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

Get unlimited access to the best preparation resource for CBSE/Class-8 : get questions, notes, tests, video lectures and more- for all subjects of CBSE/Class-8.

Get video tutorial on: Examrace YouTube Channel

NCERT Class 8 Science Chapter 1: Crop Production & Management

  • 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

Illustration: Preparation of Soil

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

Illustration: Preparation of Soil

Cultivator: Tractor driven and saves time and labor

Illustration: Preparation of Soil

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

Illustration: 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

Illustration: Sowing

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.

Illustration: 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.

Illustration: Traditional Method of Irrigation

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.

Illustration: Traditional Method of Irrigation

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.

Illustration: Traditional Method of Irrigation

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

Illustration: Use Water Economically

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

Illustration: Protection from Weeds

Khurpi or Seed drill helps to remove it

Illustration: Protection from Weeds

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

Illustration: Harvesting

Winnowing - separate grain from chaff (small holdings)

Illustration: Harvesting

Combine = Harvester + Thresher

Illustration: Harvesting

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)

Illustration: Storage

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)

✍ Mayank