Farmer Focus: Foliar fertiliser saves £42 a cow

“The true method of knowledge is experiment,” as William Blake said, and in 2023 we tried out foliar nitrogen.

Previously, we used a conventional Amazone fert spreader, applying granular nitrogen fertiliser at an annual rate of 180-240kg/ha.

Targeting a reduction in chemical nitrogen use, we have been incorporating clover slowly over the past five years.

As we still have ryegrass on half the farm, we looked at another step to cut fertiliser quantities.

See also: How to improve consistency with foliar nitrogen sprays

About the author

Gillian O’Sullivan
Livestock Farmer Focus writer Gillian O’Sullivan milks 100 crossbred cows once-a-day with her husband Neil and father Michael on Ireland’s South-East coast. They operate a seasonal calving, grass-based system with milk supplied to Tirlán.
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We seized the opportunity to experiment when our trusty spreader needed replacing.

We looked at foliar fertiliser, attracted by claims of 30-50% nitrogen reduction in year one without compromising pasture production.

We invested in a Tow & Fert Multi500, a 500-litre agitation tank that mixes granular fertiliser with water.

The process involves adding 380 litres of water, about 180kg of fertiliser (mostly urea and sulphate of ammonia) with small amounts of humic acid, and vegetable oil to the tank.

The agitator dissolves the granules, and the liquid nitrogen is spread in a 9.5m-wide band behind our quad bike (a Suzuki King Quad 750).

Despite the initial adjustment to a different application method, the results were remarkable.

We aimed for 25% less fertiliser with similar grass production and achieved a 32% reduction.

We actually grew more grass (compared with a very dry 2022). With about 120kg N/ha spread over the year, we produced just over 10t/ha of dry matter (DM) off steep, shallow, poor soils.

This aligns with research in Wales, where foliar fertiliser matched conventional growth rates on dairy farms.

We learned a lot in the year. First, the weather plays a part, as a dry leaf is required for spray applications.

This proved challenging during March as there were very few dry days. In this case, there is a requirement for flexibility to give options for getting nitrogen out when it is needed.

Second, following the rules on application was important.

High humidity for better uptake meant we spread in the evening during the main growing season, targeting covers of 600-700kg DM/ha, about 10 days after grazing for better leaf uptake.

We saved more than £4,300 in fertiliser and had less nitrate leaching. We expect a return on investment within three years. It’s a financial and environmental win-win.