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A Comparison of differing Nitrogen sources for use as early spring starter fertilisers

Early Season Nitrogen Trials Plot

A trial was carried out in Sweden during Spring of 2018 comparing a number of commercially available products which had differing nitrogen sources. All products were applied at a recommend rate of 25g/m².

Against general assumptions, it was found that the source of Nitrogen had no effect on sward density as measured by NDVI. The statistically determining factor was the amount of Nitrogen applied.

As many of the products chosen had mixtures of Nitrogen source, so it was difficult to determine any underlying effect of the different Nitrogen sources.

Trials in Sweden – 2018

The table below shows the products chosen. Competitor products have been given generic names for anonymity purposes. The Indigrow “Impact” products used were the 2018 formulation, before the innovative Asset Gold coating was applied to the products when they were reformulated to become the current “ImpactPlus” range.

ProductAnalysisForm of Nitrogen
Product A4-0-14 + 2% MgO + 8% Fe4% ammonium
Indigrow Impact Perk4-0-14 + 10% Fe2% ammonium, 2% urea
Indigrow Impact All Round5-5-15 + 4% Fe + 3% MgO5% ammonium
Product B11-5-5 + 8% Fe5.6% ammonium, 5.4% urea
Indigrow Impact Accelerate14-0-1214% ammonium
Product C18-5-10 + 2.5% MgO5% nitrate, 13% ammonium
Indigrow Humik N2525-0-00.3% nitrate, 15.7% ammonium, 9% urea
Indigrow Impact CGF 25-5-1025-5-10 + 2% MgO1.2% ammonium 13.4% urea, 10.4% PSCU

Applications were made on 6th April 2018, at a soil temperature of 6°C, with frost still evident below 10cm. Dry weather conditions were recorded after application, followed by irrigation on 12th April. The first cut after application was made on 28th April.

Assessments were made on 24th April, 7th May and 17th May.

NDVI readings were taken, with the highest value on the graphs representing the most dense sward.

Early season Nitrogen Trials Graph from the 24th April 2018
Early season Nitrogen Trials Graph from the 7th May 2018
Early season Nitrogen Trials Graph from the 17th May 2018

The NDVI readings show consistently that Humik N25 provided the best increase in sward density in early season applications. All Indigrow products included in the trial still showed an increase in sward density over the control plot, even 6 weeks after application.

Trials in the UK – 2020

Following on from the initial trial in 2018, a further trial was carried out in the Spring of 2020. The objective of the trial in 2020 was to select products with distinct Nitrogen sources (predominantly only one) and compare them at the same rate of kg/ha N rather than the same application rate of 25g/m² as used in the 2018 trial.

The table below shows the product types chosen.

ProductApplication Rate (g/m²)Application Rate (kg/ha N)
CAN (nitrate)2535
CAN (nitrate)5070
UREA (urea)7.635
UREA (urea)14.870
AMS (ammonium)2535
AMS (ammonium)5070
Humik N25 (50/50 ammonium/urea)1435
Humik N25 (50/50 ammonium/urea)2870

One application was made on the 19th March. Assessments were made on 23rd March, 28th April and 27th May.

Early season Nitrogen Trials showing the mean NDVI 69 DAT - 2020

NDVI readings were taken, with the highest value on the graphs representing the most dense sward.

Both the 2018 and 2020 trials clearly show that the source of Nitrogen (be it Nitrate, Ammonium or Urea) has no significant  practical effect on sward density and that the determining factor is the amount of N applied per hectare.

Humik N25 outperformed all other products in both trials in terms of sward density and longevity.

Full trials data is available, and further information can be requested by emailing and marking your email “Comparing Nitrogen Sources”

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