# Entressafra

> Decision-support tool for family farmers in Santa Catarina, Brazil: it suggests which crops to plant between two main-crop seasons to protect the soil while still producing something to sell, eat at home or feed animals. NASA Space Apps Challenge 2026 project, challenge "Field Shift: Adapting Farms with NASA Data". The interface is available in English and Portuguese.

## How it works

- The farmer marks the field on a map (a point or the field outline) and picks the main crop: tobacco, onion, corn, soybean, irrigated rice or garlic.
- The app fetches daily NASA POWER climate data from 1995 to today for that location and NASA SRTM 30 m terrain.
- For each of 29 candidate crops it simulates every past season: growing degree days to harvest, a daily water balance (simplified FAO-56, Hargreaves ET0), frost, heat at flowering, waterlogging, rain at harvest, and whether the crop finishes before the next main-crop planting.
- The final chance blends all seasons with the 10 seasons whose recent rainfall and soil moisture are most similar to today.
- Terrain adjusts temperature by elevation (−0.65 °C per 100 m) and frost risk by position (lowland, slope, hilltop; north- or south-facing).
- It shows the top 3 options with planting and harvest periods, what the crop provides, "worked in X out of 10 years", reasons to plant it, a caution, the follow-up crop and the seed needed for the drawn area, plus a list of crops to avoid.

## Data sources

- NASA POWER (max/min temperature, corrected precipitation, root-zone soil moisture): https://power.larc.nasa.gov/
- NASA SRTM 30 m, via OpenTopoData: https://www.opentopodata.org/datasets/srtm/
- Terrain fallback: Copernicus DEM 90 m via Open-Meteo
- Maps: OpenStreetMap and Esri World Imagery
- Crop catalog: approximate reference values (FAO-56, Embrapa, Epagri), to be validated by local agronomists

## Limitations

- Proof of concept: crop parameters are reference values and need local agronomic validation.
- NASA POWER has a grid of about 50 km; SRTM terrain corrects part of the local effect.
- Does not yet include El Niño/La Niña, prices, costs or Brazil's official agricultural zoning (ZARC).
- The tool supports the decision; the farmer and the local agronomist decide.

## Links

- App: https://entressafra.pages.dev/
- Challenge: https://www.spaceappschallenge.org/2026/challenges/adapting-farms-with-nasa-data/