23 September 2014

Agriculture and Crop protection : Science

Agriculture and Crop protection : Science Ncert / Cbse Revision Notes

Crop is the group of same kind of plants grown and cultivated at one place in significant quantities. Crops in India are broadly classified into two categories namely kharif crops and rabi crops.  
  • Kharif crops are the crops planted during the rainy season.
  • Rabi crops are the crops grown during the winter season.

Agricultural practices

Agricultural practices are a collection of principles that are applied as on-farm production and the post-production processes to produce safe and healthy food. Agricultural practices include different steps
Agriculture and Crop protection, Science Ncert / Cbse Revision Notes, Class 8

Soil preparation: 

It involves loosening of the soil or turning it.
  • Ploughs are used for tilling the soil, adding manure and fertilisers and for scraping the soil.
  • A plank is used to break the crumbs into fine soil. Soil is levelled with the help of a leveller.
  • Hoe was used for tilling in olden days, but these days we use it only to remove weeds.
  • Cultivator pulled by a tractor, is also used to break the soil.

Seed selection:

 It is done to separate healthy seeds from damaged seeds.
  • Healthy seeds contain more nutrients. Seed health refers to the absence of disease-causing organisms such as fungi, nematodes, bacteria, viruses and insects.
  • Damaged seeds are hollow, discoloured and contain fewer nutrients.

Seed selection is done by soaking the seeds in a container. It can also be used to maintain and improve the quality of the crop variety. The selection of plants is based on characteristics such as the size of the plant, the colour or size of the fruits, the bulk number of grains per year, etc.

Seed sowing: 

It is done by both traditional methods and modern methods.
  • Traditional seed drill contains a funnel-shaped container through which seeds pass and get placed into the soil.
  • Modern seed drills sow seeds at a proper depth and distance, and cover them with a layer of soil.

Nursery is a place where plants are propagated and grown to a usable size. Bananas are first sown in a nursery, and later the saplings are planted to the field.
Crop protection

Agriculture is the cultivation of crop on large areas to provide food for all life forms.

Replenishment of nutrients: 

As the seeds germinate, the growing saplings should be provided with nutrients and water. Manure and fertilisers supply nutrients to the soil.  
  • Manure is the organic matter added to the soil to replenish it with nutrients. The wastes from household, animal dung and agricultural wastes are buried in small pits. Decomposition by bacteria and earthworms occurs in these pits converting organic wastes into manure.  Manure increases the water retention capacity of soil
  • Fertilisers are the chemicals which add minerals like potassium, phosphorus and nitrates to the soil.


The supply of water to crop is called as irrigation. The frequency of irrigation varies from season to season. Plants contain nearly 90% water, and need water for proper development of flowers, fruits and seeds. Irrigation can be done by two methods - Traditional methods and Modern methods.
  • Traditional methods of irrigation include moat, chain pump, dhekli and rahat, and need animal and human labour to draw water.
  • Modern methods include drip irrigation and sprinkler system which require power from solar energy or biogas.
Must Read : Harvest and Storage


The process of removal of waste plants competing with crop plants is called as weeding. Weeds are removed manually before they produce flowers and seeds. Weeds can also be controlled by using chemicals called as weedicide. Weedicides are poisonous to humans.