There is a compelling argument for the need for “balanced nutrition” when it comes to the use of fertilisers, particularly as we face into an era of reduced nitrogen allowances to meet our climate targets.

Balanced nutrition implies extending the focus beyond N, P and K through an integrated approach to nutrient management planning to determine the specific nutrient requirements at crop or individual field level, and then matching them through prescription fertiliser formulations.

Prescription nutrition is already a well-established practice in the UK, the US, New Zealand and throughout northern Europe. It is emerging in many more countries and is likely to continue to grow as more farmers and advisers realise the agronomic, economic and environmental benefits.

In Ireland, fewer than 100 different fertiliser analyses were available to the market with only five products accounting for almost 72% of all compound fertiliser sales nationally. This is in comparison to Britain where the number of different fertiliser analyses available to the market have grown from 250 in 2011 to nearly 18,000 in 2023.

Scott highlights the importance of the application of sulphur, sodium and selenium to grass crops to optimise growth and yield response from grazing animals.

Improved forage quality

In 2019, the National University of Ireland, Galway, conducted a small-scale trial comparing standard and prescription fertilisers for grass yield and quality.

The trial, based on a two-cut system, analysed soil and compared commercially available ‘standard’ compounds with prescription blends (CAN-based and protected urea-based including sulphur, sodium and selenium).

While total dry matter yield showed no statistical differences, prescription compounds improved forage quality with higher levels of crude protein, energy and water-soluble carbohydrates.

Additional application of sulphur, sodium and selenium in prescription blends led to higher nutrient levels in forage.

Improving growth rates and liveweight gain using less nitrogen fertiliser

In a 2021 on-farm trial in Northumberland, England, focusing on improving forage quality, a prescription fertiliser was compared with straight nitrogen for rearing lambs on grazed grass.

The prescription fertiliser included phosphorus, sulphur, sodium, selenium and zinc.

Despite a 15.8% reduction in nitrogen, the prescription fertiliser maintained higher grass cover and increased average nitrogen levels by 33.3%.

The lambs grazed on the prescription-treated block showed a 20.3% higher cumulative weight gain from birth to 16 weeks compared to those on straight nitrogen.

The trial suggests that balanced nutrition can offset reduced nitrogen application, potentially improving livestock efficiency.

The return on investment for the prescription fertiliser, considering fertiliser and lamb prices, was £4.86 (€5.71) for every £1 (€1.17) spent on fertiliser.

Scott finished by outlining a £3.3m (€3.88m)on-farm trial and research project that Origin Fertilisers is involved in, seeking to reduce the dependence of UK grassland farming on applied nitrogen fertilisers.


Origin Fertilisers will be conducting replicated and farm trials to identify the specific nutritional requirements of these new clover and legume varieties and evaluating whether metallo-catalyst fertiliser coatings can increase nitrogen fixation.

Although NUE-Leg is a UK-based project, it is anticipated the findings will be practically applicable across temperate grasslands in the northern and southern hemispheres.