UNIT 3 – REMOTE SENSING AND GEOSPATIAL ANALYSIS

Unit 3 – Remote Sensing & Geospatial Analysis

1. What remote sensing means in agriculture

Remote sensing helps farmers identify, describe, and monitor what is happening in their fields without being physically present.

It refers to collecting data from a distance using sensors on satellites, drones or aircraft. “Remote sensing refers to collecting data about the Earth from a distance using sensors on satellites, drones or aircraft.”

These sensors measure how surfaces reflect or emit light. Farmers can analyse this information to:

·       Monitor crop growth

·       Detect stress early

·       Observe large areas quickly

·       Apply better management decisions

In agriculture, remote sensing helps farmers monitor crops over large areas without stepping into every field.

2. Understanding NDVI (Normalized Difference Vegetation Index)

NDVI is one of the most widely used vegetation indices in agriculture. It helps farmers explain, compare, and analyse crop health.

NDVI works by comparing:

·       Red light (absorbed by healthy plants)

·       Near‑infrared light (NIR) (reflected by healthy plants)

Healthy green plants reflect more NIR light and absorb more red light; stressed or sparse vegetation reflects less NIR.

NDVI values and what they mean

NDVI ranges from –1 to +1:

·       Below 0 → water, clouds

·       Around 0 → bare soil

·       0.1–0.5 → sparse vegetation

·       Above 0.6 → dense, healthy vegetation

These values help farmers identify problem areas and apply targeted actions.

How NDVI Supports Farm Decisions

NDVI helps farmers identify, describe, explain, and analyse what is happening in their fields. It turns satellite or drone data into simple indicators of crop health.

1. Detect crop stress

NDVI allows farmers to identify areas where crops may be stressed by drought, pests or disease.

·       Compare current NDVI with historical averages

·       Spot areas where vegetation is below normal

·       Explain possible water stress or early damage

2. Monitor growth stages

NDVI helps farmers track how crops develop over time.

·       Rising NDVI → vegetative growth

·       Peak NDVI → flowering or grain filling

·       Declining NDVI → maturity or stress

This supports better planning and timing of field operations.

3. Estimate yields and biomass

NDVI values relate to leaf area and photosynthesis. Farmers can analyse NDVI patterns to:

·       Estimate biomass

·       Predict potential yields

·       Apply targeted management where needed

4. Prioritise field visits

Because remote sensing covers large areas quickly, farmers can:

·       Identify which fields need attention

·       Target scouting

·       Plan interventions more efficiently