NCERT

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

Chapter 1 Crop Production and Management Class 8 Science NCERT Solutions

Exercises

1. Select the correct word from the following list and fill in the blanks:
float, water, crop, nutrients, preparation.

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

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

(c) Damaged seeds would _____ on top of water.

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

Solution

(a) Crop
(b) Preparation
(c) Float
(d) Water, nutrients

2. Match items in column A with those in column B.

A	B
(i) Kharif crops	(a) Food for cattle
(ii) Rabi crops	(b) Urea and super phosphate
(iii) Chemical fertilizers	(c) Animal excreta, cow dung, urine and plant waste
(iv) Organic manure	(d) Wheat, gram, pea
	(e) Paddy and maize

Solution

A	B
(i) Kharif crops	(e) Paddy and maize
(ii) Rabi crops	(d) Wheat, gram, pea
(iii) Chemical fertilizers	(b) Urea and super phosphate
(iv) Organic manure	(c) Animal excreta, cow dung, urine and plant waste

3. Give two examples of each:
(a) Kharif crop
(b) Rabi crop

Solution

(a) Kharif Crop: Paddy, Maize, Millet, Soyabean.
(b) Rabi Crop: Oats, Barley, Wheat, Linseed, Mustard.

4. Write a paragraph in your own words on each of the following:
(a) Preparation of soil
(b) Sowing
(c) Weeding
(d) Threshing

Solution

(a) Preparation of soil: It is necessary to plough the soil before sowing seeds. The loose soil lets roots breathe easily, even when they go deep into it. Besides helping the roots penetrate deep into the soil, this also allows the earthworms and microorganisms in it to grow. As a result of these organisms, the soil will be enriched with humus and other essential nutrients. Tilling is the process of loosening or turning the soil. Ploughs, hoes and cultivators are the main tools used to do this.

(b) Sowing: Sowing is the act of planting seeds in the soil. Good quality seeds should be selected before sowing, and seeds can either be broadcast by hand or drilled using a seed drill.

(c) Weeding: It refers to removing unwanted plants from fields, such as weeds. Weeds compete for water, nutrients, sunlight, and other resources with the main crop, so removing them is necessary. In addition to uprooting or cutting weeds manually, weedicides can be used as well. A khurpi or tractor-driven harrow can be used to remove weeds by hand. Some examples of weedicides are linazine, dalapon, etc. It is best to remove weeds before they produce seeds and flowers.

(d) Threshing: Threshing involves separating grains from the bulk of harvested crops. Animals are used on a large scale for this process. On large farms, a machine called a combine harvester is used for both harvesting and threshing.

5. Explain how fertilisers are different from manure.

Solution

Fertilisers	Manure
These are chemical compounds rich in nitrogen, phosphorus and potassium.	These are organic sub- stances prepared from the decomposition of plants and animal wastes.
They are man-made and manufactured on a large scale in factories.	They are made by natural processes either on a small or large scale.
Chemical fertilisers are nutrient specific, that is, nitrogenous, phosphatic, etc.	They contain a mixture of various nutrients recycled from biomass wastes.
They are not easily decompose by bacteria.	They are easily decompose by bacteria.
Fertilizer do not provide any humus to the soil.	Manure provide humus to the soil and enrich the soil fertility.
Excessive fertilizers destroy soil fertility and pollute the water as they are made from chemicals.	Manures do not pollute water, they improve soil texture and water holding capacity of soil.

6. What is irrigation? Describe two methods of irrigation which conserve water.

Solution

Irrigation is the practice of supplying water to the soil regularly and in a regular quantity. Irrigation time and frequency vary according to the crop, soil, and season. Two methods of irrigation which conserve water are:
a) Sprinkler system: A sprinkler system works well on uneven or sandy soils. It has pipes with rotating nozzles that are connected to the main pipeline at regular intervals. Water is sprayed on crops as if it were raining.
b) Drip system: Drip irrigation reduces water wastage by adding water drop by drop at the root location. This is why it is a boon for drought-prone regions.

7. If wheat is sown in the kharif season, what would happen? Discuss.

Solution

If wheat crop is sown in kharif season then it is known as stress condition for wheat. Rainfall will cause water logging, reducing air in the soil, damaging the roots, preventing the seeds from germinating properly, and producing less yield.

8. Explain how soil gets affected by the continuous plantation of crops in a field?

Solution

In a field, crop plants are supplied with mineral nutrients necessary for their growth. Continuous planting of crops in the field depletes the soil’s nutrients.

9. What are weeds? How can we control them?

Solution

A weed is an undesirable plant that naturally grows along with crops. Weeding is the process of removing these unwanted plants. Following methods can be used to control weeds:
(i) Tilling: Tilling or ploughing is the process of turning the soil and loosening it. It can uproot and kill weeds.
(ii) Manual removal: This method includes physical removal of weeds by uprooting or cutting them close to the ground. This is done with the help of a khurpi or harrow.
(iii) Chemical method: In this method, weeds are controlled or killed by using chemicals called weedicides. They are sprayed in fields with a sprayer.

10. Arrange the following boxes in the proper order to make a flow chart of sugarcane crop production.