Brimpton, Berkshire, England: In the Spring of 2018, Indigrow carried out a trial in Sweden, comparing a number of commercially available products which had differing nitrogen sources. All products were applied at a recommended rate of 25g/m².

Against general assumptions, it was found that the source of nitrogen had no effect on sward density as measured by Normalised Difference Vegetation Index (NDVI), a measure of the state of plant health based on how the plant reflects light at certain frequencies (some waves are absorbed and others are reflected). 

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.

For the trial, a total of eight products were used – five from Indigrow (Indigrow Impact Perk; Indigrow Impact All Round; Indigrow Impact Accelerate; Indigrow Humik N25 and Indigrow Impact CGF 25-5-10) and three competitor products.

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.

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

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

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

Following on from the successful 2018 trial in Sweden, a further trial was carried out in the Spring of 2020 in the United Kingdom. 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.

Both the 2018 and 2020 trials clearly showed 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. Humik 25 is a new technology slow release outfield fertiliser. Humik 25 is a complex of humates and nitrogen which can only be broken down through microbial activity.

Using Impact Humik 25 provides all the benefits of slow release nitrogen, including sustained growth, fewer growth flushes and less nitrate leaching. It also provides the added benefits of humates through soil building and an increase in CEC.

Indigrow is a Full Business Member of the Asian Golf Industry Federation.