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

SHORT ANSWER TYPE QUESTIONS
 

Q. 1. Why do we have to eat food?
 Ans. Food provides us energy. The energy provided by food is utilised by the organisms for carrying out their various body functions, such as digestion, respiration and excretion. We get our food from plants and animals.

Q. 2. Explain various types of crops.
 Ans. Crops are of two types: 

(i) Kharif crops: The crops which are grown in the rainy season are called kharif crops (June to September). Paddy, maize, soyabean, groundnut, cotton are some of the major kharif crops.

(ii) Rabi crops: The crops sown in the winter season are called rabi crops (October to March). Wheat, gram, pea, mustard and linseed are some of the major rabi crops.

Q. 3. List various agricultural practices.
 Ans. The agricultural practices are listed below: 
(i) Preparation of soil
(ii) Sowing
(iii) Adding manure and fertilisers
(iv) Irrigation
(v) Protecting from weeds
(vi) Harvesting
vii) Storage.  

Q. 4. Why is the soil loosened before seeds are sown?
 Ans. The soil should be loosened before sowing. The loosened soil allows the roots to penetrate deep into soil. It helps the roots to breathe. The loosened soil helps in the growth of the earthworms and microbes present in the soil. These organisms are the friend of the farmers since they further turn and loosen the soil.
 

Q. 5. What is plough?
 Ans. This implement is made of wood and iron. It is drawn by a pair of bulls or other animals. It contains a strong triangular iron strip called ploughshare. The main part of the plough is a long log of wood which is called ploughshaft. The plough is used for tilling the soil, adding fertilisers to the crop, removing the weeds and scraping of soil. 

Q. 6. What is hoe? What is its use?
 Ans. Hoe is a simple tool which is used for removing weeds and for loosening the soil. It has a long rod of wood or the iron. A strong broad and bent plate of iron is fixed to one of its ends and works like a blade. It is also pulled by animals. 

Q. 7. Explain a method to separate healthy seeds from the damaged seeds.
 Ans. Take a beaker and fill half of it with water. Put a handful of wheat seeds and stir well. Wait for some time. We observe that some seeds float on the surface of water. These are damaged  seeds, separate them. This is a good method for separating good and healthy seeds from the damaged seeds.
 

Q. 8. Explain a traditional method of sowing.
 Ans. The tool used traditionally for sowing seeds is shaped like a funnel. The seeds are filled into the funnel and passed down through two or three pipes having sharp ends. These ends pierce into the soil and place seeds there. 

Q. 9. Explain the modern method of sowing.
 Ans. Nowadays the seed drill is used for sowing with the help of tractors. This tool sows the seeds uniformly at proper distance and depths. It ensures that seeds get covered by the  soil after sowing. This prevents damage caused by birds. It also saves time and labour. There is a sufficient distance between seeds so the plants get sufficient sunlight, nutrients and water from the soil.

Q . 10. Explain the preparation of manure by the farmers.
 Ans. Manure is an organic substance obtained from decomposition of plant or animal wastes. Farmers dump plant and animal wastes in pits at open places and allow it to decompose. The decomposition is caused by some microorganisms. The decomposed matter is used as organic manure.

Q . 11. What are fertilisers? How do they differ from manure on the basis of their formation?
 Ans. Fertilisers are the chemical substances which are rich in a particular nutrient. Fertilisers are produced in the factories while manure can be made by farmers themselves in the fields. Some fertilisers are urea, ammonium sulphate, super‑phosphate, potash, N.P.K. (Nitrogen, Phosphorus, Potassium). Fertilisers are used to get better yield of crops.

Q . 12. Explain some harmful effects of using fertilisers.
 Ans. The excessive use of fertilisers has made the soil less fertile. They have also become a source of pollution. They do not help in maintaining the soil fertility for a long time.

Q . 13. Write two advantages of manures.
 Ans. (i) The use of manure improves soil texture and water retaining capacity of the soil. (ii) It replenishes the soil with all the nutrients. 

Q . 14. What is crop rotation? Write its importance.
 Ans. The process of growing different crops alternately year by year is called crop rotation.
It helps in the replenishment of the soil with nitrogen by the process of nitrogen fixation. 

Q . 15. What is the role of water in the production of crops?
 Ans. Water is essential for plants. It helps in the germination of seeds because seeds cannot germinate under dry conditions. Nutrients dissolved in water get transported to each part of the plant. It protects the crop from frost and hot air currents. Water is important for proper growth and development of flowers, fruits and seeds of plants. Along with water minerals and fertilisers are also absorbed. Plants contain nearly 90% water. The time and frequency of irrigation varies from crop to crop, soil to soil and season to season.
 

Q . 16. Explain traditional methods of irrigation.
 Ans. The water available in wells, lakes and canals is lifted up by different methods in different regions, for taking it to the fields. Cattle or human labour is used in these methods. These methods are cheaper but less efficient. The various traditional ways are:

(i) Moat (Pulley system)

(ii) Chain pump 

(iii) Dhekli

(iv) Rahat (Lever system)

Q . 17. What is weeding? Why is it necessary?
 Ans. The process of removal of weeds is called weeding. Weeding is necessary since weeds compete with crop plants for water, nutrients, space and sunlight. Thus they affect the growth of crop. Some weeds interfere even in harvesting and may be poisonous for animals and human beings.

Q . 18. Explain the various methods of weeding.
 Ans. Farmers use many ways to remove weeds and control their growth. Tilling before sowing of crops helps in uprooting and killing weeds, which may then dry up and get mixed with the soil. The best time for the removal of weeds is before they produce flowers and seeds. The khurpi is used to remove weeds by uprooting or cutting them from time to time. A seed drill is also used to uproot weeds. Weeds are also controlled by using weedicides like 2, 4‑D.

Q . 19. Explain various methods of harvesting in our country.
 Ans. There are mainly two methods which are used to harvest the mature crops:
(i) Manual: A device called sickle is used to harvest mature crops manually.
(ii) By Machine: A machine called harvester is also used to harvest crops. A machine called combine which is in fact, a combined harvester and thresher. This machine does both the functions of harvesting and threshing at the same time. 

Q. 20. What do you know about Harvest Festival?
 Ans. After three or four months of hard work there comes the day of harvest. The sight of golden fields of standing crops, laden with grains fills the hearts of farmers with joy and a sense of well being. Men and women celebrate this period with great enthusiasm. This period of joy is called Harvest Festival. Pongal, Baishakhi, Holi, Diwali, Nabanya and Bihu are such Harvest Festivals.

Q. 21. How do the grains stored and preserved?
 Ans. Farmers store the grains in jute bags or metallic bins. However, large scale storage of grains is done in silos and granaries, to protect them from pests like rats and insects. Dried neem leaves are used for storing food grains at home. For storing large quantities of grains in big godowns, specific chemical treatments are required to protect them from pests and microorganisms.

Q . 22. Write the name of some food material, provided by animals.