Look at alternatives to nitrogen fertilisers

Buy fertiliser if you can get it – but it’s just as important to test slurry this year and know exactly how much nitrogen you have. You could make significant cost savings utilising farm nutrients on the grazing platform before considering other options such as clover or herbal leys.

Buy fertiliser if you can get it – but it’s just as important to test slurry this year and know exactly how much nitrogen you have. You could make significant cost savings utilising farm nutrients on the grazing platform before considering other options such as clover or herbal leys.

“If you look at book values in RB209, standard 6% DM slurry contains 2.6kg N/cubic metre,” says independent consultant Dr George Fisher. “Applied at 30m³/ha, this gives 78kg of total N/ha. However, farmers I’ve recently spoken to have discovered their slurry has between 3.3kg and 3.7kg N/cubic metre. Suddenly you’ve got 100 – 110kg N/ha. While slurry nitrogen isn’t all available to the grass plant, over the season it can take 30 – 40kg N/ha off your fertiliser bill and save you money.”

He agrees that slurry is trickier to apply to grazing because it needs lighter, more frequent applications using a dribble bar or injector. However, he points out that relying on clover to fix nitrogen, or introducing herbal species first requires a long-term change in mindset.

Deep roots and drought resistance offered by herbal leys are offset by lower yields, whereas a 30% clover sward will only fix 150 – 180kg N/ha with careful management. “Fertiliser prices are adding extra risk to your business at the moment, but you don’t want to solve that by adding complexity to the system. Without detailed planning, it only adds further risk,” he explains.

“White clover has a different growth habit to ryegrass. When you plate meter a paddock at 2,500kg DM/ha, you probably have 3,000kg DM/ha because clover grows outwards, as well as upwards. It’s a denser sward that requires a different calibration.”

Grass/clover swards can handle one application of up to 50kg N/ha at the start of the season to kick-start growth; any more, and grass growth swamps clover. If you have white clover in your reseed mix, see how it performs on your platform by spreading nitrogen on only half a paddock. “Trials like this will help to see whether clover can be used as a longer-term solution to high nitrogen prices,” adds Dr Fisher.