A soil fertility testing initiative being developed to optimise productivity and reduce environmental impacts is being extended to other farm types – including dairy operations.

The research builds on the work Ravensdown and the Ministry for Primary Industries have undertaken on their Primary Growth Partnership (PGP) programme to improve the targeting and application precision of fertiliser in hill country. At its Annual Meeting in Taupo, the farmer-owned co-operative committed an additional $2.5 million so other farm types may eventually benefit from the speed, accuracy and ease of aerial-based hyperspectral scanning. 

In the coming year, six dairy farms located across Canterbury, Taranaki and the Manawatu will be aerially scanned using hyperspectral remote sensing technology. The results will then be compared to actual soil tests on the ground so that a predictive model of soil fertility can be calibrated across climates and soil types. In this research phase, the aerial scans and on-ground checks will begin this spring with a special focus on measuring levels of phosphate in the soil.

Mike Manning, General Manager Innovation and Strategy for Ravensdown, says he is excited about the environmental benefits of a potential reduction in phosphate (P) loss. "We know that in those locations where high P levels in the soil occur, the risk of losses can increase. Soil testing carried out by laboratories across several years shows variability within paddocks - certain areas on any given farm will be at the optimum, but many will be above or below the optimal phosphate level."

The challenge has always been how to capture accurate soil data quickly and easily in a way that will guide important decisions around nutrient application rate.

The technology has already shown promise for hill country. So far, where farms used the sophisticated Intellispread fertiliser application system, 14% of the land was able to be excluded from receiving fertiliser because it was ineffective, culturally sensitive or environmentally vulnerable. 

The AirScan^® technology from Ravensdown scans to the square metre and can cover up to 1,000ha an hour. Results are captured by a special $700,000 camera which looks at the different wavelengths of light emitted.  “Once we have the spectral signals tested against actual results on the ground, the algorithms can be built and adjusted,” added Mike. 

“We have seen good progress in this calibration development for the hill country farms we have been researching and testing since 2014. While we would not expect to see as much variation across farms on flatter or rolling land compared to hill country, the outcome is too important to take anything other than a very robust science approach. This testing and measurement phase takes time and money, but the gains for New Zealand farming will be worth it.”

Currently Ravensdown’s mapping service HawkEye^® is used by farmers to enable fertiliser plans to be sent to ground spreading trucks for variable rate fertiliser application and proof of placement maps.

Spreading to an AirScan-enabled fertiliser plan is expected to commence within HawkEye from 2020.