Written by Rosalind Platt, managing director of UK leaders in crop nutrition, BFS Fertiliser Services. BFS is celebrating its 75th anniversary this year.
Foliar nitrogen fertiliser treatments later in the season can dramatically reduce the total amount of nitrogen needed while maintaining or increasing crop yields.
The recent turmoil in the fertiliser market has been adding to the pressures facing farmers from all sides. Another key farming imperative to move to Net Zero led us at BFS Fertiliser Services to think about how we could help farmers to use less nitrogen while maintaining yields.
Our solution was to develop a foliar nitrogen product called PolyNPlus Foliars. After five years of independent research with one of Britain’s oldest agricultural research centres, NIAB, and international farm managers and agronomists, Velcourt, PolyNPlus has been producing excellent results for farmers. The recent dramatic fluctuations in fertiliser prices have only increased the interest in these products.
What is PolyNPlus foliar nitrogen?
Nitrogen, vital to maximise yields in cereal production, is traditionally soil-applied as ammonium nitrate, urea or liquid UAN. Farmers would normally make two or three applications of soil-applied fertiliser in the spring. But, later in the season, the nitrogen use efficiency of these types of fertiliser, whether solid or liquid, can decline to 25%, especially when the conditions are dry – see chart.
When the leaf canopy is sufficient, however, PolyNPlus Foliars can replace a proportion of the soil-applied nitrogen. As a guide, and depending on soil and weather factors, 25 litres of PolyNPlus – supplying just 8kg of nitrogen between growth stages 37 and 39 – can replace 40 to 50kg of any type of soil-applied nitrogen. Or some farmers prefer to make two applications of 15 litres per hectare of PolyNPlus at growth stages 33 and 37.
This means that farmers can apply less nitrogen while maintaining or increasing yields as trials have shown. For example, Velcourt conducted a trial of Crusoe winter wheat in Casthorpe, Lincolnshire, which showed that, when using PolyNPlus, significantly lower levels of nitrogen were required to produce comparable or better yields – see chart.
PolyNPlus’s sticky nature prevents nitrate loss, avoiding groundwater contamination, and the loss of ammonia is minimal. In addition, replacing 40kg of soil-applied fertiliser with 25 litres of this product cuts the carbon footprint of the third application by 77 per cent.
Unlike conventional liquid fertilisers, PolyNPlus foliar nitrogen is safe to apply to the leaves of growing crops. It can also be tank-mixed with crop protection products, thereby reducing the number of passes required. Conventional jets or flat fan nozzles enable greater precision which means that less product is needed. Another benefit is that PolyNPlus does not contain plastics. It is available in easily distributed, reusable 1,000 litre containers requiring less storage space and, with no bags needed, there is no waste.
How PolyNPlus Foliars work
Soil-applied urea undergoes a long series of reactions before it gets into the plant. Drawing nutrients from the soil through a plant’s roots requires energy and the plant is not able to take up all of the nitrogen resulting in waste. By contrast PolyNPlus foliar nitrogen is applied directly to the leaf and assimilated into vital proteins.
PolyNPlus comprises molecules of different chain lengths. The shorter ones pass into the leaf quickly while the longer, less soluble ones are released more slowly over several weeks. Because the breakdown process occurs gradually, the plant utilises PolyNPlus most effectively and nitrogen use efficiency is greatly improved.
What farmers think
Mike Allum, who farms in Suffolk, applied 160kg of nitrogen on his winter wheat in three applications followed by 25 litres of PolyNPlus. He was delighted with the results. The good areas yielded up to 12.3 tonnes per hectare and, on average including some very poor areas badly hit by drought, achieved 10 t/ha.
An Essex farmer achieved good results with PolyNPlus on winter wheat, producing a higher yield at a lower cost. On the other hand, when he made three applications of soil-applied nitrogen (the left hand bar of the chart), he had a lower yield. He felt that was because the third application was in mid-April and was limited by lack of rainfall.
Paul Jannaway, a Wiltshire-based contractor working with several large landowners, said: ‘PolyNPlus ticks all the boxes on an environmental front. I applied it along with crop protection products which saved another pass. This meant that I was able to get the right quantity on at the correct time. The yields and quality of the products we harvested were excellent. I applied PolyNPlus in all conditions, even when it was very hot, and had absolutely no scorch. I believe we will be seeing a lot more of this product – PolyNPlus is the future.’
As well as using PolyNPlus successfully on wheat and rape, he has also used it on oats, just before the panicles or oat heads emerged and he recorded a bumper crop.
Six different formulations
The PolyNPlus product range is formulated with ureic polymers, sulphur, magnesium, manganese, micro-nutrients and organic uptake enhancers. Uniquely, there are six formulations to meet different crop needs: PolyNPlus Cereals, PolyNPlus ManMag, PolyNPlus High Sulphur, Straight PolyN. Also available with required trace elements for oilseed rape and maize are: PolyNPlus Oilseed and PolyNPlus Maize.
Beware of imitations
PolyNPlus is the only foliar nitrogen which has been extensively and independently trialled.
Foliar nitrogen is set to play an essential role in the future of farming. It is a cost-effective way to improve nitrogen use efficiency, maintain or increase yield, reduce pollution and cut a farm’s carbon footprint anticipating the Environmental Land Management scheme.