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Class VIII NCERT Science Summary Part-1 SIVA PRASAD
About Me Bachelors and Masters in Physics from Indian Institute of Science (ISc), Bangalore INSPIRE Scholar, DST Govt. of India . Interested in Physics, current affairs, economics.... Physicist, Blogger, Teacher.... Wrote UPSC CSE Mains 2017
Crops . When plants of the same kind are grown and cultivated at one place on a large scale, it is called a crop 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, cotton, etc., are kharif crops. .Rabi Crops: The crops grown in the winter season are called rabi crops. Their time period is generally from October to March. Examples of rabi crops are wheat, gram, pea, mustard and linseed.
Agricultural Practices () Preparation of soil (ii) Sowing (ii) Adding manure and fertilisers (iv) Irrigatiorn (v) Protecting from weeds (vi) Harvesting (vii) Storag
Preparation of soil Turn the soil and loosen it Tilling/ploughing 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.
Sowing . Before sowing good quality seeds are selected by the farmer Seeds are sown at proper distances and depths . An appropriate distance between the seeds is important to avoid overcrowding of plants. . This allows plants to get sufficient sunlight, nutrients and water from the soil SOI
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 . 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.
Adding manure and fertiliser 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 produced in factories. Some examples of fertilisers are urea, ammonium sulphate, super phosphate, potash, NPK (Nitrogen, Phosphorus, Potassium)
Difference between manure and Fertiliser S. No. Fertiliser Manure 1. A fertiliser is an inorganic Manure is a natural substance obtained by the decomposition of cattle dung, human waste and plant residues salt. 2. A fertiliser is prepared in Manure can be prepared in the flelds. factories. 3.A fertiliser does not provide Manure provides a lot of humus to the soil any humus to the soil 4. Fertilisers are very rich in Manure is relatively less rich in plant plant nutrients like nitrogen, nutrients. phosphorus and potassium
Irrigation The supply of water to crops at different intervals is called irrigation. . Sources of irrigation : The sources of irrigation are- wells, tubewells, ponds, lakes, rivers, dams and canals
Storage . Before storing them, the grains are properly dried in the sun to reduce the moisture in them