Satellite Imagery & NDVI Mapping Applications for Agriculture
NDVI: WHAT IS IT?
Satellite imagery and its use in modern farming systems is becoming increasingly common. The following collections of maps and images aim to show how one particular use, normalised difference vegetation index (NDVI) imagery, can be interpreted and applied to agriculture.
NDVI images are used to assess the amount of live green vegetation (biomass) contained within a target area. Higher values indicate more biomass and vigour. NDVI imagery can detect slight differences in pasture or crop growth within a paddock.
Learn about multi-spectral imagery…
NDVI: A PADDOCKS PERFORMANCE IN ONE IMAGE
NDVI values can act as a proxy for actual yield and give farmers an excellent indication of areas of high, average and low yield, as well as pasture production, within a paddock or across multiple paddocks (GRDC, 2015 & Lopresti et.al. 2015).
While NDVI maps are not the same as yield maps, they can provide very accurate indications of various aspects of crop growth, nutrition and stress, and may indicate problems which are not detectable using yield monitor data alone. Unlike yield monitor data, remote measurements of crop vigour can also be obtained mid-season, allowing acute problems to be detected and addressed while there is still time.
The outcome of a single season can be greatly improved if suitable mid-season decisions are made in a timely manner. Consider the following example showing a paddock of forage brassica. Based on an NDVI image of the paddock – it is apparent that a significant portion (bottom left of image) of the brassica isn’t performing as well. This section was impacted by significant overland water flow resulting in nitrogen deficiencies. The landowner could consider top dressing, as well as contour banks, to improve this area.
NDVI: WHAT’S YOUR CROP TELLING YOU?
NDVI mapping was used to assess a wheat crop grown in the Grenfell area during 2016. NDVI data taken of the paddock “W5” in early August showed areas of poor, average and above average vigour.
Using the map as a guide, site inspections, which included taking photos, were undertaken in August and again in October. The photos show that the NDVI values accurately reflect the varying condition of the crop in early August, with these conditions being maintained through to late October and ultimately harvest.
The 2016 growing season was exceptionally wet, and as a result many areas of the paddock were negatively affected as a result of drainage and yielded poorly whilst well-drained areas, on the other hand, yielded well.
NDVI: UTILISE +15YRS OF DATA—ZONE YOUR PADDOCKS
Variation in crop yield and pasture production within individual paddocks is affected by a range of factors including soil type, nutrient status, drainage, aspect, slope, elevation and the presence of trees and windbreaks.
The best management decisions for a paddock are based on long-term performance trends. Analyses of +15yrs. worth of NDVI imagery allows paddocks to be divided into zones based on their capability and enables the farmer to determine the cause of the variation (field investigations, soil tests) and develop suitable, targeted, management strategies for each zone.
NDVI: UTILISE +15YRS OF DATA—ZONE A SHIRE
Historical NDVI imagery of the WEDDIN LGA and adjacent LGA’s, taken during the peak of the growing season – late August to early October from 1999 until 2016, has been analysed to determine the extent and type of farming practices undertaken throughout the WEDDIN LGA and adjacent LGA’s.
Click the INTERACTIVE MAP PORTAL icons to view median NDVI values during the peak growing season throughout the WEDDIN LGA and adjacent LGA’s and identify the most productive parts of your area.
NDVI: MINIMISE WASTE & MAXIMISE PROFITS
A map showing the average September NDVI values for wheat was generated for the paddock “S1”. Two distinct zones were identified (Zone 1 & 2) with the variation in NDVI attributed to differences in drainage, pH and soil structure.
Limitations were identified with soil tests and agronomic advice used to determine ideal management strategies for each zone
NDVI imagery can be viewed whilst in the paddock through your mobile or tablet. If there is an area of land that you would like an NDVI image for please contact me through the website. To speed up the process you can use Google Earth to create a KML polygon outlining your target area.