Class 8 Science Important Questions Chapter 1: Crop Production and Management
Q.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 _____________ 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.
Answer: Water, Nutrient
Q. 2. Match items in column A with those in column B.
|(i) Kharif Crops||(a) Food for cattle|
|(ii) Rabi Crops||(b) Urea and superphosphate|
|(iii) chemical fertilizers||(c) Animal excreta, cow dung, |
urine and plant waste
|(iv) Organic manure||(d) Wheat, gram, Pea|
|(e) Paddy and maize|
|(i) Kharif Crops||(e) paddy and maize|
|(ii) Rabi Crops||(d) Wheat, gram, pea|
|(iii) chemical fertilizers||(b) Urea and superphosphate|
|(iv) Organic manure||(c) Animal excreta, cow dung,|
urine and plant waste
Q. 3. Give two examples of each.
(a) Kharif crop
Answer: Paddy and maize
(b) Rabi crop
Answer: Wheat and gram
Q. 4. Write a paragraph in your own words on each of the following.
(a) Preparation of soil
Answer: The preparation of the soil is the first step before growing a crop. One of the most important tasks in agriculture is to turn the soil and loosen it. This allows the roots to penetrate deep into the soil. The loose soil allows the roots to breathe easily even when they go deep into the soil. It is necessary to prepare the soil by tilling and leveling. Plows and levelers are used for this purpose.
Answer: Sowing is an important part of crop production. Before sowing, good quality, clean and healthy seeds of a good variety—are selected. Farmers prefer to use seeds that give a high yield. Sowing of seeds at appropriate depths and distances gives a good yield. A good variety of seeds is sown after the selection of healthy seeds. Sowing is done by seed drills.
Answer: In a field, many other undesirable plants may grow naturally along with the crop. These undesirable plants are called weeds. The removal of weeds is called weeding. Weeding is necessary since weeds compete with the crop plants for water, nutrients, space, and light. Thus, they affect the growth of the crop. Some weeds interfere even in harvesting and may be poisonous for animals and human beings.
Answer: In the harvested crop, the grain seeds need to be separated
from the chaff. This process is called threshing. This is carried out with the help of a machine called ‘combine’ which is, in fact, a harvester as well as a thresher.
5. Explain how fertilizers are different from manure.
|Fertilizer is a man-made inorganic salt.||Manure is a natural substance obtained by the|
decomposition of cattle dung and plant residues
|Fertilizers can be organic or inorganic in nature.||manure can be organic with large quantities and|
a little number of plant nutrients.
|Fertilizer does not provide any humans to the soil.||manure provides a lot of humans to the soil.|
|Fertilizers are very rich in plant nutrients like Nitrogen,|
phosphorous, and potassium.
|manure is relatively less rich in plant Nutrients|
|Its excessive use causes water pollution.||It protects the environment and helps in recycling farm waste.|
6. What is irrigation? Describe two methods of irrigation that conserve water.
Answer: The supply of water to crops at regular intervals is called irrigation. The time and frequency of irrigation vary from crop to crop, soil to soil, and season to season.
Sources of irrigation: The sources of water for irrigation are— wells, tube wells, ponds, lakes, rivers, dams, and canals.
Sprinkler System: This system is more useful on 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 is allowed to flow
through the main pipe under pressure with the help of a pump, it escapes from the rotating nozzles. It gets sprinkled on the crop as if it is raining. The sprinkler is very useful for lawns, coffee plantations, and several other crops
Drip system: In this system, the waterfalls drop by drop directly near the roots. So it is called a drip system. It is the best technique for watering fruit plants, gardens, and trees Water is not wasted at all. It is a boon in regions where the availability of water is poor.
7. If wheat is sown in the Kharif season, what would happen? Discuss.
Answer: The crops which are sown in the rainy season are called Kharif crops. The rainy season in India is generally from June to September. Wheat crop is sown from November/December to March/April. It is grown in winter and requires less water. If wheat is sown in the Kharif season, its production will be decreased.
8. Explain how soil gets affected by the continuous plantation of crops in a field.
Answer: soil contains minerals, water, air, and some living organisms. In addition, dead plants and animals get decomposed by soil organisms. In this way, various nutrients in the dead organisms are released back into the soil. These nutrients are again absorbed by plants. If a continuous plantation is done these minerals won’t get time to replenish and the crop yield decreases immediately.
9. What are weeds? How can we control them?
Answer: In a field, many other undesirable plants may grow naturally along with the crop. These undesirable plants are called weeds. Weeds are also controlled by using certain chemicals, called weedicides, like 2,4-D. These are sprayed in the fields to kill the weeds. They do not damage the crops. The weedicides are diluted with water to the extent required and sprayed in the fields with a sprayer
10. Arrange the following boxes in proper order to make a flow chart of sugarcane crop production.
11. Complete the following word puzzle with the help of the 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 are 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 the chaff.