NCERT Class 8 Science Chapter 1: Crop Production and Management YouTube Lecture Handouts
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NCERT Class 8 Science Chapter 1: Crop Production & Management
- Photosynthesis by plants β make their own food
- What about us animals and humans?
- Food is used for digestion, respiration and various other processes
- To provide food what is required?
- Regular production
- Management
- Distribution
- Till 10,000 BC people were nomadic (wandered)
- Crop: Plants of same kind are cultivated at one place on large scale (like wheat, rice)
Classification of Crops based on Types
- Cereals
- Vegetables
- Fruits
Classification of Crops based on Season
- Rabi β sown in winter (Oct to March) β wheat, gram. Pea, mustard & linseed
- Kharif β sown in rainy season (June to Sept) β paddy, maize, soyabean, groundnut and cotton
- Zaid β sown in March to June β water melon, cucumber, muskmelon, sunflower and sugarcane
What affects crop? Temperature, Humidity, Rainfall
Agricultural Practices
Several activities undertaken by farmer over a period of time
- Preparation of soil
- Sowing
- Adding manure and fertilizers
- Irrigation
- Protecting from weeds
- Harvesting
- Storage
Preparation of Soil
Loosen the soil so that roots penetrate deep
Loosened soil help in growth of earthworm (farmerΥs friend) and microbes β they again loosen the soil and add humus
Nutrients from dead plants are released back into soil & absorbed by plants
Few centimeters of top layer support plant growth β loosening brings nutrients to the top
Tilling or Ploughing: Process of loosening or turning the soil
Levelling β beneficial for sowing and irrigation and is done with leveler
Manure is added before tilling so that it mixes
Plough (made of wood or iron) β water the soil in case it is dry. Ploughed soil will have big clumps called as crumbs (now break these) β add fertilizer, till soil, remove weed β wood drawn by bulls or animals β ploughshare (triangular iron strip) with ploughshaft
Hoe: Long rod of wood or iron β strong, broad, bent iron plate acts as blade is pulled by animals.
Cultivator: Tractor driven and saves time and labor
Sowing
Select good quality, clean and healthy seeds
Farmers use seeds that give high yield
Damaged seeds become hollow and are thus lighter. Therefore, they float on water.
Traditional Tool for sowing β funnel shaped β pass down through two to three pipes having sharp ends
Seed Drill β with help of tractors β seeds are sown at uniform depth and distance. It protects seeds from been eaten by birds β saves time and labor
Appropriate distance to avoid overcrowding β get ample sunlight, nutrient and water from soil
Seeds grown in nursery β grow into seedlings (transplanted) and finally grown in nursery (flowering)
Adding Fertilizers & Manures
Added to soil as nutrients for healthy growth of plants
Soil supplies nutrient to the crop (continuous cultivation without leaving it fallow depletes soil of the nutrients)
Manures β replenishment of the soil (called manuring) by organic substance obtained from decomposition of plant and animal waste (dump waste in open and allow it to decompose) β improves texture, makes soil porous, increases microbes and water retention capacity β provides humus but is less rich in nutrient than fertilizers
Fertilizers β chemicals (made in factories) which are rich in nutrients like urea, ammonium sulphate, super phosphate, potash and NPK β get better yield but cause pollution β does not provide any humus
Crop Rotation β grow different crops alternatively β North India (legumes in one season and wheat in next β replenish soil with nitrogen) β Rhizobium bacteria in root nodules of leguminous plants fix atmospheric nitrogen
Irrigation
- Plants have 90% water (needed for germination of seeds)
- Water protects from hot air currents and frost and maintain moisture of soil
- Irrigation: Supply of water to crops at regular intervals. Time & frequency varies with crop, soil and season
- Summer β higher frequency of watering due to higher rate of evaporation
- Sources of Irrigation: Wells, tubewells, ponds, lakes, rivers, dams, canals
Traditional Method of Irrigation
Cheaper but less efficient method
Pumps used for lifting water β these are run on diesel, electricity, biogas and solar energy
Chain pump: A chain pump consists of two large wheels, connected by an endless chain.
The bottom wheel is half immersed in the water source. As the wheel is turned, the connected buckets dip into the pool and pick up water.
The chain then lifts them to the upper wheel, where the water from the buckets is transferred to the pool. The chain then carries the empty buckets back down to be refilled and the process continues.
Moat or pulley-system: It is a manual irrigation method. By this method water is directly taken out of wells with the help of pulley and is used to irrigate fields.
Rahat: In this method water is drawn out of wells by animals. Animals like cow, buffalo, oxen etc. are connected to wheel. Animals move and rotate the wheel lead to draw the water from the well.
Dhekli: In this system a rope and bucket connected to pole to obtain water from well. They connect rope and bucket on one end of a heavy stick and a heavy counter weight at the other end.
Modern Methods of Irrigation
Use Water Economically
Sprinkler Method: When there is uneven land β water flow from main pipe under pressure with pump and escape from rotating nozzles β used in lawns and coffee plantations
Drip System: Falls drop by drop in roots β best to water fruits, gardens and trees β no wastage of water and is boon in regions where water availability is poor
Protection from Weeds
Undesirable plants are called weeds
Weeds compete for water, nutrients, space and light and affect growth of crops
Weeding β process of removal of weeds
Weeds interfere in harvesting and may be poisonous
Tilling before sowing helps to uproot and kill weeds
Best time to remove weed β before they produce flower and seeds
Khurpi or Seed drill helps to remove it
Weedicides (chemicals to control weeds) like 2,4 D β donΥt damage crop and are diluted with water β but affects farmers health so must cover nose and mouth during spray
Harvesting
Cutting crop after it is mature (pulled out or cut)
3 to 4 months to mature
Done by sickle (manual) or harvester (machines)
Thrashing β separate grain from chaff
Winnowing - separate grain from chaff (small holdings)
Combine = Harvester + Thresher
Harvest Festivals β Pongal (Tamil Nadu) , Baisakhi (Punjab) , Holi, Diwali, Nabanna (West Bengal) , Bihu (Assam)
Storage
Keep it safe from moisture, insect, pest, rats etc.
Harvested grains have more moisture and are more affected
So, drying of grains is important
In jute bags or metallic bins
Large storage β silos and granaries (chemical treatment)
Dried neem leaves β home treatment
Similarly animals are reared in home or farms β animal husbandry (Fish β cod liver oil which is rich in Vitamin D)
β Mayank