NCERT Class 8 Science Chapter 1: Crop Production and Management YouTube Lecture Handouts

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  • Photosynthesis by plants – 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 – sown in winter (Oct to March) – wheat, gram. Pea, mustard & linseed

  • Kharif – sown in rainy season (June to Sept) – paddy, maize, soyabean, groundnut and cotton

  • Zaid – sown in March to June – 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 (farmer’s friend) and microbes – 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 – loosening brings nutrients to the top

  • Tilling or Ploughing: Process of loosening or turning the soil

  • Levelling – 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) – water the soil in case it is dry. Ploughed soil will have big clumps called as crumbs (now break these) – add fertilizer, till soil, remove weed – wood drawn by bulls or animals – ploughshare (triangular iron strip) with ploughshaft

Image of Preparation of soil

Image of Preparation of Soil

Image of Preparation of soil

Hoe: Long rod of wood or iron – strong, broad, bent iron plate acts as blade is pulled by animals.

Image of hoe

Image of Hoe

Image of hoe

Cultivator: Tractor driven and saves time and labor

Image of Cultivator

Image of Cultivator

Image of Cultivator

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 – funnel shaped – pass down through two to three pipes having sharp ends

Image of traditional method of sowing

Image of Traditional Method of Sowing

Image of traditional method of sowing

  • Seed Drill – with help of tractors – seeds are sown at uniform depth and distance. It protects seeds from been eaten by birds – saves time and labor

  • Appropriate distance to avoid overcrowding – get ample sunlight, nutrient and water from soil

Image of get ample sunlight, nutrient and water from soil

Image of Get Ample Sunlight, Nutrient and Water from Soil

Image of get ample sunlight, nutrient and water from soil

Seeds grown in nursery – 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 – 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) – improves texture, makes soil porous, increases microbes and water retention capacity – provides humus but is less rich in nutrient than fertilizers

  • Fertilizers – chemicals (made in factories) which are rich in nutrients like urea, ammonium sulphate, super phosphate, potash and NPK – get better yield but cause pollution – does not provide any humus

  • Crop Rotation – grow different crops alternatively – North India (legumes in one season and wheat in next – replenish soil with nitrogen) – 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 – 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 – 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.

Image of Traditional Method of Irrigation

Image of Traditional Method of Irrigation

Image of Traditional Method of Irrigation

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.

Image of Manual Irrigation Method By Water

Image of Manual Irrigation Method by Water

Image of Manual Irrigation Method By Water

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.

Image of Rahat Method

Image of Rahat Method

Image of Rahat Method

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.

Image of Dhekli System

Image of Dhekli System

Image of Dhekli System

Modern Methods of Irrigation

Use Water Economically

Sprinkler Method: When there is uneven land – water flow from main pipe under pressure with pump and escape from rotating nozzles – used in lawns and coffee plantations

Image of Drip Irrigation And Sprinkler Irrigation

Image of Drip Irrigation and Sprinkler Irrigation

Image of Drip Irrigation And Sprinkler Irrigation

Drip System: Falls drop by drop in roots – best to water fruits, gardens and trees – 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 – 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 – before they produce flower and seeds

Image of weeding

Image of Weeding

Image of weeding

Khurpi or Seed drill helps to remove it

Image of khurpi

Image of Khurpi

Image of khurpi

Weedicides (chemicals to control weeds) like 2,4 D – don’t damage crop and are diluted with water – 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 – separate grain from chaff

Image of Thresher

Image of Thresher

Image of Thresher

Winnowing - separate grain from chaff (small holdings)

Image of winnowing

Image of Winnowing

Image of winnowing

Combine = Harvester + Thresher

Image of Harvester and Thresher (Combine Machine)

Image of Harvester and Thresher (Combine Machine)

Image of Harvester and Thresher (Combine Machine)

Harvest Festivals – 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 – silos and granaries (chemical treatment)

Image of Silos

Image of Silos

Image of Silos

  • Dried neem leaves – home treatment

  • Similarly animals are reared in home or farms – animal husbandry (Fish – cod liver oil which is rich in Vitamin D)