Soil is the uppermost layer of the earth and is essential for agriculture. It is composed of different materials and has distinct horizontal layers called horizons. The topsoil horizon, or A-horizon, is dark and rich in nutrients and humus. Below this is the B-horizon, which contains less humus and compact soil particles. The lowest C-horizon is made up of small rock fragments. Soil types like sandy, clayey and loamy are determined by particle size, and each has different properties for water retention and drainage. Human activities that pollute soil with plastics, chemicals and pesticides can destroy its fertility.

1. CHAPTER
SOIL
BY- RITIMA SINGH MANHAS
APS RAKHMUTHI

2. WHAT IS SOIL?
SOIL IS THE UPPER MOST LAYER OF THE EARTH.
IT IS ESSENTIAL FOR THE AGRICULTURE AND IT
IS HOME OF MANY ORGANISMS.
SOIL IS OF DIFFERENT TYPES AND IT HAS
DIFFERENT LAYERS .
THE DIFFERENT TYPES OF SOIL HAS DIFFERENT
PARTICLE SIZE.
SOIL = ROCK PATICLES + HUMUS

3. SOIL PROFILE
SOIL PROFILE IS COMPOSED OF DIFFRENT LAYERS
OF THE SOIL .THE VERTICAL SECTION OF
DIFFERENT LAYERS OF SOIL IS CALLED SOIL
PROFILE.
 IT IS COMPOSED OF VARIOUS LAYERS CALLED
AS HORIZONS.
THE VARIOUS HORIZONS OF SOIL ARE :
I. A- HORIZON
II. B- HORIZON
III. C-HORIZON
IV. BEDROCK

4. A- HORIZON
IT IS DARK IN COLOUR AS IT IS RICH IN HUMUS.
DUE TO THE PRESENCE OF HUMUS IT IS RICH IN
NUTRIENTS AND HELP IN HEALTHY GROWTH OF
THE PLANTS .
THIS LAYER IS GENERALLY SOFT POROUS AND
CAN RETAIN MORE AMOUNT OF WATER.
IT IS ALSO CALLED AS TOP-SOIL.
IT IS HOME OF MANY ORGANISMS. ROOTS OF
PLANT EMBEDDED COMPLETELY IN THIS LAYER.

5. B-HORIZON
IT IS ALSO CALLED AS MIDDLE LAYER.
IT HAS LESS AMOUT OF HUMUS.
THE SOIL PARTICLES IN THIS LAYER ARE
COMPACTLY ARRANGED .
THIS LAYER OF SOIL IS GENRALLY HARD.

6. C- HORIZON
IT IS THIRD LAYER OF THE SOIL , IT IS MADE
UP OF SMALL LUMPS OF THE ROCKS .
THE C-HORIZON IS FOLLOWED BY THE BED
ROCK. THE BED ROCK IS HARD TO DIG BY THE
SPADE.

7. SOIL TYPES
ON THE BASES OF THE PARTICLE SIZE THE SOIL
IS OF VARIOUS TYPES :
I. SANDY SOIL
II. CLAYEY SOIL
III. LOAMY SOIL
IV. BLACK SOIL

8. CLAYEY SOIL
CLAYEY SOIL IS A FINE GRAINED SOIL
MATERIAL.
PARTICLES BEING SMALLER PACK LIGHTLY
TOGETHER ,LEAVING LITTLE SPACE FOR AIR.
THEY ARE NO SO AERATED BUT HAS HIGHEST
WATER HOLDING CAPACITY.

9. SANDY SOIL
 SANDY SOIL IS OFTEN DRY, NUTRIENT
DEFCIENT AND FAST DRAINING.
THE SIZE SANDY PARTICLES ARE LARGE-
0.05-2.00mm IN DIAMETER
THE SANDY SOIL HAS LOWEST WATER
HOLDING CAPACITY.

10. PROPERTIES OF SOIL
A. PERCOLATION RATE
Percolation rate= amount of water/percolation time
 PERCOLATION RATE OF WATER IS HIGHEST IN
SANDY SOIL AND LEAST IN THE CLAYEY SOIL.
B. MOISTURE IN SOIL AND ABSORPTION
 SOIL MOISTURE AND WATER ABSORPTION
CAPACITY OF SOIL ALSO VARIES AMONG
DIFFERENT SOIL TYPES.
 LOAMY SOIL AS MAIMUM ACCURURATE
WATER HOLDING CAPACITY WHILE SANDY SOIL
HAS LEAST.

11. SOIL AND CROPS
CROP GROWN SOIL TYPE
WHEAT AND GRAM CLAYEY AND
LOAMY SOIL
PADDY CLAYEY SOIL
PULSES LOAMY SOIL
COTTON SAND LOAM OR
LOAMY SOIL

12. SOIL POLLUTION
CONTAMINATION OF TOP LAYER OF SOIL
MAKING SOIL UNFIT FOR CULTIVATION IS
CALLED SOIL POLLUTION
FACTORS LEADING TO SOIL POLLUTION
VARIOUS HUMAN ACTIVITIES AND
PRODUCTS POLLUTE THE SOIL. THESE
POLLUTANTS DESTROY THE FERTILITY OF
THE SOIL AND HARM THE
ORGANISMSLIVING IN THE SOIL.

13. VARIOUS SOIL LOLLUTNTS
POLYTHENE BAGS
PLASTIC PRODUCTS
CHEMICALS
PESTICIDES

14. PREVENTIVE MESURES
TREATING WASTE PRODUCTS BEFORE
DISPOSAL.
REDUCING USE OF POLYTHENE BAGS.
MINMISING THE USE OF PRODUCTS MADE OF
PLASTIC.
PLASTIC PRODUCTS AND POLYTHENE BAGS
ARE BANDED TO AAVOID THE SOIL POLLUTION.