Crop Production and Management (Class 8 Science) - Detailed Notes

Introduction to Crops

  • Definition: When plants of the same kind are cultivated on a large scale at one place, it is called a crop.
  • Example: Crop of wheat means all the plants grown in a field are of wheat.
  • Cereal Crops: Grains like wheat, rice, maize, and barley are called cereal crops.

Types of Crops

  • Kharif Crops:
    • Season: Grown in the rainy season (June to September).
    • Water Requirement: Require a lot of water.
    • Examples: Paddy (rice), maize, soybean, groundnut, cotton.
  • Rabi Crops:
    • Season: Grown in the winter season (October to March).
    • Examples: Wheat, gram, pea, mustard, linseed.

Basic Agricultural Practices

  • Preparation of Soil:

    • Importance: Allows roots to penetrate deep, enables breathing, helps growth of earthworms and microbes, brings nutrient-rich soil to the top.
    • Processes:
      • Tilling/Plowing: Loosening and turning the soil.
      • Levelling: Done after plowing to break crumbs with a plank or leveler.
    • Tools:
      • Plow (Traditional): Wooden or iron, drawn by oxen or camels. Has a strong triangular iron strip called plowshare.
      • Hoe (Traditional): Simple tool for removing weeds and loosening soil. Has a long rod of wood/iron, strong broad plate of iron fixed to one end.
      • Cultivator (Modern): Used for plowing, attached to a tractor. Saves labor and time.

  • Sowing:

    • Seed Selection: Good quality, clean, healthy seeds are preferred. Test by putting seeds in water; damaged seeds float.
    • Tools:
      • Traditional Tool: Funnel-shaped, seeds passed through two or three pipes with sharp ends.
      • Seed Drill (Modern): Used with tractors. Sows seeds uniformly at proper distance and depth. Ensures seeds are covered by soil after sowing. Saves time and labor.

  • Adding Manure and Fertilizers:

    • Manure:
      • Definition: Organic substance obtained from decomposition of plant and animal waste.
      • Preparation: Farmers dump waste in pits and allow decomposition.
      • Benefits: Enhances water holding capacity of soil, makes soil porous for gas exchange, increases friendly microbes, improves soil texture.
    • Fertilizers:
      • Definition: Chemical substances rich in specific nutrients.
      • Examples: Urea, ammonium sulphate, superphosphate, potash, NPK (nitrogen, phosphorus, potassium).
      • Drawbacks: Excessive use makes soil less fertile, causes water pollution.
    • Crop Rotation: Alternate planting of different crops (e.g., legumes after cereals) to replenish soil with nitrogen naturally.
    • Comparison (Manure vs. Fertilizers):
      • Fertilizers: Man-made, inorganic salts; prepared in factories; don't provide humus; very rich in nutrients.
      • Manure: Natural substance; prepared in fields; provides humus; less rich in nutrients.

  • Irrigation:

    • Definition: Supply of water to crops at regular intervals.
    • Sources: Wells, tubewells, ponds, lakes, rivers, dams, canals.
    • Traditional Methods:
      • Moat (Pulley system): Water lifted using a pulley.
      • Chain Pump: Water lifted by chain.
      • Dhekli: Water lifted using a lever system.
      • Rahat (Lever system): Animal-operated system.
      • Note: These methods are cheaper but less efficient.
    • Modern Methods:
      • Sprinkler System: Water supplied through pipes to nozzles, sprayed like rain. Useful on uneven land where less water is available.
      • Drip System: Water falls drop by drop directly near the roots. Best for fruit plants, gardens, trees. Efficient, no water wastage.

  • Protecting from Weeds:

    • Weeds: Unwanted plants that grow along with crops and compete for water, nutrients, space, and light.
    • Weeding: Removal of weeds.
    • Methods:
      • Manual Removal: Tilling before sowing helps, manual removal (khurpi), repeated uprooting/cutting close to the ground.
      • Weedicides: Chemicals like 2,4-D, sprayed in fields. Do not damage crops.

  • Harvesting:

    • Definition: Cutting of crop after it is mature.
    • Methods:
      • Traditional: Sickle (manual).
      • Modern: Combine harvester (combines harvesting and threshing).
    • Threshing: Separation of grain from chaff.
    • Winnowing: Used by small farmers to separate grain and chaff.
    • Harvest Festivals: Lohri, Bihu, Pongal, Onam, Navanya, Holi.

  • Storage:

    • Importance: Protection from moisture, insects, rats, and microorganisms.
    • Preparation: Grains need to be dried before storage to reduce moisture.
    • Methods:
      • Small Scale: Jute bags, metallic bins. Dried neem leaves are used.
      • Large Scale: Silos and granaries. Chemical treatments are used.

Animal Husbandry:

  • Definition: Rearing animals on a large scale and providing them with proper food, shelter, and care.
  • Benefits: Provides food like milk, eggs, meat; fish is good for health (cod liver oil).