Chapter 1 – Crop Production and Management
Study Notes
In order to provide food for a large population, regular production, proper management and distribution of food is necessary.
Agriculture (Latin word Ager-field and culture-cultivation) is the applied branch of biology which involves the practice of cultivating crops as well as rearing animals.
When plants of same type are grown and cultivated in a field at large scale, it is called a crop (fasal in Hindi), e.g., wheat crop, paddy crop, etc.
Two broad cropping patterns can be identified on the basis of particular season in which they grow. These are
The crops that are sown in rainy season are called kharif crops or summer crops. These are sown in June-July and harvested at the end of monsoon season, i.e., during September, e.g., paddy (rice), maize, soybean, cotton, groundnut, millets, etc.
The crops that are grown in winter season are called rabi crops or winter crops. These are sown during October-November and harvested by March, e.g., wheat, gram, pea, mustard and linseed.
Paddy or rice crops are grown in rainy season because it requires a lot of water. It cannot be grown in winter season. Similarly, wheat cannot be grown in rainy season because wheat plant cannot tolerate too much water.
Q.1. Fill in the blank:
The same kind of plants grown and cultivated on a large scale at a place is called ................
Ans: crop
Q.2. Give two examples of each. (a) Kharif crop (b) Rabi crop
Ans: (a) Soybean and groundnut are two examples of kharif crops.
(b) Pea and mustard are two examples of rabi crops.
The various agricultural practices of crop production involve:
• Preparation of soil
• Sowing
• Adding manure and fertilisers
• Irrigation
• Protection from weeds
• Harvesting
• Storage
The first step for crop production is soil preparation. Soil is the uppermost layer of the earth where plants are grown.
It provides water, air, minerals, humus, etc. to the plants. Soil is prepared for sowing seeds by three major methods:
The process of loosening and turning the soil is called ploughing or tilling. It is done by using a plough. The loosening and turning of soil by ploughing is beneficial because of the following reasons:
(i) Plant roots can penetrate freely and deeper into soil and plants are held firmly to the ground.
(ii) Loose soil helps the plant roots to breathe easily.
(iii) Ploughing turns the soil to enrich it with nutrients so that plant can use these nutrients.
(iv) It also helps in removing weeds.
The ploughed soil becomes loose, therefore there are chances that it can be blown away by wind or washed away by water causing soil erosion. To prevent soil erosion, the ploughed soil is levelled by pressing it with a wooden or iron leveller. Levelling also helps in the uniform distribution of water in the fields during irrigation. The ploughed field may have big pieces of soil called crumbs. Levelling helps to break these crumbs with a plank and prevents loss of moisture from the loose soil.
Continuous growing of crops makes the soil poorer in certain nutrients. Therefore, farmers have to add manure to the fields to replenish the soil with nutrients. This process is called manuring. Sometimes, manure is added to the soil before tilling. This helps in proper mixing of manure with soil.
Q.3. Fill in the blank:
The first step before growing crops is .............. .of the soil.
Ans: preparation
The above-mentioned practices are done by using various tools. These tools are called agricultural implements.
These include plough, hoe and cultivator.
(i) Plough: It is the most ancient tool used for tilling the soil, adding manures and fertilisers, removing weeds, scraping of soil, etc. This is made of wood (iron) and drawn by a pair of bulls (horses, camels, etc.) and operated by man. It comprises of strong triangular iron strip called ploughshare.
The main part of the plough is a long log of wood (which is called plough-shaft), with a handle at one end and a beam on other end which is placed on bull's necks. The indigenous wooden plough is increasingly being replaced by iron ploughs now-a-days.
(ii) Hoe: It is used for removing weeds and for loosening soil. It is simple in structure with a long rod of wood or iron with a broad, bent and strong iron plate at one of its ends which works like. a blade. It is also pulled by animals.
(iii) Cultivator: Now-a-days ploughing is done by tractor-driven cultivator. It is a modern form of plough which can dig into a considerable area of soil at the same time. A cultivator saves both labour and time.
Sowing is the process of scattering or putting seeds into the soil, so as to grow a new crop plant. It is the most important part of crop production. Before sowing, good quality of seeds are selected to produce healthy plants and high yield of crops.
To separate good and healthy seeds from the damaged ones:
Take a beaker and fill half of it with water. Now put some seeds of wheat in it and stir well. After some time; most of the seeds will settle down while some seeds will float on top. This is the method of selecting good and healthy seeds.
The seeds that settle down in the bottom of beaker are heavy and healthy seeds, while the seeds that float on the top of water are spoiled seeds. These seeds may .be damaged due to disease or eaten by pest to become hollow and light and thus float on water.
Q.4. Fill in the blank:
Damaged seeds would ............... on top of water.
Ans: float
Q.5. If wheat is sown in the kharif season, what would happen? Discuss.
Ans: Wheat seeds need low temperature and less humidity to grow. If they are sown in kharif season, (i.e., rainy season), the seeds would get destroyed due to excess of water and would not grow.
Before sowing, it is important to know about the tools used for sowing seeds. Sowing is done either manually or by using machines as described below:
1. Traditional Tools
It was used by farmers earlier in their field for sowing seeds. Its upper funnel-shaped part is filled by seeds. The seeds pass down through two or three pipes having sharp ends. These ends pierce into the soil and place seed in that space.
2. Manual Sowing
Seeds are sown in the soil by hand or manually. In this method; the seeds are scattered in the entire field unevenly by sprinkling them into the soil by hand. This process is called broadcasting. This method is not good because there is uneven distribution of seeds and the seeds can be picked up by birds from the soil surface.
3. Seed Drill
It is a mechanical method of sowing by using a tractor. Seed drill is a long iron tube having funnel at the top. This is tied with the plough and seeds are put into the funnel of seed drill. These seeds are gradually released and sown into the soil furrows made by plough. The seeds are sown uniformly and get covered by the soil after sowing.
This mechanical method also protects the seeds from the damage caused by birds. It also saves time and labour. The advantage of sowing seeds at appropriate distance and depth is that, it prevents overcrowding of plants and each plant gets sufficient sunlight, nutrients and water from soil.
Crops like paddy (rice) and vegetables like tomato and chillies are first grown in nursery and allowed to grow into tiny plants called seedlings by providing them favourable conditions and good nutrients. The healthy seedlings are then transferred or transplanted to the regular field. This process of transferring the seedlings from the nursery to the main field by hand (manually) is called transplantation or transplanting'.
The process of transplantation helps to select better and healthy seedlings for the cultivation of crops. It also helps in better penetration of roots in the soil and promotes better development of shoot system of plants. Transplantation allows the seedling to be planted at the right spacings so that plants may get uniform light nutrients and water. It protects the plant from overcrowding.
Manure and fertilisers are the substances that are rich in nutrients and are added to the soil for healthy growth of plants. Addition of manure or fertiliser to the soil is called manuring. Farmers add manure to the fields to replenish the soil with nutrients. Improper or insufficient use of manure makes plants weak.
Manures are organic substances derived from the decomposition of plant and animal wastes like cow dung, urine, etc. Plant and animal wastes are dumped in pits at open places and allowed it to decompose by some microorganisms.
The decomposed matter is used as organic manure.
Fertilisers are chemicals which are rich in a particular nutrient in concentrated form and provide quick nourishment of that plant nutrient. These are easily soluble in water and easily absorbable by the plants. They are different from manure as fertilisers are produced in factories. Some examples of fertilisers are: urea, ammonium sulphate, super phosphate, potash, NPK (Nitrogen, Phosphorus, Potassium).
The excessive use of fertiliser is harmful because it makes the soil acidic or alkaline (i.e., less fertile) and also causes water pollution.
|
Manure |
Fertiliser |
|
Manure is a natural substance obtained by the decomposition of animal wastes like cow dung, human waste and plant residues. |
Fertiliser is an inorganic salt which contains necessary plant nutrients. |
|
Manure is relatively less rich in plant nutrients. |
Fertiliser contains a rich amount of nutrients like nitrogen, phosphorus and potassium in concentrated form. |
|
Manures are prepared in the field by decomposing wastes. |
Fertilisers are prepared in the factories. |
|
Manure provides humus to the soil in large amount. |
Fertiliser does not provide humus to the soil. |
|
Manures are not soluble in soil; therefore, absorbed by plants at a very slow rate. |
Fertilisers are highly soluble in water and readily absorbed by the plants. |
Advantages of Manure Over Fertilisers
The organic manure is considered better than fertilisers. This is because
(i) it enhances the water holding capacity of the soil.
(ii) it makes the soil porous due to which exchange of gases becomes easy.
(iii) it increases the number of friendly microbes.
(iv) it improves the texture of the soil.
Activity: To show the effect of manure and fertiliser on the growth of plant:
Take three pots and mark them A, B and C. In pot A, add some soil mixed with cow dung manure. In pot B, add soil mixed with urea (chemical fertiliser) and in pot C, put some soil only. Pour same amount of water in each. pot and plant the seedlings of moong or gram (already germinated). Keep the pots in sunlight and water them daily. After 7-10 days the growth of seedlings should be observed.
Due to presence of fertiliser, pot B shows maximum growth while pot A exhibits relatively less growth in comparison to pot B, but pot C (pot with ordinary soil) shows minimum growth.
This activity makes it clear that fertilisers are soluble in water thus, the plant grows fastest in pot A. Manure is less soluble, therefore plants grow but at slower rate as in pot B. It also shows that manure arid fertilisers are required for better growth of plants.
Q.6. Match the items in Column I with those in Column II.
|
Column I |
Column II |
|
(a) Kharif crops |
(i) Food for cattle |
|
(b) Rabi crops |
(ii) Urea and super phosphate |
|
(c) Chemical fertilisers |
(iii) Animal excreta, cow dung, urine and plant waste |
|
(d) Organic manure |
(iv) Wheat, gram and pea |
|
|
(v) Paddy and maize |
Ans:
|
Column I |
Column II |
|
(a) Kharif crops |
(v) Paddy and maize |
|
(b) Rabi crops |
(iv) Wheat, gram and pea |
|
(c) Chemical fertilisers |
(ii) Urea and super phosphate |
|
(d) Organic manure |
(iii) Animal excreta, cow dung, urine and plant waste |
Nitrogen Fixation
Sometimes, fertility of soil is increased by growing leguminous plants or crops like pulses, pea, beans, groundnut, dover, etc. These plants possess nitrogen fixing bacteria called Rhizobium in their roots which can directly fix the atmospheric nitrogen into nitrogenous compounds. These compounds can be used by the plants easily to increase the crop yield naturally.
Crop Rotation
It is a practice in which different types of crops, especially leguminous and non-leguminous crops are grown alternately in the same field. This procedure is followed in order to improve the fertility of soil, e.g., crops like cereals; vegetables, etc. deplete nitrogen from the soil. Therefore, leguminous crops are grown alternatively after these crops, to maintain the nitrogen level of the soil Rotation of crops also saves a lot of nitrogenous or chemical fertilisers.
Mixed Cropping
It is also a method of increasing soil fertility by growing two or more crops together in the same field. In this method, crops are chosen so that the nutrient needs of one crop are fulfilled by other, e.g., leguminous crops and cereal crops, are grown together. This is the natural method of increasing soil fertility.
Q.7. Explain how soil gets affected by the continuous plantation of crops in a field.
Ans: Soil is the source for plants from which they derive their mineral nutrients, essential for their growth. If crops are grown continuously in the same field, for a long period of time, the soil becomes poorer in nutrients. Thus, soil gets deficient in nutrients and the field becomes infertile.
Water is important for proper growth and development of flowers, fruits and seeds of plant. The process of supplying water to crops at different intervals is called irrigation. The frequency and time of irrigation differ from crop to crop, soil to soil and season to season. e.g., in summers frequency of irrigation is required at higher rate than in rainy or winter season. This is because the rate of evaporation of water from soil is high in summer season.
Water is absorbed by the plant roots along with minerals and fertilisers. Water is essential because germination of seeds does not take place under dry conditions. Water also protects the crop from both frost and hot air currents.
For healthy crop growth; fields have to be watered regularly to maintain moisture of the soil. Plants contain nearly 90% water.
Water supplied for irrigation can be taken from different sources like rain, wells, tubewells, ponds, lakes, rivers, dams and canals.
Traditional Methods of Irrigation
Water from the sources such as wells, lakes and canals, is lifted by different methods for taking it to the fields.
Traditional methods of irrigation include Cattle or human labour, moat or pully system, dhekli, chain pump and rahat or lever system. They run on diesel, biogas, electricity and solar energy.
Traditional methods use manpower and animal power and there is a wastage of water also during irrigation. To overcome these problems, modern methods of irrigation are used.
The main methods are
(i) Sprinkler system: In this system, there is a main pipeline laid in the field and attached with revolving nozzles at regular intervals. Water from the resources like tubewells escapes from rotating nozzles and is sprinkled like rain on the crops. This system of irrigation is useful on uneven land where sufficient water is not available and in sandy soil.
(ii) Drip system: In this system, a network of narrow pipes or tubes is laid down in the field with small holes. When water flows through the narrow pipes, it falls drop by drop just near the roots of plants.
In this method there is no wastage of water as water falls drop by drop, therefore this system of irrigation is very useful in regions where availability of water is poor. It is the best technique for watering fruit plants, gardens and trees.
While the plants are grown in the field, many small, unwanted plants also germinate and grow in the field along with the crop plant. These unwanted, wild plants that grow along with the cultivated crops are called weeds. The removal of weeds from the field is called weeding. The unwanted plants are harmful because they consume the nutrient, fertiliser and water necessary for crop plant and reduces crop yield. Some weeds interfere in harvesting and are poisonous for animals and humans. Therefore, it is necessary to remove weeds from time-to-time.
Some of the common weeds that are found in wheat and rice fields are wild oat, grass, Amaranthus or chaulai and Chenopodium or bathua. Types of weeds vary from field-to-field or crop to crop or even from season-to-season.
Weeding can be done either manually or by spraying weedicides as discussed below:
Manual Weeding
In this method, the weeds are removed from the crop field by pulling them up by hands and throwing away.
Another method of manual weeding is by using trowel or khurpi. Weeds are physically removed by digging or cutting them close to the ground from time-to-time.
Spraying Weedicides
Certain chemicals called weedicides (herbicides) like 2,4-D. are sprayed in the fields to kill the weeds but crops remain unaffected. It should be sprayed during the vegetative growth of weeds before flowering and seed formation else weeds become difficult to control. Precautionary measures such as covering nose and mouth with cloth should be taken, while spraying these as they impose health hazards.
Pests are organisms that damage the crops. Pest include rodents (rats) and insects like locusts, weevils, termites, etc. These are controlled by using pesticides and insecticides, that kill pests, their eggs and larvae but do not have ill effect on plants. These are usually used during storage of grains. BHC (gammaxane), malathion and disyston are the examples of insecticides.
Q.8. What are weeds? How can we control them?
Ans: Weeds are the undesirable (unwanted) plants that may grow naturally along with the crop. They are hazardous to the crops as they compete with the crop for food, nutrients, water and sunlight. Hence, they must be controlled. The process of controlling or removing weeds from the field is known as weeding. There are several methods to remove weeds such as tilling in which weeds are uprooted. They are removed manually by cutting with the help of khurpi. They are also controlled by chemicals known as weedicides which kill the weeds, e.g., 2,4-D.
The process of cutting and gathering mature (ripened) crop is called harvesting. When crops get matured, they usually turn yellow or golden or brown. In harvesting, crops are pulled out or cut close to the ground. Harvesting in our country is either done manually by sickle or by a machine called harvester.
The process by which the grain seeds are separated from the chaff is called threshing. This is carried out with the help of a machine called combine which is a combination of a harvester and thresher.
Sometimes, stubs of crop plants left in the field after harvesting are burnt by the farmers. This should be avoided because it causes air pollution and may cause accidental fire to the harvested crop and damage it. Their shifts can be retained in the field to increase soil fertility.
After threshing, the grains are separated from chaff by the process called as winnowing. In this process, the mixture of grain, hay and chaff is dropped from a height in blowing wind.
The heavier seed, fall straight to the ground whereas the chaff and hay are much lighter and are carried away by wind. The grains form a separate heap and can be collected and packed in gunny bags.
Q.9. Write a paragraph in your own words on each of the following.
(a) Preparation of soil (b) Sowing (c) Weeding (d) Threshing
Ans: (a) Preparation of soil: It is the first step before sowing the crop. In this, the soil is ploughed to loosen it and make it aerated which allows the roots to breathe easily. This also helps earthworms and microbes in the soil that bring the nutrient rich soil to the top. The process of loosening and turning of soil is called tilling or ploughing, which is followed by levelling and manuring.
(b) Sowing: The process in which the seeds are embedded in the soil for crop production is called sowing. Traditionally, funnel-like tools are used for sowing. But now-a-days, seeds are sown by a seed drill implement. It scatters the seeds at regular intervals in the soil.
(c) Weeding: It is the removal of weeds from the field. It is essential as weeds are harmful for the growth of crops because they compete with the crop plants for water, nutrients, space and light.
(d) Threshing: The process in which the grain seeds are separated from chaff is called threshing. This is carried out with the help of a machine called combine that is a combination of a harvester and thresher.
The big containers that are used for the storage of grains in large quantities are called silos. They protect the stored grains from pests and insects.
Farmers store grains in jute bags or metallic bins. However, large scale storage of grains is done in silos and granaries to protect them from pests like rats and insects.
To protect the grain from microorganism dried neem leaves are used by the farmers. The food grains are bought from the farmers by the Government Agencies like Food Corporation of, India (FCI) and stored in its godown. These are then supplied throughout the country round the year. Food grains filled in gunny bags can be easily transported and distributed at various places.
Besides plants, some animals also provide us food. The food obtained by animals are rich in protein (that are not present in plants), good amount of fats but less amount of carbohydrates. Animals are mainly categorised into two major types on the basis of food obtained from them. These are:
(i) Milk yielding animals also called as milch animals: Cow, buffalo and goat are the examples of milk yielding animals. These are also called as dairy animals.
(ii) Egg and meat yielding animals: Goat, sheep, fish and poultry (like duck, chicken) are meat and egg yielding animals.
(iii) Honey is another nutritious substance that is obtained from honeybees.
The process of rearing animals, by providing them proper food, shelter and care is called animal husbandry. The rearing of fish in coastal areas (large scale) and in rivers and lakes (small scale) for food is called pisciculture. Fishes are an important source of animal food in coastal areas. They are highly nutritious and rich in vitamin-A and vitamin-D. Cod liver oil or Cod fish liver oil is rich in vitamin-D.
Q.10. Fill in the blank:
For growing a crop, sufficient sunlight, ................ and ................. from the soil are essential.
Ans: water, nutrients
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