Climate
Cold winters, hot dry summers
A regional condition potentially favourable to the pistachio cycle, subject to parcel-level validation.
Location
Territory and location
An Iberian inland farming context, with a tradition of permanent crops and a contrasted climate.
Carviçais · Torre de Moncorvo · Douro Superior · Portugal
Farming tradition
Almond · olive · vine
The municipality stands out for permanent crops and Mediterranean microclimates.
Infrastructure
Water and electricity available
An advantage reported by the promoters; flow rate and quality must be confirmed in due diligence.
Iberian position
Inland Portugal, close to Spain
Potential to connect Portuguese production to Iberian technical know-how, processing and commercial channels.
The parcels
Three parcels measured over orthophotography. The names are internal; the definitive land registry will be confirmed in due diligence.
| Parcel | Area (ha) | Elevation (m) | Perimeter (m) |
|---|---|---|---|
| I — Airstrip land | 11.76 | 458 | 2,393 |
| II — South | 18.11 | 430 | 1,846 |
| III — East | 20.09 | 380 | 1,804 |
| Land assembled | 49.96 |
Orchard planned 40 ha
Margin available +10.0 ha
Elevation range 78 m
380–458 m
Distance between extremes 6.2 km
The land assembled exceeds the planned orchard by about 10 ha. That margin absorbs tracks, headlands, the reservoir and farm buildings without eating into planted area — and leaves room for scrub that is not cleared.
Geographic setting
Base cartography: OpenStreetMap
Climate, ten years of record
Daily temperatures from the ERA5-Land reanalysis at the centre of each parcel, from 2016 to 2025, adjusted to the elevation the terrain model gives the land. This is the record that was missing to answer the two questions that decide the crop: whether winter chill accumulates and whether late frost threatens flowering.
- Source
- Reanálise ERA5-Land (ECMWF), através do arquivo histórico da Open-Meteo · 2016–2025
Chill hours per winter 1,137–1,168 h
Decade average, below 7.2 °C from November to February
Weakest winter on record 869 h
What decides whether the cultivar breaks bud: no year fell below what Kerman needs
Growing degree days 1,998–2,118
Base 10 °C, April to October
Years with frost after 15 March 2 / 10
Across ten years of record
Seasonal averages
| Parcel | Winter | Spring | Summer | Autumn | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Lows | Mean | Highs | Lows | Mean | Highs | Lows | Mean | Highs | Lows | Mean | Highs | |
| I — Terreno da pista | 3.2 | 7.1 | 11.5 | 7.6 | 13.0 | 18.4 | 16.5 | 23.2 | 29.7 | 10.6 | 15.4 | 20.5 |
| II — Sul | 3.8 | 7.6 | 12.1 | 8.2 | 13.6 | 19.0 | 17.1 | 23.8 | 30.3 | 11.2 | 16.0 | 21.0 |
| III — Nascente | 3.6 | 7.4 | 11.8 | 8.0 | 13.4 | 18.8 | 17.1 | 23.7 | 30.3 | 11.0 | 15.7 | 20.7 |
Decade average for each season, in degrees. The middle column is the mean of daily temperatures; the others average the highs and the lows.
Accumulated chill, winter by winter
Year by year
| Year | I — Terreno da pista | II — Sul | III — Nascente | Growing degree days | Late frosts | Last frost | Extremes |
|---|---|---|---|---|---|---|---|
| 2016 | 1,214 h | 1,217 h | 1,295 h | 1,912 | 0 | — | -2.2 / 39.4 |
| 2017 | 1,297 h | 1,320 h | 1,382 h | 2,172 | 1 | 2017-03-25 | -4.0 / 39.4 |
| 2018 | 1,200 h | 1,095 h | 1,207 h | 1,904 | 2 | 2018-03-22 | -2.4 / 40.8 |
| 2019 | 1,176 h | 1,205 h | 1,179 h | 1,897 | 0 | — | -3.1 / 37.8 |
| 2020 | 1,094 h | 998 h | 1,073 h | 1,965 | 0 | — | -3.3 / 38.8 |
| 2021 | 1,374 h | 1,234 h | 1,293 h | 1,813 | 0 | — | -3.6 / 37.7 |
| 2022 | 1,193 h | 1,189 h | 1,239 h | 2,246 | 0 | — | -2.5 / 42.3 |
| 2023 | 874 h | 880 h | 869 h | 2,087 | 0 | — | -2.6 / 39.6 |
| 2024 | 1,027 h | 1,060 h | 997 h | 1,895 | 0 | — | -2.1 / 39.2 |
| 2025 | 1,141 h | 1,173 h | 1,141 h | 2,092 | 0 | — | -3.3 / 39.7 |
What the record shows
Winter chill arrives, with room to spare
The three parcels accumulate between 1,137 and 1,168 chill hours per winter, against the roughly 800 Kerman requires to break bud reliably. Even the weakest winter of the decade stayed above that requirement on all three, at 869 to 880 hours. This is the requirement that most often rules pistachio out in the southern Iberian Peninsula, and here it is settled.
Late frosts all fell before flowering
Frost after 15 March occurred in 2 of the ten years, and always during March. None in April, which is when pistachio flowers at this latitude. The risk is real and should not be dismissed, but ten years of record show no episode catching open flower.
Summer supplies the heat for ripening
Between 1,998 and 2,118 growing degree days from April to October, with summer highs averaging 29.7 to 30.3 °C. Pistachio needs hot, dry summers to fill and split the nut, and that is what these parcels offer.
Extreme heat is real and has to be irrigated
The record shows absolute highs of 41.3 to 42.3 °C. Pistachio tolerates them better than almost any other fruit crop, but in years like those the irrigation allowance stops being a comfort and becomes what separates a harvest from a shortfall.
Soil and water
Soil profile from SoilGrids and a water balance computed over the same ten years as the temperature record. It replaces neither laboratory analysis nor a measured flow rate, but it says enough to steer rootstock choice, ground correction and irrigation sizing.
- Soil source
- SoilGrids 2.0 (ISRIC — World Soil Information), grelha de 250 m
- Climate source
- Reanálise ERA5 (ECMWF), através do arquivo histórico da Open-Meteo · 2016–2025
Soil pH 5.7
Pistachio prefers 7.0 to 7.8: this soil is acidic and calls for liming
Dominant texture franco-arenoso
Free drainage, which pistachio demands — and little stored water
Coarse fragments 32 %
Schist substrate: it cuts the volume of soil the roots can work
Available water reserve 70 mm
Under five days of autonomy in the peak month
Soil profile
| Parcel | Depth | pH | Clay | Silt | Sand | Stones | Organic C | CEC |
|---|---|---|---|---|---|---|---|---|
| I — Terreno da pista | 0-5cm | 5.6 | 13 % | 33 % | 55 % | 30 % | 70.4 | 23.9 |
| 5-15cm | 5.6 | 12 % | 34 % | 54 % | 36 % | 22.4 | 20.8 | |
| 15-30cm | 5.6 | 17 % | 30 % | 53 % | 34 % | 29.9 | 20.3 | |
| 30-60cm | 5.7 | 20 % | 30 % | 51 % | 32 % | 17.8 | 18.5 | |
| 60-100cm | 5.8 | 20 % | 29 % | 51 % | 32 % | 11.4 | 18.1 | |
| II — Sul | 0-5cm | 5.6 | 14 % | 31 % | 55 % | 31 % | 73.0 | 22.5 |
| 5-15cm | 5.6 | 13 % | 33 % | 55 % | 36 % | 21.9 | 19.0 | |
| 15-30cm | 5.6 | 16 % | 29 % | 54 % | 34 % | 28.8 | 18.9 | |
| 30-60cm | 5.7 | 19 % | 29 % | 52 % | 32 % | 16.7 | 17.7 | |
| 60-100cm | 5.8 | 18 % | 29 % | 53 % | 32 % | 12.0 | 17.8 | |
| III — Nascente | 0-5cm | 5.7 | 15 % | 34 % | 51 % | 29 % | 97.0 | 26.3 |
| 5-15cm | 5.7 | 15 % | 35 % | 51 % | 32 % | 39.1 | 20.9 | |
| 15-30cm | 5.7 | 18 % | 32 % | 50 % | 31 % | 43.3 | 18.7 | |
| 30-60cm | 5.7 | 20 % | 31 % | 49 % | 32 % | 17.5 | 17.7 | |
| 60-100cm | 5.7 | 20 % | 29 % | 51 % | 33 % | 11.6 | 16.2 |
Averages weighted by horizon thickness, down to one metre. Texture refers to the fine fraction; stones are the share of volume taken by coarse fragments.
Average water year
Rainfall covers the winter and is missing exactly when the tree grows. July brings 9 mm against 191 of reference evapotranspiration.
| Month | Rainfall | Usable | ET₀ | Kc | ETc | Irrigation |
|---|---|---|---|---|---|---|
| Jan | 67 | 54 | 30 | — | — | — |
| Feb | 51 | 41 | 45 | — | — | — |
| Mar | 71 | 56 | 73 | — | — | — |
| Apr | 68 | 54 | 100 | 0.45 | 45 | — |
| May | 41 | 33 | 138 | 0.70 | 97 | 64 |
| Jun | 33 | 26 | 156 | 0.95 | 149 | 123 |
| Jul | 9 | 7 | 190 | 1.10 | 209 | 202 |
| Aug | 7 | 5 | 173 | 1.05 | 182 | 177 |
| Sep | 34 | 27 | 114 | 0.75 | 86 | 59 |
| Oct | 77 | 61 | 72 | 0.45 | 33 | — |
| Nov | 77 | 61 | 36 | — | — | — |
| Dec | 75 | 60 | 24 | — | — | — |
Monthly decade averages, in millimetres. The requirement is what remains once usable rainfall is deducted, using crop coefficients for a mature pistachio orchard.
What the water source has to deliver
| Strategy | Per hectare | Across the orchard | Peak flow | Seven-day reserve |
|---|---|---|---|---|
| Full comfort — 100 % of ETc | 7,048 m³ | 281,920 m³ | 147 m³/h | 20,636 m³ |
| Controlled deficit — 60 % | 4,229 m³ | 169,160 m³ | 88 m³/h | 12,382 m³ |
| Support irrigation — 35 % | 2,467 m³ | 98,680 m³ | 52 m³/h | 7,223 m³ |
| Young orchard, years 1 to 4 | 1,741 m³ | 69,640 m³ | — | — |
Pistachio withstands deficit irrigation better than almost any other fruit crop, and the strategy chosen triples the volume required. Flow computed for 20 hours of irrigation per day in the peak month.
What this settles
The soil is acidic, not calcareous
pH sits around 5.7 throughout the profile, and pistachio prefers 7.0 to 7.8. The usual conversation about this crop turns on tolerance of lime; here the problem is the reverse. It calls for liming before planting, and it changes the rootstock criterion: no longer resistance to chlorosis, but vigour in poor, acidic ground.
Drains well, holds little
Loam to sandy loam over schist, with roughly a third of the volume taken by stones. Drainage is excellent, and that matters because pistachio dies of root asphyxia long before it dies of drought. The trade-off is storage: barely over 70 mm, of which 35 are usable between waterings.
Frequent irrigation, small volumes
With that reserve and a July peak of 7 mm a day, the maximum interval between waterings falls under five days. There is no room for long shifts: the system has to be localised and high-frequency, which is precisely what drip does.
The irrigation strategy is still open
Running the orchard at full comfort or on support irrigation changes the annual volume by a factor of three, and with it the flow the source must guarantee. The yield assumed in the model is consistent with deficit irrigation; aiming for comfort would raise production but demand a far more generous water source.
Land characterisation
Each parcel was analysed from Sentinel-2 imagery and the Copernicus elevation model, over a summer composite. The land is divided into 20-metre cells, from which vegetation vigour, elevation, slope and aspect are extracted; those cells are then grouped into homogeneous strata.
- Source
- Sentinel-2 L2A e Copernicus DEM GLO-30, via Copernicus Data Space Ecosystem
- Method
- Estratificação: célula de 20 m, composto de verão, k-means com 4 grupos
I — Terreno da pista
Seasonal composite: verao-2025-N · Cells analysed: 291 (20 × 20 m) · Valid coverage: 100%
Spectral indices
NDVI 0.470 Vegetation vigour. Above 0.6 means dense cover; below 0.2, near-bare soil.
EVI 0.235 Vigour corrected for soil and atmospheric effects. Useful where cover is patchy.
NDMI -0.022 Vegetation moisture. Negative values indicate water stress at the end of summer.
NDWI -0.525 Surface water. Negative across dry ground, as expected here.
NBR 0.225 Sensitive to burnt area and dry biomass. High values indicate healthy vegetation.
Terrain
- Elevation
- 411–534 m · 468 m
- Mean slope
- 17.6° · 32 %
- Maximum slope
- 34.2° · 68 %
- Dominant aspect
- South
Geographic setting
Each square is a 20 × 20 m cell. Pick an indicator to see it across the land; hover a cell for all its values.
Loading the grid…
View the strata 4
| Stratum | Suggested class | Area | NDVI | Elevation | Slope | North. | East. | Land cover | Confidence |
|---|---|---|---|---|---|---|---|---|---|
| STR-01 | Mosaico arbustivo | 3.92 | 0.461 | 476 | 27.2° | -0.93 | -0.12 | Scrub and shrubs | 73% |
| STR-02 | Mosaico arbustivo | 3.52 | 0.447 | 461 | 10.0° | -0.42 | 0.68 | Sparse vegetation | 54% |
| STR-03 | Mosaico arbustivo | 3.12 | 0.535 | 450 | 16.8° | 0.21 | -0.82 | Scrub and shrubs | 57% |
| STR-04 | Vegetação esparsa | 1.08 | 0.389 | 517 | 10.0° | 0.19 | -0.81 | Sparse vegetation | 70% |
II — Sul
Seasonal composite: verao-2025-N · Cells analysed: 455 (20 × 20 m) · Valid coverage: 100%
Spectral indices
NDVI 0.390 Vegetation vigour. Above 0.6 means dense cover; below 0.2, near-bare soil.
EVI 0.170 Vigour corrected for soil and atmospheric effects. Useful where cover is patchy.
NDMI -0.170 Vegetation moisture. Negative values indicate water stress at the end of summer.
NDWI -0.492 Surface water. Negative across dry ground, as expected here.
NBR 0.059 Sensitive to burnt area and dry biomass. High values indicate healthy vegetation.
Terrain
- Elevation
- 316–444 m · 380 m
- Mean slope
- 20.9° · 38 %
- Maximum slope
- 40.5° · 85 %
- Dominant aspect
- South
Geographic setting
Each square is a 20 × 20 m cell. Pick an indicator to see it across the land; hover a cell for all its values.
Loading the grid…
View the strata 4
| Stratum | Suggested class | Area | NDVI | Elevation | Slope | North. | East. | Land cover | Confidence |
|---|---|---|---|---|---|---|---|---|---|
| STR-01 | Vegetação esparsa | 6.64 | 0.406 | 357 | 29.7° | -0.92 | -0.05 | Sparse vegetation | 58% |
| STR-02 | Vegetação esparsa | 4.68 | 0.385 | 375 | 18.3° | 0.04 | -0.93 | Sparse vegetation | 61% |
| STR-03 | Vegetação esparsa | 4.44 | 0.365 | 411 | 17.2° | -0.96 | -0.03 | Sparse vegetation | 61% |
| STR-04 | Vegetação esparsa | 2.44 | 0.405 | 393 | 8.9° | 0.04 | 0.94 | Sparse vegetation | 56% |
III — Nascente
Seasonal composite: verao-2025-N · Cells analysed: 506 (20 × 20 m) · Valid coverage: 100%
Spectral indices
NDVI 0.657 Vegetation vigour. Above 0.6 means dense cover; below 0.2, near-bare soil.
EVI 0.387 Vigour corrected for soil and atmospheric effects. Useful where cover is patchy.
NDMI 0.143 Vegetation moisture. Negative values indicate water stress at the end of summer.
NDWI -0.637 Surface water. Negative across dry ground, as expected here.
NBR 0.412 Sensitive to burnt area and dry biomass. High values indicate healthy vegetation.
Terrain
- Elevation
- 350–528 m · 418 m
- Mean slope
- 23.4° · 43 %
- Maximum slope
- 42.5° · 92 %
- Dominant aspect
- North
Geographic setting
Each square is a 20 × 20 m cell. Pick an indicator to see it across the land; hover a cell for all its values.
Loading the grid…
View the strata 4
| Stratum | Suggested class | Area | NDVI | Elevation | Slope | North. | East. | Land cover | Confidence |
|---|---|---|---|---|---|---|---|---|---|
| STR-01 | Floresta mista | 8.80 | 0.672 | 432 | 37.6° | 0.95 | -0.11 | Mixed forest | 81% |
| STR-02 | Mosaico arbustivo | 4.08 | 0.639 | 429 | 12.7° | -0.02 | -1.00 | Scrub and shrubs | 54% |
| STR-03 | Mosaico arbustivo | 3.92 | 0.533 | 417 | 13.8° | -0.63 | 0.38 | Scrub and shrubs | 54% |
| STR-04 | Floresta densa | 3.44 | 0.781 | 371 | 10.6° | 0.58 | 0.38 | Dense forest | 60% |
Slope and mechanisation
The measured slopes are substantial: harvesting with a trunk shaker calls for ground below 20 to 25 % incline, and all three parcels average above that. That is why the steeper zones are terraced — see the technical concept. The stratification above decides where to terrace and where to use ground that is already flat: 18.5 ha sit below 25 % incline and can be planted without earthworks; the remaining 31.6 ha need terracing.