🌿 Water Requirement of Major Field Crops
Crop-wise water requirement and critical irrigation stages in rice, groundnut, finger millet, sugarcane, maize, cotton, sorghum, and pulses.
Different crops do not need the same amount of water. Some require standing water or frequent irrigation, while others are comparatively drought tolerant. Even within one crop, certain growth stages are more sensitive than others. This lesson organizes the crop-wise water requirement values and critical stages given in the source.
Why crop-wise water requirement differs
The source makes it clear that water requirement depends on:
- crop species
- crop duration
- growth stage
- root behavior
- season and climate
- management practice
That is why rice, sugarcane, maize, cotton, and pulses all respond differently to irrigation.
A useful way to study this lesson is to focus on two things for each crop:
- total water requirement
- critical stages of irrigation
Rice
Total water requirement
The source gives:
- 1100 to 1250 mm
It also notes that daily consumptive use may vary from:
- 6 to 10 mm
Distribution of water use
According to the source:
- about 40 mm may be used in nursery raising
- around 200 mm may be needed for land preparation and puddling
- the major share is used in field irrigation
Critical management points
The source divides rice growth in relation to water into:
- seedling
- vegetative
- reproductive
- ripening
Important points:
- shallow water is adequate just after transplanting
- about 5 cm submergence is commonly maintained during root establishment and tillering
- mid-season drainage at maximum tillering may improve root aeration and reduce non-effective tillers
- flowering is a critical stage and stress here causes severe yield loss
- water demand falls during ripening and water can be withdrawn before harvest
The source also notes that irrigating after disappearance of ponded water rather than continuous submergence can save substantial irrigation water.
Groundnut
Total water requirement
The source gives:
- 500 to 550 mm
Critical stages
Water demand is relatively low:
- during early establishment
- near final maturity
Peak requirement occurs between:
- peg penetration
- pod development
This makes flowering to pod development an especially important period for irrigation.
Finger millet
Total water requirement
The source gives:
- about 350 mm
Irrigation behaviour
Finger millet is described as:
- drought tolerant
Important irrigation points in the source:
- pre-planting irrigation
- life irrigation after transplanting
- brief withholding after establishment for stronger growth
- later irrigation at critical stages such as:
- primordial initiation
- flowering
- grain filling
Sugarcane
Total water requirement
The source gives:
- 1800 to 2200 mm
This makes sugarcane one of the highest water-requiring crops in the lesson.
Critical phase
The source identifies the formative phase, roughly the first 120 days, as a critical period.
Important ideas:
- uniform emergence needs frequent but smaller irrigations early
- grand growth also needs good moisture supply
- as ripening approaches, moisture should gradually decline so sucrose accumulation improves
So sugarcane needs abundant water, but not the same pattern at every stage.
Maize
Total water requirement
The source gives:
- 500 to 600 mm
Critical stages
The source lists stages such as:
- sowing
- four-leaf stage
- knee-high stage
- grand growth
- tasseling
- silking
- early dough
- late dough
Among these, the most critical are:
- tasseling
- silking
- early dough
Stress at these stages can sharply reduce grain set and yield.
Cotton
Total water requirement
The source gives:
- 550 to 600 mm
Water-use pattern
The source notes that:
- early-season use is low
- water use rises sharply as flowering and boll development increase
- peak use may reach around 10 mm/day under heavy reproductive load
Critical stage
Moisture is especially important during:
- flowering
- boll development
The source also warns that excess irrigation during non-critical stages may encourage vegetative growth because cotton is an indeterminate crop, which can reduce boll setting.
Sorghum
Total water requirement
The source gives:
- 350 to 500 mm
Critical stages
The source identifies:
- booting
- flowering
- dough stage
as key irrigation stages.
It also notes an early irrigation after sowing and another around 15 days after sowing to encourage secondary root development.
Pulses
Total water requirement
The source gives:
- 200 to 450 mm
Many pulses are often grown under rainfed conditions, but irrigated summer pulses may need 3 to 4 irrigations at stages such as:
- germination
- flowering
- pod formation
This shows that even relatively low-water crops still have critical stages where timely irrigation matters a lot.
Comparative crop water requirement table
The source gives the following approximate values:
| Crop | Duration (days) | Water requirement (mm) | Number of irrigations |
|---|---|---|---|
| Rice | 135 | 1250 | 18 |
| Groundnut | 105 | 550 | 10 |
| Sorghum | 100 | 350 | 6 |
| Maize | 110 | 500 | 8 |
| Sugarcane | 365 | 2000 | 24 |
| Finger millet (Ragi) | 100 | 350 | 6 |
| Cotton | 165 | 550 | 11 |
| Pulses | 65 | 350 | 4 |
These values are approximate and vary with:
- soil
- climate
- season
- irrigation method
But they are still useful for comparative revision.
How to study this lesson efficiently
A simple revision method is:
High-water crops
- rice
- sugarcane
Medium-water crops
- maize
- cotton
- groundnut
Lower-water or drought-tolerant group
- finger millet
- sorghum
- many pulses
Then separately memorize the critical stages for each.
Summary Cheat Sheet
| Crop | Key point |
|---|---|
| Rice | Very high water need; flowering is critical; controlled submergence and mid-season drainage improve efficiency. |
| Groundnut | Peak need from peg penetration to pod development. |
| Finger millet | Drought tolerant but still needs irrigation at key reproductive stages. |
| Sugarcane | Very high water requirement, especially during the formative and grand-growth phases. |
| Maize | Tasseling, silking, and early dough are critical stages. |
| Cotton | Flowering and boll development need good moisture; excess water may encourage unwanted vegetative growth. |
| Sorghum | Booting, flowering, and dough stages are critical. |
| Pulses | Lower total requirement, but timely irrigation at flowering and pod formation is important. |
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