NCERT Solutions for Class 8 Science Chapter 1 Crop Production and Management

Ans : (a) The same kind of plants grown and cultivated on a large scale at a place is called crop 
(b) The first step before growing crops is  preparation 
(c) Damaged seeds would float on top of water. 
(d) For growing a crop, sufficient sunlight and  water and  nutrients from the soil are essential. 

Ans : (a) Kharif crop — paddy 
(b) Rabi crop — Wheat, gram 

Ans : (a) Preparation of soil: 
It is the first method to be followed before growing a crop. This method is usually employed for loosening the soil to allow the root to penetrate deep into it. The loosening of the soil helps in the growth of several soil microbes, earthworms etc., which enrich the soil with humus and other essential nutrients. Plants require nutrients for their proper growth and functioning. The process of loosening is called tilling or ploughing the soil. Tilling of soil brings the nutrient-rich soil to the top. This helps the plants to utilize the nutrients for their growth. 


(b) Sowing: 
Sowing is another important step in crop production. It is the process of placing the seed in or on the soil for future growth. The seeds that are selected for growing should be of good quality. This will improve the net yield of the crop. Sowing is usually done with the help of either a traditional tool or a seed drill. The traditional tool is shaped like a funnel. It was used earlier for sowing seeds. Nowadays, seed drills that make the use of tractors are used for sowing seeds. This tool disperses seeds uniformly and sows seeds at proper depth. Sowing by this method saves time and also protects the seeds from birds. 


(c) Weeding:
Some important weeding methods are: 
(i) 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. 
(ii) Tilling before sowing of crops also helps in removing weeds. Tilling uproots the weeds. The best time for removal of weeds is before they produce flowers and seeds. 
(iii) 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. 
(d) Threshing: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. 

Ans : Differences between fertilisers and manure:
 

Ans : Irrigation is the process by which water is supplied to crops at different intervals. The time and frequency of irrigation varies according to different seasons, crops, and soil types. There are various sources of irrigation such as wells, canals, rivers, dams, ponds, and lakes. Two methods of irrigation which help in conservation of water are: 
a) 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. 


b) 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.