CBSE Class 9 Science Improvement in Food Resources Exam Notes

CBSE Class 9 Science Improvement in Food Resources Exam Notes. Please refer to the examination notes which you can use for preparing and revising for exams. These notes will help you to revise the concepts quickly and get good marks.

CROP SEASONS

Kharif Season Crops :

*These crops are grown during the rainy season from the month of June to October, e.g., Paddy (rice), soyabean.

Rabi Season Crops :

*These crops are grown during the winter reason from the month of November to April. e.g. wheat, gram, peas.

*Crop rotation can be defined as the practice of growing of different crops on a piece of land in a preplanned succession.

Improvement in food resources can be classified into three steps -

CROP VARIETY IMPROVEMENT

This step is depends on a crop variety that can give a good yield.

A common way for getting a new variety having all desirable change is "Hybridization."

Crops for high yield, should have following characters -

(i) Resisstance for biotic & abiotic factors.

(ii) Resistance to disease & pests.

Ø CROP PRODUCTION MANAGEMENT

Crop production management included practices which help in lomering of soil erosion., provide better facility for maximum utilization of nutrient, improve the fertility of soil enhance crop production.

 Nutrient management :

Like other living organisms, plants also require nutrients for building their structure and maintaining their body functions. The plants require inorganic elements, which they chiefly obtain from the soil, where these elements occur in the form of minerals. Besides soil, the nutrients are also supplied to plants by air and water. The major elements supplied by air are carbon and oxygen. The hydrogen comes mainly from water. Soil is the main source to supply rest of essential elements to plants. There are sixteen elements which are essential for plants. These are

Out of sixteen nutrient elements required by plants, Carbon and oxygen are supplied by air, Hydrogen is supplied by water and remaining thirteen (13) elements are supplied by soil. Six of these elements are required in large amounts. They are called macro-nutrients. The elements categorized as macronutrients are : Nitrogen, Phosphorus, Potassium, Calcium, Magnesium and sulphur. The remaining seven elements , required in trace or micro amounts, are called micronutrients. They are Iron, Boron, Zinc, Copper, Molybdenum and Chlorine.

Nutrients Supplied by air, water and soil.

To overcome the problem of deficiency of mineral nutrients and to increase the yield, the soil can be enriched by supplying these nutrients from the external sources. The major materials which are added into the soil to improve and maintain its fertility are grouped under two broad categories :

 Manures and fertilizers : Manures :

Manure are organic substances obtained from the decomposition of animal wastes, like cow dung and vegetable wastes by the action of microbes.

Types of Manures :

(i) Farmyard Manure (FYM) -

It is formed by the decomposition of a mixture of cattle excreta (dung), urine of cattle, litter and roughage.

By the action of micro-organisms all these materials decompose and are used as farmyard manure (FYM).

(ii) Compost :

Compost is a biological process in which the above mentioned organic matter is decomposed by both aerobic and anaerobic micro-organisms.

(iii) Green Manuring :

The practice of green manuring includes growing turning or ploughing and mixing of green crops with soil to improve physical structure and soil fertility.

Green manures may include both leguminous and non leguminous plants.

Fertilizers :

Fertilizers are the sources of plant nutrients manufactured commercially from chemicals. They are inorganic or organic compounds containing necessary plant nutrients such as nitrogen, phosphorus and potassium.

The chemical substance which can be used as a fertilizer must have the following characteristics :

• It must be soluble in water.

• It should be easily assimilated by plants.

• It should be fairly stable.

• It should not be injurious to plants.

• It should not disturb pH of the soil.

• It should be cheap.

Fertilizers are classified according to the element (N, P or K) which they supply to the soil. (i) Nitrogeneous fertilizers

(ii) Phosphatic fertilizers

(iii) Potash fertilizers

(iv) NPK fertilizers

(i) Nitrogenous Fertilizers :

The important nitrogenous compounds used as fertilizers are : Ammonium sulphate, (NH₄)₂SO₄

Calcium cyanamide, CaCN₂

Calcium ammonium nitrate, Ca(NO₃)₂, NH₄NO₃

Basic calcium nitrate, Ca(NO₃)₂, CaO Urea, (NH₂–CO–NH₂)

(ii) Phosphatic Fertilizers :

The minerals of phosphorus such as phosphorite, [Ca3(PO₄)2] and apatire, [3Ca3(PO₄)2·CaF₂] are sparingly soluble in water and thus do not serve as source of phosphorus for plants. These are, therefore, converted into soluble materials which can act as good fertilizers. The important phosphatic fertilizers are :

Calcium superphosphate

Nitrophosphate Triple phosphate Phosphatic slag

(iii) Potash Fertilizers :

Potassium nitrate, potassium chloride and potassium sulphate are used as fertilizers.

(iv) NPK Fertilizers :

Fertilizers containing N, P and K in suitable adjusted proportions are known as NPK fertilizers. These are obtained by mixing nitrogenous, phosphatic and potash fertilizers in suitable proportions.

 Irrigation :

Irrigation the process of providing water to the soil for the purpose of supplying moisture essential for plant growth.

 Irrigation method :

Wells : There are two types of wells, namely dug wells and tube wells. In a dug well, water is collected from water bearing strate. Tube wells can tap water from the deeper strate. From these wells, water is lifted by pumps for irrigation.

Canals : This is usually an elaborate and extensive irrigation system. In this system canals receive water from one or more reservoirs or from rivers. The main canal is divided into branch canals having further distributaries to irrigate fields.

River Lift Systems : In areas where canal flow is insufficient or irregular due to inadequate reservoir release, the lift system is more rational. Water is directly drawn from the rivers for supplementing irrigation in areas close to river.

 Tanks : These are small storage reservoirs, which intercept and store the run-off of smaller catchement areas.

 Cropping pattern

Mixed Croppoing :

The process of mixing seeds of two or more different crops and then sowing then in the same field is called

mixed cropping.

Example of mixed cropping - (a) Wheat + mustard

(b) Maize + urad

(c) Arhar + mung

(d) Ground nut + sunflower

 Advantages of Mixed Cropping :

There is lesser risk of total crop failure because if one crop fails, then the other crop helps the farmers to overcome his loss.

Farmers get a variety of products for their family by growing crops under the mixed cropping system, e.g. cereals, pulses, fodder and vegetables may be grown simultaneously.

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