\n6. Its excessive use causes water pollution. It cannot replenish the organic matter of soil.<\/td>\n | 6. It protects the environment and helps in recycling the farm waste.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Question 6. \nWhat is irrigation? Describe two methods of irrigation which conserve water. \nAnswer: \nPlants need plenty of water to grow. Farmers need to supply water to the crops at regular intervals. This practice is called irrigation. Two methods of irrigation which conserve water are as follows:<\/p>\n a. Sprinkler System: The sprinkler system is composed of a series of pipelines. Vertical sprinklers are fitted at suitable gaps on the pipes. Water is pushed through the pipes with the help of a pump. The nozzle of the sprinkler keeps on rotating. It results in a jet of water being sprinkled on plants. Sprinkler system is ideal for irrigation on uneven land.<\/p>\n b. Drip Irrigation: In this system, pipes are laid near the base and along the queue of plants. The pipes have small holes at frequent gaps. The holes facilitate gradual dripping of water on the base of plants. This method is ideal for areas which are suffering from shortage of water.<\/p>\n Question 7. \nIf wheat is sown in the kharif season, what would happen? Discuss. \nAnswer: \nKharif come during rainy season hence it is not a wise idea to grow wheat in Kharif season. Crop of wheat requires moderate temperature, moderate amount of water and a long period of frost-free days. If wheat is grown in kharif season it may not grow properly because of very high temperature. Some of the plants may also get damaged due to flooding. This will result in poor yield.<\/p>\n Question 8. \nExplain how soil gets affected by the continuous plantation of crops in a field. \nAnswer: \nWe know that plants take nutrients from the soil and thus exhaust the soil from most of the nutrients with passage of time. Thus, continuous plantation of crops in the field results in loss of fertility of the soil. The soil may become infertile in the long run because the soil does not get enough time to replenish its lost nutrients.<\/p>\n Question 9. \nWhat are weeds? How can we control them? \nAnswer: \nAny unwanted plant which grows along with crops is called weed. Removal of weeds is called weeding. Weeding is usually done manually by using a trowel. Weeds are also removed during ploughing. Weedicides are the chemicals which destroy weeds. 2, 4-D is an example of weedicide. Weedicides are sprayed before flowering and seeding in weeds.<\/p>\n <\/p>\n Question 10. \nArrange the following boxes in proper order to make a flow chart of sugarcane crop production. \n \nAnswer: \nFlow chart of the production: \n<\/p>\n Question 11. \nComplete the following cross word puzzle with the help of clues given below. \nDown \n1. Providing water to the crops. \n2. Keeping crop grains for a long time under proper conditions. \n5. Certain plants of the same kind grown on a large scale. \nAcross \n3. A machine used for cutting the matured crop. \n4. A rabi crop that is also one of the pulses. \n6. A process of separating the grain from chaff. \n \nAnswer: \n1. Irrigation \n2. Storage \n3. Harvester \n4. Gram \n5. Crop \n6. Winnowing<\/p>\n NCERT Extended Learning Activities and Projects<\/span><\/p>\nQuestion 1. \nSow some seeds in the soil and arrange to water them by drip irrigation. Observe daily. \na. Do you think it can save water? \nb. Note the changes in the seed. \nHint: \na. Yes, it will save water because in the drip irrigation method, pipes are laid near the base and along the queue of plants. The pipes have small holes at frequent gaps. The holes facilitate gradual dripping of water on the base of plants. This method is ideal for areas which are suffering from shortage of water.<\/p>\n b. We can see the change in seed day by day. As long as we give proper care and sunlight to the seed, it grows properly. Adding manure\/fertiliser to the soil will help the seed to grow faster.<\/p>\n Question 2. \nCollect different types of seeds and put them in small bags. Label them. \nHint: \nSeeds should be as dry as possible when you collect them. Pick a dry day when there isn’t too much wind as many seeds are very light and can easily be blown away.<\/p>\n Question 3. \nCollect pictures of some other agricultural machines and paste them in a file. Write their names and uses. \nHint: \nThe following agricultural machines are used nowadays: \nShredders and cutters, wheel tractor-scrapper, cotton harvester, tillage planter, drag harrow, sprayer.<\/p>\n <\/p>\n Question 4. \nVisit a farm, nursery or a garden nearby. Gather information about \na. importance of seed selection. \nb. method of irrigation. \nc. effect of extreme cold and extreme hot weather on the plants. \nd. effect of continuous rain on the plants. \ne. fertilisers\/manure used. \nHint: \na. By removing the inferior seeds, the farmer is able to grow stronger and healthier seedlings. While seed selection is mainly aimed at obtaining healthier seeds, it can also be used to maintain and improve the quality of the crop variety. In a crop field, farmers may observe differences in traits between plants.<\/p>\n b. There are two types of modem irrigation methods:<\/p>\n \n- Sprinkler irrigation is a method of irrigation in which water is sprayed or sprinkled through the air in the form of rain-like drops.<\/li>\n
- In drip irrigation method, pipes are laid near the base and along the queue of plants. The pipes have small holes at frequent gaps. The holes facilitate gradual dripping of water on the base of plants.<\/li>\n<\/ol>\n
c. Extreme heat will slow down the growth and also increase moisture loss in the plants. The temperatures for optimal growth vary with the type of plant. Extremely hot or cold soil temperatures can also hamper the plant growth and seed germination.<\/p>\n d. Rainwater drains out nutrients and minerals that the plant needs to survive from the soil. If it rains continuously, the soil will lose its fertility and the plants won\u2019t get the required nutrients. Plants get destroyed due to excess of rain.<\/p>\n e. Fertilisers supply specific type of nutrients to the plant. Fertilisers are the chemicals which add minerals like potassium, phosphorus and nitrates to soil. They use manure because it is a cheap fertiliser and environment- friendly. Fertilisers are used because they increase crop production.<\/p>\n Activity 1<\/span><\/p>\nObjective: To observe the effect of manure and fertilisers on the growth of plants. \nMaterials Required: Three empty flower pots, soil, cow dung manure, urea fertiliser, water and some gram seeds. \nProcedure:<\/p>\n \n- Take three empty flower pots and mark them A, B, and C.<\/li>\n
- Put some ordinary soil in pot A. Add some soil mixed with little cow-dung manure in pot B and take some soil mixed with a little urea fertiliser in pot C.<\/li>\n
- Pour the same amount of water in all the three flower pots.<\/li>\n
- Now take some gram seeds and germinate them.<\/li>\n
- Select equal sized seedlings of gram.<\/li>\n
- Plant these seedlings in each of the three flower pots.<\/li>\n
- Keep the flower pots in a sunny place and water them daily.<\/li>\n
- Observe and compare the growth of seedlings in the three flower pots after 7 to 10 days.<\/li>\n<\/ul>\n
\nObservations:<\/p>\n
\n- The pot A containing ordinary soil shows slow and poor growth.<\/li>\n
- The pot B containing manure shows better growth.<\/li>\n
- The pot C containing the fertiliser shows the fastest growth.<\/li>\n<\/ul>\n
Conclusion: This activity shows that manure and fertilisers are essential for better growth of plants.<\/p>\n iv. Irrigation: Plants need plenty of water to grow. Farmers need to supply water to the crops at regular intervals. This practice is called irrigation. Different types of crops require different amount and frequency of irrigation. Kharif crops need more water than rabi crops.<\/p>\n Sources of Irrigation: Wells, tube-wells, ponds, lakes, rivers, canals, etc., are the sources of irrigation.<\/p>\n Traditional Methods of Irrigation: In the traditional methods, human or animal labour is used. Following are some traditional methods of irrigation: \na. Moat (pulley-system): This is composed of a pulley and a rope. A bucket is tied to one end of the rope. Another end of the rope is pulled through over the pulley in order to draw water. \n<\/p>\n b. Chain Pump: Chain pump is composed of a wheel which is turned with the help of a chain. Many circular discs are fitted along with the chain. Movement of discs along with the chain helps in drawing water. \n<\/p>\n c. Dhekli: Dhekli is composed of a long wooden beam which turns around a lever. A bucket is fitted at the longer end of the beam. The shorter end is pressed and raised by foot to fill and lift water. \n<\/p>\n d. Rahat: Rahat is also called Persian wheel because its concept came from Persia. Rahat is composed of a big wheel with buckets fitted on the rim. Rahat is turned with the help of cattle, which helps in drawing water from a reservoir. \n \nManual pumps are now being replaced by motor-driven pumps. Such motors are powered either by electricity or by diesel engine.<\/p>\n Modern Methods of Irrigation: There are two modem methods of irrigation as follows: \na. Sprinkler System: The sprinkler system is composed of a series of pipelines. Vertical sprinklers are fitted at suitable gaps on the pipes. Water is pushed through the pipes with the help of a pump. The nozzle of the sprinkler keeps on rotating. It results \n<\/p>\n b. Drip Irrigation: In this system, pipes are laid near the base and along the queue of plants. The pipes have small holes at frequent gaps. The holes facilitate gradual dripping of water on the base of plants or directly on the roots. This method is ideal for areas which are suffering from shortage of water. \n<\/p>\n v. Protection from Weeds \nWeeds: Any unwanted plant which grows along with the main crop is called weed. \nWeeding: The removal of weeds is called weeding. Weeding is necessary because weeds affect the growth of the crop by competing with the crop plants for water, nutrients, space and light. \nWeed Control: The best time for the removal of weeds is before they produce flowers and seeds. The manual removal includes physical removal of weeds by uprooting or cutting them close to the ground, from time to time with the help of a khurpi. Weeds are also controlled by spraying certain chemicals, called weedicides, in the fields to kill the weeds. These chemicals do not damage the crops.<\/p>\n vi. Harvesting: The cutting of crop after it is mature is called harvesting. In harvesting, the crops are pulled out or cut close to the ground. Harvesting is done manually by sickle or by a machine.<\/p>\n Threshing: In the harvested crop, the seed grains need to be separated from the chaff with the help of a machine called \u2018combine\u2019. It is in fact a combined harvester and thresher. This process is called threshing. \nWinnowing: Separation of grains and chaff in small land holdings is called winnowing. Winnowing is done manually or by machines. \n<\/p>\n vii. Storage: Grains obtained by threshing are dried in the Sun. The dried grains are stored in gunny bags and placed in properly ventilated cemented halls, known as godowns. Farmers keep dried grains in jute bags or metallic bins or mud bins. Large scale storage of grains is done in silos and granaries. For storing large quantities of grains in big godowns, specific chemical treatments are used to protect them from pests and microorganisms. \n<\/p>\n \n- Food from Animals: Animals are an important source of food for us. Many animals are reared for milk. Some animals are reared for meat, e.g., goats and poultry. Fish is an important source of meat. Honey is obtained from honeybees.<\/li>\n
- Animal Husbandry: Food is obtained from animals for which animals are reared and provided with proper food, shelter and care. When done on a large scale, it is called animal husbandry.<\/li>\n<\/ul>\n
Class 8 Science Chapter 1 Crop Production and Management Additional Important Questions and Answers<\/h3>\nVery Short Answer Type Questions<\/span><\/p>\nQuestion 1. \nWhat is agriculture? \nAnswer: \nCultivation of plants and rearing of animals for food and other beneficial products and services is called agriculture.<\/p>\n Question 2. \nWhat is a crop? \nAnswer: \nWhen plants of the same kind are grown and cultivated at one place on a large scale, it is called a crop.<\/p>\n Question 3. \nWhich agricultural practice comes first: harvesting or weeding? \nAnswer: \nWeeding.<\/p>\n <\/p>\n Question 4. \nWhat is sowing? \nAnswer: \nPutting seeds in soil is called sowing.<\/p>\n Question 5. \nWhat are fertilisers? \nAnswer: \nFertilisers are chemicals which contain a particular plant nutrient.<\/p>\n Question 6. \nWhat is irrigation? \nAnswer: \nThe process of supplying water to crops at regular intervals is called irrigation.<\/p>\n Question 7. \nWhat are weeds? \nAnswer: \nUnwanted plants which grow along with the crops are called weeds.<\/p>\n Question 8. \nWhat is winnowing? \nAnswer: \nSeparation of grains from chaff with the help of blowing wind is called winnowing.<\/p>\n Question 9. \nWhat is manure? \nAnswer: \nManure is an organic substance prepared by the decomposition of plants and animals waste.<\/p>\n Question 10. \nWhat are manures and fertilisers used for? \nAnswer: \nManures and fertilisers are used to maintain the fertility of the soil and enhance crop yield.<\/p>\n <\/p>\n Question 11. \nWrite any two uses of hoe. \nAnswer:<\/p>\n \n- It is used to remove the weeds,<\/li>\n
- It is used to loosen the soil.<\/li>\n<\/ol>\n
Question 12. \nWhat do you mean by storage? \nAnswer: \nThe process of keeping the grains viable for a longer time by saving them from moisture, insects, rats and microorganisms is called storage.<\/p>\n Question 13. \nMention three animals which provide meat. \nAnswer: \nGoat, pig and poultry.<\/p>\n Question 14. \nWhat do you mean by animal husbandry? \nAnswer: \nAnimal husbandry is the process of rearing animals by providing them proper food, shelter and care at a large scale.<\/p>\n Question 15. \nWhy is it necessary to dry grains before storage? \nAnswer: \nThe grains are properly dried in the Sun to reduce the moisture in them. This prevents the attack by insects, pests, fungi and bacteria. Moisture changes colour of grains and they lose their germination capacity.<\/p>\n Question 16. \nWrite some sources of irrigation. \nAnswer: \nWells, tube wells, ponds, rivers and canals are the main sources of irrigation.<\/p>\n Question 17. \nWhich oil is obtained from fish and which vitamin is it rich in? \nAnswer: \nCod liver oil is obtained from fish which is rich in vitamin D.<\/p>\n Short Answer Type Questions<\/span><\/p>\nQuestion 1. \nWhat is humus? How is it formed? \nAnswer: \nHumus is an organic matter rich in nutrients. It is formed by the microbial action on dead and decaying animal bodies and leaves. It is generally formed on those spots where there are denser layers of trees. The soil below it becomes dark having more number of bacteria. These bacteria decompose the decaying organic matter and convert it into manure.<\/p>\n <\/p>\n Question 2. \nExplain the traditional method of sowing. \nAnswer: \nTraditionally, the tool used for sowing is shaped like a funnel. The seeds to be sown are filled into the funnel and passed down through two or three pipes, having sharp ends. These sharp ends pierce into the soil and place the seeds in the soil. Broadcasting is another method in which seeds are simply scattered in the soil manually by hands.<\/p>\n Question 3. \nExplain the modern method of sowing. \nAnswer: \nThe modem method of sowing seeds is through a seed drill. The seed drill is powered by a tractor and it helps to sow the seeds uniformly at proper distances and depths. It also ensures that seeds, once dropped, get covered by the soil after sowing. This prevents the wastage of seeds caused due to damage by the birds. It also saves time and labour and ensures a uniform spreading of the seeds.<\/p>\n Question 4. \nWhat is the significance of ploughing? \nAnswer: \nSignificance of ploughing:<\/p>\n |