NCERT Solution Class 8 Science Chapter 1 - Crop Production and Management

The supply of water to crops at regular intervals is called irrigation. Methods of irrigation which conserve water are as follows:

a) Drip Irrigation: Here, the water goes drop by drop directly into the roots; this method is very useful as it conserves the water and also helps in avoiding weeds.

b) Sprinkler system: This method is in use mainly in uneven land where sufficient water is not available. The perpendicular pipes, having rotating nozzles on top, are joined to the main pipeline at regular intervals. When water is allowed to flow through the main pipe under pressure with the help of a pump, it escapes from the rotating nozzles. It gets sprinkled on the crop as if it is raining.

(a) The same kind of plants grown and cultivated on a large scale at a place is called the crop.

(b) The first step before growing crops is the preparation of the soil.

(c) Damaged seeds would float on top of the water.

(d) For growing a crop, sufficient sunlight and water and nutrients from the soil are essential.

Kharif crops – Paddy and maize

Rabi crops – Wheat and pea

a) Preparation of the soil is the first step in agriculture. Preparation of the soil is done to loosen the soil, which is essential for root penetration into the soil. This allows the roots to breathe easily. Loosening of the soil allows the growth of earthworms and microorganisms, which will help to keep the soil fertile by adding humus to the soil. Loosening of soil also brings nutrient-rich soil to the top layer, which is essential for the growth of plants.

b) Sowing is an important process in crop production. First, healthy seeds are selected before sowing. After selecting healthy seeds, sowing is done by either traditional methods or by using the equipment’s seed drill.

c) Removal of unnecessary plants from the field is called weeding. Weeds compete with crop plants for nutrients and water. This will reduce the yield of the desired crops. Weeds also interfere while harvesting and get mixed with crops. Some weeds are poisonous to animals and humans. Tilling is a common method that helps remove weeds before sowing crops, and manual methods like the physical removal of plants are also used to remove weeds. Weedicides are sprayed to get rid of weeds, but this method may affect the health of farmers because of the chemicals used as weedicides.

d) Process of separating the chaff from the crop is known as threshing. Threshing is carried by a machine called ‘combine’, which is a harvester as well as a thresher. Threshing is also done by winnowing, where the blow of air is used to separate the chaff from crops.

Wheat crops may get destroyed if sown in the Kharif season because of unfavourable temperatures, pests and adaptable conditions for the plants to grow. Kharif comes during the rainy season; hence it is not a wise idea to grow wheat in the Kharif season.

Plants require nutrients for their growth. Without optimum nutrients, plants will die. Continuous plantation of crops results in the depletion of certain nutrients like Nitrogen, Phosphorus, Potassium, etc. This results in a decrease in yield due to loss of nutrients; hence there should be a gap between crops in order to get a good yield.

In a field, many other undesirable plants may grow naturally along with the crop. These undesirable plants are called weeds. Weeds can be controlled by methods called weeding. Tilling before sowing the crops helps in uprooting and killing weeds, which may then dry up and get mixed with the soil. Weeds are also controlled by using certain chemicals called weedicides.