CBSE Class 8 Science Advanced Biology Crop Production and Management Notes Set 01

Crop Production and Management

Key Terms

Sustainable agriculture, horticulture, aquaculture, olericulture, fumigation, macronutrient, micronutrient, organic farming, vermicomposting, biofertiliser, fertigation, animal husbandry.

Introduction

1. Every living thing needs food. Food gives the material for growth and repair, protects the body from disease and supplies the energy for all life activities.
2. Only green plants are autotrophs: they prepare their own food by photosynthesis, in which sunlight energy is used to combine carbon dioxide and water into carbohydrates.
3. Animals and human beings are heterotrophs; they depend on plants, or on other animals, for food.
4. People eat roots, stems, leaves, flowers, fruits and seeds of plants as cereals, vegetables, spices and fruits.

1.1 Agriculture

The word agriculture comes from the Latin words ager (field, land) and cultura (cultivation). It is the science and art of growing crops and rearing livestock for economic purposes. Farming covers rearing animals, cultivating the land, raising crops, harvesting and marketing the produce.

(a) Branches of Agriculture

(b) Sources of Food

Crops are plants grown by people for food, fodder, fibre, flowers, timber and so on. About 2000 species are cultivated as food. The edible parts are of the following kinds.

1. Seeds. Not every seed is safe to eat: a large lemon seed can choke a person, and apple and cherry seeds contain cyanide, a poison. The edible seeds are grouped as follows.
(i) Cereals such as wheat, rice, maize, barley and sorghum are rich in carbohydrates.
(ii) Pulses are legumes such as gram (chana), pea (matar), black gram (urad), green gram (moong), pigeon pea (arhar), cow pea (lobia) and lentil (masoor). They are excellent sources of protein.
(iii) Oil seeds such as cotton seed, niger (ramtil), sunflower, soybean, linseed, rapeseed, groundnut, sesame, mustard and olive supply oils, fats and fatty acids.
(iv) Nuts (dry fruits) such as almond, walnut and cashew are rich in proteins and fatty acids, so they are energy-giving foods.

2. Fruits. Apple, orange, mango, banana, pineapple, pomegranate, pear, peach, apricot, grapes, dates, custard apple and others. A fruit is a ripened ovary and supplies vitamins, minerals, roughage, proteins, carbohydrates and fats.

3. Vegetables. These are edible parts of herbaceous plants, eaten raw or cooked.
(i) Roots: carrot, radish, turnip, sweet potato, beetroot.
(ii) Stems: mustard, bamboo, banana and asparagus stems; the underground modified stems potato, onion, garlic and ginger. Sugarcane stems give cane juice and jaggery.
(iii) Leafy vegetables: spinach, lettuce, cabbage, turnip and radish leaves, mustard, methi, bathua and curry leaf.
(iv) Inflorescence (flower) vegetables: broccoli and cauliflower; flowers of banana, fennel, gourd and saffron.
(v) Fruit vegetables: tomato, pumpkin, brinjal, jackfruit, bitter gourd, bottle gourd, ridged gourd, cluster bean, cucumber, lady's finger.

4. Spices. Leaves, stems, flowers, fruits or seeds that make food tasty: chilli, turmeric, black pepper, cumin, fenugreek.
5. Fodder crops. Green feed for cattle: berseem, oat, sudan grass, sorghum.
6. Other crops. Fibres (cotton), tobacco, tea, coffee, cocoa (chocolate), peppermint.

(c) Improvement in Food Resources

1. It protects the soil and renews its fertility and the natural resource base.
2. It makes the best use of farm resources.
3. It reduces the use of non-renewable resources and of bought inputs.
4. It gives farmers a steady and dependable income.
5. It encourages family farming and the life of farm communities.

1.2 Basic Crop Practising

When plants of one kind are grown on a large scale in one place, they are called a crop. India is a vast country, so temperature, humidity and rainfall differ from region to region.

(a) Crop Seasons

Crops differ in the temperature, climate and photoperiod they need. Photoperiod is the length of daily sunlight, which affects growth, flowering, the making of storage organs and leaf fall. India has three main crop seasons.

(b) Crop Production Management

India depends on agriculture: about 70% of its people work in it and it contributes about 40% of the Gross National Product. The methods a farmer follows depend on the size of the land holding, his education and his finances. Crop production management means controlling every aspect of production so as to get the largest and best yield. It has three parts: nutrient management, agricultural practices and cropping pattern.

The basic practices of crop production are carried out in this order: 1. preparation of soil, 2. sowing, 3. adding manure and fertilisers, 4. irrigation, 5. harvesting, 6. storage.

(I) Preparation of Soil

Preparing the soil is the first step. Turning and loosening the soil lets roots go deep and breathe easily. It includes the following operations.

(i) Ploughing (tilling). Loosening and turning the soil is called ploughing or tilling. It is done with a plough made of wood or iron, and it leaves big lumps of soil called crumbs. Ploughing loosens the soil, overturns it and airs it well, so roots can go deeper.
(ii) Levelling. The field is made even before sowing by a leveller, a flat wooden or iron plank about 1.8 to 2 m long, with a log on it for weight. Levelling smooths the soil surface and breaks the crumbs.

(iii) Agricultural implements. The tools used in cultivation are agricultural implements. Some are worked by hand, some are drawn by bullocks or camels, and tractors and combine harvesters are used nowadays.

Care of implements. Sharpen the tip of the plough from time to time so that it enters the soil easily. Do not leave tools in the open in rain, because they rust. Iron tools can be cleaned of rust by rubbing with a piece of brick. Tractors and combines should be serviced now and then. Sprayers must be washed well with water before and after each use.

(II) Sowing

Sowing is the most important step, and it starts with choosing good seeds. Good seeds are clean, healthy and of a high-yielding variety, free from insects and pests. To select them, put the seeds in water: sound seeds are heavy and sink, while damaged seeds are hollow and light, so they float.

Seeds are sown in two ways. Broadcasting is scattering the seeds by hand at random. In the seed drill method, seeds drop through tubes into furrows at the proper spacing and depth and are covered with soil at once. This keeps birds from eating them and saves time and labour.

Transplantation. Seeds are first sown in a nursery and the young seedlings are later moved to the main field, as is done with paddy. Land that is not cultivated is called fallow land.

Precautions while sowing: keep the proper spacing, treat the seeds with fungicide, and sow at the proper depth.

(III) Nutrient Management

Plants get their nutrients from air, water and soil. About 40 elements occur in plant ash, but only 16 are essential for growth. Carbon and oxygen come from air, hydrogen from water, and the other 13, which are minerals, come from the soil.

Essential nutrients were divided into two groups by Maze (1915).
1. Macronutrients are needed in easily measurable amounts, more than 1 ppm of the plant body (more than 1 mg per gram of dry weight). Of the 13 mineral elements, six are macronutrients: nitrogen, phosphorus, potassium, calcium, magnesium and sulphur.
2. Micronutrients are needed in tiny amounts, less than 1 mg per gram of dry matter. Seven mineral elements are micronutrients: iron, manganese, boron, zinc, copper, molybdenum and chlorine.

Mineral replenishment. Soil is the main store of plant nutrients, and crops keep drawing minerals out of it. If they are not put back regularly, plants show disorders of structure, growth, reproduction and function and fall ill more easily. Minerals are replaced by adding manures and fertilisers.

(iii) Manures and Fertilisers

Both make up for the shortage of nutrients and organic matter in the soil of the fields.

Manures. Manures are natural fertilisers made from rotted animal excreta and plant waste. They are bulky and give a large amount of organic matter but only a small amount of nutrients. Types: farmyard manure (FYM), compost, green manure and vermicompost.

Advantages of manures: 1. they are cheap; 2. they add organic matter to the soil; 3. they reduce soil erosion; 4. they help the soil hold more water; 5. they increase the number of friendly microbes; 6. they make the soil porous, so gases are exchanged easily; 7. they improve soil texture.
Disadvantages of manures: 1. they are bulky and the nutrients are not absorbed easily; 2. they contain little nutrient.

Fertilisers. Fertilisers are plant nutrients made in factories from chemicals. They supply nitrogen, phosphorus and potassium (NPK) and promote vegetative growth (leaves, branches, flowers), producing healthy plants.
Advantages of fertilisers: 1. they supply specific nutrients; 2. they are needed in small amounts; 3. they dissolve in water, so plants absorb them quickly.
Disadvantages of fertilisers: 1. they pollute water; 2. they can change the chemical make-up of the soil; 3. they can cause eutrophication of nearby water bodies.

Fertilisers are of four groups: 1. nitrogenous (rich in nitrogen); 2. phosphatic (rich in phosphate); 3. potassium (rich in potassium); 4. complex (containing two or more nutrients).

Biofertilisers. Living organisms that enrich the soil with nutrients are biofertilisers. They are renewable and cause no pollution. In India the main ones are nitrogen-fixing micro-organisms (non-symbiotic and symbiotic bacteria and cyanobacteria) and phosphate-solubilising micro-organisms. Two much-used examples are Rhizobium cultures and blue-green algae such as Anabaena and Nostoc. Rhizobium lives in the root nodules of legumes and fixes atmospheric nitrogen.

(IV) Irrigation

Supplying water to the crop plants in the field through canals, reservoirs, wells, tube wells and so on is called irrigation.

Purposes of irrigation: 1. it supplies hydrogen and oxygen, two of the essential macronutrients; 2. it keeps the soil moist so seeds germinate; 3. it helps roots grow and lengthen; 4. it helps roots absorb nutrients from the soil; 5. it increases the number of aerial branches (tillers), giving a better yield.

Wells and tube wells work well where the underground water is not saline; canal water is used elsewhere. Too much irrigation causes water-logging and raises the salt content of the surface, and roots in waterlogged soil do not get air.

Water resources and wise use. India has large surface water resources (12 major and 8 composite river basins) and ground water refilled by rain. More than 55 per cent of the cropped area has no irrigation and depends on rain. Water is precious, so irrigation should use proper soil and water management. Efficiency is raised by: choosing suitable crops and cropping systems; applying only the right amount of water at the right time; keeping weeds under control; and scheduling irrigation properly.

Water need depends on two factors. Crop-based: the need varies with the crop and its stage of growth; paddy is transplanted in standing water and needs continuous water, but wheat, gram, cotton and maize do not. Soil-based: if wheat is grown in sandy soil and in clay soil, the sandy soil needs more frequent irrigation than the clay soil.

Irrigation Systems

Traditional methods. Water from wells, lakes and canals is lifted by cattle or human labour. They are cheap but less efficient. They are: (A) moat (pulley system), (B) chain pump, (C) dhekli and rahat (lever system).

In the moat a rope runs over a pulley and the bucket is drawn up from the well by hand or by bullocks. In the chain pump a wheel with a chain of buckets lifts water into a trough; pumps like this may be driven by diesel, biogas, electricity or solar energy.

The dhekli uses a long pole balanced on a post, with a bucket at one end and a weight at the other, so that the weight helps to raise the full bucket. The rahat (Persian wheel) is a wheel with pots that is turned by a bullock.

Modern methods use water economically.
[A] Sprinkler system. A perforated ring or a small stand with a revolving nozzle is fixed on a base and sprays water over the crop like rain, spreading it evenly and giving only the required quantity. It is water-efficient and is being introduced in the canal-irrigated areas of Haryana, Rajasthan and Madhya Pradesh (and also in Maharashtra, Karnataka, Andhra Pradesh, Odisha and Tamil Nadu for fruit crops).
[B] Drip system. Water falls drop by drop right at the roots through pipes with drippers. It is encouraged in Maharashtra, Karnataka, Andhra Pradesh, Odisha and Tamil Nadu for fruit crops. Fertigation is applying fertiliser along with the water through drip irrigation, so as to get the maximum yield from the water available.

(V) Harvesting

1. Cutting the crop when it has matured is called harvesting. It is done by hand with a sickle or by a machine called a harvester.
2. The grain must then be separated from the chaff; this is threshing. A combine is a machine that harvests and threshes together.
3. Farmers with small land holdings separate grain from chaff by winnowing, by hand or with a winnowing machine; the lighter chaff is blown away.
4. The harvest is celebrated with joy all over India. Festivals linked to harvest are Pongal, Baisakhi, Holi, Diwali, Nabanya and Bihu.

(c) Crop Protection Management

(I) Weed Control

Weeds are unwanted plants growing in the cultivated field; any plant other than the crop is a weed. They compete with the crop for water, nutrients, space and light. Removing them is called weeding. Examples are amaranthus (chaulai) and wild oat. The methods are given below.

1. Mechanical methods. Pulling weeds out by hand; ploughing, which uproots most of them; and removing the weeds that come up during crop growth with a trowel (khurpa).
2. Cultural methods. Proper bed preparation, timely sowing, intercropping and crop rotation.
3. Chemical methods. Spraying chemical weed killers called herbicides or weedicides, for example 2,4-D (2,4-dichlorophenoxyacetic acid), atrazine, fluchloralin and isoproturon.
4. Biological control. Deliberately using insects or other organisms that eat and specially destroy the weed. The best Indian example is the removal of prickly pear cactus (Opuntia) by cochineal insects in Maharashtra and Tamil Nadu. Aquatic weeds are controlled by the grass carp fish.
Usually a combination of these methods gives the best result.

(II) Diseases of Crop Plants

Many pathogens live in the environment; when conditions suit them they spread and cause disease. By the way they spread, crop diseases are of four types.

Control. Seed-borne and soil-borne diseases are controlled by treating the seed or the soil. Air-borne diseases are controlled by spraying a fungicide on the infected parts.

(III) Storage of Grain

Most crops are harvested once a year, so grain is stored to give a steady supply through the year. It is stored at three levels: 1. at the farmer (producer) level, called rural storage; 2. at the trader's level, in gunny bags; 3. at the Food Corporation of India (FCI) level, in silos. About 9.3 per cent of stored grain is lost every year to spoilage.

Causes of loss. (A) Biotic (living) factors: insects, rodents, birds, mites. (B) Abiotic (non-living) factors: temperature, moisture, humidity and the material of the storage container.
Preventive measures: drying before storage, keeping the store clean, treatment with plant products (for example neem leaves), treating seeds with antimicrobial chemicals before sowing, and using improved storage structures.
Fumigation. Pesticides that kill insects by forming poisonous fumes are fumigants, and using them is fumigation. A fumigant may be a solid, liquid or gas; it turns into vapour or reacts with moisture in the air to make poisonous fumes.

(IV) Cropping Pattern

Cropping patterns are ways of raising crops that give the most benefit from the same land and reduce the risk of crop failure, disease and pest attack. The common patterns are mixed cropping, intercropping and crop rotation.

(i) Mixed cropping. 1. Seeds of two crops are mixed and sown together with no fixed pattern. 2. The same fertilisers and pesticides serve both crops. 3. The crops are harvested, threshed, sold and eaten as a mixture.
Combinations used in India: maize + urad, cotton + moong, groundnut + sunflower, sorghum + pigeon pea, wheat + gram, barley + gram, wheat + mustard.
Advantages: the risk of total crop failure from an uncertain monsoon falls; soil fertility improves; pest attack is much less likely.

(ii) Intercropping. Two or more crops are grown together in the same field in definite row patterns, to raise the yield per unit area.
Advantages: it uses sunlight, land and water better; it checks soil erosion; because the crops mature at different times they can be harvested and threshed separately.

(iii) Crop rotation. Growing one crop in the same field for many years uses up the same nutrients and lets diseases and pests build up. So different crops are grown in the field one after another in a planned order, which is crop rotation. By duration it is of three types.

Advantages of crop rotation: 1. it controls pests and weeds, because most pathogens survive on crop remains only for a short time and do not infect many different crops; 2. it lowers the need for fertilisers, for example the nitrogen in the soil is kept up when leguminous crops alternate with others.

(V) Crop Variety Improvement

Hybridisation is crossing genetically different plants to produce a new kind, the hybrid. The cross may be between two varieties (intervarietal), between two species of the same genus (interspecific) or between different genera (intergeneric). It brings the good characters of both parents into one variety. Intervarietal crossing is the commonest.

Green Revolution in India. The big rise in food-grain yield, especially wheat, in the 1970s is called the Green Revolution. The American scientist Dr N. E. Borlaug (Nobel Prize, 1970) was behind the triple dwarf Mexican wheat varieties, which M. S. Swaminathan, the Father of the Green Revolution in India, adapted to Indian taste by gamma irradiation. It made India self-sufficient in food, built up the buffer stock of grain and gave work and better income to many people.

1.3 Differential Agriculture Practice

(a) Organic Farming

This is raising crops that are free from pollution. Healthy cropping systems supply the best nutrients and keep pests and weeds in check, with little or no chemical fertiliser, pesticide or herbicide. Farm wastes are recycled as manure. Biofertilisers include nitrogen-fixing bacteria and blue-green algae and mineral-solubilising bacteria. Biopesticides are organisms or their extracts that repel or kill weeds, insects and pests; neem leaves are often used for this in grain storage. Mixed cropping, intercropping and crop rotation help to control insects, pests and weeds.

Advantages: 1. it prevents pollution of every part of the environment; 2. farm wastes are recycled; 3. the food has no pesticide or toxic chemical in it; 4. it maintains soil health; 5. its cropping system keeps pests and weeds under check.

(b) Sustainable Agriculture

To feed India's growing population, scientists such as Swaminathan and Kurien developed methods to raise food output, which led to a number of revolutions that made India self-reliant. Efforts continue to raise pulse production, called the golden revolution. Sustainable agriculture is the use of farming and production management methods that give the maximum yield while (i) conserving natural resources, (ii) keeping the environment in balance and (iii) meeting changing human needs. To secure the livelihood of farmers, practices such as mixed farming, crop rotation, intercropping and integrated farming (integrated agriculture) are adopted.

1. Farming: harnessing solar energy through plants and animals in the form of economic produce.
2. Conservation: careful use, preservation or restoration of the natural environment and resources.
3. Integrated agriculture: combining agriculture with other kinds of culture such as pisciculture (fish), aquaculture, apiculture (bee keeping), sericulture (silkworm rearing), poultry, piggery and livestock production (animal husbandry).
4. Advantage of sustainable agriculture: it is a production and distribution system that combines natural biological cycles and controls.

(c) Animal Husbandry

The branch of agriculture that deals with feeding, caring for and breeding domestic animals is animal husbandry. To husband means to use a resource carefully, without waste. It needs planning for the animals' shelter, breeding, health, disease control and economic use. Livestock are animals raised for farm purposes, for example cattle (cow, bull, ox), buffalo, yak, horse, ass, goat, sheep and camel. Related activities are cattle production, poultry, fish farming and bee keeping; the by-product of the honeycomb is wax.

Add to Your Knowledge

1. India has a subtropical climate, plenty of sunshine and little frost in most areas, so crops can be grown all through the year.
2. Green revolution: more food grains. Blue revolution: more fish. White revolution: more milk. Yellow revolution: more oil.
3. In modern sanitation water carries away human waste. Sewage has a solid part, the sludge, and a liquid part, the effluent (sewage water). Dried sludge can be used as a soil conditioner in lawns and flower gardens, and sewage water is rich in plant nutrients, so it can be used for fertilising and irrigating.
4. Vermicomposting is the breakdown of organic waste by earthworms. An earthworm aerates, crushes and mixes the waste; chemically it breaks it down and biologically it stimulates decomposition. Indian species used: Dichogaster bolaui, Drawida willsi, Perionyx excavatus; exotic species: Eisenia foetida, Eudrilus eugeniae.
5. Selection by people is artificial selection. Over a long time it can give varieties very different from the starting plants; broccoli, cabbage and cauliflower have all been obtained from wild cabbage.

Important Points

1. Banana is the world's number one fruit crop and the fourth largest crop after wheat, rice and maize; it is grown in more than 100 countries and India grows more bananas than any other country.
2. More than 6000 kinds of apples are grown worldwide; China is the largest producer.
3. Goats are believed to be the first domesticated animal. Pigs are thought to be the fourth most intelligent animal, after chimpanzees, dolphins and elephants.
4. Subsistence farmers grow just enough food for themselves and their families and do not sell it in the market.

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