The Land and Food Annual 2017 by Claire Massey

Author:Claire Massey [Claire Massey]
Language: eng
Format: epub
ISBN: 9780995100107
Publisher: Massey University Press
Published: 2017-04-12T04:00:00+00:00

IN ANOTHER AREA, reducing the amount of nitrogen applied in the first place is important. At the most basic level, plants need air, sunlight, water and nutrients. As crops and pasture grow, nutrients (primarily nitrogen, phosphorus, potassium and sulphur) are depleted: if they are not replenished, yields drop and land becomes less productive. The main fertilisers used in New Zealand are superphosphate and urea, and there is an increasing awareness that their use must be carefully managed to minimise the environmental effect. Massey University’s Centre for Precision Agriculture, led by Professor Ian Yule, is conducting research into how this can be better achieved.

‘Precision agriculture is, in essence, about measurement, and then application of fertiliser based on that measurement,’ he says. ‘It started in the late eighties, in America, but that was simply about using GPS to try and map out ways to increase yield and be more efficient with the use of machinery. Overseas it was used more around the corn and soybean industries in the US and wheat and cereals in Europe. Our work in New Zealand has been much more around pasture. The rest of the world is catching up a bit in terms of looking at pasture, accepting the fact that it is highly variable and trying to understand why it’s so variable so we can optimise the fertiliser inputs so that we don’t overdo it in some places and underdo it others. It’s becoming much more part of everyday agriculture, where information is needed to make sound decisions.’

Currently, the research group is involved in a large project in collaboration with Ravensdown Fertiliser and AgResearch, with the aim of optimising fertiliser application in hill country. ‘We are looking at using airborne sensors to work out the nutrient concentration of pasture, and from that we can look at what the likely productivity is. The idea is to then apply fertiliser in a much more precise way than has been done in the past.’

One part of the research involves working out what a fertiliser plan for a farm should look like, and another aspect is investigating how to apply it more accurately: ‘We are trying to gain an understanding of how accurate we can be from planes, by using computer control on the aircraft to switch the fertiliser on and off. This way we can better avoid going over boundaries, and allow for wind.

‘We are doing something similar with Lincoln Agritech, working with a project called Optimum-N. We are supplying them with maps of nitrogen concentration on farms — complete maps of what the nitrogen concentration is within the pasture.’ For this, they use a piece of technology called a hyperspectral imaging system. At every wavelength across the visible and infrared spectrum, an object absorbs and reflects varying amounts of light: this determines its colour and, at the same time, its spectral signature.

‘By working out the subtleties of the signature, we can work out the nitrogen concentration. A urine patch in grass, for example, which contains a lot of

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