NCERT Solutions are prepared by our subject experts to provide accurate and easy solutions for all the problems covered in class 8 NCERT textbooks. Step by step are given for better understanding.
CBSE NCERT Solutions for Class 8 Science Chapter 1:
Write a paragraph in your own words on each of the following.
(a) Preparation of soil
(a) Preparation of soil : It is the very first step before growing a crop and involves tilling and loosening the soil. This helps the roots to penetrate deep in the soil. The loose soil allows the roots to breath easily even in deeper soil layers. The process of loosening and tilling of the soil is called tilling or ploughing. This is done by using a plough.
(b) Sowing is the process of putting the seeds into the soil for growing crops. We need to use quality seeds for sowing. Sowing is done manually using mechanical equipment like Seed Drill. Seeds of few plants like rice are first grown in a separate area and then transplanted in the fields.
(c) Weeding: The undesirable plants grown along with the crop are called weeds. Removal of weeds is called weeding. Weeding is done as weeds compete with the crop plants for water, nutrients, space and light thereby adversely affecting the growth of the crop.
(d) Threshing is the process of separating grains or seeds from chaff. It is done after harvesting the crop. It is usually carried out with the help of a machine known as 'Combine'. This machine is a combined harvester and thresher. It harvests plants as well as cleans grains.
What is irrigation? Describe two methods of irrigation which conserve water.
Supply of water to crops at appropriate intervals is called irrigation. The time
and frequency of irrigation varies according to different seasons, crops, and soil types.
Two methods of irrigation which help in conservation of water are:
→ Sprinkler system: This system is more useful on uneven land, having fewer water supplies. In this method, water is supplied using pipes to one or more central locations within the field. When water is allowed to flow under high pressure with the help of a pump, it gets sprinkled on the crops.
→ Drip system: In this system, water is delivered at or near the roots of plants, drop by drop. This is the most efficient method of irrigation as there is no wastage of water at all. This method is important in areas where water availability is poor.
What are weeds? How can we control them?
Weeds are unwanted wild plants that grow in the field. Weeds compete with
the crop for nutrients, light, and space. As a result, crop plants get lesser nutrients, light, and space for their development.
Some important weeding methods are:
→ Weeds can be controlled using weedicides. It is a chemical, which is sprayed in the fields to kill all available weeds. Weedicides are not harmful to crops.
→ Tilling before sowing of crops also helps in removing weeds. Tilling uproots the weeds. The best time for the removal of weeds is before they produce flowers and seeds.
→ The manual method of removing weeds is with the help of a khurpi. It involves regular uprooting or cutting of weeds close to the ground.