Considering the price of fertiliser this year, farmers must be conscious of application rates as grass growth slows.

During the mid-season, it is easy to continue spreading nitrogen at the same rate behind cows, while farmers who took cuts of silage or hay during the week will also be keen to replace whatever nutrients that were taken off.

However, soil and plant nutrition specialist with Teagasc, Veronica Nyhan, has warned that farmers must be conscious of reduced demands for nitrogen.

Nyhan noted that as growth rates slows with the current moisture deficits, the plant's ability to uptake high volumes of nitrogen also falls.

That means farms spreading full rates could be leaking profits, especially if we get thunderstorms as a result of the heat, which would lead to fertiliser being washed off the hard ground rather than into it.

Fertiliser rates

Nyhan recommended that farms which have not yet had growth rates slip below 50kg of dry matter (DM)/ha can continue with planned nitrogen applications.

This will be the case for a lot of farms along the north-west, especially heavier farms.

However, farms with dry land more toward the south-east will more than likely have had growth rates drop below that 50kg mark this week.

Nyhan recommended these farms reduce application rates and consider using compounds such as nitrogen (N) phosphorus (P), potassium (K), or NK products rather than straight N.

The nutrient specialist also noted that farms with soil moisture deficits greater than 75mm should delay applications until after rainfall.

At the end of the day, every farm is different and no one size will fit all, so Nyhan recommended to regularly walk the farm, monitoring grass growth and moisture deficits to determine how much should be spread.

Nutrients

Farmers who cut silage during the week will be keen to get fertiliser out, especially if the farm's soil is lacking in major elements such as P and K.

It is no secret that many soils across the country are index one or two for K, and are therefore deficient in this element, meaning they are not maximising their full potential.

The deficiency of K has been particularly bad in silage ground as every four bales/acre removes 24 units of K, but deficiencies have being becoming more common in grazing areas in recent years too.

Therefore farmers should consider products that have N, K, and sulphur (S) but no P, such as 29:0:15+S in hopes of replenishing K.