Grassland farmers could soon avail of tool aiming to increase fertiliser savings

Fertiliser giant Yara is set to pilot its sensor technology on grassland farms in the UK and Ireland, AgriLand can reveal.

The ‘N-Sensor’ technology has existed since 1996, but has only been used on arable land in the UK and Ireland up until now.

Adaptions to software and successful trials mean that – for the first time – grassland farmers will be able to use the technology too.

The firm is set to make the announcement later this week at the UK farm technology show ‘Dairy Tech’.

Yara, N-sensor, Valtra, Kotkaniemi
Yara’s N-Sensor technology will soon be available to grassland farmers

It comes at a time when farmers are coming under more scrutiny for their fertiliser use, and could also reduce waste in the industry.

The technology has the potential to save farmers thousands, as a sensor attached to the tractor cab is able to detect the level of nitrogen in the crop growth and through a computer system adapt the level of fertiliser applied accordingly.

It means that the fertiliser will be applied heaviest to the areas that need it, rather than a blanket coverage across the whole field.

It aims to achieve:
  • Increased yields;
  • Fertiliser savings;
  • Grass quality improvements;
  • Less lodging.

Speaking exclusively to AgriLand ahead of Dairy Tech, Yara’s Ireland and UK country agronomist Philip Cosgrave explained that the problems arise as nutrient supply within a field can be highly variable.

He said the Grass Sense project demonstrated the optimum nitrogen rate for first-cut silage varied substantially from 60 to 165kg N/ha.

As a result of this variation in soil type, a uniform application of nitrogen fertiliser results in both over and under-fertilisation.

Nitrogen efficiency

By measuring the current local nitrogen supply, the software is able to adapt the fertiliser rate accordingly – resulting in better nitrogen efficiency.

Cosgrave said: “We’re looking at nitrogen here which is not something regularly tested in soils. Nitrogen is fundamental for photosynthesis; so, if you maximise photosynthesis then you increase volume mass levels.

“Applied nitrogen allows us to capture more of the sun’s energy and convert it to biomass; but, we’re doing well if we achieve 60-70% nitrogen use efficiency on well-managed first cuts and this is why we need a technology like the N-Sensor.

When we make the process more efficient we reduce cost, but also nitrogen loss to the environment.

“Nitrogen is a significant input on silage swards; but, by redistributing nitrogen applications within a field we can achieve more kilograms of dry matter for every kilogram of nitrogen applied – it’s like a dairy farmer feeding to yield.”

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How it works

The N-Sensor measures and analyses the light reflected by the crop, calculates the nitrogen demand and – using software – is able to adjust the rate of application of fertisiliser accordingly.

The software also produces a high-resolution image of the field for future planning purposes.

The N-Sensor technology has been shown to have an extremely high rate of accuracy, predicting grass nitrogen uptake on first-cut silage fields. The correlation is slightly lower in second-cut fields, but still “strong” in scientific terms.

The reason being that the technology measures the grass chlorophyll in the crop, which is closely correlated to the amount of nitrogen.

Cosgrave suggests “split applications” of fertiliser allow the unit to get around this.

He said: “You apply a base dressing – you apply 50% straight away and then you come back three weeks later.”

The technology is available from £3,000 annual rental for the passive N-Sensor, which is suitable for use in daylight and cloud. The ALS (‘Active Light Source’) model is more expensive, but also facilitates night spreading.