Vegetation Index: How Is It Used in Precision Agriculture?

What Is Vegetation Index (VI)?

Workings of Vegetation Indices: How Are They Measured From Space?

  1. Green cover percentage
  2. Leaf area index
  3. Green biomass
  4. Chlorophyll content
  5. Absorbed photosynthetically active radiation (APAR), etc., to derive conclusions.
  1. Blue (450 nm-510 nm)
  2. Green (510 nm-580 nm)
  3. Red (630 nm-690 nm)
  4. Near-infrared (NIR) (770 nm-895 nm)
  5. Short wave infrared (SWIR) (1100 nm-3000 nm)

The Application of Vegetation Index in Precision Agriculture

  • Physicochemical monitoring: Parameters like greenness, chlorophyll proxy, temperature, evapotranspiration, and soil moisture are derived, which can be further used to leverage optimal plant growth.
  • Near-real-time data: It helps offer near-real-time data of a plot or a region to stay updated about the essential parameters without paying a physical visit. It saves time and effort of investigation before taking a management call. Using this real-time data is also helpful to ensure timely actions and take a step forward to the expected crop quality.
  • Farm activity planning: With VI, the timing of sowing, spraying, crop protection, irrigation, harvesting, and other activities can be determined optimally. With information like this, one can take timely calls to optimise input and resource usage as well.

Examples of Vegetation Indices

NDVI (Normalized Difference Vegetation Index)

NDVI = (NIR-Red) / (NIR+Red).

Source: Phenospex

NDRE (Normalized Difference Red Edge)

NDRE = (NIR-RedEdge) / (NIR+RedEdge)

Source: EOS

VHI (Vegetation Health Index)

Source: FAO

LAI (Leaf Area Index)

LAI = leaf area / ground area, m2 / m2

Source: Land Products Validation and Characterisation in support to Proba-V, S-2 and S-3 mission

EVI (Enhanced Vegetation Index)

EVI = 2.5 * ((NIR — Red) / ((NIR) + (C1 * Red) — (C2 * Blue) + L))

Source: CAESCG, CC BY-SA 4.0, via Wikimedia Commons

GRVI (Green Ratio Vegetation Index)

GRVI = (Green — Red) ÷ (Green + Red)

NBR (Normalized Burn Ratio)

NBR= (NIR — SWIR) / (NIR + SWIR)

Woodbury Fire burn scar, GOES-17 NBR 1936 UTC 1 July 2019 (left), S-NPP NBR 1936 UTC 1 July 2019 (right), along with 2019 Fire Perimeters (black outlines). Source: Wide World of SPoRT

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