Soils give a mechanical support to plants from which they extract nutrients. soil provides shelters for many animal types, from invertebrates such as worms and insects up to mammals like rabbits, moles, foxes and badgers. It also provides habitats colonised by a staggering variety of microorganisms. This module is about the microbial life in soils.
Soils give a mechanical support to plants from which they extract nutrients. soil provides shelters for many animal types, from invertebrates such as worms and insects up to mammals like rabbits, moles, foxes and badgers. It also provides habitats colonised by a staggering variety of microorganisms. This module is about the microbial life in soils.
Plant microbe interaction by dr. ashwin chekeAshwin Cheke
PLANT MICROBE – INTERACTIONS AND THEIR MUTUAL BENEFITS IN ENHANCING SOIL HEALTH AND AGRICULTURAL PRODUCTION ,
IT ALSO INCREASE CROP PRODUCTIVITY AND IMPROVE SOIL HEALTH
Agricultural Microbiology: Role of microbes in soil fertilitySarthakMoharana
Description on different microbes which plays role in maintaining soil fertility.
Fertile soils teem with microorganisms, which directly contribute to the biological fertility of that soil.
Biological fertility is under-studied and our scientific knowledge of it is incomplete.
In addition to fertility, soil microorganisms also play essential roles in the nutrient cycles that are fundamentally important to life on the planet.
In the past, agricultural practices have failed to promote healthy populations of microorganisms, limiting production yields and threatening sustainability.
Scientific research is exploring new and exciting possibilities for the restoration and promotion of healthy microbial populations in the soil.
‘Soil is essential for the maintenance of biodiversity above and below ground. The wealth of biodiversity below ground is vast and unappreciated: millions of microorganisms live and reproduce in a few grams of topsoil, an ecosystem essential for life on earth…’
From: Australian Soils and Landscape, An Illustrated Compendium
Soil Biology relates to the organisms within soil that carry out a wide range of processes that are important for soil health and fertility
These organisms decompose and recycle soil organic matter (SOM), improve nutrient availability and soil structure, transmit or prevent diseases, and degrade pollutants.
The total number of organisms, species diversity and their activity will fluctuate with changes in the soil environment.
These living organisms can be classified by size into:
macrofauna (> 10 mm) such as earthworms, termites and other large insects
mesofauna (range in size from 200 um to 10 mm) such as mites and collembola (or springtails)
microfauna (20 - 200 um) such as protozoa and nematodes
microflora such as fungi and bacteria
Collectively, these groups make up the soil biota and the total mass of organisms comprises the soil biomass
70 - 80% of soil biota exists in the top 10cm of soil
In 1 gram of soil, there is potentially over100,000 different species and greater than10 million different individuals
Different types of soil biology have different roles and functions:
Ecosystem engineers such as ants and earthworms that primarily alter the physical structure of soil but also have an influence on the overall rates of nutrient cycling and energy flows.
Litter transformers that fragment plant litter & improve availability to microbes
Importance of soil biology:For farmers there are 3 components to consider in terms of why soil biology is important:
the natural processes themselves (engineers, litter transformers & microfood web processors)
the impact of management on these processes
the combined effect on plant performance
Soil biology provides both direct and indirect benefits to the environment in that they can:
Decompose plant residues
Regulate plant nutrient supply and loss (e.g. N, P, K, Fe)
Improve soil structure (aggregate stability)
Degrade pesticides and herbicides
Regulate water quality (e.g. filters nutrients)
Capture and release greenhouse gases (carbon dioxide, methane, nitrous oxide)
Organic matter decomposition (By this process, plant and animal residues are broken down by micro-organisms into more simpler compounds, other slimy compounds, other slimy intermediate products organic acids and more resistant compound humus. All these products combinedly influence the physical and chemical properties of soil and hence the plant growth).
(a) De-nitrification process carried out by a particular micro-organisms and causes loss of gaseous nitrogen
Plant microbe interaction by dr. ashwin chekeAshwin Cheke
PLANT MICROBE – INTERACTIONS AND THEIR MUTUAL BENEFITS IN ENHANCING SOIL HEALTH AND AGRICULTURAL PRODUCTION ,
IT ALSO INCREASE CROP PRODUCTIVITY AND IMPROVE SOIL HEALTH
Agricultural Microbiology: Role of microbes in soil fertilitySarthakMoharana
Description on different microbes which plays role in maintaining soil fertility.
Fertile soils teem with microorganisms, which directly contribute to the biological fertility of that soil.
Biological fertility is under-studied and our scientific knowledge of it is incomplete.
In addition to fertility, soil microorganisms also play essential roles in the nutrient cycles that are fundamentally important to life on the planet.
In the past, agricultural practices have failed to promote healthy populations of microorganisms, limiting production yields and threatening sustainability.
Scientific research is exploring new and exciting possibilities for the restoration and promotion of healthy microbial populations in the soil.
‘Soil is essential for the maintenance of biodiversity above and below ground. The wealth of biodiversity below ground is vast and unappreciated: millions of microorganisms live and reproduce in a few grams of topsoil, an ecosystem essential for life on earth…’
From: Australian Soils and Landscape, An Illustrated Compendium
Soil Biology relates to the organisms within soil that carry out a wide range of processes that are important for soil health and fertility
These organisms decompose and recycle soil organic matter (SOM), improve nutrient availability and soil structure, transmit or prevent diseases, and degrade pollutants.
The total number of organisms, species diversity and their activity will fluctuate with changes in the soil environment.
These living organisms can be classified by size into:
macrofauna (> 10 mm) such as earthworms, termites and other large insects
mesofauna (range in size from 200 um to 10 mm) such as mites and collembola (or springtails)
microfauna (20 - 200 um) such as protozoa and nematodes
microflora such as fungi and bacteria
Collectively, these groups make up the soil biota and the total mass of organisms comprises the soil biomass
70 - 80% of soil biota exists in the top 10cm of soil
In 1 gram of soil, there is potentially over100,000 different species and greater than10 million different individuals
Different types of soil biology have different roles and functions:
Ecosystem engineers such as ants and earthworms that primarily alter the physical structure of soil but also have an influence on the overall rates of nutrient cycling and energy flows.
Litter transformers that fragment plant litter & improve availability to microbes
Importance of soil biology:For farmers there are 3 components to consider in terms of why soil biology is important:
the natural processes themselves (engineers, litter transformers & microfood web processors)
the impact of management on these processes
the combined effect on plant performance
Soil biology provides both direct and indirect benefits to the environment in that they can:
Decompose plant residues
Regulate plant nutrient supply and loss (e.g. N, P, K, Fe)
Improve soil structure (aggregate stability)
Degrade pesticides and herbicides
Regulate water quality (e.g. filters nutrients)
Capture and release greenhouse gases (carbon dioxide, methane, nitrous oxide)
Organic matter decomposition (By this process, plant and animal residues are broken down by micro-organisms into more simpler compounds, other slimy compounds, other slimy intermediate products organic acids and more resistant compound humus. All these products combinedly influence the physical and chemical properties of soil and hence the plant growth).
(a) De-nitrification process carried out by a particular micro-organisms and causes loss of gaseous nitrogen
Micro- organisms transform organic matter into plant nutrients that are assimilated by plants. Soil organisms represent a large fraction of global terrestrial .
Micro- organisms transform organic matter into plant nutrients that are assimilated by plants. Soil organisms represent a large fraction of global terrestrial .
Micro- organisms transform organic matter into plant nutrients that are assimilated by plants. Soil organisms represent a large fraction of global terrestrial .
how to swap pi coins to foreign currency withdrawable.DOT TECH
As of my last update, Pi is still in the testing phase and is not tradable on any exchanges.
However, Pi Network has announced plans to launch its Testnet and Mainnet in the future, which may include listing Pi on exchanges.
The current method for selling pi coins involves exchanging them with a pi vendor who purchases pi coins for investment reasons.
If you want to sell your pi coins, reach out to a pi vendor and sell them to anyone looking to sell pi coins from any country around the globe.
Below is the contact information for my personal pi vendor.
Telegram: @Pi_vendor_247
where can I find a legit pi merchant onlineDOT TECH
Yes. This is very easy what you need is a recommendation from someone who has successfully traded pi coins before with a merchant.
Who is a pi merchant?
A pi merchant is someone who buys pi network coins and resell them to Investors looking forward to hold thousands of pi coins before the open mainnet.
I will leave the telegram contact of my personal pi merchant to trade with
@Pi_vendor_247
Falcon stands out as a top-tier P2P Invoice Discounting platform in India, bridging esteemed blue-chip companies and eager investors. Our goal is to transform the investment landscape in India by establishing a comprehensive destination for borrowers and investors with diverse profiles and needs, all while minimizing risk. What sets Falcon apart is the elimination of intermediaries such as commercial banks and depository institutions, allowing investors to enjoy higher yields.
how to sell pi coins effectively (from 50 - 100k pi)DOT TECH
Anywhere in the world, including Africa, America, and Europe, you can sell Pi Network Coins online and receive cash through online payment options.
Pi has not yet been launched on any exchange because we are currently using the confined Mainnet. The planned launch date for Pi is June 28, 2026.
Reselling to investors who want to hold until the mainnet launch in 2026 is currently the sole way to sell.
Consequently, right now. All you need to do is select the right pi network provider.
Who is a pi merchant?
An individual who buys coins from miners on the pi network and resells them to investors hoping to hang onto them until the mainnet is launched is known as a pi merchant.
debuts.
I'll provide you the Telegram username
@Pi_vendor_247
The Evolution of Non-Banking Financial Companies (NBFCs) in India: Challenges...beulahfernandes8
Role in Financial System
NBFCs are critical in bridging the financial inclusion gap.
They provide specialized financial services that cater to segments often neglected by traditional banks.
Economic Impact
NBFCs contribute significantly to India's GDP.
They support sectors like micro, small, and medium enterprises (MSMEs), housing finance, and personal loans.
US Economic Outlook - Being Decided - M Capital Group August 2021.pdfpchutichetpong
The U.S. economy is continuing its impressive recovery from the COVID-19 pandemic and not slowing down despite re-occurring bumps. The U.S. savings rate reached its highest ever recorded level at 34% in April 2020 and Americans seem ready to spend. The sectors that had been hurt the most by the pandemic specifically reduced consumer spending, like retail, leisure, hospitality, and travel, are now experiencing massive growth in revenue and job openings.
Could this growth lead to a “Roaring Twenties”? As quickly as the U.S. economy contracted, experiencing a 9.1% drop in economic output relative to the business cycle in Q2 2020, the largest in recorded history, it has rebounded beyond expectations. This surprising growth seems to be fueled by the U.S. government’s aggressive fiscal and monetary policies, and an increase in consumer spending as mobility restrictions are lifted. Unemployment rates between June 2020 and June 2021 decreased by 5.2%, while the demand for labor is increasing, coupled with increasing wages to incentivize Americans to rejoin the labor force. Schools and businesses are expected to fully reopen soon. In parallel, vaccination rates across the country and the world continue to rise, with full vaccination rates of 50% and 14.8% respectively.
However, it is not completely smooth sailing from here. According to M Capital Group, the main risks that threaten the continued growth of the U.S. economy are inflation, unsettled trade relations, and another wave of Covid-19 mutations that could shut down the world again. Have we learned from the past year of COVID-19 and adapted our economy accordingly?
“In order for the U.S. economy to continue growing, whether there is another wave or not, the U.S. needs to focus on diversifying supply chains, supporting business investment, and maintaining consumer spending,” says Grace Feeley, a research analyst at M Capital Group.
While the economic indicators are positive, the risks are coming closer to manifesting and threatening such growth. The new variants spreading throughout the world, Delta, Lambda, and Gamma, are vaccine-resistant and muddy the predictions made about the economy and health of the country. These variants bring back the feeling of uncertainty that has wreaked havoc not only on the stock market but the mindset of people around the world. MCG provides unique insight on how to mitigate these risks to possibly ensure a bright economic future.
how to sell pi coins in South Korea profitably.DOT TECH
Yes. You can sell your pi network coins in South Korea or any other country, by finding a verified pi merchant
What is a verified pi merchant?
Since pi network is not launched yet on any exchange, the only way you can sell pi coins is by selling to a verified pi merchant, and this is because pi network is not launched yet on any exchange and no pre-sale or ico offerings Is done on pi.
Since there is no pre-sale, the only way exchanges can get pi is by buying from miners. So a pi merchant facilitates these transactions by acting as a bridge for both transactions.
How can i find a pi vendor/merchant?
Well for those who haven't traded with a pi merchant or who don't already have one. I will leave the telegram id of my personal pi merchant who i trade pi with.
Tele gram: @Pi_vendor_247
#pi #sell #nigeria #pinetwork #picoins #sellpi #Nigerian #tradepi #pinetworkcoins #sellmypi
Financial Assets: Debit vs Equity Securities.pptxWrito-Finance
financial assets represent claim for future benefit or cash. Financial assets are formed by establishing contracts between participants. These financial assets are used for collection of huge amounts of money for business purposes.
Two major Types: Debt Securities and Equity Securities.
Debt Securities are Also known as fixed-income securities or instruments. The type of assets is formed by establishing contracts between investor and issuer of the asset.
• The first type of Debit securities is BONDS. Bonds are issued by corporations and government (both local and national government).
• The second important type of Debit security is NOTES. Apart from similarities associated with notes and bonds, notes have shorter term maturity.
• The 3rd important type of Debit security is TRESURY BILLS. These securities have short-term ranging from three months, six months, and one year. Issuer of such securities are governments.
• Above discussed debit securities are mostly issued by governments and corporations. CERTIFICATE OF DEPOSITS CDs are issued by Banks and Financial Institutions. Risk factor associated with CDs gets reduced when issued by reputable institutions or Banks.
Following are the risk attached with debt securities: Credit risk, interest rate risk and currency risk
There are no fixed maturity dates in such securities, and asset’s value is determined by company’s performance. There are two major types of equity securities: common stock and preferred stock.
Common Stock: These are simple equity securities and bear no complexities which the preferred stock bears. Holders of such securities or instrument have the voting rights when it comes to select the company’s board of director or the business decisions to be made.
Preferred Stock: Preferred stocks are sometime referred to as hybrid securities, because it contains elements of both debit security and equity security. Preferred stock confers ownership rights to security holder that is why it is equity instrument
<a href="https://www.writofinance.com/equity-securities-features-types-risk/" >Equity securities </a> as a whole is used for capital funding for companies. Companies have multiple expenses to cover. Potential growth of company is required in competitive market. So, these securities are used for capital generation, and then uses it for company’s growth.
Concluding remarks
Both are employed in business. Businesses are often established through debit securities, then what is the need for equity securities. Companies have to cover multiple expenses and expansion of business. They can also use equity instruments for repayment of debits. So, there are multiple uses for securities. As an investor, you need tools for analysis. Investment decisions are made by carefully analyzing the market. For better analysis of the stock market, investors often employ financial analysis of companies.
how can I sell pi coins after successfully completing KYCDOT TECH
Pi coins is not launched yet in any exchange 💱 this means it's not swappable, the current pi displaying on coin market cap is the iou version of pi. And you can learn all about that on my previous post.
RIGHT NOW THE ONLY WAY you can sell pi coins is through verified pi merchants. A pi merchant is someone who buys pi coins and resell them to exchanges and crypto whales. Looking forward to hold massive quantities of pi coins before the mainnet launch.
This is because pi network is not doing any pre-sale or ico offerings, the only way to get my coins is from buying from miners. So a merchant facilitates the transactions between the miners and these exchanges holding pi.
I and my friends has sold more than 6000 pi coins successfully with this method. I will be happy to share the contact of my personal pi merchant. The one i trade with, if you have your own merchant you can trade with them. For those who are new.
Message: @Pi_vendor_247 on telegram.
I wouldn't advise you selling all percentage of the pi coins. Leave at least a before so its a win win during open mainnet. Have a nice day pioneers ♥️
#kyc #mainnet #picoins #pi #sellpi #piwallet
#pinetwork
Even tho Pi network is not listed on any exchange yet.
Buying/Selling or investing in pi network coins is highly possible through the help of vendors. You can buy from vendors[ buy directly from the pi network miners and resell it]. I will leave the telegram contact of my personal vendor.
@Pi_vendor_247
What price will pi network be listed on exchangesDOT TECH
The rate at which pi will be listed is practically unknown. But due to speculations surrounding it the predicted rate is tends to be from 30$ — 50$.
So if you are interested in selling your pi network coins at a high rate tho. Or you can't wait till the mainnet launch in 2026. You can easily trade your pi coins with a merchant.
A merchant is someone who buys pi coins from miners and resell them to Investors looking forward to hold massive quantities till mainnet launch.
I will leave the telegram contact of my personal pi vendor to trade with.
@Pi_vendor_247
1. Institute of Agricultural science RGSC BHU
SSC-411-(0+10)10
Topic:- Soil Organisms, functions and their role in
Soil fertility
Submitted to:
Dr. Ashish Latare
(Assistant professor)
Submitted by:
Anup Kumar
B.sc.(Ag) 4th year
ID No.:- 16311
Ex Roll No:-16230AGC008
2. CONTENT
1. Soil Organisms
2. Classification of soil organisms
3. Classification of Bacteria
4. Soil flora
5. Nitrogen fixing systems
6. Soil fauna
7. Interaction among soil organisms
8. Role of organism in soil fertility
9. Soil fertility evaluation by biological tests-
10. Harmful Activities of Soil Organisms
3. Soil Organisms
1) The organisms that live in the soil are called soil organism.
2) Micro organisms are numerous in number with monopolized
biological activity in soils (60-80% of total biological
activity).The study of living organisms in soil is called Soil
biology.
3) The organisms in the soil, not only help in development of
soils but carryout a number of transformations facilitating
the availability of nutrients to the plants. In the absence of
the activities of these organisms, in soil, life on earth would
have come to a halt, as all available nutrients would have
ended up locked in the organic, disrupting the nutrient
cycles.
4. Continued…..
4) The soil is teeming with millions of living organisms which
make it a living and a dynamic system. Under microscope it
reveals a complex arrangement of soil particles and pore
spaces filled with air and water. It is in these pore spaces
that plant roots and millions of organisms develop, ranging
from microscopic to macroscopic in size.
5) The soil organisms are classified into two broad groups ,viz.
soil flora and soil fauna,important groups as follows
6. Classification of Bacteria
A. Heterotrophic
1) nitrogen fixing-
a) Symbiotic(Rhizobium)
b) Non-Symbiotic- Aerobic(Azatobactor)
Anaerobic(Clostridium)
c) Associative symbiotic -Azospirillum
1) Non-nitrogen fixing-
a) Aerobic-Ammonifiers
b) Anaerobic- Denitrifiers
A. Autotrophic-a) Chemoautotrophic(Thiobascillus )
b) Photoautotrophic (Chlorobium)
7. SOIL FLORA
1) SOIL MACROFLORA- Eg. Roots of higher plants
Functions in soil-
1) The dead plant
contribute to the
formation of the soil
organic matter which ,
provides food, energy
and nutrients to
microorganisms and
also higher plants – a
process of cycling of
plant nutrients .
8. Continued…..
2) Decay of plant roots add O.M. to soil , thereby changing
soil properties viz. soil aggregation ,CEC,water and
nutrient retention capacity, etc. of soil.
3) While proliferating , the roots exert tremendous
pressure on surrounding particles. When roots decay ,
the vacant space makes room for water and air to move
it as well as more food to the microbes, influencing
therby microbial activity in soil.
9. 2) SOIL MICROFLORA-
a) Bacteria :
1) Bacteria are primitive ,very
minute, unicelluar
organisms.
2) They are known for rapid
proliferation. Size varies
from 0.5 to 1 micron in
diameter and 1 to 10 micron
(length).
3) They have flagella and are
motile.
4) They are most abundant in
soil. 300 to 3000 kg of live
weight of bacteria/ha., 0.01
to 0.4 % of total soil mass
10. Continued…..
5) Shape may be round (cocci), rod like (bacilli) or spiral
(spirilla). In the soil, the rod shaped ones seem to
predominate.
6) Bacterial population vary from few billion to three trillion
in each kilogram of soil.
7) Types on the basis of temp.
- <10 0C
Psychrophiles
Mesophiles -
Thermophiles -
20 0C-40 0C
>40 0C
5) The genera –Pseudomonas, Azotobacter, Bacillus,
Agrobacterium, Arthrobacter- are most abundant .The
genus Bacillus has largest species followed by
Pseudomonas.
11. Functions of Bacteria –
1) Biological fixation of N.
2) Symbiotic and non-symbiotic N-fixation.
3) Decomposition of carbohydrates and lignins.
4) Decomposition of proteins with the liberation of
ammonia or ammonification, nitrification ,and
denitrification.
5) transformation of C,N,P,S,Fe,Mn.
12. Fungi
1) They are longer than
bacteria , aerobic and
heterotrophic in nature
(Saprophytic in nature).
2) Fungi are broadly
grouped in to yeasts,
molds and mushrooms,
out of which molds and
mushrooms are
important in soils.
3) Fungi dominates in acid
soils.
13. Continued…..
4) Important molds in soils are Penicillium, Mucor,
Fusarium and Aspergillus.
5) Prefer acid medium (4.5-6.5). Some fungi can
tolerate even pH 9.0.
6) Mushroom fungi are found in forests and
grasslands. Mushroom fungi are not widely
distributed like molds, but are of much significance
especially in breaking down of woody tissue.
14. Functions of fungi-
1) A mutually beneficial (symbiotic) association
between numerous fungi and the roots of higher
plants is called ‘Mycorrhizae” (fungus root), is
useful in adsorption of nutrients.
Eg. VAM-fungi
2) Fungi decomposes almost anything in organic that
cannot tackle by bacteria.They decompose
carbohydrates,celluloses,sugars,proteins,fats and
lignins.
15. Actinomycetes
1) Thread / Filamentous
bacteria. Next to
bacteria in abundance.
2) A common genus is
streptomyces.
3) Actinomycetes have
transitional
charecteristics between
bacteria and fungi,
sometimes called fungi-
like bacteria.
4) They are more abundant
in dry and tropical soil.
16. Functions of Actinomycetes
1) Actinomycetes can degrade all sorts of organic
substances such as celluloses, polysaccharides,
proteins,fats,etc.
2) But, they are slower activity than bacteria and
fungi.For this reason , organic residues first attacked
by bacteria and fungi, later on actinomycetes.
3) It produce very little mycelium ,so less contribute to
humus.
17. Algae
Charecteristics-
1) Chlorophyll containing
organism, Aerobic,
Photoautotrophic.
2) Blue green algae(BGA) ,
also called cynobacteria
are free living N-fixer
3) ‘Heterocyst’ cells found in
which N-fixation done.It
provide anaerobic
environment
Algae in rice field
18. Continued…..
4) Soil algae have been divided mainly into four classes,viz.
Ex:-a) Blue green algae/Cynophyta -(Anabaena, Nostoc,)-
dominates in tropical soil
b) Chlorophyta-grass green algae-dominates in
temperate regions.
c)Xanthophyta- yellow green algae
d)Bacillariophyta- golden-brown algae or diatoms
Use in agriculture-
Azolla-anabaena symbiosis can increase 10-15% rice yield
19. Nitrogen fixing systems
N- Fixing System Organism
Involved
Plant Involved Site
of fixation
Nitrogen
kg N/ha/year
Legumes
(Symbiotic)
Rhizobium
(bacteria )
Legumes Nodules 50-100
Non- legumes
(Symbiotic)
Frankia
(Actinomycetes)
BGA(Anabaena)
Alnus
Casuarinas
Azolla(Fern)
Nodules
Leaf
50-100
Associative
symbiotic
Associative
symbiotic
Non- legumes Rhizosphere 5-30
Non- Symbiotic BGA
Azatobacter,
Beijerinckia,
(aerobic)
Clostridium
(anaerobic)
Not Soil & Water 10-50
5-30
5-20
20. B) SOIL FAUNA
1)SOIL MACROFAUNA-
Earthworms-
1. These having slender
cylindrical bodies with varing
diameters.
2. These feed on dead organic
tissues and soil materials.
3. Mineral soil constituents are
digested and decomposed in
digestive system.
4. Their excretaare richer in
bacteria and available
mineral nutrients.
5. They are more common in
fine texture soil
21. Continued…..
Ants-
1. Ants are the most
widespread species of
insects in soil, and
consume plant
residues.
2. But are more active in
humifying insects than
plants.
23. 2) SOIL MICROFAUNA-
1) Soil protozoa-are
unicellular but larger than
bacteria, size varing from
few microns to few cm,
found in all arable soils.
Functions-
1. The role of protozoa in soil
is not definitely known.
2. As they feed on bacteria
and actinomycetes , they
probably help to maintain
a favourable balance of
the microflora in soil.
24. 2) Nematodes-
Also called eelworms, thread
worms or round worms.
There are various types of
nematode found as-
1. saprophytic(feed on decaying
O.M.),
2. predatory(feed on
earthworm) and
3. parasitic (feed on roots of
higher plants), this one
(parasitic) cause lossof vigour
of root system and make
plants growing in nematode
infested soil soil liable to
diseases.
25. 3) SOIL VIRUSES
1. These are ultramicroscopic
obligate parasite(have head-
tail structure , with diameter
0.05 to 0.1 micron) always
requiring a living host for their
multiplication.
2. They are much smaller than
bacteria , only visible through
electron microscope.
3. The viruses in soil is known as
bacteriophases.
4. When they parasitize and
destroy a bacterium of
agricultural importance like
Rhizobium, they attain
economic importance.
26. Interaction among soil organisms-
Soil organisms interact with each other, with the plant roots, and
with the environment.
Some interactions are as follows-
1. The association existing between one organism and another
whether of symbiotic or antagonistic influences the
population and activity of soil microbes.
2. The predatory habit of protozoa and some mycobacteria
which feed on bacteria may suppress or eliminate certain
bacteria.
3. Activities of some of the microorganisms are beneficial to
each other. For instance organic acids liberated by fungi,
increase in oxygen by the activity of algae, change in soil
reaction etc. favours the activity or bacteria and other
organisms in soil.
27. Role of organism in soil fertility
1. Soil microbes break down organic matter.
2. Soil microbes recycle nutrients.
3. Soil microbes create humus.
4. Soil microbes create soil structure.
5. Soil microbes fix nitrogen.
6. Soil organisms promote plant growth.
7. Soil microbes control pests and diseases.
28. Soil fertility evaluation by biological tests-
1. Neubauer seedling method
2. Standard and Demont technique
3. Microbiological methods
4. Sacket and Stewart technique
5. Melich Cunninghamella-plaque test
6. Mulder Aspergillus niger-test
29. Harmful Activities of Soil Organisms
1. Rodents, snails, slugs, termites, insect larvae and
nematodes cause great damage to plants.
2. Mainly fungi, but bacteria and actinomycetes ,also, are
responsible for many soil borne diseases of crop plants.
3. Offer lot of competition to higher plants.
4. Under conditions of poor drainage, depletes the available
oxygen and hampers the normal growth of plants.
5. Under anaerobic conditions, bacteria transform some of
the nutrients to unavailable form (k & Zn etc.) and some
nutrients to be available in toxic levels ( Fe & Mn etc.)
30. “There can be no life without soil and no soil
without life; they have evolved together.”
-Charles E. Kellogg