This article brings you the CBSE Class 9 Science notes on chapter 15 ‘Improvement in Food Resources’ (Part-II) . This part is in continuation with Part I notes where we discussed about the food, its sources, different crop seasons, manure, fertilizers, irrigation and other related facts. Here, you will learn the next remaining topics.
Main topics covered in this part of CBSE Class 9 Science, Improvement in Food Resources: Chapter Notes (Part –II), are:
- Crop Patterns
- Crop Protection Management
- Weeds and Methods to Control it
- Pests and Methods to Control it
- Storage of Grains
- Animal Husbandry
- Breeds of Cow
Key notes for Chapter- Improvement in Food Resources, are:
Different patterns are followed to obtain maximum production from a crop field. They are:
1. Mixed Cropping 2. Inter Cropping 3. Crop Rotation
1. Mixed Cropping: It is the practice of cultivating two or more crops simultaneously on the same piece of land.
Most common examples of crops grown together are:
Wheat and Mustard
Groundnut and Sunflower
Wheat and Gram
Barley and Chick pea
Advantages of Mixed Cropping:
- It minimizes the risk of crop failure.
- It facilitates the optimum utilization of soil.
- Minimizes the damage caused by pests.
- Varieties of produce can be harvested at the same time
2. Inter cropping: It is the practice of cultivating two or more crops in the same space at the same time in a definite pattern like few rows of one followed by few rows of other.
Advantages of Intercropping:
- It helps to maintain the soil fertility.
- It makes better use of resources.
- Each crop can be harvested, threshed and marketed separately.
- Application of pesticides and fertilizers is more convenient due to well defined patterns of crops.
Criteria of Selection of crops for Mixed cropping and Intercropping:
Two or more crops chosen for mixed cropping as well as intercropping should be such that they have different nutrient requirements so that maximum utilisation of the soil nutrients takes place. Also, their water needs, rooting patterns, etc., must be different.
3. Crop Rotation: Crop rotation is policy of growing different crops one after another on the same filed.
If same crop is grown again and again on the same field, same nutrients are extracted from soil again and again causing those nutrients to get depleted. So different crops should be planted to maintain the supply of all essential nutrients in soil.
Advantages of crop rotation:
- Fertility of soil is maintained for longer period.
- The chemical nature of soil is not altered.
- It helps in weed and pest control.
- It reduces the use of chemical fertilizers.
Crop Protection Management
When the crop is in the field, it needs protection against weeds, insect pests and other diseases.
Weed : Weeds are unwanted plants in the cultivated field. For example, Xanthium (Gokhroo), Amaranthus (Chaulai), etc.
How weeds are harmful to main crop?
- They compete for food, space, light and essential nutrients therby reduce the growth of the main crop.
- They promote the attack by crop pests and diseases by acting as alternate host to insects and microorganisms.
- During harvesting, weeds get mixed up with crop to lower down its quality.
Methods of weed control:
Weeds can be controlled by following ways:
- Manual removal of weeds.
- Adopting cultural methods like proper bed preparation, timely sowing of crops, intercropping and crop rotation.
- Using weedicides like 2,4- D (2,4-dichlorophenoxy acetic acid), MCPA (2-methyl, 4-chlorophenoxy acetic acid), Atrazine and Butachlor.
Insect pests: Insects which destroy or damage crop plants are called insect pests.
They affect overall health of the crop and reduce yield.
They attack the plants in following three ways:
- They cut the root, stem and leaves.
- They suck the cell sap from various parts of the plants.
- They bore into the stem and fruits.
Methods of insect pests control:
Using pesticides: The chemical used to eliminate pests are called pesticides. They include insecticides (for killing the insects), weeedicides (for killing the weeds), rodenticides (for killing rats), and fungicides (for killing the fungi).
Using natural insecticides: Like neem, nicotine, pyrethrum, etc.
Storage of Grains
In order to make the seasonal foods available throughout the year, they are stored in safe storage.
During storage, they may get destroyed and wasted by following factors:
1. Biotic factors: The include living organisms like insects, birds, mites, bacteria, fungi.
2. Abiotic factors: They include non-living environmental like moisture contents, humidity of air, improper temperature etc.
Preventive measures to be used while storage of food grains are given below:
- Drying: The harvested food grains should be dried properly before storage.
- Cleaning and maintenance of hygiene before storage: The food grains should be properly cleaned and then filled in absolutely dry and clean gunny bags before keeping in godowns, warehouses or stores.
- Regular check on godowns: Godown, warehouses and stores should be properly cleaned, dried and repaired.
- Fumigation: Those pesticides which can destroy insects by forming toxic fumes are called fumigants and process of their use is called fumigation.
Fumigants may be solid, liquid or gaseous.
For example, aluminium phosphate (solid fumigant), Ethylene dichloride-carbon tetrachloride (EDCT) (liquid fumigant), Methyl bromide (gaseous fumigant) are some commonly used fumigants.
Animal husbandry is the scientific management of domestic animals in an efficient manner to obtain food and other useful products from them.
Cattle farming: It is the raising of cattle for yield of milk by females and draught labour for agriculture work.
Milch Animals: These includes milk producing animals(female cattle).
Draught Animals: These are the animals which do not produce milk and are used for agricultural work.
Lactation Period: Female cattle give milk after birth of calf (baby). The time duration for which she gives milk is called lactation period.
Breeds of Cow
1. Indegenous breeds: They are local or desi breeds. For example: Red Sindhi and Sahiwal (high lactation yield).
2. Exotic breeds: They are the foreign breeds. For example: Jersey and Brown Swiss (Disease resistant species).
3. Hybrid breeds: They are the offsprings of cross between indigenous and exotic breeds to get desirable character.
Some successful cross-breeds are:
(i) Karan Swiss: Cross-breed of Brown Swiss and Sahiwal.
(ii) Karan Fries: Cross-breed of Holstein-Friesian and Sahiwal.
Try the following questions:
Q1. Distinguish between weeds, insects pests
Q2. Define the term hybridization and photoperiod.
Q3. How do biotic and abiotic factors affect crop production?
Q4. Write two examples of pesticides and fumigants each.