Decision guides · Citrus (Nagpur mandarin)
What is satellite farming? What a satellite sees in your orchard, and what it cannot
A satellite is a camera in the sky. A few pass over India every 5 days and their images are free. One tree is not visible, but whether a block of the orchard changed since last week is. That is what we tell you on WhatsApp every week. Under cloud, we say so.
Last checked (AI-assisted): 15 Oct 2026. Checked on 15 Oct 2026 against published ICAR, state agricultural university and FAO guidance with AI assistance. Not yet reviewed by an agronomist or tested with farmers. No spray, pesticide, fertiliser or irrigation amount is given here; for those, test your soil and ask your KVK or an agronomist.
Where the images come from
Two satellites called Sentinel-2 pass over the same place every 5 days; one 10 m by 10 m patch is one point in the image, about 40 points to an acre. NASA's HLS and Europe's Sentinel-1 (radar) are complementary sources.
Public agencies provide these images free. That is why Watch can be free.
How greenness is measured from an image
Green leaves absorb red light and reflect another light the eye cannot see. The ratio of the two gives a 'greenness index' (NDVI) between 0 and 1; dense healthy trees score higher.
VarshaKrishi computes this number for your orchard in every image and compares it with your orchard's own earlier numbers. Not with the neighbour's, with your own.
What it sees
Whether orchard greenness rose or fell. Which block differs from the rest. In the monsoon, an estimate from radar of whether water is standing. Water stress, but only once it shows on the leaves, which is a little late.
What it does not see
One tree, one branch, one fruit. Insects, fungus, disease marks. Soil moisture (that is checked on the ground). Anything under cloud. In an orchard under half a hectare, only a coarse trend.
So the satellite does not replace walking the orchard; it is a helper that says where to look this week.
What the weekly message contains
One of four states: Watch (something changed, check), No reliable signal (cloud), Baseline building (new orchard), and, only in Decide after agronomist review, Act (for example irrigate). Every message carries the image date and the source.
What to check in your field or orchard this week
- Have you sent your orchard's location on WhatsApp? (without it no image can be linked)
- How old was the image date in the last message?
- Did you walk to the block the message pointed at?
A Watch message says only what changed and what to check. It never names a product, a fertiliser or an irrigation amount.
Questions
Will the satellite find my orchard?
Yes, once you send the location (a pin or the boundary). A wrong location means the neighbour's orchard gets measured, so check it carefully.
Who sees images of my orchard?
The images are from public satellites; anyone can see them. Your name, phone number and orchard location we share with no one without your consent.
Is this AI?
We do not use the word. Greenness numbers come from standard formulas (NDVI, FAO-56) and every message names its source. All the formulas are on the methods page.
Want a weekly message for your field?
Call us to join. Free to watch. What changed in your field or orchard, every week, with the date and the source.
Sources
- European Space Agency: Sentinel-2 mission (10 m optical imagery, revisit about 5 days) · sentinels.copernicus.eu/web/sentinel/missions/sentinel-2
- NASA Harmonized Landsat Sentinel-2 (HLS) product · hls.gsfc.nasa.gov/
- European Space Agency: Sentinel-1 mission (radar, sees through cloud) · sentinels.copernicus.eu/web/sentinel/missions/sentinel-1
- Rouse et al. (1974): the NDVI vegetation index · ntrs.nasa.gov/citations/19740022614
More guides
- Nagpur orange bahar management: ambia or mrig, when to stress, when to water
- How much water does an orange tree need? When to irrigate Nagpur orange
- Drip irrigation for orange trees: a month-by-month schedule
- Citrus fruit drop: causes, and what to check first
- Why citrus leaves turn yellow: read the pattern, find the cause, then act
- What are ambia and mrig bahar? Choosing the right one for your orchard
- Water stress: the sign on the tree, the sign in the soil, the sign from the satellite
- Nagpur orange season: when to harvest ambia and mrig fruit
- Weather and irrigation: how the five-day forecast changes the watering schedule
- Ambia bahar orange crop insurance in Maharashtra: what it covers, who can enrol, how to apply
- Nagpur orange planting (santra lagwad): soil, spacing, pit size, rootstock and planting time
- Nagpur orange fertiliser (santra khat vyavasthapan): what to ask your KVK before you apply
- Nagpur orange season and GI tag: when ambia and mrig bahar fruit reach the market
- How to see a satellite image of your own field for free: Copernicus Browser, NASA Worldview and ISRO Bhuvan
- NDVI full form and meaning: what NDVI is and what it tells you about an orange orchard
- Cotton in Vidarbha: what to check, and when, from sowing to picking
- Soybean in Vidarbha: what to check, and when, from sowing to harvest
- Tur (pigeonpea) in Vidarbha: what to check, and when, from sowing to harvest
- Chana (chickpea) in Vidarbha: what to check, and when, from sowing to harvest
How we compute this and what the limits are: the methods page