A new soil mapping service has the potential to deliver soil data at a level previously unseen. Geoff Ashcroft sought the views of growers and agronomists about the accuracy and capability of the system.
Taking 800 data points per hectare, Hutchinsons TerraMap service appears to be revealing more about soil than any other sampling system which has gone before it.
This high-definition soil scanning and data analytics service from the agronomy business' Omnia precision farming division makes use of a gamma ray spectrometer in combination with traditional soil sampling.
By measuring and recording naturally emitted radiation found in soil, TerraMap is said to be able to produce a much more detailed set of maps than was possible before, with repeatable accuracy.
Such is the detail available that Hutchinsons claims TerraMap is unrivalled by traditionally practiced zonal testing and electro-conductivity (EC) scanning methods.
Oliver Wood, Hutchinsons precision technology manager, says: “We've been looking for a number of years to find a better way to map soil data. Grid testing has been a good start, but at just one sample every hectare, it lacks definition in the same way wider combine headers are diluting yield sampling data.
“We don't want to guess or fudge the blank spaces between samples - we want as much ‘real' data as is possible and practical to get."
According to Mr Wood, TerraMap's advanced data is now helping unlock more of a soil's potential, with a greater level of accuracy too.
“The results are stable and unlikely to mislead," he says. "And it will focus the mind on interpretation."
The amount of soil data which can be collected is extensive and has enabled Hutchinsons to offer two levels of data provision for growers. The first comprises sand, silt, clay, texture, elevation, pH, magnesium, potash and phosphate. This standard service costs £24 per hectare.
Those seeking the ultimate in soil data can choose the premium service, which adds map sets for calcium, sodium, sulphur, manganese, molybdenum, zinc, copper, boron, iron, cation exchange capacity, organic matter and available plant water, lifting the cost to £32/ha.
“We would scan a field in year one for example, then in year four we would recollect a set of soil samples from exactly the same areas and update that data. And the entire scanning process would start all over again in year eight," says Mr Wood.
Working closely with growers and incorporating known farm-derived data, such as weed pressure points, slug pressure zones and seedbed conditions, the firm can create much more accurately defined variable rate application maps for P, K and seed rate changes for example.
"We are mindful of not showing variations for the sake of it, and that means using meaningful scales to determine elements of soil content which can be interpreted as actionable data," Mr Wood says.
“If you can measure it, you can manage it - but the measurements need to be accurate to begin with."
In the field: Charles Parkinson, Lincolnshire
At 1,000-hectare Manor Farm, Essendine, Stamford, grower Charles Parkinson is keen to see how TerraMap can add value to his arable operation. Cropping currently includes winter wheat, winter barley, oilseed rape, plus winter and spring beans.
“We've been carrying out variable rate P and K applications over the last 10 years and have recently started to operate variable rate drilling," he says.
"With that in mind, TerraMap offers a big jump in accuracy."
Immediately after harvest 2019, Mr Parkinson had 120ha scanned and converted into variable rate seeding maps.
Unfortunately, the wet autumn prevented the entire acreage from being planted using the maps, but enough crop is in the ground to draw conclusions post-harvest 2020, he says.
"We've only managed to drill 30ha using the TerraMap defined variable rate seed maps, but we're actually quite excited about the data that's on offer.
“Soil texture maps, for example, are an essential part of the management process. We've a range of soil types across the farm, varying from limestone brash to heavy clay. The soil texture maps we now have correlate perfectly with our yield maps. I'm very pleased with the clarification it's provided."
Mr Parkinson has been variable rate drilling at Manor Farm for the last few years as a means of battling black-grass. Using farm-saved seed, the business is in a position to boost seed rates by 20kg/ha in heavily infested areas, without incurring high seed costs.
“We use a Horsch Pronto six-metre drill equipped with IsoBus, so we can import variable rate seed maps for the drill to follow," he says.
"The next step is to look at other variances, not just black-grass incidence."
As part of its own trials, the farm singled out fields for mapping which delivered the greatest yield variations.
"There is no point just using it on consistent fields – I figured we'd go for the extremes to see what could be recovered from the lower yielding areas," Mr Parkinson adds.
“We need to assess what works and what doesn't. We may end up spending less on poor areas and more on strong performing areas, or vice versa. It's all up for assessment."
The Parkinson family also chose to assess both levels of the TerraMap service for its field mapping trials.
“Some of the data is good to see but doesn't yet translate into an actionable plan for our rotation. A variable rate organic matter map looks lovely, but we are not yet in a position to influence it.
“But from what we've seen so far, it looks increasingly likely that we'll sample the rest of the farm this summer, using the standard service," says Mr Parkinson.
The agronomist's view: Jack Richardson
Lincolnshire-based Farmacy agronomist Jack Richardson has had a few growers test the water since the TerraMap service became available last autumn.
"It's early days, but there are a few who wanted a look to understand what data they can acquire," he says.
“The biggest change is resolution and the ability to see variations much more accurately. And this means better diagnosis for yield management.
“Understanding more about soil texture - silt, sand and clay content - will unlock a lot of potential for many growers. In some places, I've seen a correlation between potash and yield, where strong yields have revealed a high historic off-take with potash."
With access to advanced data sets from TerraMap, Mr Richardson believes it will become much easier to identify areas which may have something missing.
"Linked with on-farm knowledge of field-specific areas, this data will back up what you might already suspect. But, more importantly, it is more likely to lead you to what is required to put the problem right."
He says previous sampling methods were good, but too much assumption was required to fill in the unsampled areas. And it was the same with pH testing.
"It was easy for anyone to assume that variations were gradual between grid samples, but TerraMap is proving those variations are much more dramatic - and diverse," he says.
“When one-hectare sampling was all we had to make use of, it was a good step forward, but the repeatable accuracy of a gamma ray spectrometer can steer you precisely to those areas of variation.
"Any data is good data, but this level of detail will lift a grower's soil knowledge to another level and this could mean targeting inputs where they are going to give the best results, rather than simply accepting an average yield."
He says growers also take a different view when they see map data for their own fields.
“All of a sudden, data becomes relatable," he says. "And there's a connection between on-farm knowledge and areas pin-pointed by scanning.
TerraMap uses a gamma ray spectrometer to measure naturally emitted isotopes from soil.
These are caesium-137, uranium-238, potassium-40 and thorium-232-all with a long half-life that affords stable and repeatable measurement.
Manufactured by Canadian firm SoilOptix, the passive spectrometer is essentially a scaled down version of airborne sensors which have been used in mineral prospecting for many years.
It contains a sodium-iodine crystal which flashes when radionuclides hit it. Radionuclides are atoms that contain excess nuclear energy, which is emitted as gamma radiation that can be interpreted by the SoilOptix spectrometer.
Mounted to a UTV, the spectrometer scans and records soil data as it travels at a forward speed of 10-12mph.
Each pass occurs about 10-12 metres from the previous run, building an instant high-definition picture for the UTV operator which is shown on an in-cab terminal as high, medium and low areas.
From this terminal, the map defines areas of change where soil samples can be immediately identified and gathered by the operator during the same visit.
This process effectively calibrates each scan to the field, and the two levels of data can then be combined to give access to up to 21 layers of field-specific map data.
It has few limitations, though heavy rain is the biggest concern.
"Rainfall does dampen the level of radiation being emitted," says Mr Wood. “So we won't scan while it's raining."