Edaphix

1Soil texture

🪨

USDA texture class

Select soil type

Enter sand, silt and clay percentages below. They must sum to 100%.

Sand %

Silt %

Clay %

Sum: 100%

⚠ Sand + Silt + Clay must equal 100% before proceeding.

Loam

Sand 42% · Silt 38% · Clay 20%

📐

USDA soil texture triangle

2Soil parameters

✏️

Editable soil parameters

Water retention

θ_FC (33 kPa) ↺ from curve

θ_PWP (1500 kPa) ↺ from curve

Physical properties

Bulk density (g/cm³) ↺ re-estimate

K_sat (mm/day) ↺ re-estimate

Derived (auto-updated)

θ_sat

—

Porosity

—

van Genuchten parameters

α (kPa⁻¹) ↺ class default

n ↺ class default

θ_r residual ↺ class default

θ_sat

—

📈

Soil characteristic curve preview

Retention curve θ(h)

FC (33 kPa)

PWP (1500 kPa)

Irr. threshold (dashed crosshair)

3Soil characteristic curve

📊

Reference points

Saturation θ_sat	—
Field capacity θ_FC (−33 kPa)	—
Irrigation threshold (−— kPa)	—
Wilting point θ_PWP (−1500 kPa)	—
Residual θ_r	—
Plant available water (FC−PWP)	—

⚙️

van Genuchten parameters

α (kPa⁻¹)	—
n	—
m = 1−1/n	—
Bulk density ρ_b	—
K_sat	—
Soil texture class	—

📈

Soil characteristic curve

Retention curve θ(h)

FC

PWP

Irrigation threshold

4Plant parameters & water balance

🌿

Plant parameters

Root depth (cm)

Management allowable deficit (MAD)

Total available water (TAW)

—

(θ_FC−θ_PWP) × root depth

Readily available water (RAW)

—

TAW × MAD

📈

Retention curve with water balance

Retention curve θ(h)

FC

PWP

Irr. threshold (dashed crosshair)

Crop reference — FAO-56 typical values

Crop	Root depth cm	Root depth in	MAD fraction	MAD %	Sensitivity
Wheat Winter / Spring cereal	120	47.2	0.55	55%	Moderate
Maize / Corn Summer cereal	100	39.4	0.55	55%	Moderate
Rice (paddy) Flooded / upland	50	19.7	0.20	20%	Sensitive
Sorghum Cereal / fodder	100	39.4	0.55	55%	Moderate
Barley Spring / winter cereal	100	39.4	0.55	55%	Moderate
Soybean Legume / oilseed	80	31.5	0.50	50%	Moderate
Cotton Fiber crop	120	47.2	0.65	65%	Tolerant
Alfalfa Perennial forage	150	59.1	0.55	55%	Moderate
Sugarcane Sugar crop	120	47.2	0.65	65%	Tolerant
Sunflower Oilseed	100	39.4	0.45	45%	Moderate
Peanut / Groundnut Legume / oilseed	60	23.6	0.50	50%	Moderate
Potato Root / tuber	40	15.7	0.35	35%	Sensitive
Sweet potato Root / tuber	60	23.6	0.65	65%	Tolerant
Sugar beet Root crop	90	35.4	0.50	50%	Moderate
Tomato Fruiting vegetable	70	27.6	0.40	40%	Sensitive
Pepper Fruiting vegetable	50	19.7	0.30	30%	Sensitive
Cucumber Fruiting vegetable	60	23.6	0.50	50%	Moderate
Eggplant / Aubergine Fruiting vegetable	70	27.6	0.45	45%	Moderate
Cabbage / Broccoli Brassica	50	19.7	0.45	45%	Moderate
Onion Bulb vegetable	30	11.8	0.30	30%	Sensitive
Garlic Bulb vegetable	30	11.8	0.30	30%	Sensitive
Carrot Root vegetable	50	19.7	0.35	35%	Sensitive
Lettuce Leafy vegetable	30	11.8	0.30	30%	Sensitive
Spinach Leafy vegetable	30	11.8	0.20	20%	Sensitive
Strawberry Berry / small fruit	25	9.8	0.20	20%	Sensitive
Watermelon Cucurbit	80	31.5	0.40	40%	Sensitive
Citrus Evergreen tree fruit	120	47.2	0.50	50%	Moderate
Apple / Pear Deciduous tree fruit	150	59.1	0.50	50%	Moderate
Peach / Nectarine Stone fruit	100	39.4	0.50	50%	Moderate
Apricot Stone fruit	100	39.4	0.50	50%	Moderate
Avocado Tropical tree fruit	100	39.4	0.70	70%	Tolerant
Banana Tropical fruit	50	19.7	0.35	35%	Sensitive
Vineyard / Grapes Tree fruit / wine	100	39.4	0.45	45%	Moderate
Olive Evergreen tree	120	47.2	0.65	65%	Tolerant
Almond Nut tree	150	59.1	0.40	40%	Sensitive
Walnut Nut tree	170	66.9	0.50	50%	Moderate
Pistachio Nut tree	150	59.1	0.60	60%	Tolerant
Grass / Turf Forage / lawn	60	23.6	0.55	55%	Moderate
Bermuda grass Tropical forage	60	23.6	0.55	55%	Moderate

Source: FAO Irrigation and Drainage Paper No. 56 (Allen et al. 1998) · MAD ≤40% high-sensitivity crops · MAD 45–55% standard crops · MAD ≥60% drought-tolerant crops