Learning objectives
- Describe surface, sprinkler and drip irrigation
- State advantages and problems of irrigation
- Explain methods and benefits of drainage
1. Irrigation methods
Surface irrigation (basin, furrow, flood) is cheap but wastes water. Sprinkler irrigation sprays water like rain and suits uneven land, but wets foliage, which can encourage leaf diseases. Drip (trickle) irrigation delivers water directly to the roots through emitters — the most efficient, and it keeps leaves dry.
- Benefit: all-year cropping and higher yields
- Problem: salinisation and waterlogging if poorly managed
- Problem: high cost of equipment
2. Drainage
Surface drainage uses open ditches and cambered beds; subsurface drainage uses buried perforated pipes or mole drains. Good drainage improves aeration, warms the soil faster, and reduces root rots such as Pythium and Phytophthora that thrive in waterlogged soil.
Key definitions
- Irrigation
- Artificial application of water to soil to support crop growth.
- Salinisation
- Accumulation of soluble salts in soil, often due to poor irrigation and drainage.
- Waterlogging
- Saturation of soil with water so that air spaces are filled and roots lack oxygen.
Exam tips
- Link irrigation/drainage to plant health — examiners reward the disease connection (leaf wetness, root rot).
Practice exam questions & model answers
Q1.State three advantages of drip irrigation over sprinkler irrigation.
Drip irrigation uses less water because it is delivered directly to the root zone; it keeps leaves dry, reducing foliar fungal diseases; it reduces weed growth between rows; and fertiliser can be applied through it (fertigation).
Q2.Give four benefits of farm drainage.
It improves soil aeration for root respiration, allows the soil to warm faster, prevents root rot diseases, reduces salinisation, and makes land workable earlier for tillage.
Continue revising
Plant Cell Structure and Function
Plant BiologyPhotosynthesis: Process, Equation and Limiting Factors
BotanyLeaf Structure, Stomata and Transpiration
Agricultural SciencePlant Nutrition, NPK and Soil Fertility
Put the theory to work — diagnose a real leaf photo or browse the disease library.