Welcome dear students! Today we are going to learn about Crop Production and Management from Class 8 Science.
Let us begin our journey into the world of agriculture. Paheli and Boojho went to their uncle's house during the summer vacation. Their uncle is a farmer. One day they saw some tools like khurpi, sickle, shovel, plough, and others in the field. Paheli wanted to know where and how we use these tools. Food has to be produced on a large scale. In order to provide food for a large population, regular production, proper management and distribution is necessary.
[CHECKPOINT]
You have learnt that all living organisms require food. Plants can make their food themselves. Can you recall how green plants synthesise their own food? Animals including humans cannot make their own food. So, where do animals get their food from? But, first of all why do we have to eat food? You already know that energy from the food is utilised by organisms for carrying out their various body functions, such as digestion, respiration and excretion. We get our food from plants, or animals, or both. Since we all need food, how can we provide food to a large number of people in our country? Till ten thousand B.C.E. people were nomadic. They were wandering in groups from place to place in search of food and shelter. They ate raw fruits and vegetables and started hunting animals for food. Later, they could cultivate land and produce rice, wheat and other food crops. Thus, was born Agriculture.
[CHECKPOINT]
When plants of the same kind are cultivated at one place on a large scale, it is called a crop. For example, crop of wheat means that all the plants grown in a field are that of wheat. You already know that crops are of different types like cereals, vegetables and fruits. These can be classified on the basis of the season in which they grow. India is a vast country. The climatic conditions like temperature, humidity and rainfall vary from one region to another. Accordingly, there is a rich variety of crops grown in different parts of the country. Despite this diversity, two broad cropping patterns can be identified. These are: First, Kharif Crops. The crops which are sown in the rainy season are called kharif crops. The rainy season in India is generally from June to September. Paddy, maize, soyabean, groundnut and cotton are kharif crops. Second, Rabi Crops. The crops grown in the winter season, October to March, are called rabi crops. Examples of rabi crops are wheat, gram, pea, mustard and linseed. Besides these, pulses and vegetables are grown during summer at many places.
[CHECKPOINT]
Now let us move to section one point two, Basic Practices of Crop Production. You might wonder why paddy cannot be grown in the winter season. Paddy requires a lot of water. Therefore, it is grown only in the rainy season. Cultivation of crops involves several activities undertaken by farmers over a period of time. You may find that these activities are similar to those carried out by a gardener or even by you when you grow ornamental plants in your house. These activities or tasks are referred to as agricultural practices which are listed below. First, preparation of soil. Second, sowing. Third, adding manure and fertilisers. Fourth, irrigation. Fifth, protecting from weeds. Sixth, harvesting. Seventh, storage.
[CHECKPOINT]
Section one point three covers Preparation of Soil. The preparation of 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. Why does the loosening of soil allow the roots to breathe easily? The loosened soil helps in the growth of earthworms and microbes present in the soil. These organisms are friends of the farmer since they further turn and loosen the soil and add humus to it. But why the soil needs to be turned and loosened? You have learnt in the previous classes that 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. Since only a few centimetres of the top layer of soil supports plant growth, turning and loosening of soil brings the nutrient-rich soil to the top so that plants can use these nutrients. Thus, turning and loosening of soil is very important for cultivation of crops. The process of loosening and turning of the soil is called tilling or ploughing. This is done by using a plough. Ploughs are made of wood or iron. If the soil is very dry, it may need watering before ploughing. The ploughed field may have big clumps of soil called crumbs. It is necessary to break these crumbs. Levelling the field is beneficial for sowing as well as for irrigation. Levelling of soil is done with the help of a leveller. Sometimes, manure is added to the soil before tilling. This helps in proper mixing of manure with soil. The soil is moistened before sowing.
[CHECKPOINT]
Before sowing the seeds, it is necessary to break soil clumps to get better yield. This is done with the help of various tools. The main tools used for this purpose are the plough, hoe and cultivator. Let us look at the plough. This is being used since ancient times for tilling the soil, adding fertilisers to the crop, removing the weeds and turning the soil. This is made of wood and is drawn by a pair of bulls or other animals like horses and camels. It contains a strong triangular iron strip called ploughshare. The main part of the plough is a long log of wood which is called a ploughshaft. There is a handle at one end of the shaft. The other end is attached to a beam which is placed on the bulls necks. One pair of bulls and a man can easily operate the plough. In Figure one point one a, we see a diagram of the plough showing the beam, the ploughshaft, and the ploughshare. The indigenous wooden plough is increasingly being replaced by iron ploughs nowadays. Next is the hoe. It is a simple tool which is used for removing weeds and for loosening the soil. It has a long rod of wood or iron. A strong, broad and bent plate of iron is fixed to one of its ends and works like a blade. It is pulled by animals. In Figure one point one b, we see an illustration of a hoe being used. Nowadays ploughing is done by tractor driven cultivator. The use of cultivator saves labour and time. Figure one point one c shows a cultivator driven by a tractor.
[CHECKPOINT]
Now we come to section one point four, Sowing. 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 which give high yield. Let us discuss selection of seeds. One day I saw my mother put some gram seeds in a vessel and pour some water on them. After a few minutes some seeds started to float on top. I wonder why some seeds float on water! Let us perform Activity one point one. Take a beaker and fill half of it with water. Put a handful of wheat seeds and stir well. Wait for some time. Are there seeds which float on water? Would those be lighter or heavier than those which sink? Why would they be lighter? Damaged seeds become hollow and are thus lighter. Therefore, they float on water. This is a good method for separating good, healthy seeds from the damaged ones.
[CHECKPOINT]
Before sowing, one of the important tasks is to know about the tools used for sowing seeds. The traditional tool used for sowing seeds is shaped like a funnel. In Figure one point two a, we see this traditional method of sowing. The seeds are filled into the funnel, passed down through two or three pipes having sharp ends. These ends pierce into the soil and place seeds there. Appropriate distance between the seeds is necessary to avoid overcrowding of plants. This allows plants to get sufficient sunlight, nutrients and water from the soil. At times a few plants may have to be removed to prevent overcrowding. Seeds of a few plants such as paddy are first grown in a nursery. When they grow into seedlings, they are transplanted to the field manually. Some forest plants and flowering plants are also grown in the nursery.
[CHECKPOINT]
Nowadays the seed drill is used for sowing with the help of tractors. Figure one point two b shows a seed drill. This sows the seeds uniformly at equal distance and depth. It ensures that seeds get covered by the soil after sowing. This protects seeds from being eaten by birds. Sowing by using a seed drill saves time and labour. Let us move to section one point five, Adding Manure and Fertilisers. The substances which are added to the soil in the form of nutrients for the healthy growth of plants are called manure and fertilisers. Soil supplies mineral nutrients to the crop plants. These nutrients are essential for the growth of plants. In certain areas, farmers grow crop after crop in the same field. The field is never left uncultivated or fallow. Imagine what happens to the nutrients? Continuous cultivation of crops makes the soil poor in nutrients. Therefore, farmers have to add manure to the fields to replenish the soil with nutrients. This process is called manuring. Improper or insufficient manuring results in weak plants.
[CHECKPOINT]
Manure is an organic substance obtained from the decomposition of plant or animal wastes. Farmers dump plant and animal waste 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. You have already learnt about vermicomposting in Class six. Let us perform Activity one point two. Take moong or gram seeds and germinate them. Select three equal sized seedlings. Take three empty glasses or similar vessels. Mark them A, B and C. To glass A add little amount of soil mixed with a little cow dung manure. In glass B put the same amount of soil mixed with a little urea. Take the same amount of soil in glass C without adding anything. Figure one point three a shows the preparation of this experiment. Now pour the same amount of water in each glass and plant the seedlings in them. Keep them in a safe place and water them daily. After seven to ten days observe their growth. Figure one point three b shows the growing seedlings with manure and fertiliser. Did plants in all the glasses grow at the same pace? Which glass showed better growth of plants? In which glass was the growth fastest?
[CHECKPOINT]
Fertilisers are chemicals which are rich in a particular nutrient. How are they different from manure? Fertilisers are produced in factories. Some examples of fertilisers are urea, ammonium sulphate, super phosphate, potash, NPK which stands for Nitrogen, Phosphorus, Potassium. The use of fertilisers has helped farmers to get better yield of crops such as wheat, paddy and maize. But excessive use of fertilisers has made the soil less fertile. Fertilisers have also become a source of water pollution. Therefore, in order to maintain the fertility of the soil, we have to substitute fertilisers with organic manure or leave the field uncultivated, or fallow, in between two crops. The use of manure improves soil texture as well as its water retaining capacity. It replenishes the soil with nutrients. Another method of replenishing the soil with nutrients is through crop rotation. This can be done by growing different crops alternately. Earlier, farmers in northern India used to grow legumes as fodder in one season and wheat in the next season. This helped in the replenishment of the soil with nitrogen. Farmers are being encouraged to adopt this practice. In the previous classes, you have learnt about Rhizobium bacteria. These are present in the nodules of roots of leguminous plants. They fix atmospheric nitrogen.
[CHECKPOINT]
Let us look at the differences between fertiliser and manure as presented in Table one point one. First, fertiliser is a man-made inorganic salt, while manure is a natural substance obtained by the decomposition of cattle dung and plant residues. Second, fertiliser is prepared in factories, while manure can be prepared in the fields. Third, fertiliser does not provide any humus to the soil, while manure provides a lot of humus to the soil. Fourth, fertilisers are very rich in plant nutrients like nitrogen, phosphorus and potassium, while manure is relatively less rich in plant nutrients. The organic manure is considered better than fertilisers. This is because it enhances the water holding capacity of the soil, it makes the soil porous due to which exchange of gases becomes easy, it increases the number of friendly microbes, and it improves the texture of the soil.
[CHECKPOINT]
Now we come to section one point six, Irrigation. All living beings need water to live. Water is important for proper growth and development. Water is absorbed by the plant roots. Along with water, minerals and fertilisers are also absorbed. Plants contain nearly ninety percent water. Water is essential because germination of seeds does not take place under dry conditions. Nutrients dissolved in water are transported to each part of the plant. Water also protects the crop from both frost and hot air currents. To maintain the moisture of the soil for healthy crop growth, fields have to be watered regularly. The supply of water to crops at regular intervals is called irrigation. The time and frequency of irrigation varies from crop to crop, soil to soil and season to season. In summer, the frequency of watering is higher. Why is it so? Could it be due to the increased rate of evaporation of water from the soil and the leaves? The sources of water for irrigation are wells, tubewells, ponds, lakes, rivers, dams and canals.
[CHECKPOINT]
Traditional Methods of Irrigation use water available in wells, lakes and canals lifted up by different methods. Cattle or human labour is used in these methods. So these methods are cheaper, but less efficient. The various traditional ways are moat, which is a pulley system, chain pump, dhekli, and rahat, which is a lever system. Figures one point four a through d illustrate these methods. Figure one point four a shows a moat. Figure one point four b shows a chain pump. Figure one point four c shows a dhekli. Figure one point four d shows a rahat. Pumps are commonly used for lifting water. Diesel, biogas, electricity and solar energy is used to run these pumps. Modern Methods of Irrigation help us to use water economically. The main methods used are as follows. First, 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 the rotating nozzles. It gets sprinkled on the crop as if it is raining. Sprinkler is very useful for lawns, coffee plantation and several other crops. Figure one point five a shows the sprinkler system.
[CHECKPOINT]
Second, Drip system. In this system, the water falls drop by drop directly near the roots. So it is called drip system. It is the best technique for watering fruit plants, gardens and trees. Figure one point five b shows the drip system. Water is not wasted at all. It is a boon in regions where availability of water is poor. Section one point seven covers Protection from Weeds. Boojho and Paheli went to a nearby wheat field and saw that there were some other plants in the field, growing along with wheat plants. Have these other plants been planted purposely? 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.
[CHECKPOINT]
Farmers adopt many ways to remove weeds and control their growth. Tilling before sowing of crops helps in uprooting and killing of 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 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. A seed drill is also used to uproot weeds. Weeds are also controlled by using certain chemicals, called weedicides, like two comma four dash 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. Figure one point six shows a farmer spraying weedicide. Do weedicides have any effect on the person handling the weedicide sprayer? As already mentioned, the weedicides are sprayed during the vegetative growth of weeds before flowering and seed formation. Spraying of weedicides may affect the health of farmers. So they should use these chemicals very carefully. They should cover their nose and mouth with a piece of cloth during spraying of these chemicals.
[CHECKPOINT]
Now let us learn about section one point eight, Harvesting. Harvesting of a crop is an important task. The cutting of crop after it is mature is called harvesting. In harvesting, crops are pulled out or cut close to the ground. It usually takes three to four months for a cereal crop to mature. Harvesting in our country is either done manually by sickle or by a machine called harvester. Figure one point seven shows a sickle. 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. Figure one point eight shows a combine. After harvesting, sometimes stubs are left in the field, which are burnt by farmers. Paheli is worried. She knows that it causes pollution. It may also catch fire and damage the crops lying in the fields. Farmers with small holdings of land do the separation of grain and chaff by winnowing. Figure one point nine shows a winnowing machine. You have already studied this in Class six.
[CHECKPOINT]
After three or four months of hard work there comes the day of the harvest. The sight of golden fields of standing crop, laden with grain, fills the hearts of farmers with joy and a sense of well-being. The efforts of the past season have borne fruit and it is time to relax and enjoy a little. The period of harvest is, thus, of great joy and happiness in all parts of India. Men and women celebrate it with great enthusiasm. Special festivals associated with the harvest season are Pongal, Baisakhi, Holi, Diwali, Nabanya and Bihu. Section one point nine is Storage. Storage of produce is an important task. If the harvested grains are to be kept for longer time, they should be safe from moisture, insects, rats and microorganisms. Harvested grains have more moisture. If freshly harvested grains, or seeds, are stored without drying, they may get spoilt or attacked by organisms, making them unfit for use or for germination. Hence, before storing them, the grains are properly dried in the sun to reduce the moisture in them. This prevents the attack by insect pests, bacteria and fungi.
[CHECKPOINT]
I saw my mother putting some dried neem leaves in an iron drum containing wheat. I wonder why? Farmers store 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. Figure one point ten a shows silos for storage of grains. Figure one point ten b shows storage of grains in gunny bags in granaries. 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. Let us move to section one point ten, Food from Animals. Let us complete Activity one point three. Make a table in your notebook with columns for serial number, food, and sources. Row one: Milk, sourced from cow, buffalo, she-goat, she-camel. You can fill the remaining rows with examples like eggs from hens and ducks, meat from goats and sheep, and fish from various aquatic species.
[CHECKPOINT]
After completing this table, you must have seen that, like plants, animals also provide us with different kinds of food. Many people living in the coastal areas consume fish as a major part of their diet. In the previous classes you have learnt about the food that we obtain from plants. We have just seen that the process of crop production involves a number of steps like selection of seeds, sowing, and so on. Similarly, animals reared at home or in farms, have to be provided with proper food, shelter and care. When this is done on a large scale, it is called animal husbandry. Fish is good for health. We get cod liver oil from fish which is rich in vitamin D. Now let us review what we have learnt. In order to provide food to our growing population, we need to adopt certain agricultural practices. Same kind of plants cultivated at a place constitute a crop. In India, crops can be broadly categorised into two types based on seasons, rabi and kharif crops. It is necessary to prepare soil by tilling and levelling. Ploughs and levellers are used for this purpose. Sowing of seeds at appropriate depths and distances gives good yield. Good variety of seeds are sown after selection of healthy seeds. Sowing is done by seed drills. Soil needs replenishment and enrichment through the use of organic manure and fertilisers. Use of chemical fertilisers has increased tremendously with the introduction of new crop varieties. Supply of water to crops at appropriate intervals is called irrigation. Weeding involves removal of unwanted and uncultivated plants called weeds. Harvesting is the cutting of the mature crop manually or by machines. Separation of the grains from the chaff is called threshing. Proper storage of grains is necessary to protect them from pests and microorganisms. Food is also obtained from animals for which animals are reared. This is called animal husbandry.
[CHECKPOINT]
Now, dear students, it is time to work through the exercises. Let us solve them together step by step. Exercise one asks you to select the correct word from the list and fill in the blanks. The list is float, water, crop, nutrients, preparation. Part a: The same kind of plants grown and cultivated on a large scale at a place is called crop. Part b: The first step before growing crops is preparation of the soil. Part c: Damaged seeds would float on top of water. Part d: For growing a crop, sufficient sunlight and water and nutrients from the soil are essential. Exercise two asks you to match items in column A with those in column B. i Kharif crops matches with e Paddy and maize. ii Rabi crops matches with d Wheat, gram, pea. iii Chemical fertilisers matches with b Urea and super phosphate. iv Organic manure matches with c Animal excreta, cow dung urine and plant waste. Note that a Food for cattle is an extra option in column B and does not match with the given items in column A. Exercise three asks for two examples of each. Part a: Kharif crop examples are paddy and maize. Part b: Rabi crop examples are wheat and gram.
[CHECKPOINT]
Exercise four asks you to write a paragraph in your own words on each topic. Part a, Preparation of soil: Preparation of soil is the first step before growing a crop. It involves turning and loosening the soil, a process called tilling or ploughing. This allows roots to penetrate deep, breathe easily, and access nutrient-rich topsoil. It also promotes the growth of earthworms and microbes. Tools like ploughs, hoes, and cultivators are used. The soil is then levelled with a leveller for uniform sowing and irrigation. Part b, Sowing: Sowing is the process of placing seeds in the soil. Good quality, healthy seeds are selected first. Damaged seeds are separated by floating them in water. Seeds are then sown using traditional funnel tools or modern seed drills which place seeds at uniform distance and depth. Proper spacing prevents overcrowding and ensures adequate sunlight, water, and nutrients. Some seeds are first grown in nurseries and later transplanted. Part c, Weeding: Weeds are undesirable plants that grow naturally alongside crops. They compete with crops for water, nutrients, space, and light, reducing crop yield. Some weeds are poisonous or interfere with harvesting. Weeding is the removal of these weeds. It is done by tilling before sowing, manual removal using a khurpi, using a seed drill, or spraying weedicides like two comma four dash D before flowering. Part d, Threshing: Threshing is the process of separating grain seeds from the chaff after harvesting. It is carried out using a machine called a combine, which acts as both a harvester and a thresher. For small landholdings, farmers use winnowing machines to separate grain from chaff using wind.
[CHECKPOINT]
Exercise five asks you to explain how fertilisers are different from manure. Fertilisers are man-made inorganic salts prepared in factories, rich in specific nutrients like nitrogen, phosphorus, and potassium, but they do not provide humus to the soil. Manure is a natural substance obtained from the decomposition of cattle dung and plant residues, prepared in fields, provides abundant humus, improves soil texture and water retention, and is relatively less rich in specific plant nutrients compared to fertilisers. Exercise six asks what irrigation is and to describe two water conserving methods. Irrigation is the supply of water to crops at regular intervals. Two methods that conserve water are the sprinkler system and the drip system. The sprinkler system uses perpendicular pipes with rotating nozzles joined to a main pipeline. Water flows under pressure and sprays over the crop like rain, making it ideal for uneven land and crops like lawns and coffee. The drip system delivers water drop by drop directly near the roots. It prevents water wastage completely and is best for fruit plants, gardens, and trees in water-scarce regions.
[CHECKPOINT]
Exercise seven asks what would happen if wheat is sown in the kharif season. Wheat is a rabi crop that requires cool winter conditions for growth. The kharif season is the rainy season from June to September, which brings excessive water and warm temperatures. If wheat is sown in the kharif season, the excess water will damage the crop, the warm and humid conditions will promote diseases and pests, and the crop will not mature properly, leading to very poor yield or complete crop failure. Exercise eight asks how soil gets affected by continuous plantation of crops in a field. Continuous cultivation of crops without leaving the field fallow depletes the soil of essential nutrients like nitrogen, phosphorus, and potassium. Plants absorb these nutrients for growth, and without replenishment through manure, fertilisers, or crop rotation, the soil becomes poor in fertility. This leads to weaker plants, reduced crop yields, and degraded soil structure over time. Exercise nine asks what weeds are and how to control them. Weeds are undesirable plants that grow naturally along with the crop. They can be controlled by tilling the soil before sowing to uproot them, manual removal using a khurpi, using a seed drill to uproot them, or spraying weedicides like two comma four dash D. Weedicides should be sprayed carefully during the vegetative stage before flowering, and farmers should cover their nose and mouth for safety.
[CHECKPOINT]
Exercise ten asks you to arrange boxes in proper order for a flow chart of sugarcane crop production. The correct sequence is: One, Preparation of soil. Two, Ploughing the field. Three, Manuring. Four, Sowing. Five, Irrigation. Six, Harvesting. Seven, Sending crop to sugar factory. Exercise eleven is a word puzzle. Let us solve it using the clues. Down clues: One, Providing water to the crops. Answer is IRRIGATION. Two, Keeping crop grains for a long time under proper conditions. Answer is STORAGE. Five, Certain plants of the same kind grown on a large scale. Answer is CROP. Across clues: Three, A machine used for cutting the matured crop. Answer is HARVESTER. Four, A rabi crop that is also one of the pulses. Answer is GRAM. Six, A process of separating the grain from chaff. Answer is WINNOWING. Filling the grid: One I R R I G A T I O N. Two S T O R A G E. Three H A R V E S T E R. Four G R A M. Five C R O P. Six W I N N O W I N G.
[CHECKPOINT]
Let us briefly look at the extended learning activities and projects. First, sow some seeds and arrange drip irrigation. Observe daily to see if it saves water and note seed changes. Second, collect different seeds in labelled bags. Third, collect pictures of agricultural machines and write their names and uses. Fourth, visit a farm or nursery to gather information on seed selection importance, irrigation methods, effects of extreme cold, extreme hot weather, continuous rain, and fertilisers or manure used. Here is an example for field trip work. Himanshu and his friends visited Thikri village and Shri Jiwan Patel's farmhouse. They asked about his work. Shri Patel said his grandfather started seventy five years ago, growing wheat, gram, soyabean and moong. He explained that earlier they used traditional tools like sickle, bullock plough, and trowel, depending on rain. Now they use modern irrigation, tractors, cultivators, seed drills, and harvesters. They use good quality seeds, conduct soil testing, and use manure and fertilisers. They get nine to eleven quintals of gram per acre and twenty to twenty five quintals of wheat per acre. Mohan saw earthworms. Shri Patel explained earthworms turn and loosen soil for aeration. David collected seeds, fertilisers, and soil samples. The visit provided useful information on modern agricultural practices.
Thank you for listening! Keep revising and practicing. Goodbye! [CHAPTER_COMPLETE]