Irrigation Water Guide (Quick Estimate by Crop, Soil, and Heat)

Q: "Can this tool do precise ET-based irrigation?"

"No. This is a quick estimate. A more precise approach usually starts with ET from temperature, solar radiation, wind, and humidity, then applies crop coefficients."

Q: "Which units does it support?"

"The base output is L per plant. If you also enter area and plant count, you can switch to L per m² or mm. One millimeter equals one liter per square meter."

Q: "My field dries out quickly."

"The tool adjusts for soil type, but if the field still dries fast, increasing watering frequency instead of making one big jump can be more stable. That is especially common in sandy soil."

Q: "Do fruit trees still show L per plant?"

"For fruit tree categories, the result is shown as L/tree because that is easier to read in practice."

Pick a crop category, soil type, heat level, mulch option, and irrigation method to see a practical water range for one irrigation event.

Minimal input Range output L per plant, L per m², and mm Share URL and restore last state

Important

This tool is a guide only. Even for the same crop, water needs can change a lot with region, wind, sunlight, growth stage, bed shape, and drainage. Check soil moisture at 5 cm to 10 cm depth and adjust from there.

How to use

Choose the crop category, soil, heat level, mulch condition, and irrigation method.
Review the range and switch between L per plant, L per m², and mm if needed.
Adjust the amount or frequency after checking soil moisture and crop condition.

Examples

Fruiting vegetables with drip irrigation on a hot day

Input: Fruiting vegetables, loam, high heat, mulch on, drip, L per plant

Output: Estimated water per irrigation: 1.0 - 2.4 L/plant, with condition tags and adjustment notes.

Convert leafy vegetables for 10 m² and 20 plants

Input: Leafy vegetables, sand, high heat, no mulch, sprinkler, mm, area 10 m², plant count 20

Output: 0.8 - 2.2 mm, with total water 8.5 - 22.0 L per irrigation and a dryness warning.

Glossary

Sand

Soil that dries quickly and loses water and nutrients easily.

Loam

A balanced reference soil used as the base condition in this tool.

Clay

Soil that holds water well but can stay wet too long.

Drip irrigation

Watering close to the root zone with relatively low loss.

mm

An area-based water depth where 1 mm equals 1 L per m².

Calculation formulas

Range low = Base low x Soil factor x Heat factor x Mulch factor x Irrigation method factor
Range high = Base high x Soil factor x Heat factor x Mulch factor x Irrigation method factor
Total water (L) = L per plant or tree x Plant count
L per m² = Total water (L) ÷ Area (m²)
mm = L per m²

Quick logic behind the estimate

This page does not try to be a full ET model. It uses a base range and a small set of adjustment factors so the result stays practical in field use.

Base ranges

Crop category	Low	High	Unit
Leafy vegetables	0.3	0.8	L/plant
Fruiting vegetables	1.0	2.5	L/plant
Root vegetables	0.6	1.8	L/plant
Legumes	0.6	1.6	L/plant
Fruit trees (young)	10	25	L/tree
Fruit trees (mature)	30	80	L/tree

Factors

Group	Condition	Factor
Soil	Sand	1.10
Soil	Loam	1.00
Soil	Clay	0.90
Heat	Low	0.80
Heat	Medium	1.00
Heat	High	1.25
Mulch	On	0.85
Mulch	Off	1.00
Method	Drip	0.90
Method	Sprinkler	1.00

The tool keeps the result as a range, then rounds to practical steps: 0.1 L below 5 L, 0.5 L up to 30 L, and 1 L above that.

How soil type changes irrigation volume

Sandy soil dries out quickly, so smaller amounts with more frequent irrigation often stay steadier than one large watering.
Loam stays closest to the base range and makes the effect of the other conditions easier to read.
Clay can look dry on the surface while the root zone is still wet, so digging and checking is important.

Hot-weather irrigation notes

High temperature, strong sun, and dry wind can raise water demand even when the air temperature looks similar.
If plants only wilt during midday and recover by evening, avoid overreacting with a sudden large increase.
Sprinkler irrigation changes more with wind, so review the amount more often on unstable days.

FAQ (ET, units, and fast-drying fields)

Can this tool do precise ET-based irrigation?

No. This is a quick estimate. A more precise approach usually starts with ET from temperature, solar radiation, wind, and humidity, then applies crop coefficients.

Which units does it support?

The base output is L per plant. If you also enter area and plant count, you can switch to L per m² or mm. One millimeter equals one liter per square meter.

My field dries out quickly.

The tool adjusts for soil type, but if the field still dries fast, increasing watering frequency instead of making one big jump can be more stable. That is especially common in sandy soil.

Do fruit trees still show L per plant?

For fruit tree categories, the result is shown as L/tree because that is easier to read in practice.

Notice

Disclaimer. This result is only a guide. Water needs can shift a lot with region, weather, wind, sunlight, growth stage, drainage, mulch material, bed shape, and fertilization.
Check soil moisture at 5 cm to 10 cm depth and adjust the amount or frequency if you see signs of overwatering or drought.
If you see disease, root damage, muddy soil, or severe wilting, review drainage and root-zone conditions as well, not only irrigation volume.