Remote Sensing  02/25/13 1:45:08 PM

Southern Co-operative Services
Remote Sensing Program in Precision Agriculture
By Dale Cowan - CCA-ON
Senior Agronomist/Sales Manager
Southern Co-operative Services

Precision Agriculture is a management concept based upon the fact that fields are highly variable. It is the idea of capturing that variability, measuring it and coming up with production strategies that hold the promise of improving production practices, yields and ultimately profits.

The initial use of grid sampling and yield monitors gave us a different looks at the variability within the field at a smaller scale, defined the amount of variability and the extent of it across the field landscape.

Capturing and analyzing these various pieces or map layers of information have offered some solutions and at other times caused more questions to be asked. Either way it is progress. Often times knowing the right question to ask can be as important as the answer.

Remote Sensing
Remote sensing by definition is the ability to take a measurement of an attribute or feature of an object from a distance without actual being in physical contact. More specifically in agriculture it involves the use of sensors to take measurements of various aspects of a crop.

AGRIS Co-operative has purchased an UAV (Unmanned Aerial Vehicle) to assist in the capture of aerial imagery. The UAV is small plane with the capacity to carry a standard digital coloured, or infrared camera, on board GPS, gyros for stability and pitot tube for accurate performance measurements.

A completely autonomous unit we can fly single fields at any time with reasonable weather conditions. With custom software we can create field specific flight plans for acquiring images and analyze it post flight. Within a few hours the imagery would be available for viewing and analysis.

The addition of timely data capture can offer another layer of information that may well enhance the soil sampling, fertility, scouting and decisions concerning use of crop inputs or other management factors.

Early Spring – Establishment of Management Zones
In the early spring flying the fields when the snow is gone will reveal the subtle changes in field topography, drainage and soil types. Using either the coloured digital or infrared camera, the captured imagery may well reveal regions that may more closely match crop production patterns.

The result of these images will be to establish management zones. These zones if deemed to be stable year in and year out can be used to acquire future soil samples, guide fertility recommendations, application maps and seeding maps that will be used over and over, a onetime investment to establish management zones.

In Season Imagery- Assessment of crop growth
In crop imagery with the infrared camera is perhaps the most intriguing part of the service. Healthy green tissue reflects back more infrared wavelengths of light. The camera sensor picks up these differences across the field. The captured data can be further analyzed to produce a Normalized Difference Vegetative Index (NDVI).

The resulting map will show distinct areas of more vigorous growth contrasting with those areas of more stressed growth that are reflecting at lower levels. The significance of the NDVI is we can see stresses in a crop likely up to 2 weeks ahead of seeing them with the naked eye. Although we cannot tell what the stress is it does point to troubled areas.
These areas will need a scouting activity to determine the cause of the stress (ground truthing). This may serve to alert growers to developing disease, presence of insects, or nutrient impacts. Regardless of the cause of the stress these areas will show up in the image.

In season opportunities

  • Fly winter wheat fields at green up to assess stand vigour and understand what percentage of the field is under stress.
  • A post-harvest flight to track red clover establishment and use that for variable rate N management next season.
  • Sugar beet fields for signs of stress, however sugar beet tops are high in nitrogen, more vigorous areas may have more N carryover to succeeding crops. Follow up with nitrate soil tests in those areas.
  • Flying fields and plots (OFDs) multiple times in season to track treatments and check strips for micronutrients and fungicide response. Are they working?
  • Check on irrigation patterns and performance in tomatoes and other crops.
  • Fly orchards and vineyards to check at various critical growth stages looking for opportunities and developing problem areas. Are they increasing or getting smaller?
  • Corn and soybean fields at R stages to assess stress and prepare for fungicide applications. Assess variety and hybrid vigour. Which hybrid performs best in which part of the field? (Drive the need for planters that carry more than one hybrid?)
  • Fly soybean fields to determine the extent of SCN and guide sampling for confirmation of SCN population numbers (fly yearly to see impacts of management) Set up to drop SCN resistance varieties in sensitive areas (drills and planters that carry two varieties?)
The pictures below show the progression of image capture and processing that can help define management zones to optimize observations and the wise and judicious use of inputs.

Image from the digital camera: showing definite patterns likely portraying topography and soil type changes. (Images courtesy of Felix Weber)

In Infrared image early season may show areas of greater growth or emergence (more red) and areas of low growth or less bio mass accumulation (less red). Indicating areas in the field to investigate for population, root rots, etc,or any factor limiting crop growth. Knowing the extend or size (acres) of area may faciltate the observations and resulting solutions.

An Image Classification to enhance the data so we can better see areas that are distinctly different.
(green- more vigour, yellow less , red even less growth.

The possibilities of this technology are endless. Early season bare-ground images will reveal differences in topography and soil textures which may be useful in defining management zones for subsequent soil sampling, fertility and seeding maps. In season images with infrared camera will reveal differences in crop growth that may not be visible to the naked eye until two weeks later.

Programs will be available shortly. You will be able to choose the “mission” that is most advantageous to your operation.
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