CROP PRODUCTION AND MANAGEMENT Class 8 Ncert SCIENCE PDF
CHAPTER 1
CROP PRODUCTION AND MANAGEMENT
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, etc., in the field.
You have learnt that all living organisms require food. Plants can make their food themselves. Animals including humans cannot make their own food. So, where do animals get their food from?
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? 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.
1.1 Agricultural Practices
Till 10,000 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”.
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:
(i) 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.
(ii) 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.
1.2 Basic Practices of Crop Production
Cultivation of crops involves several activities undertaken by farmers over a period of time. These activities are similar to those carried out by a gardener when growing ornamental plants. These activities or tasks are referred to as agricultural practices and are listed below:
(i) Preparation of soil
(ii) Sowing
(iii) Adding manure and fertilisers
(iv) Irrigation
(v) Protecting from weeds
(vi) Harvesting
(vii) Storage
1.3 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.
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.
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.
Agricultural Implements
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.
Plough: This is used for tilling the soil, adding fertilisers to the crop, removing the weeds and turning the soil. It is made of wood and is drawn by a pair of bulls or other animals (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.
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.
Cultivator: Nowadays ploughing is done by tractor‑driven cultivator. The use of cultivator saves labour and time.
1.4 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.
Selection of Seeds
Take a beaker and fill half of it with water. Put a handful of wheat seeds and stir well. Wait for some time. Some seeds float on water. Damaged seeds become hollow and are thus lighter and float on water. This is a good method for separating good, healthy seeds from the damaged ones.
Before sowing, one of the important tasks is to know about the tools used for sowing seeds.
Traditional tool: The tool used traditionally for sowing seeds is shaped like a funnel. 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.
Seed drill: Nowadays the seed drill is used for sowing with the help of tractors. 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.
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.
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.
1.5 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. 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.
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.
Fertilisers are chemicals which are rich in a particular nutrient. Fertilisers are produced in factories. Some examples of fertilisers are urea, ammonium sulphate, super phosphate, potash, NPK (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, fertilisers need to be substituted with organic manure or the field should be left uncultivated (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.
Rhizobium bacteria are present in the nodules of roots of leguminous plants. They fix atmospheric nitrogen.
Table 1.1: Differences between Fertiliser and Manure
Fertiliser is a man‑made inorganic salt. Manure is a natural substance obtained by the decomposition of cattle dung and plant residues.
Fertiliser is prepared in factories. Manure can be prepared in the fields.
Fertiliser does not provide any humus to the soil. Manure provides a lot of humus to the soil.
Fertilisers are very rich in plant nutrients like nitrogen, phosphorus and potassium. Manure is relatively less rich in plant nutrients.
Advantages of Manure: The organic manure is considered better than fertilisers 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.
it improves the texture of the soil.
1.6 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 90% 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 because of the increased rate of evaporation of water from the soil and the leaves.
Sources of irrigation: The sources of water for irrigation are wells, tubewells, ponds, lakes, rivers, dams and canals.
Traditional Methods of Irrigation
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. So 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)
Pumps are commonly used for lifting water. Diesel, biogas, electricity and solar energy are used to run these pumps.
Modern Methods of Irrigation
Modern methods of irrigation help to use water economically. The main methods used 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 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.
(ii) 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. Water is not wasted at all. It is a boon in regions where availability of water is poor.
1.7 Protection from Weeds
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.
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 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. Spraying of weedicides may affect the health of farmers, so they should cover their nose and mouth with a piece of cloth during spraying.
1.8 Harvesting
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 3 to 4 months for a cereal crop to mature.
Harvesting in our country is either done manually by sickle or by a machine called harvester.
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.
Farmers with small holdings of land do the separation of grain and chaff by winnowing.
1.9 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 (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.
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.
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.
1.10 Food from Animals
After completing a table of food items and sources, it is seen that, like plants, animals also provide different kinds of food. Many people living in the coastal areas consume fish as a major part of their diet.
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. Cod liver oil from fish is rich in vitamin D.
Comments