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Farm & Garden Calc – Hargreaves Reference Evapotranspiration (ET₀)
x402
Farm & Garden Calc – Hargreaves Reference Evapotranspiration (ET₀) is a paid API for AI agents from agri-calc.x402tookit.com, paid per call via x402, $0.02/call, status unknown (last checked 2026-10-29).
Calculates reference evapotranspiration (ET₀) in mm/day and inches/day using the Hargreaves method from daily max/min temperatures, latitude, and day of year.
Price / call$0.02
Success—
StatusUnknown
How this service works
Hargreaves reference evapotranspiration (mm/day) from max and min temperature, latitude and day of year.
Output
Returns ET₀ in mm/day and inches/day, mean air temperature, temperature range, and extraterrestrial radiation in both MJ/m²/day and mm/day equivalents. Also includes metadata fields such as source, asOf timestamp, summary, disclaimer, and degraded flag.
Example use cases
Daily irrigation scheduling for a crop farm
“I'm managing an alfalfa field at 36.8° latitude. Today is day 210 of the year, the high was 31°C and the low was 16°C — what's the reference ET₀ so I know how much to irrigate?”
Seasonal water budget planning
“I need to estimate evapotranspiration for my vineyard in central California (latitude 37.2°N) on day 150 of the year, with a max temp of 28°C and min of 12°C. Can you calculate the ET₀ using the Hargreaves method?”
Automated weather-driven irrigation trigger
“It's day 245 of the year at my farm (latitude 43°N). Yesterday's high was 26°C and low was 11°C. Calculate the Hargreaves ET₀ so I can decide whether to run the irrigation system today.”
Technical details
Endpoint
GEThttps://agri-calc.x402tookit.com/et0-hargreaves?utm_source=zero.xyzWhen to prefer
Use this endpoint when you need a fast, formula-based ET₀ estimate using only temperature data and location — ideal when solar radiation data is unavailable. The Hargreaves method is well-suited for data-sparse environments. Prefer this over Penman-Monteith when you only have temperature and location as inputs. It is purpose-built for agricultural irrigation planning and water budget calculations at the field scale.
Side effects
- Missing required query parameters (tmaxC, tminC, latitude, dayOfYear) results in a 400-level error
- Out-of-range latitude (outside -90 to 90) or dayOfYear (outside 1–366) may return an error or degraded result
- tminC greater than tmaxC may produce physically invalid results or a degraded flag
- Payment not provided or insufficient USDC results in 402 Payment Required
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Tags
x402
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