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Class 8 Science NCERT-Biology
Chapter 1: Crop Production and Management
** We know that all living organisms require food. Plants can make their food themselves. Animals including humans can not make their own food. We get our food from plants, or animals, or both. ** The energy from food is utilised by organisms for carrying out their various body functions, such as digestion, respiration and excretion. In order to provide food for a large population- regular production, proper management and distribution of food is necessarv Birth of agriculture: ** Till 10,000 B.C. 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 for animals for food Later, they could cultivate land and produce rice, wheat and other food crops. Thus, was born 'Agriculture'
Crops and their typess When plants of the same kind are grown and 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. 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. kharif crops and rabi crops.
Kharif Crops: a. The crops which are sown in t he rainy season are called Knarif crops. The rainy season in India is generally from June to September c. Paddy, maize, soyabean, groundnut, cotton, etc., are kharif crops Rabi Crops: a. The crops grown in the winter season are called rabi crops. b. Their time period is generally from October to March. c. Examples of rabi crops are * Besides these, pulses and vegetables are grown during summer at many places wheat, gram, pea, mustard and linseed
* Agricultural practices include following activities: 1. Preparation of soil 2. Sowing 3. Adding manure and fertilisers 4. Irrigation 5. Protecting from weeds 6. Harvesting 7. Storage * Preparation of Soil: a. Soil is turned and loosened to allow 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. b. The loosened soil helps in the growth of earthworms and microbes present in the soil. These organisms are friends of the farmer since thev further turn and loosen the soil and add humus to it
c. 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 d. The process of loosening and turning of the soil is called tilling or ploughing. This is done by using a plough. e. Sometimes, manure is added to the soil before tilling. This helps in proper mixing of manure with soil. The soil is watered before sowing
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. 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 growing of crops makes the soil poorer in certain 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.
Fertilizer vs Manure: Fertilizer Manure 1. It is an Inorganic salt. 1. It is a natural substance obtained by the decomposition of cattle dung, human waste and plant residues 2. It is prepared in factories. 2. Prepared in fields. 3. A fertiliser does not provide any humus to the soil. 3. Manure provides a lot of humus to the soil. 4. Fertilisers are very rich in plant nutrients like4 Manure is relatively less rich in plant nutrients. nitrogen, phosphorus and potassium.
Fertilisers: Fertilizers are chemical substances which are rich in a particular nutrient and the 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, we have to substitute fertilisers by organic manure or leave the field 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 all the nutrients.