Getting the most out of the drone on your farm

Tuesday, March 8, 2016

The value of owning an unmanned aerial system is in direct proportion to what you find, what you can evaluate, what you can understand and what you can fix that increases revenue.

by DALE COWAN

Reports from retailer associations from the past Christmas season indicated that approximately one million unmanned aerial systems (UAS), commonly known as drones, were purchased over the holiday season and given as gifts in North America. Maybe you were one of them?

Most drones sold were small (under 0.5 kilograms) and easily connected to your smart device. Within five minutes of opening the box, you were annoying the dog, the cat and the neighbours, and bouncing it off hydro lines, cars and your house. I witnessed my neighbour's eight-year-olds try to fly one on the front lawn on Christmas morning in their pajamas and with no adult supervision. This surely will be a source of heartburn for Transport Canada and eventually for all serious users of drone technology.

Assuming you still have one operational by spring and you are a farmer, what will you do with it in the cropping season? The first thing you will do is to visit the Transport Canada website and understand what you need to do to gain approval to fly one even on your own property. What are your obligations to obtain a Special Flight Operation Certificate (SFOC) and what rules must you adhere to?

Most small drones are quad copters with limited range. Each drone connects to a smart phone device with its own Wi-Fi signal. Cheaper models may have a range of 200 metres or less, which means that, once you are more than 200 metres from your drone, you may no longer have control of it. Some drones have a feature that causes them to stay stationary or return to the launch point if they lose connection.

The more expensive models costing up to $2,000 can have a range of up to two kilometres. With these you can do some serious in-crop scouting. Most of these UAS devices will have come with a standard colour, high-definition video recorder, allowing an operator from the edge of the field to fly quickly over for a general observation and observe a host of field features.

Things like drainage, drowned spots in wheat fields and nutrient issues will be clearly visible on the smart device and be recorded as a video or using the still image option to capture areas of interest for further review. After reviewing the video, the operator has the option to go and look in person at the areas of interest. Two things are obvious here.

First, the view from above is always more revealing. You can find areas sooner than you would if you had walked the field and you will see things that you may well have missed on a walk-through. Secondly, once you navigate to the areas of interest, you can start to apply some agronomic knowledge. What happened here – tile blow out, winterkill from ponding water, fertilizer plug-up on the starter fertilizer applicator, erosion, weed control issues, soil compaction? Awareness that problems exist is the first step to better management decisions.

Now let's assume you have stepped up and bought a UAS with a price tag approaching $10,000. You most likely have bought a high-end sensor, such as a near-infrared camera or a multispec sensor or considered thermal imaging. Either fixed wing or rotary, these units have more sophisticated flight controls, come with mission-planning software and may come with processing software.  Most will capture a series of overlapping images from a digital-type sensor (camera) that will require processing before they can be viewed. This process involves ortho-correction – aligning the images and taking out distortion caused by movement during flight, such as pitch and roll that distorts camera angle and therefore image quality. It then mosaics the overlapping images into one picture.

The files can be quite large, often exceeding 300MB, and further manipulation to get to a manageable file size is another step. Once this is done, then often the appropriate file format can be brought into a Geographic Information System (GIS) for further analysis.  

One of the most common analysis performed when crops are fully canopied is an NDVI, Normalized Difference Vegetative Index. The scanners on the UAV that are used to produce an NDVI capture both red and near infrared wavelengths of light reflectance.  The resulting map will indicate areas with different amounts of plant biomass based on reflectance values indicating more chlorophyll or greenness and more plant growth or vigor represented by higher NDVI values. These differing values on a map can be used to represent areas in the field where crops are growing well contrasted to areas where they are not. It will direct your attention to those areas for further analysis. It does not however offer any explanation as to why the crop growth is the way it is. That requires knowledge of the field, other growth factors and management input for interpretation. These maps can be assumed to represent areas in the field where crops are growing well, contrasted to areas where they are not. It will direct your attention to those areas for further analysis, but it does not offer any explanation as to why the crop growth is the way it is. That requires knowledge of the field, other growth factors and management.

Alternative web based analysis services have emerged where you can send your final mosaic image for further processing. You will need to understand that these are analysis based services and very good ones and often times offer no or very little interpretation of your image. They do not know you. It is important to avoid disappointment and to manage your expectations before you spend the money to know the difference between analysis and interpretation.

Some of the most recent offerings provide analysis of plant population on rowed crops, such as corn or tomatoes. An early-season image of the field, where plants in the row are not yet touching, can be put through an object-based logarithm to recognize and count plants, giving final populations per acre. Another service can do plant height evaluations and detect unevenness in crop height across the field. Again, neither will tell you why, but can help you ask the right questions and evaluate the most relevant activity that may have caused the differences.

In the case of plant population, this means checking the planter performance, secondary tillage practices and soil conditions. In the plant height tool, look at root diseases or drainage issues. If the crop is soybeans, look at soybean cyst nematode for example.

UAS devices are another tool in the farmer's toolbox.  The value of owning a UAS is in direct proportion to what you find, what you can evaluate, what you can understand and what you can fix that increases revenue.  Whichever service provider you choose, online or local, take the time to understand what is being offered and give some thought to how and maybe who will help interpret what you find. Web based services include AgPixel (www.agpixel.com) and Datamapper (https://www.datamapper.com/algorithms). BF

Dale Cowan is a Certified Crop Adviser in Ontario and the Senior Agronomist and Sales Manager for Agris and Wanstead Co-operatives, located in southwestern Ontario.