Samacheer Kalvi 8th Science Solutions Chapter 21 Pdf

Samacheer Kalvi 8th Science Solutions Chapter 21 Pdf

Tamilnadu Board Samacheer Kalvi 8th Science Solutions Chapter 21: Tamilnadu State Board Solution Class 8 Science Chapter 21 – Crop Production and Management.

Samacheer Kalvi 8th Science Solutions Chapter 21: Overview

Board

Samacheer Kalvi
Class

8

Subject

Science
Chapter

21

Chapter Name

Crop Production and Management


Samacheer Kalvi 8th Science Solutions Chapter 21 Pdf

(I) Choose the best answer.

(1) The process of placing seeds in the soil is called as

(a ) ploughing                (b) sowing

( c) crop production      (d) crop rotation

(2) Organismthat control insects and pests of plant crops is

(a) bio – pesticides          (b) bio -fertilizers

( c ) earthworms             ( d) neem leaves

(3) The method in which water flows over the soil surface and allow it to infiltrate is

( a) irrigation               (b) surface irrigation

(c ) springler irrigation  (d) drip irrigation

(4) Effective microorganism preparation is not used in

( a) seed treatment         (b) foliar spray

( c) soil treatment            (d) bio- predators

(5) Which of the following is not present in Panchagavya ?

( a) Cow dung                  ( b) Cow’s urine

( c) Curd                            (d) Sugar

(II) Fill in the blanks.

( 1 ) The process of actively growing seedlingfrom one place and planting in the main field for further growth is called transplantation.

( 2 ) Weed is a plant growing in a place where it is not wanted.

(3) The chemicals used for killing the weeds or inhibiting their growth are called as herbicides.

(4)  Heirloom seedstransfer theirunique characteristics to the descents .

(5) Krishi Vigyan Kendra centersserve as the ultimate link between ICAR and farmers .

(6) Several popular high yielding varieties of major crops have been developed by IARI

( III) Match the following .

Bio- pesticide Neem Leaves
Bio- predators Bacillus thuringiensis
Bio- fertilizer Control white flies
Bio- indicators Improve soil fertility
Bio – repellants Quality of environment

Answer

Bio- pesticide Bacillus thuringiensis
Bio- predators Control white flies
Bio- fertilizer Improve soil fertility
Bio- indicators Quality of environment
Bio – repellants  Neem Leaves

(IV) Answer briefly.

1 ) Define ploughing.

Ploughing or tilling refers to the process in which the soil is loosened and turned upwards and downwards for the purpose of promoting the availability of nutrients in the root area of cultivating crop. Plough, Hoe and Cultivator are for instance, some of the most essential agricultural implements that are used for the purpose of field preparation.

2) Name the methods of sowing.

Sowing by hand , Seed drill and Dibbling are  for instance , some of the most effective methods of sowing.

Explanation:

Sowing by hand

One of the easiest method of sowing seeds is to scatter the seeds by hand . This method is considered as one of the most economical technique of sowing seeds.

Seed Drill

Seed drill is regarded as a modern technique for sowing the seeds. This method proves to be more effective when compared with sowing by hand. The attachment of iron drills to a tractor, is the most efficient method of seed drill.

Dibbling

Dibbling refers to the process in which the seeds are placed inside holes or pits by maintaining an equivalent distance. This method is usually executed by using hand.

3) What is foliar spray?

The application of liquid fertilizer directly to the leaves of plants , for the purpose of feeding them is known as foliar feeding . These essential elements are absorbed by the plants with the help of the stomata in their leaves.

4) Give a brief account on Krishi Vigyan Kendra.

Krishi Vigyan Kendra as the name suggests, refers to a farm science centre. The main purpose of this centre is to provide an ultimate connection between ICAR(Indian Council of Agricultural Research ) and farmers. It mainly laid emphasis on the practical application of agricultural research findings in a particular location . KVKwas first established at Pondicherry in the year 1974. From then onwards, KVK has become widespread in almost all the state and the number tends to flourish in a continuous manner.

5) What is bio – indicator?  How does it help human beings?

A bio – indicator refers to any living organisms that plays an important role in disclosing the qualitative status of the ecosystem. Biological indicators are mainly used for the purpose of screening the changes that occurs in the natural ecosystem of the environment. It also helps us to understand the changes that are brought about by the human activities of large-scale population.

6) What do you mean by weeding?

Weed refers to those unwanted plants that grows automatically with the main crop plant. When weeds are removed , then it is known as weeding. Weeding is regarded as an essential procedure because until the weeds are removed, it is not possible to acquire the expected yield. Due to this reason, various ways are adopted by the farmers in order to execute weeding and regulate the growth of these unwanted plants.

7) What is crop rotation?

Crop rotation refers to a method in which a series of different crops are planted in the same field following a systematic sequence. The two important methods that are utilised for the purpose of crop production are mono cropping and mixed cropping. When same crop are planted in a repeated manner, in the same field ,in every subsequent year then it is known as mono cropping.  When two or more than two crops are cultivated at the same time on the same land, in the absence of any sequence, then it is known as mixed cropping.

8) What is green manure ?

Sun hemp or guar are for instance, some of the plants that are grown previously in the field before executing the method of sowing seeds. The gradual decomposition of these plants leads to the formation of green manure, which ultimately contributes in rendering essential nutrients to the soil. These green manure is mainly used for the purpose of enhancing the growth and boosting the productivity of the crops.

(V) Answer in detail .

1 ) Explain the agricultural practices.

The various agricultural practices are as follows:

  • Soil preparation

The loosening of top soil is considered as one of the most effective method in agricultural processes. The loosened soil plays an important role in facilitating the growth of earthworm and soil microbes. Various methods are utilised for the purpose of soil preparation. These methods are as follows :

a ) Ploughing

Ploughing or tilling refers to the process in which the soil is loosened and turned upwards and downwards for the purpose of promoting the availability of nutrients in the root area of cultivating crop. Plough, Hoe and Cultivator are for instance, some of the most essential agricultural implements that are used for the purpose of field preparation.

b) Leveling

The top soil becomes quite loose ,after the ploughing of field. Leveller refers to those implement that is mainly used for the purpose of lavelling the field . Heavy wooden or iron plank is one such example. Due to the lavelling of the field, the water gets evenly distributed during the process of irrigation.

c) Basal Manuring

Manuring contributes in enhancing the fertility of the soil. Sun hemp or guar are for instance , some of the plants that are grown previously in the field before executing the method of sowing seeds. The gradual decomposition of these plants leads to the formation of green manure, which ultimately contributes in rendering essential nutrients to the soil. These green manure is mainly used for the purpose of enhancing the growth and boosting the productivity of the crops.

  • Sowing of seeds

Sowing of seeds constitutes the second essential step in crop production. Sowing of seeds is usually done ,after the completion of soil preparation.

a ) Sowing by hand

One of the easiest method of sowing seeds is to scatter the seeds by hand . This method is considered as one of the most economical technique of sowing seeds.

b) Seed Drill

Seed drill is regarded as a modern technique for sowing the seeds. This method proves to be more effective when compared with sowing by hand. The attachment of iron drills to a tractor, is the most efficient method of seed drill.

c) Dibbling

Dibbling refers to the process in which the seeds are placed inside holes or pits by maintaining an equivalent distance. This method is usually executed by using hand.

  • Adding Manure and Fertilizers

Manure and fertilizers refers to those essential substances that are added to the soil for the purpose of enhancing plants growth. These nutrients contributes in fostering the plants growth. The decomposition of organic wastes of dead plants and animals contributes in the formation of manure. These organic manure plays an important role in maintaining the fertility of the soil. Fertilizers on the other hand, are mainly used for the purpose of improving the growth of plants and boosting the productivity of the crops.

  • Irrigation

Irrigation refers to a method in which the crops are supplied with water at regular period of intervals. There is a variation in the time and frequency of irrigation. Wells, ponds ,lakes and rivers constitutes some of the important sources of irrigation. Traditional methods and modern methods are mainly the two different methods that are used in irrigation.

a ) Traditional Methods

In traditional methods, irrigation is carried out by using hands. Here, water is pulled out by a farmer from wells or canals and is carried to the agricultural field.

b) Modern Methods

The modern irrigation methods performs an essential role in overcoming the existing problems of the traditional method of irrigation. It also contributes in distributing the moisture uniformly in the field. Sprinkler system and Drip system constitutes the two important systems of modern method.

  • Weeding

Weed refers to those unwanted plants that grows automatically with the main crop plant. When weeds are removed , then it is known as weeding. Weeding is regarded as an essential procedure because until the weeds are removed, it is not possible to acquire the expected yield. Due to this reason, various ways are adopted by the farmers in order to execute weeding and regulate the growth of these unwanted plants.

  • Harvesting of crops

Harvesting refers to the process of cutting and gathering a crop. Different methods are utilised for the purpose of harvesting. These methods are as follows :

Manual harvesting

Manual harvesting is regarded as one of the most efficient method of harvesting. In this method, crops are harvested in the absence of any tools. Ground nut and green gram are some of the most relevant examples.

Mechanical method

This method is mainly used for harvesting small sized farms with the help of farm instruments. Sickle depicts a perfect example.

Machine harvesting

This method is mainly used for harvesting large-sized agricultural fields.

  • Storage of food grains

Storage is considered as one of the most effective feature of post harvest technology because the crops are produced only on a seasonal basis but it is needed throughout the year for the purpose of consumption. So, for this reason it is necessary to store the food grains.

2 ) Give a detailed account on irrigation.

Irrigation

Irrigation refers to a method in which the crops are supplied with water at regular period of intervals. There is a variation in the time and frequency of irrigation. Wells, ponds ,lakes and rivers constitutes some of the important sources of irrigation. Effective irrigation refers to the process in which an appropriate quantity of water is supplied to the crops in an uniform manner, by following the correct time duration with the minimal expenditure. Traditional methods and modern methods are mainly the two different methods that are used in irrigation.

a ) Traditional Methods

In traditional methods, irrigation is carried out by using hands. Here, water is pulled out by a farmer from wells or canals and is carried to the agricultural field. In order to lift water from various sources, pumps are also used to a considerable extent. Diesel, biogas, electricity and solar energy are for  instance, some of the most essential sources of energy that is required for operating these pumps.

b) Modern Methods

The modern irrigation methods performs an essential role in overcoming the existing problems of the traditional method of irrigation. It also contributes in distributing the moisture uniformly in the field. Sprinkler system and Drip system constitutes the two important systems of modern method.

Sprinkler System

The main function of a sprinkler system is to sprinkle water on the crop and it also facilities uniform distribution of water. This method proves to be quite effective in those areas, that are prone to insufficient water supply.

Drip System

In this system, a hose or a pipe is used for the purpose of releasing water in a controlled manner, so that the water can be delivered directly to the roots of plants. This method is mostly recommended in those areas, that does not have sufficient availability of water.

3) What is weed ? Explain the different methods of weed control.

Weeding

Weed refers to those unwanted plants that grows automatically with the main crop plant. When weeds are removed , then it is known as weeding. Weeding is regarded as an essential procedure because until the weeds are removed, it is not possible to acquire the expected yield. Due to this reason, various ways are adopted by the farmers in order to execute weeding and regulate the growth of these unwanted plants. Some of the methods are as follows:

Mechanical methods

This method helps in destroying the weed physically. Hand pulling is considered as one of the most effective method for controlling the growth of weeds.

Tillage methods

This is the most efficient method in which weeds of all categories are destroyed. Weeds are mainly destroyed by burying them in the soiland also by exposing them to the scorching heat of the sun by utilising the strategy of deep ploughing.

Crop rotation

In order control parasite weeds, proper rotation of crops is followed to a great extent.

Summer tillage

In this method, the annual and perennial weeds are destroyed  by utilising the strategy of deep ploughing. These weeds are also destroyed, when they are exposed to the hot rays of the sun .

Biological weed control.

Insects and  pathogens are for instance, some of the biological agents that are used for the purpose of controlling the growth of weeds. Eradication is not the ultimate aim of biological control but rather ,they are mainly focused on regulation and depletion of the weed population.

Chemical methods

Chemical methods are considered as one of the most effective method for controlling weed. Herbicides are those chemicals that are used for the purpose of destroying  weeds or retarding their growth .

Integrated weed management

In order to decrease the dependency on any one of the weed control methods, both agronomic practices and herbicides are combined for managing the growth of weeds. Due to this reason ,it is termed as integrated weed management . Integrated weed management involves several different methods like mechanical, biological ,cultural and chemical method.

Updated: December 9, 2021 — 3:00 am

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