Long Answers - Crop Production and Management, Science, Class 8 PDF Download

LONG ANSWER TYPE QUESTIONS
 

Q. 1. Explain various agricultural practices.
Ans. There are following practices used in agriculture.

(i) Preparation of soil: The first step of agriculture is preparation of soil. The soil is to turn and loosen. It helps to grow and develop the plants. The process of loosening and turning of the soil is called tilling or ploughing.
Sometimes manure is added to soil before tilling.

(ii) Sowing: After preparation of soil the second step, called sowing, takes place. Before sowing, good quality seeds are selected. The seeds should be clean and healthy.

(iii) Adding Manure and Fertilisers: Soil supplies minerals and nutrients to the crops. These nutrients are essential for growth of plants. Sometimes continuous growing of crops makes the soil poorer in certain nutrients so, some substances are added to maintain or to replenish the soil. These substances are called manure and fertilisers. Manure and fertilisers are essential to increase the crop production.

(iv) Irrigation: The process of watering the crop plants is called irrigation. Plants take all the nutrients and minerals in dissolved form. So water is most essential for germination of seeds, growth and development of plants.

(v) Harvesting: After maturation of crop it is cut off. This process is called harvesting. It is done by a sickle or by a machine called harvester.

(vi) Storage: Storage of produce is one of the most important tasks. To keep the grains for longer time it should be safe from moisture, pest, insects and other microorganisms.

Q. 2. Explain an activity to show that manure and fertilisers are essential to increase  production.
Ans. Take some green gram (moong) or gram seeds and germinate them. Select three equal sized seedlings out of these. Take three beakers and mark them A, B and C. In beaker A add little amount of soil mixed with some manure. In beaker B put some amount of soil mixed with some urea. Take some amount of soil in beaker C without adding manure or urea. Pour the same amount of water in each beaker and plant the seedlings in each. Keep them in a safe place and water them daily. After a few days we observe that all the plants in all beakers did not grow at the same place. Beaker A and B shows the better growth but in beaker B the growth was fastest. This activity shows that manure and fertilisers are essential for better growth of plants. 

Q. 3. Write the differences between manure and fertiliser.
Ans. Differences between fertilisers and manure

Q. 4. Write the advantages of manure.
Ans. The organic manure is considered better than the fertiliser. This is because:
(i) Manure enhances the water holding capacity of the soil.
(ii) It makes the soil porous due to which exchange of gases becomes easy.
(iii) It increases the number of friendly microbes in the soil.
(iv) It improves the texture of the soil.  
(v) It does not create any pollution in the soil.
(vi) It provides all the nutrients.
 

Q. 5. Explain modern methods of irrigation.
Ans. The main modern methods of irrigation are as follows:

(i) Sprinkler System: This system is more useful on the 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 rotating nozzles. It gets sprinkled on the crop as if it is raining. It is very useful for sandy soil.

(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. The system provides water to plants drop by drop. Water is not wasted at all. It is a boon in regions where availability of water is poor.