Sprinkler or Overhead Method of irrigation
Water is one of the most common limiting factors in corn production. High yields are attained if the corn plants do not suffer moisture stress at any of the growth stages, especially two weeks before and after silking (flowering).
Reduction in the potential yield of corn may range from 20-90% if the corn crop is subjected to drought at key stages of growth.
Importance of water
- Water dissolves minerals and nutrients so that these become readily available to the plants.
- It is a medium to transport nutrients from the roots as well as the movement of starch from the leaves to the other parts of the plant.
- It brings turgidity (or strength) to plant cells.
- It is essential in the various chemical reactions within the plants, particularly photosynthesis.
- It serves as the crop's cooling mechanism against heat stress through the process of transpiration (or loss of water from the leaves).
Sources of Water
Rainfall.
The optimum requirement of corn to complete its growth is 400-600 mm of rainfall per growing period.
Atmospheric water
Atmospheric water other than rainfall like dews and fogs.
Surface water
Surface water from lakes, ponds, rivers, streams or constructed reservoirs.
Ground water
Ground water reservoirs which are located in the zone of saturation where water is held below the water table.
Why Measure Soil Moisture?
Irrigation becomes a necessity when natural sources of water are not available or when there is no rainfall.
It is, therefore, important to know the soil condition with regard to moisture content as a necessary step to prevent water stress in crops.
Soil moisture metering devices, like soil moisture tester and tensiometer, are used to determine the soil's condition.
In the absence of these devices, the most practical way to approximate soil moisture level is by relating the physical relationship between the soil moisture and the feel and appearance of the soil.
Approximating Soil Moisture Level
As previously stated, the most practical way of approximating soil moisture is by relating the physical relationship between the soil moisture and the feel and appearance of the soil, described below:
When is Irrigation a Necessity?
- When the moisture level of the field reaches 50% of the available capacity
- When natural sources of water are not available
- When there is no rainfall
- When the corn plants are showing signs of stress like plant wilting, leaf rolling or folding at around 10 am-12 noon
Daily Water Requirements of Corn
Common Methods of Irrigation
Furrow.
Furrow irrigation submerges only 1/5-1/2 of the surface resulting in less evaporation, less puddling of the soil and permitting cultivation sooner after irrigation. This method is the most practical and least expensive for corn grain production.
Sprinkler or Overhead.
This system uses lightweight portable pipes for distributing the water and offers opportunity for uniform application of water. It is particularly adaptable in hilly lands.
Drip.
Application of water with minimum waste by conducting the water under pressure to relatively closely-spaced grid outlets (drippers) and discharging the water through these outlets at virtually low pressure.
Drip Method of Irrigation
Using Furrow Irrigation
- Irrigation water may be required 4-6 times throughout the growing season of corn.
- Apply at an interval of 10-14 days, starting the first irrigation one day after planting and ending at about 15-21 days before harvest, depending on the climatic condition, soil type, corn variety and maturity of the crop.
Furrow Method of Irrigation
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