Dirty deeds: Sci-fi soil-sampling tech begins testing phase

Chris Thorman, of the EIT School of Primary Industries, at the wheel of an ATV and monitoring results from ray-scanners testing soil quality. Photo / Warren Buckland

EIT researchers are testing a simple yet cutting-edge technology which is expected to be able to dramatically improve the economic and environmental outcomes of agricultural and horticultural soil management in Hawke's Bay.

The answer is in a ray-scanner, otherwise known as a spectrometer, which is mounted on the front of a quad-bike to detect soil quality - this is normally done by the time-consuming taking of core samples and subsequent laboratory testing.

But in a system developed in Canada, the Gamma Ray Spectrometer (GRS) measures natural background gamma rays given off by soils, taking up to 800 data points every hectare as the vehicle is driven over the ground, measuring the background caesium, thorium, potassium and uranium radiation levels present in all soils, and converting data into soil maps.

A small number of soil samples is taken to calibrate the readings for each block, the eventual maps resulting in significantly improved soil analysis, with readings on physical parameters, such as organic matter, sand, silt and clay percentages, carbon content, soil water-holding capacity and plant-available water, as well as nutrient values for potassium, phosphate, calcium, pH, magnesium, nitrate-nitrogen, boron, copper, iron, manganese, sulphur, sodium, and zinc.

New Zealand soils are regarded as newer in terms of impact from volcanic and earthquake activity, and actual differences are expected to be detected as the information is fed into a precision-agriculture enabled tractor to allow variable rate applications, so growers can target "inputs" such as seed, fertilisers, water and lime to better meet the crop requirements - saving money, improving crop production, and meeting the ever-increasing environmental requirements.

The research is being conducted by Chris Thorman and Dr Glen Robertshaw, who lecture on the Environmental Management programmes at EIT's School of Primary Industries. Thorman, who is the project lead, and Robertshaw, who is the technical lead, are conducting the research in conjunction with industry support.

"If this system can be validated for New Zealand soil conditions, it would give growers unparalleled detail of their soils, and may help us understand how we can manage our growing operations to sustainably protect our soils while reducing the cost per tonne of produce," Thorman said.

Robertshaw said the potential for better environmental management of soils could be significant.

"It's the old saying, 'If you can measure it you can manage it', and we hope this will be a practical and cost-effective management tool for the industry," he said.

Thorman said New Zealand's international markets want to know "we are producing food in an environmentally sustainable way."

"Understanding and managing our soils is the first step in doing this," he said.

Field-testing started near Ōtāne last week and will continue at different sites over the next few weeks, with the GRS team working with the industry to test the technology and validate the systems to ensure it has value for growers across New Zealand.

Sponsors include Zespri, Vegetables Research & Innovation, Foundation for Arable research, EIT Research and Innovation, FMG, Fruitometry, SoilOpix, and Startafresh.