SEBA Class 10 Solanaceous Crop Cultivator
Chapter 1 Irrigation Management in Vegetable Crops
C. Short answers questions.
1. Define irrigation and enlist the role of irrigation water.
Definition of Irrigation:
Irrigation is the artificial application of water to the soil in order to maintain proper soil moisture for plant growth. It is a planned practice to ensure that crops get sufficient water when needed, especially when rainfall is not reliable.
Role of Irrigation Water:
• Helps in the growth and development of plants.
• Assists plants in absorbing and transporting minerals from the soil.
• Essential for various biochemical reactions inside the plant.
• Necessary for photosynthesis, the process through which plants make food.
• Helps plants manage heat or frost stress.
• Required for seed germination and proper seedling establishment.
• Maintains adequate moisture in the root zone for healthy plant growth.
• Supports high yield and good quality vegetable production.
• Reduces dependence on unpredictable rainfall.
• If properly scheduled, helps conserve water and control weed growth.
• Allows multiple crops to be grown in the same field during a year.
2. Point out the criteria for suitability of irrigation water.
Answer: The following criteria must be met to consider water suitable for irrigation:
pH Range:The pH of irrigation water should be between 6.5 to 8.5.
Salinity (Electrical Conductivity - EC):
• Measures the total dissolved salts in water.
• Water with EC below 1500 micromhos/cm is considered good for irrigation.
Sodium Adsorption Ratio (SAR):
• Indicates the proportion of sodium to calcium and magnesium.
• High SAR affects soil structure and reduces permeability.
• SAR value should be below 10 in irrigation water.
Residual Sodium Carbonate (RSC):
• High RSC increases pH and SAR, leading to soil alkalinity.
• RSC should be below 1.5 mg/litre in irrigation water.
Management includes:
• Adding gypsum or sulphur with lime, followed by leaching.
• More frequent irrigation.
• Avoiding sprinkler irrigation.
• Avoiding chloride and boron-based fertilisers.
• Selecting salt-tolerant crops.
Boron Content:
• High boron levels are toxic to plants.
• Boron content should be below 1.0 ppm in irrigation water.
• If high, it should be diluted as it cannot be removed easily.
Use of Quality Testing Instruments:
pH meter: Measures acidity or alkalinity of water.
EC meter: Measures total dissolved salts or salinity level.
Regular testing helps determine if the water is fit for irrigation or needs treatment.
3. When is water suitable for irrigation?
Answer: Water is suitable for irrigation when:
• The pH of the water is in the range of 6.5 to 8.5.
• The electrical conductivity (EC) is below 1500 micromhos/cm, indicating low salinity.
• The Sodium Adsorption Ratio (SAR) is below 10, meaning low sodium content compared to calcium and magnesium.
• The Residual Sodium Carbonate (RSC) is less than 1.5 mg/litre, to prevent alkalinity issues.
• The boron content is below 1.0 ppm, since higher levels can be toxic to plants.
• The water does not contain harmful levels of salts, heavy metals, or toxic substances.
• The water does not affect soil structure or plant health negatively.
• The water has been tested using proper instruments like pH meters and EC meters to confirm its suitability.
4. Classify irrigation sources with proper examples.
Answer: Irrigation sources are classified into two main types:
1. Surface Water Sources: These are sources of water available on the surface of the earth.
Examples: Rivers, Canals, Ponds, Lakes, Dams
Features:
• Easily accessible in many areas
• Generally good quality water
• Depends on rainfall and geographical features
2. Groundwater Sources: These are sources of water found below the earth’s surface, extracted using different methods.
Examples: Dug wells, Tube wells, Bore wells
Features:
• Water is available throughout the year (if not overused)
• Quality varies – can be good or poor (may contain salts or toxins)
• Useful in areas where surface water is not available.
5. How is water testing helpful for a farmer?
Answer: Water testing is very helpful for a farmer in the following ways:
Determines Suitability for Irrigation: Testing helps to know whether the water is fit for irrigating crops or not.
Identifies Water Quality Problems: It helps detect harmful elements like excess salts, toxic metals, or high boron levels that may damage crops or soil.
Helps in Choosing the Right Crops: Based on water quality, farmers can choose crops that are tolerant to certain water conditions (e.g., saline or alkaline water).
Prevents Soil Damage: Poor quality water can harm soil structure. Testing helps avoid long-term soil health issues.
Improves Crop Yield and Quality: Using good quality water ensures better plant growth, higher yield, and good quality produce.
Guides Water Treatment Needs: If water is not suitable, testing shows what kind of treatment (e.g., gypsum addition or dilution) is needed.
Supports Efficient Fertiliser Use: Helps avoid using fertilisers that may react negatively with certain water components (e.g., avoid chloride with poor-quality water).
Ensures Sustainable Farming: Regular water testing supports long-term productivity of soil and safe food production.
Water testing is a simple but powerful tool that helps farmers make informed decisions for better crop management and soil conservation.
