Aerial Imaging for Data Collection

August 2015

A new imaging tool is being evaluated for use on hill country by Massey University

An imaging tool used in space exploration and by the military is now being used by Massey University to gain information from the land to help farmers make the best management decisions.  The sensor is flown over land to gather images from more than 450 wave bands including visible, near, short and infra-red. Maps of farms are developed featuring pasture quality, nutrient content and concentration, potassium and sulphur levels, land surface temperatures, areas of poor drainage and nutrient movements on slopes into sinks.

Sensors have been around for some time in agriculture especially in the hands of cropping farmers. The sensors use reflected light to measure crop biomass and chlorophyll content. It captures variability which gives growers information which can be used to adjust inputs like nitrogen.

Crop sensors measure crop canopy and reflectance at specific electromagnetic wavelengths. Vegetative material has a spectral signature and its characteristics differ between healthy and stressed. There are a range of crop canopy sensors on the market – they operate on the same principles but there are differences in the technical setup.

Professor in Precision Ag at Massey University, Ian Yule says remote sensing has tended to focus on the efficient use of nitrogen. This focus has come from a perspective of yield maximisation and increasing nutrient use efficiency. The main reason is that the sensors used have had limited scope.

He says more sophisticated sensors allow the presence of other nutrients and their concentrations to be estimated.

Massey University aerial imaging technology was first developed for military reconnaissance and space exploration. The technology is being used as part of Pioneering to Precision – a Primary Growth Partnership (PGP) programme between Ravensdown and the Ministry for Primary Industries (MPI) looking to improve how fertiliser is applied to hill country.

Ian Yule says involvement in the PGP programme was the catalyst for purchasing the $500,000 Fenix hyper spectral imaging system. He says the remote sensor will enable New Zealand to capture unprecedented levels of data about the nutrient content of large sections of land that may have been previously inaccessible.

He says it’s like turning the whole of New Zealand into a living lab, where you can observe exactly what is going on and describe it in greater detail than ever before.

Ian says the tool can make New Zealand agriculture more efficient, profitable and environmentally friendly. He says it would be a great advantage for accurately applying fertiliser on hill country but also has applications in the dairy sector. The sensor can cover a whole catchment to show where the hotspots are, to help determine where there is nitrogen run-off for example.

The seven-year PGP programme that this sensor will be part of aims to improve hill country sheep and beef farming productivity, while protecting the environment through more efficient application of fertiliser. It is hoped the research conducted using the sensor will help to improve grazing and stock management strategies of hill country farmers because they will have a better understanding of their land and its ecological requirements throughout each seasonal change.

Part of the project is to develop ways to use Geographical Information Systems (GIS) to store, analyse and display the site specific data that is gathered.

The information collected includes soil and sensory data, pasture cuts and other samples which will be used to catalogue the different species and combination species of plants, soil fertility and ecology, grazing management and climatic impacts on pasture production.

Another part of the project is developing hyperspectral remote sensing and imaging technology. The new technology will be used to identify and categorise plant physiology, chemistry and genetic makeup of different plant species.

Researchers are working on methods to extrapolate that data and use it to relate the spectral images to the nutrient needs of different species.  This will help identify the productivity and usefulness of current pasture or terrain and allow researchers to identify any potential problems or risks.

Aircraft-born hyperspectral sensors will be used to take instrument measurements of the pasture. Ian comments that the sensor measures reflectance of the first surface the sensor meets.

It’s hoped that in the future farmers can look at how they can improve pasture production by understanding at what point they need to apply a nutrient to manage a certain species, plant new seedlings or apply fertiliser to support the growth of new pasture.

Another research project which has grown out of the highly accurate data delivered by the sensor is work on developing an automated fertiliser delivery control system that could be applied to a standard aerial topdressing aircraft. The goal is to better predict where a fertiliser particle will land once it is released via an automatic hopper door. This new technology will allow the fertiliser to be dropped via a fully automated process that is linked to an aircraft’s Global Positioning System (GPS) to provide more accurate spreading on hill country farmland.