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Agritech topic 07 of 14

DRONES, SATELLITES AND REMOTE SENSING

Agricultural Drones

An agricultural drone is an unmanned aerial vehicle used to collect images, survey fields or perform selected agricultural operations.

Types of agricultural drones

RGB-camera drones

Capture conventional photographs and videos. They are useful for field inspections, crop establishment checks, drainage observations and documentation.

Multispectral drones

Capture selected wavelength bands, including visible and near-infrared light. Their imagery can help assess crop vigor and identify areas requiring field inspection.

Thermal-camera drones

Measure apparent surface temperatures and can help investigate selected crop-water or heat-stress patterns.

Spraying drones

Carry and distribute approved agricultural liquids. Their effectiveness depends on product suitability, droplet characteristics, flight height, wind, crop structure and operating conditions.

Common applications

  • Crop stand assessment.
  • Detection of visible crop stress.
  • Mapping field boundaries.
  • Identification of damaged or flooded areas.
  • Orchard and plantation surveys.
  • Selected precision-spraying operations.
  • Monitoring difficult-to-access fields.

Limitations and safety considerations

A drone image does not automatically identify the cause of crop stress. Nutrient deficiency, water stress, disease and other problems may produce similar visual symptoms.

Drones also require trained operators, maintenance, safe battery handling and compliance with applicable aviation, privacy and agricultural chemical regulations.

Drone spraying must follow approved product labels and safety procedures. Operators should prevent spray drift, protect nearby people and sensitive areas, and avoid unsafe operations around electrical lines or aircraft.

Practical example

A farmer growing cotton in Punjab obtains aerial images of a field showing uneven crop growth.

The images identify several areas for inspection. The farmer visits those areas and checks soil moisture, plant roots, nutrient status and insect pressure before deciding on corrective action.

In this example, the drone improves the speed of scouting, while the final diagnosis relies on field observations and agronomic knowledge.

Satellite-Based Agriculture

Satellite imagery provides repeated observations of land and crop conditions over large geographical areas.

Important satellite data sources

  • Sentinel-2: optical imagery useful for vegetation monitoring and field analysis.
  • Landsat: long-term satellite observations useful for land and crop studies.
  • Sentinel-1: radar imagery that can provide information under cloudy conditions.
  • Commercial high-resolution satellites: may provide more detailed imagery, usually subject to licensing or service fees.

Vegetation indices

Vegetation indices are calculations based on satellite or sensor measurements.

The Normalized Difference Vegetation Index (NDVI), for example, uses red and near-infrared reflectance to estimate vegetation greenness and vigor.

NDVI can help identify differences in crop growth, but it is not a direct measurement of yield or plant health.

Other indices, including NDRE, may be useful for particular crops, growth stages and sensor configurations.

Applications in Pakistan

Satellite-based monitoring can support:

  • Regional crop-area estimation.
  • Crop-growth assessment.
  • Flood and drought monitoring.
  • Orchard and plantation mapping.
  • Agricultural land-use analysis.
  • Irrigation planning and research.
  • Large-scale agricultural insurance assessments.

Satellite monitoring is particularly useful for large areas, but its practical value depends on image resolution, cloud cover, revisit frequency, crop stage and the availability of reliable ground observations.