Opting for a nutritionally balanced prescription fertiliser as opposed to a straight nitrogen application on grassland this season could see several key metrics across the farm improve and, crucially, a bigger return on investment.

Applying prescription blended fertilisers to counteract soil nutrient deficiencies can help improve factors like forage quality, plant nutrient uptake and animal growth rates, and farmers should be looking at the wider benefits that prescription applications can bring.

The focus on securing straight nitrogen supplies for this coming season will have inevitably taken precedent, but making the most of any fertiliser application will be essential this year, according to Peter Scott, technical director at Origin Fertilisers.

“A balanced fertiliser grade targeting key nutritional areas within the soil, rather than a straight ammonium nitrate (AN) application, offers significant benefits for the availability and uptake of many key nutrients, as well as helping to improve nitrogen use efficiency (NUE).

“With current fertiliser prices high, many farmers may resort to a straight nitrogen application to help reduce input costs, but our data shows using a balanced fertiliser which considers more than just nitrogen, will result in better quality forage.

“Nitrogen can’t grow quality grass on its own and the addition of other nutrients such as sulphur, manganese and molybdenum help to improve nitrogen uptake from the soil into the plant.”

Many farms are now regularly taking soil samples and data can be used to enhance the soil nutritional balance. Blended fertilisers can play a key role in targeting the specific nutrient shortages within the profile.

“By using broad spectrum soil analysis, the full nutrient reserves within the soil are assessed as opposed to looking at only phosphate, potash and magnesium. Adding both macro and micronutrients to the fertiliser blend can correct deficient areas and ultimately create a more rounded nutrient profile in both the soil and the forage,” said Mr Scott.

“This is where targeted nutrition is so effective as the additional nutrients create a synergy – the supply of one deficient nutrient improves the availability and uptake of others.

“For instance, we know that sulphur can increase dry matter yield and raise protein content. Including this in a prescription fertiliser application can help farmers reduce the kg/ha of nitrogen applied, as plants will use nitrogen more efficiently with the help of additional nutrients.

“While not required by the grass sward, adding sodium to the fertiliser will improve palatability and digestibility of the forage, encouraging livestock to graze tighter for longer,” added Mr Scott.

Getting the soil nutrients correct will have direct advantages for plant uptake and availability, which will contribute to better quality forage, healthier animals and less wastage as a result.

Prescription matching is essential to having key nutrients available at the stage the animal requires them the most. Boosting sodium reserves within the soil profile will help make the forage more palatable and will contribute to improved forage intake, while enriched crude protein levels can have direct influence on growth rates.

“Farmers should be thinking of fertiliser as not only a food source for grass, but for the animals, too. It is the cheapest form of feed for livestock, so by feeding the soil to achieve the right forage quality, costs of supplementary feeds will reduce further down the line,” explained Mr Scott.

“If there is a need to buy in minerals to finish off animals, farmers will be selective as to what is included to improve certain growth or nutrient factors, but with the right soil nutrition, these nutrients can be available to the animal earlier and have a greater influence at critical growth stages.


Prescription fertiliser increases lamb growth rates

A practical on-farm study showed that a targeted soil nutrition programme, such as Nutri-Match prescription fertiliser from Origin Fertilisers, as opposed to straight AN, increased soil fertility, forage quality and lamb weight gains.

The trial, at Lemmington Hill Head, Alnwick, Northumberland, was a split field set up with one half applied with Origin’s Nutri-Match fertiliser 23-11-0 + 8Na + 9SO3 + Mo + Zn + Mn + Se, developed specifically for the trial based on the deficiencies in the soil’s profile, while the other half had a straight AN application.

This showed that by prescription matching fertiliser inputs to soil requirements, it was possible to reduce N application by 15% and at the same time achieve a 20.7% higher growth rate from lambs. All lambs involved in the trial were Aberfield crosses and reared as twins, so growth rates were representative across the board.

“We included seven additional nutrients compared with the straight AN application and reduced the overall nitrogen content in the blend by 15%,” said Abby Kellett, nutrition agronomist covering Northumberland, for Origin Fertilisers.

“However, considering the nitrogen drop across the Nutri-Match treatment, there was over 30% more nitrogen in the forage and the liveweight gain per kg of nitrogen applied was 50% higher on the Nutri-Match area.”

During the first eight-weeks of life, lambs grazing the AN treated area gained on average 330g/hd/day, which led to an eight-week average of 23.51kg/hd, while the blended treated pasture registered 358g/hd/day which translated to 25.28kg/hd.

“The eight-week weight is a key performance indicator as lambs that have underperformed up until this period tend not to recover this additional weight gain later in the year,” added Miss Kellett.

“It was most beneficial in influencing lamb growth rates at eight weeks and older, as from this point onwards, grass makes up more than 80% of their diet as opposed to milk from the ewe. It is reasonable to suggest that as the mother is grazing the same pasture, the milk quality is also improved.”


The farmer’s perspective...

James Drummond, who farms at Lemmington Hill Head, was pleased with the results and the forage produced on the 'prescription' area was better quality, yielded more and contributed to better lamb growth.

“Early live weight gains are so important to reduce days to slaughter and achieving this higher output will also translate into healthier and better-quality ewe lambs for the following year," he said.

“The extra weight gain I can get into lambs earlier in the season offers more options. By adding better soil nutrition, I could be selling more breeding lambs per year, which is added value on the bottom line.

"If I can get prime lambs through my system quicker to reduce food costs and free up pasture, then I’m saving in multiple areas,” added Mr Drummond.

“I’ve always wanted to be as productive as I can from a forage-based system and produce forage in an environmentally sensitive way that is good for the animal and offers a good return on my investment.”