DIFFERENT KINDS OF CROPS
Till 10,000 B.C.E. people were nomadic. They were wandering in groups from place to place in search of food and shelter. They ate raw fruits and vegetables and started hunting animals for food. Later, they could cultivate the land and produce rice, wheat, and other food crops. Thus, was born ‘Agriculture’.
When plants of the same kind are cultivated at one place on a large scale, it is called a crop. For example, a crop of wheat means that all the plants grown in a field are that of wheat.
You already know that crops are of different types like cereals, vegetables, and fruits. These can be classified on the basis of the season in which they grow. India is a vast country. The climatic conditions like temperature, humidity, and rainfall vary from one region to another. Accordingly, there is rich variety of crops grown in different parts of the country. Despite this diversity, two broad cropping patterns can be identified. These are:
Kharif Crops: The crops which are sown in the rainy season are called kharif crops. The rainy season in India is generally from June to September. Paddy, maize, soya bean, groundnut, and cotton are kharif crops.
Rabi Crops: The crops grown in the winter season (October to March) are called rabi crops. Examples of rabi crops are wheat, gram, pea, mustard, and linseed.
Besides these, pulses and vegetables are grown during summer at many places.
Source: This topic is taken from NCERT TEXTBOOK
BASIC PRACTICES OF CROP PRODUCTION
Why paddy can not be grown in the winter season?
Paddy requires a lot of water. Therefore, it is grown only in the rainy season.
Cultivation of crops involves several activities undertaken by farmers over a period of time. You may find that these activities are similar to those carried out by a gardener or even by you when you grow ornamental plants in your house. These activities or tasks are referred to as agricultural practices which are listed below:
a. Preparation of soil
b. Sowing
c. Adding manure and fertilisers
d. Irrigation
e. Protecting from weeds
f. Harvesting
g. Storage
Source: This topic is taken from NCERT TEXTBOOK
PREPARATION OF SOIL
The preparation of the soil is the first step before growing a crop. One of the most important tasks in agriculture is to turn the soil and loosen it. This allows the roots to penetrate deep into the soil. The loose soil allows the roots to breathe easily even when they go deep into the soil. Why does the loosening of soil allow the roots to breathe easily?
The loosened soil helps in the growth of earthworms and microbes present in the soil. These organisms are friends of the farmer since they further turn and loosen the soil and add humus to it. But why the soil needs to be turned and loosened?
You have learnt in the previous classes that soil contains minerals, water, air, and some living organisms. In addition, dead plants and animals get decomposed by soil organisms. In this way, various nutrients in the dead organisms are released back into the soil. These nutrients are again absorbed by plants.
Since only a few centimetres of the top layer of soil supports plant growth, turning and loosening of soil brings the nutrient-rich soil to the top so that plants can use these nutrients. Thus, turning and loosening of soil is very important for the cultivation of crops.
The process of loosening and turning of the soil is called tilling or ploughing. This is done by using a plough. Ploughs are made of wood or iron. If the soil is very dry, it may need watering before ploughing. The ploughed field may have big clumps of soil called crumbs. It is necessary to break these crumbs. Levelling the field is beneficial for sowing as well as for irrigation. Levelling of soil is done with the help of a leveller. Sometimes, manure is added to the soil before tilling. This helps in proper mixing of manure with soil. The soil is moistened before sowing.
Source: This topic is taken from NCERT TEXTBOOK
AGRICULTURAL IMPLEMENTS- PLOUGH, HOE AND CULTIVATOR
Before sowing the seeds, it is necessary to break soil clumps to get better yield. This is done with the help of various tools. The main tools used for this purpose are the plough, hoe, and cultivator.
Plough
This is being used since ancient times for tilling the soil, adding fertilisers to the crop, removing the weeds and turning the soil. This is made of wood and is drawn by a pair of bulls or other animals (horses and camels). It contains a strong triangular iron strip called ploughshare. The main part of the plough is a long log of wood which is called a ploughshaft. There is a handle at one end of the shaft. The other end is attached to a beam which is placed on the bulls’ necks. One pair of bulls and a man can easily operate the plough [Fig. 1.1 (a)].
Figure 1.1(a): The plough
The indigenous wooden plough is increasingly being replaced by iron ploughs nowadays.
Hoe
It is a simple tool which is used for removing weeds and for loosening the soil. It has a long rod of wood or iron. A strong, broad, and bent plate of iron is fixed to one of its ends and works like a blade. It is pulled by animals [Fig. 1.1 (b)].
Figure 1.1(b): A hoe
Cultivator
Nowadays ploughing is done by a tractor-driven cultivator. The use of a cultivator saves labour and time. [Fig. 1.1 (c)].
Figure 1.1(c): Cultivator driven by a tractor
Source: This topic is taken from NCERT TEXTBOOK
SELECTION OF SEED AND SOWING
Sowing is an important part of crop production. Before sowing, good quality, clean and healthy seeds of a good variety—are selected. Farmers prefer to use seeds which give high yield.
Activity 1.1:
* Take a beaker and fill half of it with water.
* Put a handful of wheat seeds and stir well.
* Wait for some time.
Are there seeds which float on water? Would those be lighter or heavier than those which sink? Why would they be lighter? Damaged seeds become hollow and are thus lighter. Therefore, they float on water.
This is a good method for separating good, healthy seeds from the damaged ones.
Before sowing, one of the important tasks is to know about the tools used for sowing seeds [Fig. 1.2 (a), (b)].
Traditional tool :
The tool used traditionally for sowing seeds is shaped like a funnel [Fig. 1.2 (a)]. The seeds are filled into the funnel, passed down through two or three pipes having sharp ends. These ends pierce into the soil and place seeds there.
Figure 1.2(a): Traditional method of sowing
Seed drill :
Nowadays the seed drill [Fig.1.2 (b)] is used for sowing with the help of tractors. This sows the seeds uniformly at equal distance and depth. It ensures that seeds get covered by the soil after sowing. This protects seeds from being eaten by birds. Sowing by using a seed drill saves time and labour.
Figure 1.2(b): Seed drill
Seeds of a few plants such as paddy are first grown in a nursery. When they grow into seedlings, they are transplanted to the field manually. Some forest plants and flowering plants are also grown in the nursery.
Appropriate distance between the seeds is necessary to avoid overcrowding of plants. This allows plants to get sufficient sunlight, nutrients and water from the soil. At times a few plants may have to be removed to prevent overcrowding.
Source: This topic is taken from NCERT TEXTBOOK
ADDING MANURE AND FERTILISERS
The substances which are added to the soil in the form of nutrients for the healthy growth of plants are called manure and fertilisers.
Soil supplies mineral nutrients to the crop plants. These nutrients are essential for the growth of plants. In certain areas, farmers grow crop after crop in the same field. The field is never left uncultivated or fallow. Imagine what happens to the nutrients?
Continuous cultivation of crops makes the soil poor in nutrients. Therefore, farmers have to add manure to the fields to replenish the soil with nutrients. This process is called manuring. Improper or insufficient manuring results in weak plants.
Manure is an organic substance obtained from the decomposition of plant or animal wastes. Farmers dump plant and animal waste in pits at open places and allow it to decompose. The decomposition is caused by some microorganisms. The decomposed matter is used as organic manure. You have already learnt about vermicomposting in Class VI.
Activity 1.2:
* Take moong or gram seeds and germinate them. Select three equal-sized seedlings.
* Take three empty glasses or similar vessels. Mark them A, B and C.
* To glass A add little amount of soil mixed with a little cow dung manure.
* In glass B put the same amount of soil mixed with a little urea.
* Take the same amount of soil in glass C without adding anything [Fig. 1.3(a)].
Figure 1.3(a): Preparation of the experiment
* Now pour the same amount of water in each glass and plant the seedlings in them.
* Keep them in a safe place and water them daily.
* After 7 to 10 days observe their growth [Fig. 1.3(b)].
Figure 1.3(b): Growing seedlings with manure and fertiliser
Did plants in all the glasses grow at the same pace? Which glass showed better growth of plants? In which glass was the growth fastest?
Fertilisers are chemicals which are rich in a particular nutrient. How are they different from manure? Fertilisers are produced in factories. Some examples of fertilisers are— urea, ammonium sulphate, super phosphate, potash, NPK (Nitrogen, Phosphorus, Potassium).
The use of fertilisers has helped farmers to get better yield of crops such as wheat, paddy and maize. But excessive use of fertilisers has made the soil less fertile. Fertilisers have also become a source of water pollution. Therefore, in order to maintain the fertility of the soil, we have to substitute fertilisers with organic manure or leave the field uncultivated (fallow) in between two crops.
The use of manure improves soil texture as well as its water-retaining capacity. It replenishes the soil with nutrients.
Source: This topic is taken from NCERT TEXTBOOK
CROP ROTATION
Another method of replenishing the soil with nutrients is through crop rotation. This can be done by growing different crops alternately. Earlier, farmers in northern India used to grow legumes as fodder in one season and wheat in the next season. This helped in the replenishment of the soil with nitrogen. Farmers are being encouraged to adopt this practice.
In the previous classes, you have learnt about Rhizobium bacteria. These are present in the nodules of roots of leguminous plants. They fix atmospheric nitrogen.
Source: This topic is taken from NCERT TEXTBOOK
DIFFERENCE BETWEEN A FERTILISER AND MANURE
S. No. |
Fertiliser |
Manure |
1. |
Fertiliser is a man-made inorganic salt. |
Manure is a natural substance obtained by the decomposition of cattle dung and plant residues. |
2. |
Fertiliser is prepared in factories. |
Manure can be prepared in the fields. |
3. |
Fertiliser does not provide any humus to the soil. |
Manure provides a lot of humus to the soil. |
4. |
Fertilisers are very rich in plant nutrients like nitrogen, phosphorus and potassium. |
Manure is relatively less rich in plant nutrients. |
Table 1.1: Differences between Fertiliser and Manure
Table 1.1 gives the differences between a fertiliser and manure.
Advantages of Manure
The organic manure is considered better than fertilisers. This is because
* it enhances the water holding capacity of the soil.
* it makes the soil porous due to which exchange of gases becomes easy.
* it increases the number of friendly microbes.
* it improves the texture of the soil.
Source: This topic is taken from NCERT TEXTBOOK