Rethink needed on fertiliser applications for tillage crops

Farmers have been urged to give careful consideration to the fertilisers they use to grow tillage crops, as soil fertility levels have dropped in recent years.

Speaking at Wednesday’s Crops and Cultivation open day in Oak Park, Teagasc’s Mark Plunkett said: “The fertiliser use survey shows that, especially between 2007 and 2011, we have been under supplying phosphorous (P) and potassium (K).

“This has resulted in a reduction in soil fertility levels; there’s somewhere in the region of 45-60% of soils at index one and two for P and K and we only have 22% of our soils at index three,” the Teagasc specialist said.

Source: Teagasc

Unfortunately for tillage growers, Plunkett said this will have a negative impact on the yield potential of tillage crops.

If you take a 7.5t/ha crop of spring barley, it requires 86kg/ha of K. For winter barley, a 10t/ha crop requires somewhere in the region of 100kg/ha of K and an 11t/ha crop of winter wheat needs 110kg/ha of K.

“In 2007 and 2011, we weren’t supplying sufficient levels of potassium in our fertiliser. This is the reason why somewhere in the region of 45% of our soils are at index one and two and this will impact on yield,” Plunkett said.

Key tips:
  • Know what you are working with – use soil test results;
  • Put a fertiliser plan in place;
  • Use the correct product.

Changing the mindset on fertiliser use

The Teagasc representative added that farmers now need to focus more on using compound products such as 10:10:20 or 12:8:20 to fertilise their crops.

“The days of three bags/ac are gone and we really need to be using four bags/ac of products like 10:10:20 or 12:8:20.

For spring cereals, it’s very important to put all of the P and K into the seedbed at sowing because you are building yield potential at that stage.

“In the first three-to-six weeks of establishment, it’s very important to have all of the nutrients there – especially P and K to drive yield potential,” he concluded.