crop health & ag Mapping
The use of remote sensing, GIS, GPS, and precision agriculture technology is the key to identifying variability and making better crop management decisions.
Crops vary, even within the same field. Precision agriculture technology enables better identification, analysis, and management of this temporal and spatial in-field variability. Precision Ag is all about reducing this variability through more focused and targeted efforts— efforts which should increase production by maintaining crop quality and quantity.
When talking about remote sensing in precision agriculture, we immediately think of sensors and vegetation indices. Vegetation or vegetative index is calculated using different spectral bands, usually depending on what type of plant stress you are trying to visualise. The most commonly known is NDVI (Normalised Difference Vegetation Index).
Crop Health Mapping (NDVI)
As a farmer, you know the ins and outs of your farm, how it breaths, when it thrives, and when it’s in distress. With boots on ground and hand-tending, your eyes are trained to notice every important detail. But what about the things that your eye isn’t trained to see, simply because our human eye can’t see certain wavelengths? And what if those wavelengths tell an invisible story about your farm health?
Understanding your crops’ health status isn’t the easiest thing to do. Sure, you can use the “eye test”. But, what if there was an easy, fast and efficient way to see the health of plants and their status and progress over time? That’s where Normalized Difference Vegetation Index (NDVI) data comes in.
NDVI is a measurement of plant health based on how a plant reflects light (usually sunlight) at specific frequencies. Multispectal sensors detect indicators invisible to the naked eye, utilising light reflections and absorptions to calculate an NDVI score. Healthy plants absorb most of the visible light while reflecting a large amount of the near-infrared light. Unhealthy plants do the opposite. NDVI is an extremely helpful tool to assess plant health, and understanding it is important.
This scan shows the extent of the vineyard affected by the roots from the gum trees bordering the vineyard block. The area extents some 7 to 8 rows into the vineyard, and shows the need for management decisions to be made to remedy the problem.
This NDVI scan identified significant areas of broken canopy throughout the block. This level of dead or unproductive vines will significantly affect the yield. This will eventually lead to a block where the inputs will outweigh the production value.
Detection of an irrigation leak in a vineyard. This section was about 40 metres in from the end of the row, and was difficult to see even when close to the actual leak. Note, that is leak was a complete break in the irrigation line. Not only was water being lost, but the rest of the row was stressing from lack of water.
Reasons why you should collect aerial data in Vineyards
Aerial imagery can be such a valuable visual tool throughout the entire course of the growing season, from bud burst to harvest. NDVI mapping can be used for identifying areas of concern in regard from nutrient deficiencies, irrigation and cover crop management, to disease and pest control.
1. To monitor impact of vineyard management practices
Collecting data multiple times across the growing season allows growers to track the progress of their vineyard and monitor the impact of their vineyard management practices. Adjust your applications and efforts to achieve the desired vigor levels, making adjustments according to results.
2. To detect issues before they become problems
Aerial imagery provides growers with the ability to identify areas of concern before they are visible to the naked eye, and take the necessary action. An area of high vigor may indicate a water leak, or an area of low vigor may be caused by nutrient deficiency or disease.
3. To make changes sooner
There are critical points in the growing season when the fruit is developing and maturing, and the result of this process can dramatically affect the taste, acidity, and overall quality of the grapes produced. Monitoring your vineyard in such an efficient and time effective manor allows you to make decisions quicker to ensure you are optimising the quality and yield of your vineyard.