NCERT Solutions for Class 8th Science
Chapter 1. Crop Production And Management
Text Book Exercise
Text Book Exercise
Ques: Explain how fertilisers are different from manure.
Ans: Fertilisers are different from manure in following manner.
(i) It is prepared by organic substances.
(ii) It is rich in all nutrients.
(iii) ex. Compost Manure.
(i) It is prepared by chemical substances.
(ii) It is rich in particular nutrients.
(iii) Urea, Potash and ammonium sulphate etc.
Ques: What is irrigation? Describe two methods of irrigation which conserve water.
Ans : The supply of water to crops at different intervals is called irrigation.
There are two modern methods of irrigation which conserve water.
(i) Sprinkler system – This system is more useful on the uneven land where sufficient water is not available.
(ii) Drip system – In this system, the water falls drop by drop just at the position of the roots. So it is called drip system. It is the best technique for watering fruit plants, gardens and trees.
Ques: If wheat is sown in the kharif season, what would happen? Discuss.
Ans: In kharif season, there have a lot of rainfall. Where, wheat does not need the heavy rainfall. It will be destroyed as well as water logging.
Ques: Explain how soil gets affected by the continuous plantation of crops in a field.
Ans: Continuous plantation of crops makes the soil deficient in certain nutrient in a field. Further the crops do not grow well. To avoid this, the following practices should be done.
(i) Crop rotation.
(ii) Manuring the soil
(iii) Leaving field fallow.
Ques: What are weeds? How can we control them?
Ans : Many other undesirable plants may grow naturally along with the crop. These undesirable plants are called weeds. Weeds are harmful for crops. These take all nutrients water and light from soils which are added for crops. Weeds can be removed manually or by using weedicides. Manually there is used a Khurpi while by using weedicides we use chemical substances like 2, 4-D, which damage only weeds and do not harm to crops.