Class 8 Science Chapter 1 | Crop Production and Management | Textbook Solutions
Extra questions from Class 8 Science Chapter 1 Crop Production and Management can be found here. Textbook solutions are given below.
1. Select the correct word from the following list and fill in the blanks.
(float, water, crop, nutrients, preparation)
(a) The same kind of plants grown and cultivated on a large scale at a place is called ………………………..
(b) The first step before growing crops is the …………………………… of the soil.
(c) Damaged seeds would …………………………….. on top of water
(d) For growing a crop, sufficient sunlight and ……………………….. and ………………………. from the soil are essential.
water and nutrients
2. Match items in column A with items in Column B (Refer textbook Page 14)
(i) Kharif crops – paddy and maize
(ii) Rabi crops – wheat, gram and pea
(iii) Chemical fertilisers – Urea and Super Phosphate
(iv) Organic manure – animal excreta, cow dung, urine and plant waste
3. Give two examples of each
(a) Kharif crop – Rice, cotton
(b) Rabi crop – mustard, wheat
4. Write a paragraph in your words on each of the following.
(a) Preparation of soil
This is the first step in the cultivation of crops. Before seeds are sown, the soil has to be turned and loosened. This is done to ensure that roots can penetrate deeper and breathe easily. Loosening of the soil also allows the growth of earthworms and friendly microbes which further turn the soil and facilitate the growth of plants. In addition, turning of the soil brings the nutrient-rich soil to the top. The process of turning and loosening soil is called tilling or ploughing. This is done using a plough.
Once the soil is prepared, the seeds are sown. Farmers prefer to sow good quality seeds that also give good yield. Both traditional and modern methods are used for sowing seeds. The traditional tool is shaped like a funnel. The seeds are filled in a funnel and made to pass through two or three pipes having sharp ends. These pipes pierce into the soil and plant the seeds there. A seed drill is a modern tool used for sowing seeds with the help of a tractor. The seed drill sows the seeds at equal distance and depth and also ensure that the seeds get covered by the soil after sowing.
Weeds are unwanted plants that grow naturally along with crops. As weeds compete with crops for nutrients, water, sunlight and space, they need to be removed to ensure the healthy growth of crops. Weeding is the process of removal of weeds. Farmers sometimes manually remove the weeds. They may also use chemicals like weedicides. These chemicals kill the weeds but they do not damage the crops.
Threshing is the process of removing chaff from the grain. This is carried out with the help of a machine called combine which is a harvester as well as a thresher.
5. Explain how fertilisers are different from manure
- It is a man-made inorganic substance
- It is produced in factories.
- It is very rich in plant nutrients like nitrogen, phosphorus and potassium.
- It does not add any humus to the soil.
- Manure is an organic substance obtained from decomposed plants and cattle dung.
- It is prepared in open fields or pits.
- Manure adds humus to the soil and increases its water retaining capacity.
- Compared to chemical fertilizers, manure is less rich in plant nutrients.
6. What is irrigation? Describe two methods of irrigation which conserve water.
Irrigation is the process of artificially watering the plants to ensure their proper growth. Main sources of irrigation are wells, tube wells, rivers, ponds, canals and dams.
Two methods of irrigation that help to conserve water are: sprinkler irrigation and drip irrigation
This is suitable for irrigating uneven land. In sprinkler system, perpendicular pipes with rotating nozzles on top are joined to the main pipeline at regular intervals. When water flows through the main pipe, due to pressure it escapes through the nozzles and gets sprinkled on the crops. This is a good method for watering lawns, coffee plantations etc.
Drip irrigation system
In drip irrigation system water falls directly near the roots drop by drop. This is good for watering trees, fruit plants etc.
7. If wheat is sown in the kharif season, what would happen? Discuss.
Wheat is a rabi crop. That means it is sown in the winter season from October to March. The cultivation of wheat requires less water; hence, if it is grown during the rainy season, its yield will reduce substantially.
8. Explain how soil gets affected by the continuous plantation of crops in a field.
Crops require nutrients found in the soil. Continuous plantation of crops will make the soil poorer in certain nutrients and thus make it less fertile.
9. What are the weeds? How can we control them?
Weeds are unwanted plants that naturally grow along with crops. Weeds should be removed because they affect the growth of crops. One way of removing weeds is to till the soil before sowing seeds. This will uproot the weeds and cause them to dry up and mix with the soil. Chemicals like weedicides are also used to control weeds.