High resolution soil scanning based on gamma-ray detection technology will deliver 'game-changing' soil mapping, according to agronomy business Hutchinsons, which has launched a new service to growers.
TerraMap delivers resolutions of more than 800 points per hectare, compared to typically eight data points/ha using typical hectare grid sampling, providing high definition mapping of all common nutrients, pH, soil organic matter and cation exchange capacity (CEC), as well as elevation and plant available water.
Hutchinsons precision technology manager Oliver Wood says: "We have been looking for a new method of mapping soils which provides more accurate and repeatable results and can also leverage the multi-layer analysis in Omnia."
The results from TerraMap are used to create maps in the Hutchinsons Omnia system, which can then be overlaid with additional field information to create accurate, consistent and detailed variable rate plans, says the firm.
Data collection in-field is carried out in two steps: scanning to 10-to 12-metre widths using a sensor mounted on a lightweight ATV, followed by soil sampling at one sample per 3-4ha to calibrate the scan and allow each scan to be used to create individual map layers.
One pass of the scanner can deliver up to 21 map layers.
Manufactured by Canadian company SoilOptix, TerraMaps scanning technology is based on a scaled down version of aircraft-mounted gamma-ray spectrometers used in mineral prospecting, and has been used successfully in other countries, says Hutchinsons.
The system measures naturally-emitted radioactive isotopes - caesium-137, potassium-40, uranium-238 and thorium-232 and is entirely passive -i.e. the sensor creates no soil disturbance.
There are few limitations to when TerraMap can be used - offering a much wider operating window
compared to other soil scanning systems," says Mr Wood.
The sensor is said to be unaffected by crop cover, soil compaction, cultivation status or soil moisture levels. It does not require in-field or field-to-field calibration, says Hutchinsons.
The technology is, however, affected by heavy rain during operation, which 'dampens down' the radiation.
Hutchinsons is offering TerraMap as a standard or premium service. The standard service measures nine criteria: P, K, Mg, pH and percentage of clay, sand and silt, plus texture and elevation. In addition to these the premium service also measures calcium, manganese, boron, copper, molybdenum, iron, zinc, sulphur, OM, CEC and plant available water. Costs will be £24/ha for the standard service and £32/ha for the premium service.
In the field: Thurlow Estate, Suffolk
Soils on the Thurlow Estate were last scanned in 2012 using an electroconductivity technique but this approach created questions over results from the estate's chalky soils, together with suspected compaction interference, says estate director Andrew Crossley.
Hutchinsons has been testing TerraMap on the estate for the last 18 months and it has given different results, particularly in relation to soil texture.
"When we were introduced to the TerraMap system we felt it would work well with our soil type, so it was worth giving it a go," said Mr Crossley.
"The results have been impressive and are more accurate than previous attempts.
"We look forward to seeing how this will integrate this autumn with our precision farming to give us more accurate variable rate plans, especially on our chalky soils".
TerraMap sensing technology
- Gamma-ray spectrometer
- Contains a sodium-iodine crystal which flash when radionuclides hit it
- Flashes are measured by a photo multiplier tube
- Data processing conducted by SoilOptix converts flash data to scan results
- TerraMap scans: Sand, silt, clay, texture, P K, Mg, pH, elevation, Ca, Na, S,Mn, B, Cu, Zn, Mo, Fe, CEC, organic matter, plant available water