Using fertilisers efficiently must be a priority
New reseeds and pastures that are high in ryegrass content will give at least a 25% better response to N, provided that they have adequate lime, P and K.
More than 50% of our fairly good grassland areas contain too little ryegrass.
And more than 50% of soil samples (many of which are taken from fairly high ryegrass content areas) are too low in lime, P and K.
So it can be concluded that farmers are wasting a lot of money on N fertilisers.
Many surveys have indicated that the average output from Irish pastures is only about 50% of potential.
There are many situations where nitrogen can be cut back without loss of production — such as where slurry (applied in spring) is properly used, and where pasture contains a lot of clover.
Most of our slurry is applied after first cut silage or during the summer.
If more of it could be applied in the spring, it would supply a lot of extra nitrogen.
Despite the proven value of clover, it is largely ignored by the majority of farmers.
Bloat is often quoted as a reason for not using clover, but it is not a problem with properly managed clover pastures. However, there is a traditional bias against clover among farmers, and among advisers and researchers, mainly due to the very low cost in the past of N fertiliser.
However, Teagasc research on clover and nitrogen, headed up by Dr James Humphreys, Moorepark, during the past decade has created a new interest in clover which is now bearing fruit on many farms. Moorepark trials indicate that including white clover in grass swards receiving up to 250kg N/ha can increase production by 1.1 tonnes of dry matter per hectare (worth over €200).
At moderate stocking rates of about 2.2 cows per hectare, James Humphreys of Moorepark says that €7,000 can be saved in the N fertiliser bill for a 50-hectare dairy farm with a clover-based pasture.
For several years, this saving was achieved on the Teagasc Solohead farm, producing over 2,800 gallons of milk per hectare, using only 72 units of N per acre, with moderate levels of concentrate feeding.
Even if part of a farm was converted into a clover based sward with very low fertiliser N, it would give a significant saving.
The management of clover-based swards is different to high-N swards, but not necessarily more difficult.
The best times to lay down a clover-based sward are in the spring, or surface seeding into a bare, clean ryegrass stubble, after a heavy crop of first cut silage.
There are other situations where nitrogen can be cut back without loss of production, such as where farms are under-stocked and grass is poorly managed.
In the past decade, many intensive farmers have found that they get better performance from animals by reducing N fertiliser to the levels recommended by Teagasc.
Farmers must realise that fertiliser price and fertiliser value are two very different concepts.
Despite the increases in price, all fertilisers are very good value for money when required, because without adequate fertilisers and lime, production will be very poor.
In the peak growing season, one bag of CAN has the potential to grow an extra 340 kg of feed dry matter, which is equivalent to over two tonnes of fresh grass or silage, for a cost of around €14.
That is a financial return of about four to one on good quality ryegrass pasture that has adequate P, K and lime.
Unfortunately, due to the bad weather in the spring this year, a lot of N was badly utilised, especially on water-logged soils.
As the season progresses, the response to nitrogen gradually reduces.
On average, there is twice the response to N fertiliser in mid-August compared to mid-September.
