Unit 19

Materials used in Agriculture

On the basis of fulfillment of food requirements, living creatures are divided into two types:

i) Autotrophs

ii) Heterotrophs

- Autotrophs: The organisms which can synthesize their own food from carbon dioxide, water and sunlight are called autotrophs. All green plants are autotrophs.

- Heterotrophs: The organisms which cannot synthesize their own food are called heterotrophs. Human beings, animals are heterotrophs.

How do we get food?

1. Agriculture: The growing of plants or crops to obtain food is called agriculture.

2. Animal Husbandry: The branch of agriculture concerned with animals that are raised for meat, milk, fiber and other products is called animal husbandry.

- Crops: The plants grown and cared in the field for getting food are known as crops. Eg: Grains, vegetables, fruits etc.

- Plant Nutrients: The minerals required by plants for its growth and survival are called plant nutrients. There are two types of plant nutrients:

i) Macronutrients

ii) Micronutrients

- Macronutrients: The mineral element needed by the plants in large amounts are called macronutrients. Eg: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorous, Potassium, Calcium, Magnesium, Sulphur etc.

- Micronutrients: The mineral element needed by the plants in very small amounts are called micronutrients. Eg: Manganese, Iron, Copper, Zinc, Boron, Chlorine, Molybdenum etc.

- Soil: The upper layer of the earth crust in which plants are grown is called soil.

Function of soil for the growth of plant

It provides plant nutrients.
It provides water through the roots.
It provides oxygen to the roots through aeration.
It holds or supports the plant.
It provides humus.

Agricultural Practices

Preparation of Soil: Soil is prepared in three steps viz. Ploughing, levelling and manuring.
Sowing: Sowing is process of scattering or putting seeds in the soil for growing crop plants. It can be done either by hand or using seed drill. Also, the seedlings are transferred from nursery to main field in this process which is known as transplantation.
Use of Fertilizer : Organic and chemical fertilizers are used.
Irrigation: Irrigation is process of supplying water to crops. Water is supplied by canals, reservoir etc.
Control of weed: Unwanted plants from crop field are removed here.
Use of pesticides: They are used to control pests in crops.
Harvesting: Cutting and gathering of matured food crops is harvesting.
Threshing and Winnowing: Threshing means beating grains out of harvested crops. Winnowing is separation of grain from chaff and hey with the help of wind.

Fertilizer

- Fertilizers are the substances which are used to increase the fertility of soil for the good growth of plants. There are two types of fertilizer in general:

i) Organic fertilizer

ii) Chemical fertilizer

- Organic fertilizer: The fertilizer made by the action of bacteria and fungi over the animal wastes and plant buried into the soil is called organic fertilizer. Eg: Powder of mustard cake, bone meal, ash etc. Organic fertilizer are also of two types:

Compost fertilizer: It is natural substance obtained by the decomposition of animal waste like animal dung, human wastes and plant residue, which supplies plant nutrients and humus to the soil.
Advantages of compost fertilizer:

It doesn’t change the acidity and alkalinity of soil.

It consists of organic substance which helps in good growth of plant.

It preserves water in the soil.

It prevents erosion and leaching.

It is biodegradable and doesn’t pollute the environment.

Green fertilizer: Fertilizer obtained by decomposition of green plants in the soil of the field is called Green fertilizer. Eg: leaves of Adhatoda (asuro), Mugwort (Tite-pati), Marijuana (Ganja) etc.

- Chemical fertilizer: A salt or an organic compound containing necessary plant nutrients like nitrogen, phosphorous or potassium is called chemical fertilizer.

- Difference between Compost fertilizer and Chemical fertilizer:

Compost Fertilizer	Chemical Fertilizer
1. Compost fertilizer is prepared from decomposed organic waste.	1. Chemical fertilizer is manufactured using chemical processes.
2. It improves soil structure and fertility.	2. It increases crop yield quickly.
3. Nutrients are released slowly.	3. Nutrients are released quickly.
4. It is environment-friendly.	4. Excessive use may harm the environment.
5. It is cheaper and can be prepared at home.	5. It is costlier and must be purchased.
6. Example: Farmyard manure, vermicompost.	6. Example: Urea, DAP, NPK.

NPK Fertilizer

- NPK fertilizers are three component fertilizers providing nitogen, phosphorous and potassium. There are two types of NPK fertilizers- Compound NPK fertilizers & Blended NPK fertilizers.

🌱 Nitrogenous Fertilizers

Urea — NH₂–CO–NH₂
Ammonium Nitrate — (NH₄)NO₃
Ammonium Sulfate — (NH₄)₂SO₄

🌿 Importance of Nitrogen in Plants

Essential for the manufacture of proteins, protoplasm, and chlorophyll.
Increases the rate of plant growth.
Helps in storage of proteins and synthesis of large amounts of chlorophyll.

⚠️ Effects of Nitrogen Deficiency

Plant growth stops and crop production decreases.
Leaves turn yellow.
Flowers do not bloom properly.
Fruits and seeds become small.

🧬 Phosphorus Fertilizers

Single Super Phosphate (SSP) — Ca(H₂PO₄)₂
Triple Super Phosphate (TSP) — 3Ca(H₂PO₄)₂
Ammonium Phosphate (DAP) — (NH₄)₃PO₄

⚡ Importance of Phosphorus in Plants

Essential for root development and early plant growth.
Helps in energy transfer and storage (ATP formation).
Promotes flowering, fruiting, and seed formation.

⚠️ Effects of Phosphorus Deficiency

Poor root growth and delayed maturity.
Leaves may turn dark green or purplish.
Reduced flowering and fruit formation.
Low crop yield.

🛡️ Potassium Fertilizers

Muriate of Potash (MOP) — KCl
Sulfate of Potash (SOP) — K₂SO₄
Potassium Nitrate — KNO₃

💧 Importance of Potassium in Plants

Regulates water balance and opening–closing of stomata.
Improves disease resistance and stress tolerance.
Enhances quality of fruits, grains, and seeds.

⚠️ Effects of Potassium Deficiency

Yellowing or scorching of leaf margins.
Weak stems and lodging of plants.
Poor fruit quality and reduced yield.
Reduces immune power of plant.

Disadvantages of Overuse of Chemical Fertilizer

Overuse of chemical fertilizer changes nature of soil. Either the soil becomes too acidic or too alkaline.
Overuse of chemical fertilizer pollutes the water and make unfit for human consumption.
Overuse of chemical fertilizer kills the aquatic animals like fish.

Pesticides

- The poisonous substance used to remove, destroy, kill or control harmful pest like rodents, insects, mites, fungi, bacteria, virus is called pesticides.

- Pesticides are of different types - Insecticides, fungicide, rodenticide, herbicide etc.

- Insecticides: The chemical compounds that are used to kill or control harmful insects are called insecticides. They are of two types:

i) Bio-Insecticides

ii) Chemical Insecticides

- Bio-Insecticides: The insecticides made from natural substances to kill or control insects are called bioinsecticides. Eg: Ash, Adhatoda, Neem leaves etc.

- Chemical Insecticides: Man made chemical compounds used to kill or control harmful insects are called chemical insecticides. eg: DDT, BHC etc.

- Advantages of Bioinsecticides:

It is pollution free.
It has no harmful effect on human and crop.
It is biodegradable.

- Disadvantages of Chemical insecticides:

It pollutes water which harms aquatic organisms.
Contact with chemical insecticide effects the nervous system and glandular system in human,
Effects growth and reproductive capacity of birds and fishes.
Promotes respiratory diseases.
It not only kill harmful insects but also kill useful insect.

- Precautions while using chemical insecticides:

1. Manual for using insecticide should be studied properly.

2. Suitable cloth, mask and gloves should be used while spraying the insecticide.

3. Insecticide should not come in contact with eye and mouth.

4. Insecticide should be spread in the direction of air.

5. The equipment used to spray insecticide should be washed properly after its use.

6. Hand should be washed properly after handling the equipment.

- Conservation of soil quality:

1. Frequent test of quality of soil.

2. Use of suitable farming technology like:

(i) Crop rotation

(ii) Multiple cropping

(iii) Maximum use of organic fertilizer

(iv) Minimum use of chemical fertilizer

(v) Suitable irrigation technology

3. Proper use of land

Activities

1. Chemical fertilizers and pesticides used in farming have caused negative effects on human health. Write any five slogans to create awareness about this issue.

2. Farmers are confused about whether to use chemical fertilizers to increase crop production or not. What suggestions would you give to them?