Class 8 science chapter 1 extra questions part 4

Q. 1. In which season, the frequency of irrigation is required at a higher rate?

Answer: Watering of crops at regular intervals is called irrigation. The time and 

frequency of irrigation depend on types of crop, soil and season. In summer, the 

frequency of watering is higher because in summer temperature is high due to which 

the rate of evaporation of water from the soil and the leaves increases.

Q. 2. Name some sources of irrigation.

Answer: The sources of water for irrigation are wells, tube-wells, ponds, lakes, rivers,

dams, and canals.

Q. 3. In which method of irrigation, there is no wastage of water?

Answer: One of the modern methods of irrigation is the Drip system. In this system, the 

water falls drop by drop directly near the roots of the plants, hence water is not wasted 

at all.

Q. 4. Why are unwanted plants harmful? What are they called?

Answer: Undesirable plants which grow naturally along with the crop are called weeds.

The weeds are harmful because weeds compete with the crop plants for water, 

nutrients, space, and light. Thus, they affect the growth of the crop. Therefore, weeds 

need to be removed from the crop field.

Q. 5. Name the tool used for manual weeding.

Answer: Weeds can be removed manually with the help of khurpi.