Importance of Soil - Crop and Soil Science - Lecture Slides, Slides for Botany and Agriculture. Punjab Engineering College

Botany and Agriculture

Description: These are the lecture slides of Crop and Soil Science. Key important points are: Importance of Soil, History of Soil, Soil Misuse, Nonrenewable Resource, Fragile Layer of Life, Solid Part, Interface Between the Two, Soil Forms, Proper Temperature, Plant Roots
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Chapter One

The Importance of Soil

The Importance of Soil • The history of Soil

– Dates back all the way to the Egyptians civilization of 4,000 years ago

– Recently in the US history supplies another example of soil misuse. This is with the Dust bowl of the 1930’s.

– The Dust bowl was a drought that misused the soil in having wind erosion.

The Importance of Soil • Additional acreage is lost due to urbanization

or degradation . • Soil is a nonrenewable resource

The Importance of Soil • Most of the time we take soil for granted. • Soil is a very thin and often fragile layer of life

supporting material.

The Importance of Soil • Facts about the earth

– Earth consists of solid part (core, mantle, and crust) and the atmosphere surrounding it.

– Most of the earth is covered by sea – Where continents exist the crust is thicker – This is usually about 50 miles thick

The Importance of Soil • The atmosphere is about 170 miles deep. • The soil forms a very thin interface between

the two.

The Importance of Soil • What does living things need?

– Proper temperature – Oxygen – Water – Carbon – Other nutrients – These factors are exchanged in the soil that

allow elements to be recycled rather than lost

The Importance of Soil • Oxygen:

– Plant roots need oxygen to grow.

– Gases will pass in and out of the soil to supply the

oxygen for the roots

The Importance of Soil – Temperature

• Plants will grow best in certain soil temperature ranges. • Most plants will root in temperature around 40-50

degrees F.

• Water: – Seldom stays in one place

The Importance of Soil • Carbon:

– Plant leaves collect sunlight to use the energy in the process of photosynthesis.

– Which involves converting atmosphere carbon to biological carbon

– Atmosphere carbon = carbon dioxide – Biological carbon = simple sugars

The Importance of Soil • Nutrients :

– Plant nutrients are chemicals a plant needs to grow.

– There are two types of nutrients cycles • Nitrogen cycle • Mineral cycle

The Importance of Soil • Nitrogen:

– Comes directly from the atmosphere where it occurs as a gas that plants cannot use.

4 Needs of Soil • There are four needs of the soil

– Anchorage

– Water

– Oxygen

– Nutrients

4 Needs of Soil • Anchorage:

– This is where plants grow freely and are firmly supported or anchored so they can grow to reach the sunlight.

– Water: – Soil will provide the plants with all the water

the plant needs – Roots are the best water absorbing body .

4 Needs of Soil • Oxygen:

– Call creature even plants need oxygen. Plants release oxygen during photosynthesis but consume it during respiration.

4 Needs of Soil • Nutrients:

– There are 16 nutrients usually considered to be needed for plants.

– Plants obtain 13 of the 16 nutrients from the soil itself.

– Other nutrients come from Air and water. • Carbon • Oxygen • hydrogen

3 phase system • What is soil Matrix?

– It is the arrangement of solid particles and pore spaces which consists of three phases of solid , liquid, and gases.

3 phase system • The ideal Soil Type:

– 50% solid material – 45 % mineral particles – 5% organic matter – 25% water – 25% gases

3 phase system • Root Growth:

– Water reaches the root by two ways • Either water flows toward the root • Or the root grows into moist soil

Ag Uses of Soil • Humans depend on soil to grow food, fiber,

timber, and ornamental plants.

• Most Ag uses require different soil types and management practices

4 Types of Ag Uses • 1. Cropland:

– Cropland is land which soil is worked and crops are planted, cared for, and harvested.

– Crops that are grown • Annual crops are corn and soybeans • Fiber crops are cotton horticultural crops like


4 Types of Ag Uses • Annual Crops:

– Require yearly soil preparation

– Perennial Forages: – Are alfalfa. – Which are crops that are in the ground for a few years – These crops keeps the soil completely cover and keeps

the soil in place.

4 Types of Ag Uses • Perennial Hort. crops:

– This includes fruits, nuts, and nursery stock

4 Types of Ag Uses • 2. Grazing Land:

– Much of the land in the US is grazed by cattle and sheep

4 Types of Ag Uses • 3. Forest

– Foresters probably disturb soil the least,

– 4. Other Uses – This usually deals with growing plants in tiny pots and

usually with Landscapers

Non Ag Uses of Soil • A few of the Non Ag uses of soil are:

– Recreation – Foundations – Waste Disposal – Building Materials

Non Ag Uses of Soil • Recreation:

– Recreational uses of the soil can be: • Sitting in a urban park and seeing kids play on the

playground, softball diamond, • They can also be golf courses, campgrounds. • Most demanding recreational use is the use of playing

fields. As most of the time there is a demand to have good grow on turf that can with stand about anything.

Non Ag Uses of Soil • Foundations:

– A good builder usually will have the soil tested to a dept of several feet.

– The structural soundness of a building depends on the amount of soil that is under the building.

Land Uses in the US • 27% is in rangeland • 26% is in cropland • 27% is in forestland • 2% is in conservation reserve land • 4% is in other land • 6% is in urban land • 8% is in pastureland

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