This document discusses key concepts in soil science related to soil water. It defines several soil moisture constants including field capacity, wilting coefficient, hygroscopic coefficient, and available water capacity. It also describes the processes of infiltration, percolation, and permeability that govern the entry and movement of water into and through soil. Finally, it discusses saturated and unsaturated water flow in soil and the phenomenon of soil moisture hysteresis.
Soil water movement
Soil water movement
Soil water movement
Soil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movement
Soils can process and hold considerable amount of water. They can take in water, and will keep doing so until they are full, or until the rate at which they can transmit water into and through the pores is exceeded. Some of this water will steadily drain through the soil (via gravity) and end up in the waterways and streams, but much of it will be retained, despite the influence of gravity. Much of this retained water can be used by plants and other organisms, thus contributing to land productivity and soil health.
Soil water movement
Soil water movement
Soil water movement
Soil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movementSoil water movement
Soils can process and hold considerable amount of water. They can take in water, and will keep doing so until they are full, or until the rate at which they can transmit water into and through the pores is exceeded. Some of this water will steadily drain through the soil (via gravity) and end up in the waterways and streams, but much of it will be retained, despite the influence of gravity. Much of this retained water can be used by plants and other organisms, thus contributing to land productivity and soil health.
Soil moisture characteristic curve is the relationship between the water content and the soil water potential, ψ.
It describes the functional relationship between soil water content and its energy status in terms of its matric potential under equilibrium conditions.
This curve is characteristic for different types of soil.
It is also called the Water retention curve
Classes and availability of soil water | Soil water Relationshipvishal shinde
Classes and Availability of Soil Water (Soil Moisture Relationship)
Gravitational water is that part in excess of hygroscopic and capillary water which will move out of the soil if favourable drainage is provided.
Capillary water is that part in excess of hygroscopic water which exists in the pore space of the soil by molecular attraction.
When an oven-dried sample is kept open in the atmosphere, it absorbs some amount of water from the atmosphere. This is known as hygroscopic water, and is not capable of movement by the gravity or capillary forces.
Soil Moisture tension
The force per unit area that must be exerted in order to extract water from the soil is known as soil moisture tension and is expressed in terms of atmosphere (atm).
also known as Capillary potential, Capillary tension or force of suction.
Soil moisture tension is inversely proportional to moisture content of a soil of given texture and structure.
measured in the laboratory with the Help of various instruments such as centrifuge, tensiometer etc.
Soil moisture stress
Soil moisture stress is defined as the sum of the soil moisture tension and osmotic pressure of soil solution.
Osmotic pressure is the increase in the force (or tension) caused by the salts present in the soil solution.
The growth of plants is a function of both soil moisture tension as well as the osmotic pressure, and hence is a function of soil moisture stress.
Soil moisture constants
Saturation Capacity: amount of water required to fill all the pore spaces between soil particles by replacing all air held in pore spaces
Field capacity: moisture content of the soil after free drainage has removed most of the gravity water
Permeant wilting point: the soil water content at or below which plant roots cannot absorb water any more
Available moisture: difference in water content of the soil between field capacity and permanent wilting point
Readily available moisture: portion of the available moisture that is most easily extracted by plants.
It is approximately 75% of the available moisture.
Moisture equivalent: percentage of moisture retained in a small sample of wet soil 1 cm deep when subjected to centrifugal force 1000 times as greater as gravity, usually for a period of 30 min.
Moisture equivalent = Field capacity
= 1.8 to 2 permanent wilting point = 2.7 Hygroscopic coefficient
Soil-Moisture deficiency (Field moisture deficiency): water required to bring the soil moisture content to its field capacity.
soil water energy concept is all about potential energy,gravitational potential,osmotic potential,pressure potential and total potential energies including units
Soil is the home of million of organisms. In agriculture, from seed to grain, soil is a prima factor. It also acts a medium to store water for plants and form of water in soil called soil moisture. Some parameters to check the soil moisture called soil moisture constants. So, soil and water relationship is essential in agriculture.
In this topic, water which is as much as essential as soil was discussed and we’ll see how the soil, plant and water interact with each other and have a sustainable agricultural knowledge in producing staple food.
Soil water conservation methods in agricultureVaishali Sharma
This presentation includes introduction as well as all the methods in agriculture either engineering or agronomic measures used in conservation of soil and water against erosion or other deteriorative factors.
Soil moisture characteristic curve is the relationship between the water content and the soil water potential, ψ.
It describes the functional relationship between soil water content and its energy status in terms of its matric potential under equilibrium conditions.
This curve is characteristic for different types of soil.
It is also called the Water retention curve
Classes and availability of soil water | Soil water Relationshipvishal shinde
Classes and Availability of Soil Water (Soil Moisture Relationship)
Gravitational water is that part in excess of hygroscopic and capillary water which will move out of the soil if favourable drainage is provided.
Capillary water is that part in excess of hygroscopic water which exists in the pore space of the soil by molecular attraction.
When an oven-dried sample is kept open in the atmosphere, it absorbs some amount of water from the atmosphere. This is known as hygroscopic water, and is not capable of movement by the gravity or capillary forces.
Soil Moisture tension
The force per unit area that must be exerted in order to extract water from the soil is known as soil moisture tension and is expressed in terms of atmosphere (atm).
also known as Capillary potential, Capillary tension or force of suction.
Soil moisture tension is inversely proportional to moisture content of a soil of given texture and structure.
measured in the laboratory with the Help of various instruments such as centrifuge, tensiometer etc.
Soil moisture stress
Soil moisture stress is defined as the sum of the soil moisture tension and osmotic pressure of soil solution.
Osmotic pressure is the increase in the force (or tension) caused by the salts present in the soil solution.
The growth of plants is a function of both soil moisture tension as well as the osmotic pressure, and hence is a function of soil moisture stress.
Soil moisture constants
Saturation Capacity: amount of water required to fill all the pore spaces between soil particles by replacing all air held in pore spaces
Field capacity: moisture content of the soil after free drainage has removed most of the gravity water
Permeant wilting point: the soil water content at or below which plant roots cannot absorb water any more
Available moisture: difference in water content of the soil between field capacity and permanent wilting point
Readily available moisture: portion of the available moisture that is most easily extracted by plants.
It is approximately 75% of the available moisture.
Moisture equivalent: percentage of moisture retained in a small sample of wet soil 1 cm deep when subjected to centrifugal force 1000 times as greater as gravity, usually for a period of 30 min.
Moisture equivalent = Field capacity
= 1.8 to 2 permanent wilting point = 2.7 Hygroscopic coefficient
Soil-Moisture deficiency (Field moisture deficiency): water required to bring the soil moisture content to its field capacity.
soil water energy concept is all about potential energy,gravitational potential,osmotic potential,pressure potential and total potential energies including units
Soil is the home of million of organisms. In agriculture, from seed to grain, soil is a prima factor. It also acts a medium to store water for plants and form of water in soil called soil moisture. Some parameters to check the soil moisture called soil moisture constants. So, soil and water relationship is essential in agriculture.
In this topic, water which is as much as essential as soil was discussed and we’ll see how the soil, plant and water interact with each other and have a sustainable agricultural knowledge in producing staple food.
Soil water conservation methods in agricultureVaishali Sharma
This presentation includes introduction as well as all the methods in agriculture either engineering or agronomic measures used in conservation of soil and water against erosion or other deteriorative factors.
I have tried to discuss about the fundamental knowledge related to Irrigation and Flood Control in short. For more details anyone can visit the books that I have mentioned in my slide presentation. I have tried to cover major topics from books so that student can find it easy to understand and learn about irrigation and flood control. I hope it will help everyone who has interest to Irrigation Engineering.
Hydrological Cycle give knowledge about how water evaporate transpiration and precipitate in atmosphere...It is also give ratios and percentage of water stored in different region how we can utilize it from this cycle, It is complete study of Water cycle travelling in earths surface and sub-surface.
Evaporation is the process by which the liquid water is converted in to the water vapour and removed from the evaporating surface.
Evaporation is the means by which the vast amount of latent heat is transformed from the earth surface to atmosphere.
The source of energy for evaporation may be a solar radiation and the air blowing over the surface.
The energy required for the evaporation regardless of the surface where the evaporation is taking place is 2.5 MJ/KG or 590 Calories/gm of water at 2 ˚C.
Bio fertilizers_Tamil_Farmers training_Krishi Vigyan Kendra_Tenkasisethupathi siva
எந்த ஒரு பயிரும் தனக்குத் தேவையான சத்துகளைத் தன்னைச் சுற்றியுள்ள சூழல்களிலிருந்தும், மண்ணிலிருந்தும் தானாகவே கிரகித்துக் கொள்கிறது. ஆனாலும், சில சாதகமில்லா சூழ்நிலைகளில் பயிருக்குத் தேவையான அளவு ஊட்டச்சத்துகள் மண்ணிலிருந்து கிடைப்பதில் பல்வேறு காரணங்களால் சிக்கல்
இந்த நிலையில், ரசாயன உரங்கள், உயிர் உரங்களை மண்ணில் இடுவதன் மூலம் பயிரின் ஊட்டச்சத்து தேவைகளை நிறைவு செய்யலாம்.
காற்றில் இருக்கும் தழைச்சத்தை நிலைநிறுத்தியும், மண்ணில் கரையாமல் இருக்கும் மணிச்சத்தைக் கரைத்தும் கொடுக்கக்கூடிய நுண்ணுயிர்கள்
உயிர் உரங்களைத் தழைச்சத்தை நிலைப்படுத்தும் உரங்கள், மணிச்சத்தை கரைத்துக் கொடுக்கும் நுண்ணுயிர் உரங்களாகப் பிரித்து வகைப்படுத்தலாம்
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
CLASS 11 CBSE B.St Project AIDS TO TRADE - INSURANCE
Soil water
1. SAC 101 Fundamentals of Soil Science (2 + 1)
SOIL WATER
SOIL MOISTURE CONTANTS, ENTRY OF WATER
IN SOIL, HYTERISIS
2. SOIL MOISTURE CONSTANTS
The hygroscopic and capillary waters are in equilibrium
with the soil under given condition.
The hygroscopic coefficient and the maximum capillary
capacity are the two equilibrium points when the soil
contains the maximum amount of hygroscopic and
capillary waters, respectively.
The amount of water that a soil contains at each of these
equilibrium points is known as soil moisture constant.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 2
3. What are they………..?
Field capacity
Wilting coefficient
Hygroscopic coefficient
Available water capacity
Maximum water holding capacity
Sticky point moisture
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 3
4. Field Capacity
The downward movement of water all macro and micro pores are
filled up.
Application of water in the soil, all the gravitational water is
drained away and then the wet soil is almost uniformly moist.
The amount of water held by the soil at this stage is known as the
field capacity or normal moisture capacity of that soil.
At this stage only micropores or capillary pores are filled with
water and plants absorb water for their use.
At field capacity water is held with a force of 1/3 atmosphere.
Water at field capacity is readily available to plants and
microorganism.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 4
5. Wilting Co-efficient
When the water is so firmly held by the soil particles that
plant roots are unable to draw it. The plant begins to wilt.
The stage at which this occurs is termed the Wilting
point and the percentage amount of water held by the soil
at this stage is known as the Wilting Coefficient.
the soil is unable to supply water to the plant.
Water at wilting coefficient -- 15 atmosphere. ( -15 bar)
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 5
6. Hygroscopic coefficient
The hygroscopic coefficient is the maximum amount of
hygroscopic water absorbed by 100 g of dry soil under
standard conditions of humidity (50% relative humidity)
and temperature (15°C).
This tension is equal to a force of 31 atmospheres.
Water at this tension is not available to plant but may be
available to certain bacteria.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 6
7. Available water capacity
The amount of water required to apply to a soil at the
wilting point to reach the field capacity is called the
"available" water.
The available water is the difference in the amount of
water at field capacity (- 0.3 bar) and the amount of
water at the permanent wilting point (- 15 bars).
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 7
9. Maximum water holding capacity
It is also known as maximum retentive capacity.
It is the amount of moisture in a soil when its pore spaces
both micro and macro capillary are completely filled with
water.
It is a rough measure of total pore space of soil. Soil
moisture tension is very low between 1/100 th to 1/1000
th of an atmosphere or pF 1 to 0.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 9
10. Sticky point moisture
The sticky point represents the maximum moisture
content at which a soil remains friable.
It represents the moisture content of soil at which it no
longer sticks to a foreign object.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 10
11. Entry of Water into Soil
1. Infiltration: Infiltration refers to the downward entry or
movement of water into the soil surface.
It is a surface characteristic and hence primarily influenced by the
condition of the surface soil.
Soil surface with vegetative cover has more infiltration rate than
bare soil
Warm soils absorb more water than colder ones.
Coarse surface texture, granular structure and high organic matter
content in surface soil, all help to increase infiltration
Infiltration rate is comparatively lower in wet soils than dry soils
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 11
12. 2. Percolation:
The movement of water through a column of soil is
called percolation. It is important for two reasons.
This is the only source of recharge of ground water
which can be used through wells for irrigation.
Percolating waters carry plant nutrients down and often
out of reach of plant roots (leaching),
In dry region it is negligible and under high rainfall it is
high.
Sandy soils have greater percolation than clayey soil.
Vegetation and high water table reduce the percolation
loss.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 12
13. 3. Permeability:
It indicates the relative ease of movement of water
with in the soil.
•The characteristics that determine how fast air and water
move through the soil is known as permeability.
•The term hydraulic conductivity is also used which refers
to the readiness with which a soil transmits fluids through it.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 13
15. Soil Water Movement
i) Saturated Flow
ii) Unsaturated Flow
iii) Water Vapour Movement
Saturated flow: This occurs when the soil
pores are completely filled with water.
Saturated flow is water flow caused
by gravity’s pull. It begins with infiltration,
which is water movement into soil when rain
or irrigation water is on the soil surface.
When the soil profile is wetted, the
movement of more water flowing through the
wetted soil is termed percolation.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 15
16. Hydraulic conductivity can be expressed mathematically as
V = kf
Where,
V = Total volume of water moved per unit time
f = Water moving force
k = Hydraulic conductivity of soil
Factors affecting movement of water
1. Texture, 2.Structure, 3.Amount of organic matter, 4.Depth of soil
to hard pan, 5.Amount of water in the soil, 6.temperature and 7.
Pressure
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 16
17. Darcy’s law
The vertical water flow rate through soil is given by Darcy’s law.
The law states that the rate of flow of liquid or flux through
a porous medium is proportional to the hydraulic gradient in the
direction of flow of the liquid.
QW =
Where,
QW = Quantity of water in cm
k = rate constant (cm/s)
dh = Water height (head), cm
A = Soil area (Sq. cm)
dl = Soil depth (cm)
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 17
18. Unsaturated flow
Macropores full of air
Micropores = water + air
Moisture tension gradient
creates unsaturated flow
It is flow of water held with
water potentials < -1/3 bar.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 18
19. Water Vapour Movement
Movement from high soil vapour pressure to a dry soil
(low vapour pressure).
The movement of water vapour from soils takes place in
two ways:
(a)Internal movement (b)External movement
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 19
20. SOIL MOISTURE HYSTERISIS
• This is due to the presence of capillary and non
capillary pores and the effect is also called ink-
bottle effect. The moisture content is always low
during sorption and high during desorption.
10/31/18 Sethupathi Siva, M.Sc., (Ag.) in SS & AC 20
• The moisture content at different
tensions during wetting of soil
varies from the moisture content at
same tensions during drying.
• This effect is called as hysterisis.