivation system can be used. These include ploughing, discing or power harrowing or any combination of these,” he continued.
“The objective is to create a fine, firm seed bed. It’s a table top finish that growers should be aiming for.
“It is not really suited to over-seeding-based establishment systems relative to what is the case for white clover seed.”
He explained that rolling prior to, and after, planting is advised.
Seeds should be placed at depths between 5mm and 10mm. It is important for the seed to stay in or around the surface of the soil.
The AFBI scientist confirmed that red swards are best established when soil temperatures are around 8 °C. This takes in the period late April through to early June.
The advised seeding rate is 6kg/ac for stands of pure red clover or a blend of 9kg of a companion grass and 4kg of red clover when a mixed swards is required.
The optimal soil pH value for red clover establishment is 6.5. Only phosphate and potash fertilisers are required at time of sowing.