NCERT Solutions for CBSE Class 8 Science Chapter 1 – Free PDF Download
Free PDF download of NCERT Solutions Science Class 8 Solutions Chapter 1 – Crop Production and Management solved by Expert Science Teachers on CoolGyan.Org. All Chapter 1 – Crop Production and Management Questions with Solutions for NCERT to help you to revise complete Syllabus and Score More marks.
Science Revision Notes for Class 8
|Chapter Name||Crop Production and Management|
|Subject||Science NCERT Solutions|
1. Select the correct word from the following list and fill 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 crop is ___________ of soil.
(c) Damaged seeds would _________ on top of water.
(d) For growing crop, sufficient sunlight and _____ and _______ and from the soil are essential.
Ans. Select the correct word from the following list and fill 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 crop.
(b) The first step before growing crop is preparation of soil.
(c) Damaged seeds would float on top of water.
(d) For growing crop, sufficient sunlight and water and nutrients from the soil are essential.
2. Match items in column A with those in column B.
|(i) Kharif crop||(a) Food for cattle|
|(ii) Rabi crops||(b) Urea and super phosphate|
|(iii) Chemical fertilsers||(c) Animal excreta, cow dung, urine and Plant wastes.|
|(iv) Organic manure||(d) Wheat, gram, pea|
|(e) Paddy and maize.|
3. Give two examples of each.
(a) Kharif crop
(b) Rabi crop
Ans. (a) Paddy and maize.
(b) Wheat and pea.
4. Write a paragraph in your own words on each of the following.
(a) Preparation of soil (b) Sowing (c) Weeding (d) Threshing
Ans. (a) Preparation of soil:- It is the first step before growing a crop. One of the most important tasks in agriculture is to turn the soil and loosen it. The softening of soil allows the deep penetration of roots into soil. The soil preparation includes ploughing, levelling and manuring. Ploughing is done with the help of plough or tractor. Levelling is done by leveller to break the crumbs with a plank..
(b) Sowing: – The process of broadcasting seeds in soil to grow crop is called sowing. Sowing is done with the help of seed drill or traditional tool. The healthy seed is selected for proper growth. The distance between seeds must be sufficient for proper growth.
(c) Weeding: – The unwanted plants that grow along with the main crop and compete with crop for light, food and other substance are called weeds. Removal of these unwanted plants is called weeding. Weeding is done by different ways which include manual removal, seed drill and weedicides.
(d) Threshing: – In harvested crop, the grain seeds are separated from chaff. This process is called threshing. This is carried out by using a machine called “Combine”.
5. Explain how fertilsers are different from manure.
Ans. Manure is an organic substance obtained from the decomposition of plant or animal wastes but fertilsers are inorganic substance prepared in factories. Fertilsers are rich in nutrients but manure has relatively less nutrients. Manure do not harm the soil if used in greater quantity but fertilsers may harm the plants as well as soil. Manure is cheap and mostly prepared by farmers itself on the other hand fertilsers are costly and prepared in factories using chemicals.
6. What is irrigation? Describe two methods of irrigation which conserve water.
Ans. The supply of water to crops at different intervals is called irrigation. The time and frequency of irrigation differ from crop to crop, soil to soil and season to season. The main sources of irrigation are wells, tube wells, ponds, lakes, rivers, dams and canals. Irrigation is essential for proper growth of plants as without water no physiological activity is possible in living beings. The two methods of irrigation which conserve water are-
(a) Sprinkler system- This system is useful in uneven land where sufficient water is not available. The perpendicular pipes having rotating nozzles on top are joined to the main pipeline at regular intervals. When water flows through this pipe at high pressure, it escapes through the nozzles and sprinkle in all directions.
(b) Drip system- In this system water falls drop by drop just at the position of roots. It is mainly used for watering fruit plants, gardens and trees. In this method water is not wasted at all. It is mainly used in water deficient areas.
7. If wheat is sown in the Kharif season. What would happen? Discuss.
Ans. Kharif crops need lot of rainfall, whereas wheat needs winter season and not heavy rainfall. So, if wheat were sown in Kharif season, the crops will get damaged due to heavy rainfall and water logging in the field.
8. Explain how soil gets affected by the continuous plantation of crop in a field.
Ans. Continuous growing of crops makes the soil poorer in certain nutrients. To avoid this, a method of crop-rotation is adopted, which maintains the nutrients of the soil intact.
9. What are weeds? How can we control them?
Ans. The undesirable plants in the field are called weeds. These have to be removed, otherwise our own crop plants may not get sufficient water, nutrients, space and light. So, they are removed either by manual method or by using weedicides.
The manual removal includes physical removal of weeds by uprooting or cutting them close to the ground from time to time. This is done with the help of a khurpi or harrow.
By using weedicides also, we can remove weeds. These weedicides only damage weeds and do not harm crops.
10. Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.
11. Complete the following words puzzle with the help of clues given below.
1. Providing water to the crops.
2. Keeping crop grains for a long time under proper conditions.
5. Certain plants of the same kind grown on a large scale.
3. A machine used for cutting the matured crop.
4. A rabi crop that is also one of the pulses.
6. A process of separating the grain from chaff.