Improvement in Food Resources
CBSE Class 9 · Science · Notes and practice questions
Improvement in Food Resources is the Class 9 biology chapter that explains how crop yields can be raised through improved varieties, better soil and water management and crop protection, and how scientific animal husbandry of cattle, poultry, fish and honeybees adds to our food production.
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Food production must keep pace with a rising population, so this chapter looks at scientifically improving both crops and livestock. The first half is about crops: increasing yield, making plants resistant to disease and pests, and shortening the time a crop takes to mature. New varieties are produced mainly by hybridisation, the crossing of two genetically different plants, and sometimes by genetic modification. The choice of variety depends on the region's soil and climate, because no single variety suits every condition.
For crops to give a good yield, soil must supply enough nutrients. Plants need macro-nutrients such as nitrogen, phosphorus and potassium, as well as small amounts of micro-nutrients. These are supplied either as manure, which is organic matter from decomposed plant and animal waste, or as chemical fertilisers rich in specific nutrients. Water is equally important, so irrigation methods range from traditional wells and canals to water-saving drip and sprinkler systems. Cropping patterns such as mixed cropping, intercropping and crop rotation help a farmer use farmland more efficiently and reduce soil exhaustion.
Healthy crops can still be lost to weeds, insects and diseases. Weeds compete with the crop for sunlight, water and nutrients, while insects and pathogens attack the plant or its produce. Farmers control them by weedicides, pesticides and resistant varieties, and by keeping the field clean. Storage losses are another serious concern; grains attacked by fungi, insects or rodents lose quality and viability. Proper drying, clean storage bins and chemical fumigation protect harvests until they are consumed or sold.
The second half of the chapter deals with animal husbandry, the scientific rearing of useful animals. Cattle farming is practised for milk and for draught labour, so indigenous and exotic breeds are chosen or cross-bred according to need. Poultry farming keeps chickens for eggs and meat, with layers producing eggs and broilers raised for meat. Fish production combines capture fishing from natural waters with culture fishery in ponds and tanks, while beekeeping gives honey, wax and better pollination of crops. Good feed, shelter and disease control are common to all these practices.
Key terms
- Hybridisation
- The crossing of two genetically dissimilar plants or animals to produce offspring that combine desirable traits of both parents. In crops, it is a major method of variety improvement and is carried out by crossing selected parents, followed by selection of superior offspring.
- Mixed cropping
- Growing two or more crops together on the same piece of land in the same growing season, without a fixed row pattern. It reduces the risk of total crop failure and ensures some income even if one crop fails, and it makes more efficient use of resources.
- Intercropping
- Growing two or more crops simultaneously on the same land in definite alternate rows, so that the crops get enough space for sunlight, water and nutrients. It increases the productivity per unit area and makes weeding and harvesting easier.
- Crop rotation
- Growing a series of different crops in a planned sequence on the same field over successive seasons. This preserves soil fertility, breaks the life cycles of pests and diseases, and can help replenish soil nitrogen when a legume is included.
- Manure
- An organic substance prepared by the decomposition of plant and animal wastes such as cow dung, crop residues and green waste. It adds humus and improves soil water-holding capacity and aeration; it releases nutrients slowly.
- Fertiliser
- A commercially prepared chemical substance that supplies essential plant nutrients such as nitrogen, phosphorus and potassium. Fertilisers are nutrient-specific and give rapid increases in yield, but overuse can degrade soil and pollute water.
- Biofertiliser
- Living organisms that supplement soil nutrients when added to crops or soil. Examples include nitrogen-fixing bacteria like Rhizobium and blue-green algae. They are cheap and environment-friendly and restore soil fertility naturally.
- Layers and broilers
- In poultry farming, layers are birds kept for egg production, while broilers are birds raised for meat. Broilers need more protein- and energy-rich feed and careful temperature control; layers are selectively bred for high and sustained egg laying.
- Capture and culture fishery
- Capture fishery is obtaining fish from natural water bodies such as seas, rivers and lakes, where fish reproduce on their own. Culture fishery involves controlled rearing of fish in ponds, tanks or cages, with planned feeding and harvesting, so the yield is higher and predictable.
Practice questions with answers
1. What is meant by crop variety improvement? Name any two traits that can be introduced by hybridisation.
Crop variety improvement means developing new varieties of plants that have desirable characteristics such as higher yield, better quality or tolerance to stress. Hybridisation is the technique of crossing two genetically dissimilar plants to combine their useful traits. Two examples of traits sought are higher yield and resistance to insect pests.
2. What are the main sources of irrigation in India?
The chief sources of irrigation are wells and tube wells, canals from rivers, tanks and ponds. Modern drip and sprinkler systems are also used because they deliver water directly to the root zone or as fine spray, saving water and reducing wastage.
3. Differentiate between mixed cropping and intercropping.
In mixed cropping, two or more crops are grown together in the same field at the same time, without orderly rows. In intercropping, the crops are grown in a fixed row pattern, for example one row of one crop alternating with two rows of another. Intercropping reduces competition and allows easier weeding, fertilising and harvesting, while mixed cropping mainly acts as a safeguard against total failure of a single crop.
4. Why should a farmer rotate crops? Give a suitable rotation.
Crop rotation is growing different crops in sequence on the same land. It prevents the repeated uptake of the same soil nutrients and reduces soil-borne pests and diseases. Growing a legume such as gram or pea after wheat replenishes nitrogen through root nodules, so the farmer uses less fertiliser and soil fertility improves.
5. What are biofertilisers? Give two examples.
Biofertilisers are living organisms that improve soil nutrient availability. Rhizobium, which forms root nodules on legumes and fixes atmospheric nitrogen, is one example; blue-green algae or cyanobacteria, used in rice fields, is another.
6. Mention two harmful effects of using excessive chemical fertilisers.
Excess fertilisers can make the soil acidic or alkaline and reduce beneficial soil organisms over time. Leaching of fertilisers into water bodies also causes pollution and eutrophication, harming aquatic life.
7. What are broilers? What special care do they need?
Broilers are chickens raised specially for their meat. They need highly nutritious feed rich in protein, vitamins and minerals, and clean surroundings with proper temperature and ventilation. Regular vaccination and disease control are essential to get good growth in a short period.
8. Differentiate between capture fishing and culture fishery.
Capture fishing is the harvesting of fish from natural sources such as seas, rivers and lakes, with no control over breeding or feeding. Culture fishery involves rearing fish in enclosed artificial or semi-natural water bodies, where fish are fed, protected and harvested under controlled conditions, thus giving a higher yield.
9. Why is beekeeping beneficial to farmers? Name the common species of honeybee in India.
Beekeeping gives useful products such as honey and beeswax, and the bees help pollinate agricultural crops, which increases their yield. The most common Indian species Apis cerana indica is raised in boxes, while some farmers also keep Apis mellifera (Italian honeybee).
10. What precautions should be taken to protect stored grains?
Grain should be completely dried in the sun or with a drier before storage so that its moisture content is low enough to prevent fungal growth. The storage area should be clean, dry and well-aerated, and fumigants, insecticides or safe plant-based protectants can be used to destroy hidden insects and pests.
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