HIGH resolution soil scanning based on gamma-ray detection technology will deliver ‘game-changing’ soil mapping.
TerraMap delivers resolutions of more than 800 points per hectare, compared to typically eight data points/ha using 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 widths of 10-12-metres 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, TerraMap’s scanning technology is based on a scaled-down version of aircraft-mounted, gamma-ray spectrometers used in mineral prospecting, says Hutchinsons.
The system measures naturally-emitted radioactive isotopes caesium-137, potassium-40, uranium-238 and thorium-232 and is entirely passive, with the sensor creating 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.
Hutchinsons says the sensor is unaffected by crop cover, soil compaction, cultivation status or soil moisture levels and does not need in-field or field-to-field calibration.
The technology is, however, affected by heavy rain, which ‘dampens down’ the radiation.
Hutchinsons is offering TerraMap as a standard or premium service. The standard service costs £24/ha and measures P, K, Mg, pH, percentage of clay, sand and silt, plus texture and elevation. The premium service also measures calcium, manganese, boron, copper, molybdenum, iron, zinc, sulphur, OM, CEC and plant available water and costs £32/ha.
IN THE FIELD: THURLOW ESTATES, 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,” says Mr Crossley.
“The results have been impressive and more accurate than previous attempts.”
TerraMap sensing technology
- Gamma-ray spectrometer
- Contains a sodium-iodine crystal which flashes 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 and plant available water.