Quick Revision Notes: Class 8 Science

Chapter: Crop Production and Management

Madhya Pradesh Board (MP Board)

Crop (फसल): When plants of the same kind are grown and cultivated at one place on a large scale, it is called a crop.
- Example: Wheat crop means all plants grown in a field are of wheat.
Types of Crops in India:
1. Kharif Crops (खरीफ फसलें): Crops sown in the rainy season (June to September).
  - Examples: Paddy (Rice), maize, soybean, cotton, groundnut.
2. Rabi Crops (रबी फसलें): Crops grown in the winter season (October to March).
  - Examples: Wheat, gram, pea, mustard, linseed.

The cultivation of crops involves several activities undertaken by farmers over a period of time. These are called agricultural practices:

Tilling or Ploughing (जुताई): The process of loosening and turning the soil.
Benefits of Ploughing:
- Allows roots to breathe easily even when they go deep.
- Helps in the growth of earthworms and microbes (farmers' friends) which add humus to the soil.
- Brings nutrient-rich soil to the top.
Tools used: Plough (हल), Hoe (कुदाल), Cultivator (कल्टीवेटर).

Sowing: The process of putting seeds into the soil.
Precautions:
- Use good quality, clean, and healthy seeds.
- Maintain proper spacing and depth so that plants get sufficient sunlight, water, and nutrients.
Tools used: Traditional tool (funnel-shaped) and Seed drill (सीड ड्रिल - used for sowing with tractors at correct depth and distance).

Manure (खाद): An organic substance obtained from the decomposition of plant or animal wastes. It replenishes general soil organic matter and humus.
Fertilizers (उर्वरक): Chemical substances rich in particular nutrients (e.g., Urea, Ammonium sulphate, Superphosphate, NPK).
Difference between Manure and Fertilizers:
- Manure: Natural, provides humus, less rich in plant nutrients, eco-friendly.
- Fertilizer: Chemical-based, factory-made, does not provide humus, very rich in specific nutrients (Nitrogen, Phosphorus, Potassium).

Irrigation: The supply of water to crops at regular intervals.
Sources: Wells, tube-wells, ponds, lakes, rivers, dams, and canals.
Traditional Methods of Irrigation (पारंपरिक विधियाँ):
- Moat (पुली प्रणाली)
- Chain pump (चेन पंप)
- Dhekli (देखली)
- Rahat (रहट - lever system)
Modern Methods of Irrigation (आधुनिक विधियाँ):
- Sprinkler System (छिड़काव तंत्र): Useful on uneven land where sufficient water is not available; perpendicular pipes having rotating nozzles on top sprinkle water like rain.
- Drip System (ड्रिप तंत्र): Water falls drop by drop directly near the roots. It is the best technique to save water and is used in fruit plants and gardens.

Weeds (खरपतवार): Undesirable plants that grow naturally along with the crop (e.g., Amaranthus / Chaulai, Wild oat / Javi).
Weeding (निराई): The removal of weeds. It is necessary because weeds compete with crop plants for water, nutrients, space, and light.
Methods of Removal: Tilling before sowing, manual removal (using khurpi), or using chemical weedicides (e.g., 2,4-D).

Harvesting: The cutting of the crop after it is mature.
Methods: Done manually using a sickle (हसिया) or by a machine called Harvester.
Threshing (थreshing / गहाई): The process of separating the grain seeds from the chaff. (Done using a machine called Combine, which is a combined harvester and thresher).
Winnowing (उड़ाई): Separation of grain from chaff using wind.

Proper storage is necessary to protect grains from moisture, insects, rats, and microorganisms.
Grains are dried properly in the sun before storage to reduce moisture content.
Storage places: Jute bags, metallic bins, Silos, and large grain Granaries.
Neem leaves are traditionally used at home for storing food grains to protect them from pests.

Definition: Rearing animals on a large scale for food, milk, and other useful products is called animal husbandry.
Example: Dairy farming, poultry farming, pisciculture (fish farming), apiculture (bee keeping).